Amateur Radio Satellite OSCAR 40
Status Updates from NY Transfer NewsSource: AMSAT News Service
AO-40 Update - August 16, 2001
Wheel tests Orbit 365
From Peter GuelzowDear All,
Stacey Mills W4SM and James Miller G3RUH conducted another wheel session last night in Orbit #365 and the resulting calculations below were provided by Karl Meinzer DJ4ZC.
The wheels were spun up to +100 RPM. This was accomplished with quick lock on all three wheels. They were left at this speed for ~30 minutes. Telemetry before and after the spin-up, once the solar sensors re-locked showed:
2.65222 +/- 0.00002 RPM baseline 2.61468 +/- 0.00004 RPM after spin up to +100 RPM ---------- -0.0375 RPM (for +100 RPM on wheels)If all was done correctly in the s/c - and the above data bear this out - the positive spin is counted in the same direction as the z-axis. Thus by positively rotating the wheels, momentum is in the same direction as the s/c spin. Since the total angular momentum is conserved, the s/c spin must decrease, which it did. Good!
Now some data of the wheels:
Izz = 54.6*10^-3 kgm^2
Tmotor = 29.0*10^-3 Nm at 25 rad/sThe 3 wheels as a consequence of the mounting geometry produce an effective Iz as seen by the s/c (if operated with equal rpm):
Iz(3wheels) = Izz * SQR(3) = 94.57*10^-3 kgm^2
Thus the test with 100 rpm or 10.472 rad/s put a momentum of 0.9903 Nm into the axis parallel to the s/c z-axis, the other components cancel.
With the above delta of -0.0375 rpm or -3.927*10^-3 rad/s this results in a s/c Izz of 252.19 kgm^2
With the very accurate figure of the spacecraft Izz, we hope to have sufficient data to deduce from this figure the state of our fuel-tanks.
We can say with some caution that we have a working 3-axis control system!!!
More tests will be done over the next few weeks, before we will transfer the spacecraft from spin stabilization into 3-axis stabilization.
73s, Peter DB2OS for the AO-40 Team
AO-40 Update - August 15, 2001From Peter Guelzow
Wed, 15 Aug 2001 18:22:30AO-40: Momentum Wheels tested!!!
Dear All,
In Orbit #364 the wheels were powered up and synched at 0 RPM immediately!! Power drain was not detectable. No attempt was yet made in this test to spin up the wheels to 100 RPM. This will be saved for the next orbit.
In fact, running the test at 0 RPM was already the most critical test. If the wheels could not "fly" and move freely, there would never be any "sync" detection in the telemetry..
As a next step, the wheels would be programmed to say 100 rpm rotation (all in the same direction and at the same time) and than again we wait for synch, which should be there in the order of a minute. If everything goes well, then we let them run for a while to allow spin measurement of the s/c and observing power consumption.
This test would give us the most important calibration constant of the wheel system, namely the ratio of s/c MOI and to the MOI of the wheels. In fact, since the wheel MOIs are exactly known, this means that we would be able to determine s/c MOI to about 5% - from this we could possibly infer how much fuel is left in the N2O4/MMH tanks. Also this figure is needed for the 3-axis software and for planning the spin/3-axis transition.
Congratulations to Karl, Stacey, James and all involved!!!!
Here some more general information's:
Momentum Wheel with Magnetic Bearing
Attitude Control of the AMSAT AO-40 Spacecraft
Most satellites today use momentum wheels for attitude control. This way the antennas and the solar generator can always be pointed into the right direction.
Conventional momentum wheels with ball bearings frequently caused problems since in the vacuum of space the lubrication of the bearings is very difficult.
For more than 20 years it has been proposed to use magnetic bearings working with no physical contact and thus no wear.
The development of such systems turned out to be rather difficult. For space applications bearings with two active controlled axes and one passive axis had not been developed to the point which allowed them to be tested in space .
Now such a system is under testing on the AMSAT OSCAR 40 satellite and developed for by AMSAT-DL's Prof. Dr. Karl Meinzer (DJ4ZC) from the University of Marburg in cooperation with the TH Darmstadt. It is hoped that this generally makes available a technology which will improve the reliability of future 3-axis-controlled spacecraft.
Furthermore it is hoped that the experience gained with magnetic levitation systems will find applications in other areas, for instance for magnetic levitation trains and in large size electromechanical projection display systems.
More links:
http://www.amsat-dl.org/momentum.html
http://www.amsat-dl.org/journal/artikel/adlj-rad.htm
http://www.amsat.org/amsat/sats/phase3d/wheels/index.html
http://www.amsat.org/amsat/sats/phase3d/wheels.html73s, Peter DB2OS
AO-40 Update - August 13, 2001AO-40 Update, S1 Tx Stopped
From Stacey E. MillsOn orbit 362 at MA 57 (2001-08-13, 12:57:53 UTC), while AO-40 was in view of most of the eastern hemisphere, the S1 transmitter abruptly stopped transmitting part way through an A-blk. Telemetry readings up until the moment of cessation (voltages, currents, temperatures, etc.) were completely normal. No commanding or experimentation was being done at this time.
The scheduler switched the S2 on as appropriate at MA=100. Telemetry after MA=100, likewise shows no abnormalities or logged events to account for this failure.
An initial attempt to manually switch the S1 Tx back on did not appear successful. While we study this situation further, the S1 Tx has been taken out of the schedule. Thus, the U/L1 -> S2 passbands are currently active from MA 10-30 and MA 44-100. As before, RUDAK is connected to the S2 Tx (beacon off) from MA=30-44.
The message blocks have not yet been updated. This will be done within the next several orbits. The schedule may also be modified for longer passband periods, given the broader coverage of the S2 helical antenna.
As further information becomes available, we will post it here.
W4SM for the AO-40 Command Team
Link to First SCOPE Picture from AO-40 - August 8, 2001
AO-40 Update - August 3, 2001
AO-40 S1 Tx Testing
From Stacey MillsTesting of the passbands and beacons on the S1 Tx will begin on Orbit 350. The current ALON/ALAT = 338/3.
From MA =44 to 80 the S1 Tx will be active with passbands ( U/L1 -> S1 ). The Engineering beacon or middle beacon, or both may be on as well. Please avoid the middle beacon if it "pops on" in the middle of your QSO.
From MA=10 to 44 and MA = 80 to 100, the passbands will be U/L1 -> S2 as previously (middle beacon active).
AO-40 Update - August 2, 2001AO-40 Status, Orbit 349
From Stacey E. Mills2001-08-02 AO-40 Status
The command/RUDAK team currently plans to do testing and software loading on 2001-08-03 for one hour from approximately 0200U to 0300U. This will be early in Orbit 349 (the latest NORAD keps, day 211, remain 1 orbit low). By MA=36, testing should be complete. If testing starts somewhat earlier, it should finish earlier, as every effort will be made to limit this to about one hour. During testing the passbands will be closed and the middle beacon will be off or intermittently off and on. Once the middle beacon is back on continuously, the passbands will have been restored.
Finding Yourself
I get questions about once a day regarding the transponder frequencies, equations, etc. In truth, I have not measured these any more precisely than was done just before launch. This is something that anyone with proper, calibrated equipment and accurate keps can do. As a note of caution, many downconverters, drift considerably in frequency with temperature, particularly if the LO crystal is not oven stabilized. My own downconverter, which is otherwise quite good, drifts 0 to 20 KHz depending on outside temperature. This is my main excuse for not making the above measurements.
It should be noted that the middle beacon is, almost precisely, in the middle of the passband. So, to find yourself when the MB is active, here's the simple method that I use. You may well have a better technique, but this works for me.
1. Note your frequency reading on the middle beacon.The above technique is relatively fast, it avoids the middle beacon and should avoid stepping on other users. The passband of AO-40 is 250 KHZ and finding an dead spot near the top or the bottom for this is not difficult (at least for the moment), even with lots of activity, much of which seems, for some reason, to cluster in the 2401.350 to 2401.400 region.2. Move your receive frequency up or down, about 100 KHz or so from the middle beacon, to a good clear region near the top or bottom of the passband with no one around +/- 10 Khz
3. Note the above offset from the MB frequency, for example, +110 KHz
4. From the chart, calculate the middle frequency of the uplink passband you want to use.
5. Move the transmit offset amount in the opposite direction, for example, -110 KHz from the mid-band frequency.
6. Make a calculated or estimated doppler adjustment to the above transmit frequency. Early in the orbit, AO-40 is generally moving away from you, so the Tx freq. at your QTH will have to be somewhat higher, to give the calculated Tx. freq. at the satellite.
6. Transmit an intermittent carrier and keep the transmit frequency constant (please!).
7. Tune the receive frequency to find yourself.
8. Note the Rx/Tx frequency values and calculate your equation, or set this offset in your rig as required and ... off you go.
Once you have done the above once or twice, it is seldom necessary to go through all the steps again, and you should be able to find yourself quickly at the high or low end of the passband, well away from the beacon and active QSO's.
..good luck and enjoy!
AO-40 Update - July 29, 2001AO-40 command station Stacey Mills, W4SM, reported to ANS that AO-40's ALON/ALAT numbers have changed. With the latest YACE camera images analyzed, data is showing that AO-40 has drifted "backwards somewhat" to 309.8/7.4 (+/- 0.2) degrees.
Stacey reports the current data indicates that the mystery effect that the satellite is experiencing "is still very much active." Initial analysis by G3RUH shows that the effect is only slightly reduced when compared to measurements before the arcjet outgassing, even though the perigee height was increased from about 220 km to about 900 km.
W4SM reports more measurements will allow the AO-40 command team to further refine the magnitude of the mystery effect. Current data would appear to eliminate atmospheric drag as the source of the effect and also seem to make magnetic effects unlikely as well. Yet, the effect clearly exerts the bulk of its effect around perigee as observed in the solar angle values during pre- and post-perigee.
To prevent the squint angles from deteriorating further, the AO-40 command team has initiated a 3-orbit magnetorque to take the satellite back to the solar sensor edge (ALON/ALAT = 336/3). More information to follow.
RUDAK testing will continue on orbit 344 (which took place July 30th). Transponder passbands were off for this orbit. Excellent progress was made with RUDAK testing and software loading during the previous test, and command stations hope to continue with that success.
Keith, GU6EFB, was one of several stations reporting very good signals recently via AO-40. "I've been having a good time on AO-40 with lots of DX to be worked, including KK3K, DL6DBN, G3WDG, OK2UZL and N0ZHE. All were good, strong signals," said GU6EFB.
Stay tuned to ANS, the official source of AO-40 information.
[ANS thanks AMSAT-NA and AMSAT-DL for this information]
AO-40 Update - July 24, 2001From Stacey E. Mills
ALON/ALAT
As Paul Willmott reported, the latest set of images, set up and downloaded by Graham Ratcliff, show that we have drifted backwards somewhat to ALON/ALAT = 309.8 / 7.4 (+/- 0.2) degs.
Mystery Effect
The above indicates that the mystery effect (ME) is still very much active. Initial analysis by G3RUH shows that the effect is only slightly reduced when compared to measurements before the arcjet outgassing, even though perigee height has increased from about 220 km to about 900 km. More measurements will allow us to further refine the magnitude of the ME. However, current data would appear to eliminate atmospheric drag as the source of the ME, and seem to make magnetic effects unlikely as well. Yet, the ME clearly exerts the bulk of its effect around perigee as observed in the solar angle values pre- and post- perigee. Here is a substantial mystery waiting for you to solve it. The data are all there in the telemetry archives. Remember, to change ALON in the observed direction on a spinning spacecraft requires a net "upward" torque (trying to raise ALAT). However, to produce a net "upward" torque requires a "despun" force, as any spun force would sum to zero. So, any viable theory must produce a despun upward torque.
Magnetorquing
To prevent the squint angles from deteriorating further, we have initiated a 3-orbit magnetorque to take us back to the solar sensor edge at approx. ALON/ALAT = 336/3. Once there we will spin up somewhat to decrease the rate of back-drift.
Orbit 339
As mentioned previously, the U/L1 -> S2 passbands are currently scheduled to be off on orbit 339 for RUDAK testing and software loading. The middle beacon may be off for extended periods of time during this orbit as well. Do not despair if you can't hear the beacon!
KEPS
The latest NORAD keps, day 203 are in reasonable agreement with ranging-derived keps for AO-40. However, note that the orbit number remains incorrect in these. These keps set the orbit number one lower than it should be.
AO-40 Update - July 22, 2001AO-40 command station Stacey Mills, W4SM, recently posted on the AMSAT-NA bulletin board what many stations were looking for - AO-40 transponder operation was again underway!
W4SM announced the U/L1 to S2 passbands were again active from MA=10 through MA=99. The current ALON/ALAT will give some very low squint angles (especially in the Northern Hemisphere) that should provide excellent signals.
W4SM also reported that on orbit 328/329, the magnetorquer system took AO-40 to the limits of the solar sensors, with a solar angle of about 48 degrees. As soon as lock was lost, effective torquing stopped. "We also now have an extremely good fix on AO-40's current position," reported W4SM: ALON/ALAT = 325.5/6.2 (+/- 0.2 degs)
This is in very good agreement with our computer simulations, as well as other sensor data.
According to W4SM, LEILA-2 (not LEILA-1) is active. It appears that the thresholds for LEILA-2 are slightly different than for LEILA-1, so some adjustments are needed. RUDAK tests are currently scheduled for Orbit 339. The passbands will be off for this orbit and the S2 beacon may be intermittently off as well. In the near future, W4SM reports command stations will be testing the S1 transmitter passbands during times of optimal squint angle. The higher gain of the S1 antenna should give better signals farther out in the orbit, as long as the squint angle is good.
AMSAT Awards Manager Bruce Paige, KK5DO, in Houston, was among the first &stations to get on AO-40 after the transponders were reactivated. quot;It &sounds awesome," Paige said. "I am transmitting with 25 watts up, and it sounds great!" In addition to some domestic contacts, he and his daughter, Mahana, W5BTS, worked EA8/DJ9PC in the Canary Islands. Dave, WB6LLO reported great signals from AO-40 as the transponders went active. Dave worked VE3NPC and 4X1AS, in addition to stations in Japan and Australia. Jerry, W6IHG, reported making 12 contacts. Renato, CE3XK, was also active, working several stations with received downlink signals around S5.
The AMSAT-DL web site is currently featuring an AO-40 status summary format at http://www.amsat-dl.org/journal/adlj-p3d.htm
Stay tuned to ANS, the official source of AO-40 information.
[ANS thanks AMSAT-NA and AMSAT-DL for this information]
AO-40 updateFrom Stacey E. Mills
Sun, 15 Jul 2001 18:18:00 -0400Dear Folks,
AO-40 is currently at approximately ALON/ALAT 311/5, accounting for the much improved telemetry signals on the first portion of the orbit. We are torquing to approximately 320/0, at which point the solar angle will be close to 45 degs, and the solar sensor may stop triggering, thereby stopping the magnetorque. If this does occur, it is a benign condition because the sun is moving away from us at almost 1 deg/day and very quickly the solar angle will be re-established. We are chasing the sun rather than the other way around.
However, we will have to wait until the end of August to be able to move all the way back to 0/0. As soon as we can, we will move part of the way, say to 340/0. In the meantime, when we reach ~320/0 in three more orbits, we will stop magnetorquing and take pictures to verify our position. By not magnetorquing for a few weeks, we can re-calculate the value of the "mystery effect" once we have an accurate "fix." As soon as the pictures are downloaded we will activate the transponders for the first half of the orbit. We HOPE to have these back on before next weekend.
Remember that there are still a number of items to check out. In particular, we may have some days of limited or no transponder activity, and even no beacon activity, while the RUDAK team uploads software and checks out some of the RUDAK functions. These events will be announced.
Aux. Battery
I have seen a few messages about the voltage of the aux. battery. This is a Nickel metal hydride (NiMH) battery. We took it off of trickle charge quite a while ago when the temperatures were high, and we have not placed it back on charge. These cells are quite happy fully discharged and we believe that the battery will last longer if we do not keep it on trickle charge. As we have no immediate need for it, we have left it uncharged for now to prolong its life.
Best wishes.
AO-40: ArcJet UpdateFrom Stacey E. Mills
Mon, 09 Jul 2001 14:17:17Dear Folks,
I'd like to try to answer a few questions and clear up some misconceptions made in comments on the Amsat-BB about the ArcJet outgassing.
1. Was the old orbit stable?
Yes it was. I did the orbital integration and it WAS stable, at least in the sense of not suffering re-entry or melt down. However, as we all know, perigee was very close. In fact in some simulations, it was as low as 160 km. There was considerable drag at perigee, which continuously changed the mean motion and probably contributed to the perturbation in ALON (the mystery effect). The keps on the S/C had to be frequently updated. The rapidity of the perigee flyby made magnetorquing very tricky and required a lot of time to determine attitude. To improve these things we wanted to raise perigee height. That doesn't mean the old orbit wasn't stable, but it certainly wasn't optimal, and it was close enough at perigee in June to be frankly scary.
2. Was the command software controlling the arcjet faulty?
No, it most certainly was not. I wrote it, the rest of the command team checked it. It functioned perfectly in all the simulations. There is not a shred of telemetry evidence to suggest a software error.
3. Are we out of ammonia?
As far as we can tell, yes.
4. Where did it go?
We don't have all the answers, and hence we have not yet posted a full report. It appears that the TMFC (thermal mass flow controller) failed, passing far more gas than it should have. There was NO INDICATION of this in the telemetry. Spin rate changes and telemetered flow rate, etc., all appeared in a safe range. The software properly set the TMFC to 50% flow rate. This should have been ~25-30 mg/s of flow. Even fully open, the TMFC should not have exhausted more than 100 mg/s, which should have left ~60% of the ammonia unused, even after 58 hours of run time. The telemetry suggests that the gas ran out after approximately 1575 minutes (26.25 hrs.). If the tanks were full, that's 560 mg/s, far in excess of what the TMFC should have allowed. Again, we're still looking at this for better answers. As has been noted, we really only needed about half of the fuel to get to the orbit we're in, so it is quite possible that there was also a slow leak in the ammonia tanks such that we started with only approximately half of the fuel. If this were the case, then the flow would have been ~280 mg/s, still almost three times nominal maximum flow rate. Looked at another way, the new and old orbits indicate an apogee velocity change of 40 m/s. Accelerating a 500 kg mass through 1575 minutes indicates a force (thrust) of 0.213 N. That's over twice as high as would have been achieved if the motor were used in a proper powered ArcJet burn. Unlike the helium tank, the ammonia tanks have a liquid/gas interface in equilibrium, so the pressure in the tanks is not proportional to the amount of liquid they contain. Pressure is a function only of temperature as long as liquid ammonia is present. Thus, there was no way to tell how much "fuel" we had. If we did have a slow leak it is very fortunate we did not wait any longer to use the remaining fuel.
5. Why wasn't the orbit checked after the first test outgassing?
Because of changing solar angle, the mystery effect and precession moving ALON, as well as the rapidly decreasing perigee height in late June due to solar/lunar forces (which might make attitude even harder to maintain), it was important to complete the maneuver as soon as possible while conditions were right and then begin the move back to 0/0. A nominal single test burn should have produced so little change in perigee height as to be hard to detect against background "noise". In addition, waiting for good keps following the test could have required more than a week (current case in point). There was nothing in the test telemetry to suggest a problem, so we proceeded with the full maneuver. From a pragmatic point of view it was always clear that any radical departure from expected would make it highly unlikely that we would be able to maintain a stable, low-volume gas flow as needed for a powered ArcJet burn, so loss of extra ammonia would likely have little effect on the powered ArcJet use.
6. Do the command stations know what they're doing?
We like to think so. There is ABSOLUTELY NO EVIDENCE that the ammonia problem was due to a command error. I cannot state that any clearer. Please bear in mind that we all take this task extremely seriously, and we spend a HUGE amount of time on it. Just getting AO-40 into the 270/0 position for the outgassing took several weeks of effort and calculation. When there is a problem, the amount of time required goes up exponentially. The first requirement is to maintain the integrity of the spacecraft, then to gather critical information while it is still available, then to analyze the information, and then to report the findings. I freely admit that my first thought when there's a problem is NOT to post a message to the amsat-bb. This is not because we want a "cover-up," although I have been personally accused of this at least once in quite objectionable terms. The reality is that we are busy trying to figure out if we still have a safe spacecraft, and then determine what's going on. When we are sure that we have the best possible information, we fully report our findings.
7. What's going to break next?
The short answer is that we don't know. I sincerely hope that nothing else malfunctions for a long, long time, but this is after all, rocket science. Nothing is guaranteed. However, there has been the suggestion that the command stations are rushing to test things without considering failure scenarios. Nothing could be further from the truth. Weeks of discussion were devoted to the ArcJet and possible failure modes. These discussions involved the designers and builders of the ArcJet, the management team, etc. Out of these discussions came the decision to "cold outgas" before trying hot outgassing, and to orient to raise perigee, since a faulty or stuck valve in this orientation would not destroy the orbit. Consider that if we had been oriented differently we could be at -350 km rather than +850 km perigee height!!
The momentum wheels have not yet been tested. Rest assured that when they are, it will be after lengthy discussions regarding failure possibilities, recovery modes, etc. I do not regard this as a particular risky test, unlike the ArcJet, but it will still be approached very very carefully. Finally, the decision to deploy the solar panels will be much more involved. This is a "no return" event and will in all likelihood be a considerable time in the future after prolonged demonstration that the momentum wheels are fully functional and that 3-axis control software is up to the task. If there are ANY problems in this regard, we will stay in spin mode!!! Our primary goal at the moment is to get AO-40 back into an orientation where the transponders can be operational and RUDAK testing can be completed.
8. And finally
I hope this clears up at least a few points. I know this is a frustrating issue for the users and supporters, but believe me, it's also very frustrating for the command stations. A lot of software written and tested for the "hot" ArcJet, will now never be used. And my frustration is totally insignificant next to that of the wonderful folks who put years of effort into building the ArcJet, and now will not see it function. I must admit that my disappointment is compounded by some of the comments that appear on the amsat-bb questioning the abilities and motives of the command stations. I try not to take these personally, and I realize that you would all like answers. So would we. We do have a very stable orbit and we are moving back towards 0/0 to make AO-40 available for your use. All in all, it could be a lot worse, a whole lot worse. I'd like to thank all of you who have posted supportive comments on the amsat-bb. I'd even like to thank those who have questioned our abilities. At least your comments show that you're interested. We can withstand your critical scrutiny! ...if we can't we need a new hobby.
AO-40: Perigee now ~850 km !!!
From Peter Guelzow
Fri, 29 Jun 2001 20:50:05 +0000Dear All,
The blowing of cold gas through the Arcjet is over.
Enclosed a first set of keplerian elements generated from ranging data. More ranging will be done in the next few days.
AO-40 Amsat Ranging JRM 1 26609U 00072B 01176.01392904 .00000000 00000-0 10000-4 0 0047 2 26609 5.3129 179.7299 8007917 290.2832 6.8841 1.25610430 3009 Satellite: AO-40 Amsat Ranging JRM Catalog number: 26609 Epoch time: 01176.01392904 Inclination: 5.3129 deg RA of node: 179.7299 deg Eccentricity: 0.80079177 - Arg of perigee: 290.2833 deg Mean anomaly: 6.8842 deg Mean motion: 1.25610431 rev/day Decay rate: 0.0 rev/day^2 Epoch rev: 300 Semi major axis: 36289.817 km Apogee height 58972.3 km Perigee height 851.1 km RAAN dot -0.1755 deg/d Arg Peri dot 0.3488 deg/d ALON = 267° ALAT = -2°The perigee height raised from 280 km before the outgassing to 851 km after, while the apogee height is unchanged.
The good news is indeed, that AO-40 is now in a safe and stable orbit!
The bad news is, that probably all our 53 kg of ammonia is gone.
Since orbit #302 the ammonia stopped flowing and the pressure indicators in the telemetry show no more pressure in the motor and in the ammonia tanks, while the perigee is much higher than anticipated.
Stored telemetry is currently being downloaded and analyzed, which will take some time. More details later as they become available.
The spacecraft attitude will now be moved back to ALON/ALAT = 0/0 as soon as possible and command stations are currently preparing for magnetorquing.
73s Peter, DB2OS for the AO-40 team
Phase 3D/AO-40 Update - June 21, 2001
AO-40: First Successful Activation of ATOS
from Peter Guelzow, Thu 21 Jun 2001 16:57:01
Dear All,Phase 3D/AO-40 Update - May 27, 2001The first activation of the ATOS propellant feed system was performed successfully on orbit #295.
Telemetry confirmed that the heater for the ammonia, the flow rate controller, valves and pressure indicators seem to work appropriately.
The duration for the out-gassing was about 22 minutes and will now be increased during further tests.
Congratulations to the command team for another superb job!
73s
Peter DB2OS
for the AO-40 team
AO-40 experimental transponder operation has temporarily ended due to changes in the spacecraft latitude needed for arcjet cold firing. The squint pointing angle is more than 30 degrees and not currently useful for transponder operation. AMSAT-DL reports command stations have suspended transponder operation for now as the S-2 transponder remains off until further notice.
The RUDAK beacon and S-band middle beacon are continuously on.
ANS has received additional information from AMSAT-DL:
In order to escape the rapidly approaching Sun exposure (and to get ready for arcjet thruster) AO-40's ALAT number has been lowered. ALON/ALAT values will be tweaked with YACE images and command stations will continue to lower ALAT numbers before beginning to move ALON numbers past sun exposure.
X-band, K-band transmitter and C-band receiver tests have stopped as the minimum squint angle is not enough for useful signals. In addition, the RUDAK team has asked for more time for RUDAK experiments. Message blocks have been be updated to reflect these new conditions.
(end)
Stay tuned to ANS, the official source for news and information about AMSAT OSCAR 40.
ANS thanks AMSAT-NA, AMSAT-DL and the ARRL for this information
Phase 3D/AO-40 Update - May 13, 2001
AO-40 experimental transponder operation started on Saturday morning, May 5th, when the U-band and L1-band uplinks were connected to the S-2 transmitter passband downlink via the matrix switch. Operation has been extremely successful with many reports of AO-40 operation received by ANS.
ANS has also received the following from AMSAT-DL:
Dear All,
After a very successful week of S-band transponder operation, the announced test of the 10 GHz X-band downlink was not successful. Michael Fletcher, OH2AUE, along with command station W4SM tested the X-band (both the solid state and TWT) systems, and, unfortunately, the test was not successful.
The IHU-1 telemetry indicated the proper commands were received, but no power is getting to any of the X-band modules. Nothing happened and even the status of the temperature sensors in the X-band modules did not change. The values did not change when the module was commanded on, thus the conclusion that there is no electrical power within the module.
The problem must be either in the 28-volt supply or in the module power control line from the IHU. This problem was never observedduring all the testing in Orlando and Kourou. A software problem is very unlikely. It is planned to investigate this further in the next few days and another X-band attempt will be made soon.
S-band transponder operation will continue.
The LEILA system on AO-40 has been turned on for the first time! Recently, some very strong signals appeared in the passband, several dB louder than the middle beacon. At this time the AGC on the U-band receiver was suppressing up to 16 dB, clearly in sync with the strong transmissions. LEILA was switched into the U-band passband, (as seen by the MATRIX configuration). LEILA was configured for a SCAN/JAM/NOTCH mode and it worked like a charm! The threshold was set to a level which is approximately equal to the general beacon signal, which means any stronger signal will be detected by LEILA and a "police siren" sound will first be heard to give the offending station a chance to reduce power, otherwise the notch will do its best. Initial reports are that users in the passband loved it! This is the first time that such a system has been used in space for a transponder with uncoordinated multiple access.
Meanwhile, the RUDAK team has reported good progress with both CPU's running for more than 10 days. Jim, WD0E, finished loading the GPS task into RUDAK-A and also loaded the CEDEX task. Both tasks are running but commands to begin their operations have not yet been transmitted. Jim also reported that RUDAK-A telemetry continues to look normal and the SmartNode temperature sensors on the CAN bus seem to work fine.
73,
Peter, DB2OS, for the whole AO-40 team(end)
AO-40 users are reminded that +/- 5 kHz around the Middle Beacon (MB) must be avoided. If the beacon cannot be copied due to interference with users in the passband, transponder operation may be stopped.
ANS Principle Satellite Investigator Mike, N1JEZ reported that he has been testing uplink conditions with AO-40 as he watched the AGC action on the passband. His recommendations have been posted on the AMSAT bulletin board. Mike reports that he "can't wait until AO-40 is stabilized and pointing right at us! I see great DXpedition potential for a small U/S system!"
Stay tuned to ANS, the official source for news and information about AMSAT OSCAR 40.
ANS thanks AMSAT-NA, AMSAT-DL and the ARRL for this information
Phase 3D/AO-40 Update - May 06, 2001
As May begins much is happening with AO-40!
First, Peter, DB2OS, reported the RUDAK system had been activated for the first time following the December incident. Command station operator W4SM reported the power budget stayed positive and everything looked normal during the first test. The RUDAK team then began uploading programming to the RUDAK CPU's.
Jim, WD0E, reported the RUDAK-A processor was commanded through a series of tests. Commanding was quite reliable using the L-band uplink. Some initial software was loaded and executed, the real-time clock was set, a short text message was put in the downlink queue and some tests to measure deviation and frequencies were completed. RUDAK-A is now sending telemetry and a pass-through of the IHU downlink information -- on its own downlink at 2401.72 MHz. Telemetry values look normal at first glance.
James, G3RUH, reported good copy of the RUDAK beacon, which is about the same signal strength as the IHU middle beacon. Testing and commissioning plans will continue.
DB2OS then broke the big news on Thursday, May 3rd -- AO-40 was going live! Here is Peter's announcement:
Dear All,
AO-40 experimental transponder operation will start on Saturday morning, May 5th, at approximately 08:00 UTC when the U-band and L1-band uplinks will be connected to the S-2 transmitter passband downlink via the matrix switch. If there are no problems, the transponder will be usable until MA=240. It will be turned on again in the same configuration around MA=135. Schedule changes will be announced in the telemetry beacon.
Please note that this is experimental transponder operation and as such the transponders may be shut off at any time without warning and the schedule may change without prior notice. The window for transponder operation is about 10 days, before we move to try to raise perigee using the arcjet.
Also, +/- 5 kHz around the Middle Beacon (MB) must be avoided. If the beacon cannot be copied due to interference with users in the passband, the passband may be disconnected and transponder operation stopped.
It is also planned to test the U-band and V-band transmitters again when squint angles allow good visibility.
Needless to say, we all are very excited!
73,
Peter, DB2OS, and the AO-40 Command Team(end)
The uplink frequencies are 435.550-435.800 MHz and 1269.250 to 1269.500 MHz. The downlink passband is 2401.225-2401.475 MHz. The transponders are inverting, so a downward change in uplink frequency will result in an upward frequency shift in the downlink.
ANS Principle Satellite Investigator N1JEZ was first to report contacts on the AMSAT bulletin board. "Things are working quite well," said Mike, "I've successfully logged a dozen contacts in the first hour of operation including two contacts using the Mode-L uplink. I also logged my first DX contact with IZ8EDE. The comment I heard most often was how weak the S-band downlink was for some stations. In these situations, the natural tendency is to increase uplink power. Without the benefit of the LEILA system, I'm sure a few of us were running too much uplink power, but it will take a bit of time to get a good feel for uplinks and downlinks. My final tally was 24 contacts including some DX. A great first day! Let's hope for many more."
Ed, K9EK, echoed Mike's comments. "Wow, AO-40 was terrific on this first morning of transponder operation," said K9EK, "after almost 10 years, what a thrill! Heartfelt thanks to all those who have busted their backends for so many years. You are appreciated!"
Maggie, K3XS, in all likelihood made the first YL contacts through AO-40 working KB8VAO, W5VZF, W4AD, WC0Y and N4IP. Pieter, N4IP, reported signals at 51,000 km were about S-3 above the noise at his QTH. Pieter worked I8CVS using the 70cm uplink. Jerry, K5OE, told ANS that KB8VAO and N1JEZ were among the best-sounding signals. Roger, W3SZ, reported working a number of stations including AB9V, KK2L, VE7BBG, G3WDG, K5QXJ, W7AM and others.
AMSAT-NA President Robin Haighton, VE3FRH, released the following to ANS:
It was with great pleasure that I worked AO-40 early in the morning of Saturday, May 5th. Signals were generally good. To satellite enthusiasts there is nothing quite as exciting as working a new bird, especially when we have all watched and waited as AO-40 went through its troubles and (now) is returning to us as a great satellite. The very hard work of Project Leader Karl Meinzer, AMSAT-DL President Peter Guelzow and -- the worldwide supporting group of command stations and technical individuals -- is providing us with a great satellite. Thank you all!
73,
Robin, VE3FRHRobin reported working N1JEZ, WL7BQM, KB8VAO, VE3NPC, W5ACM, W3PM, W0OQC, W4AD, W4SM, K9EK, KB2WQM, KA0YOS, W3HH, AC9R and VE3BCG.
Stay tuned to ANS, the official source for news and information about AMSAT OSCAR 40.
ANS thanks AMSAT-NA, AMSAT-DL and the ARRL for this information
Initial RUDAK tests successful - May 01, 2001
This morning the RUDAK experiment on AO-40 was powered on and made available to the RUDAK team for testing. During the period from about 1400U through about 1615U the RUDAK-A processor was commanded through a series of tests by Jim White, WD0E, in Colorado. Commanding was quite reliable on the L band uplink. The gain of modulator 1 was turned up and the resulting downlink at 2401.72 was usable for most of this period as squint angles improved below 50 degrees. Some initial software was loaded and executed, the real-time clock was set, a short text message was put in the downlink queue and some tests to measure deviation and frequencies were completed. Further software loading was in progress at LOS. All testing during this period was successful, however much remains to be tested and exercised.
The plan for 5/2/2001 includes additional software loading, some initial tests on RUDAK-B, and possibly some initial telemetry. If time and squint angles allow the CAN server will be loaded and we will take a look at the 16 temperatures available through RUDAK. It may also be possible to power up the CEDEX experiment and obtain some initial radiation data.
Testing and commissioning plans after that are uncertain and will depend mainly on squint angles and pass visibility.
Please do not attempt to uplink to RUDAK until testing is completed and it is made available for general operation. That milestone will be announced on the RUDAK downlinks and via ANS. Watch www.amsat.org for further status updates as commissioning progresses.
Jim White
wd0e@amsat.org
jim@coloradosatellite.comVia the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA
Phase 3D/AO-40 Update - April 29, 2001
April continues with recovery efforts concerning AO-40. The satellite is healthy and recent reports indicate that very good telemetry along with excellent downlink signals have been received recently.
The most exciting news is that successful transponder and matrix operation has been performed. The following is from AMSAT-DL:
Dear All,AMSAT-NA President Robin Haighton, VE3FRH, recently completed a conversation with the ARRL concerning AO-40; the complete story is included here:On orbit 226, the U, L and U+L receiver passbands were connected to the (S-2) S-band downlink and were briefly checked out by command stations G3RUH and W4SM - using PSK, CW and SSB signals for the uplink. The tests worked extremely well and confirm that the matrix switch is working in these combinations. This prepares the way, with confidence, for transponder operation very soon, when the attitude approaches ALON-0/ALAT-0, via on-going magnetorquing.
Stay tuned for further announcements regarding general transponder operations!
73,
Peter, DB2OS, for the AO-40 Command Team
AMSAT-NA President Robin Haighton, VE3FRH, this week raised the possibility that AO-40 could inaugurate transponder operation this summer, if tests and orbital maneuvers between now and then go as planned. "We are learning how to fly this thing," Haighton said. "But I still think we're going to end up with a darned good satellite."
The most likely initial transponder configurations would be Mode U/S, or 435 MHz up and 2.4 GHz down -- and Mode L/S -- 1.2 GHz up and 2.4 GHz down. "It looks like a good bet," Haighton said of the probability that the two modes would prove useful from the damaged satellite. He predicted that Mode U/S operation from AO-40 would surpass what had been available a few years ago from the now-defunct AO-13. "We're getting something like 27 dB more signal."
Recent data from the spacecraft suggest that the mid-December incident that silenced AO-40 for two weeks and rendered some systems unusable also might have blown a hole in the spacecraft. Haighton said ground controllers have detected a distinct rise in temperature when the Sun faces parts of AO-40. "Speculation is there could be damage, and sunlight is getting right in," he said. That theory would go along with the loss of the satellite's omni-directional antennas, Haighton added. The speculated opening was not causing any major problems, he said, but it could explain why efforts to adjust AO-40's attitude via magnetorquing have been unpredictable.
As the AO-40 recovery effort continues, Haighton said, ground controllers plan to boost the satellite's orbit in the very near future. That process, using the onboard arcjet motor, could take up to several weeks. The AO-40 team hopes the maneuver will minimize or eliminate possible effects on the satellite's orbit caused by atmospheric expansion at the peak of the solar cycle.
AO-40 currently is approximately 200 miles above Earth at perigee and some 31,600 miles at apogee. Plans call for raising the orbit at perigee to around 320 miles. The maneuver would "hardly affect" the satellite's apogee, Haighton said. The arcjet would be operated without electrically igniting it -- using the pressure of the ammonia fuel alone. This would yield about half the normal thrust, Haighton said.
Once the orbit has been adjusted, ground controllers would orient the spacecraft's attitude and check out the various onboard transmitter and receiver systems to see what works and what does not. "We're still pretty confident that the 2-meter and 70-cm transmitters are not there," Haighton said, "but we're equally confident that the receivers for those bands still are."
The satellite has been transmitting telemetry on the 2.4 GHz (S-2) beacon, and signals reportedly have continued to improve - although the beacon has been out from time to time as needed to conserve power during eclipse periods. Ground controllers recently commanded the YACE camera to take several pictures, starting with orbit 216, and 11 images were downloaded. "The pictures show the characteristic rings and blisters that have been detected on the YACE photographs since the December 13 incident (damage to the lens from fuel residue?)," said a posting on the AMSAT-DL Web site. A prevailing theory about the image degradation was that the camera may have been damaged by direct sunlight into its lens, but James Miller, G3RUH, in an analysis subtitled "Did the Cameras Fry?" has disputed that notion.
Full deployment of the spacecraft's solar panels is still "down the road at least two to three months," Haighton said. Also uncertain was the satellite's ultimate inclination with respect to the equator. It was planned for AO-40 to have a 60-degree inclination, but given the satellite's compromised circumstances, "we'll be lucky if we can get 10 or 15 degrees," Haighton said. The current inclination is six degrees.
Paul, VP9MU, reported that additional pictures (using the YACE camera) were performed at the end of orbit 225. AO-40 then downloaded the photos via D-block telemetry through orbit 226. Paul reported that "we expect around 180 D-blocks in the complete set."
Moe, AE4JY, reported the following concerning his AO40Rcv Telemetry decoding program:
"I just found a nasty bug in the AO40Rcv program. It will crash if it is started in the minimized state. The bad part of this is that if the program is closed when minimized, it will always try to start up in a minimized state."
Moe reports a fix for this condition will be listed on the AE4JY web site in the near future.
ANS thanks AMSAT-NA, AMSAT-DL and the ARRL for this information
ARLS007 AO-40 Transponder Operation Possible This Summer - April 27, 2001
AMSAT-NA President Robin Haighton, VE3FRH, has raised the possibility that AO-40 could inaugurate transponder operation this summer, if tests and orbital maneuvers between now and then go as planned.
"We are learning how to fly this thing," Haighton said. "But I still think we're going to end up with a darned good satellite."
The most likely initial transponder configurations, Haighton said, would be Mode L/S -- 1.2 GHz up and 2.4 GHz down, Mode U/S -- 435 MHz up and 2.4 GHz down, and possibly Mode V/S -- 145 MHz up and 2.4 GHz down.
Recent data suggest that the mid-December incident that silenced AO-40 for two weeks and rendered some systems unusable also might have blown a hole on the 400-newton motor side of the spacecraft. "Speculation is there could be damage, and sunlight is getting right in," Haighton said. He noted that ground controllers have detected a distinct rise in temperature when sunlight strikes that side of the satellite.
Ground controllers plan to raise the height of the perigee in the very near future, Haighton said. That process, using the onboard arc-jet motor, could take up to several weeks. The AO-40 team hopes the maneuver will minimize or eliminate possible effects on the satellite's orbit caused by atmospheric expansion at the peak of the solar cycle.
AO-40 currently is approximately 320 km -- almost 200 miles -- above Earth at perigee, its closest point, and some 51,000 km -- or 31,600 miles -- at apogee. Plans call for raising the orbit at perigee to around 520 km, or some 320 miles.
Once the orbit has been adjusted, ground controllers would orient the spacecraft's attitude and check out the various onboard transmitter and receiver systems to see what works and what does not. "We're still pretty confident that the 2 meter and 70 cm transmitters are not there," Haighton said, "but we're equally confident that the receivers for those bands still are."
The satellite has been transmitting telemetry on the 2.4 GHz (S-2) beacon, and signals reportedly have continued to improve, although the beacon has been out from time to time, as needed to conserve power during eclipse periods.
From ARRL Headquarters, Newington, CT
Phase 3D/AO-40 Update - April 22, 2001
April continues with recovery efforts concerning AO-40. The satellite appears to be healthy and reports indicate that very good telemetry has been received recently.
AO-40 was commanded to take pictures using the YACE camera recently, starting with orbit 216. Eleven images, spaced at 2 minute intervals, were taken. As soon as the pictures were stored, the spacecraft started sending telemetry D-blocks with the images. The blocks were sent for an extended period of time with multiple repeats of the whole sequence. This allowed ground stations to collect as many D-blocks as possible.
The download of the images started immediately after the picture run with 177 blocks in the complete set. Many stations copied this data set and sent information to the AO-40 team, allowing the entire D-block information set to be extracted and analyzed. The images can be found in a compressed file (216.zip) at http://www.amsat.org/amsat/ftp/telemetry/ao40/2001/04/
Many stations around the world also reported to the AMSAT-BB about strong signals from AO-40 recently. Doug, W3HH, is an excellent example -- he reported receiving AO-40 signals using a modified downconverter and a small 2-foot dish. Doug's report noted AO-40's signals were peaking 4 to 5 S-units above the noise. Mark, NU6X, also reported good copy on AO-40 on his first try. "This is my first activity on satellite in many years and I look forward to more to come," said NU6X.
ANS thanks Paul, VP9MU, for this information (and for his efforts with AO-40 telemetry)
Phase 3D/AO-40 Update - April 15, 2001
April continues with recovery efforts concerning AO-40. The satellite appears to be healthy and reports indicate that very good telemetry has been received recently.
AMSAT-DL is reporting that the S-band beacon on AO-40 may not be transmitting continuously during each orbit. The AO-40 team received a report from Gunter, DF4PV, that he was suddenly losing the signal from the S-2 beacon transmitter. DF4PV reported the signal disappeared during a period where the satellite apparently entered an eclipse.
AMSAT-DL responded that the onboard IHU is running a software task to watch for critical situations, such as battery voltage. The IHU will turn the S-beacon off if the battery voltage drops to 26 volts This was the case recently due to a bad sun angle and a solar eclipse. The IHU automatically turned the beacon back on as these conditions ended.
This may continue for the next few orbits as well.
As predicted, AO-40 lost solar lock at the end of orbit 201 and the satellite was then officially in a hibernation state. The magnetorque system is off and will not be used until the satellite is in solar lock again. Although the SEU (sensor electronic unit) is not phase locked on the Sun, the Earth sensor continues to scan our planet.
Four pictures were recently taken during orbit 207. At the time the satellite's view was the Gulf of Mexico. In addition, the IHU-2 clock was checked and found to be correct. The spin rate was at 2.047 rpm.
In looking at the downloaded pictures, it appears the spacecraft spins about 14 degrees during camera exposure (picture distortion was minimal). The Earth's edge can be seen in three of the received images and the angular distance from the bore-sight indicates an attitude of ALON 128 - ALAT 14. This estimate agrees with the Earth sensor.
The AO-40 command team concludes that the camera and much of the IHU-2 unit is working correctly. The Earth sensor and camera mountings appear unchanged, and -- most importantly -- the team now has a firm idea on the attitude direction of the spacecraft.
73,
Peter DB2OS
for the AO-40 command teamANS thanks AMSAT-DL for this information
Phase 3D/AO-40 Update - April 8, 2001
April continues with recovery efforts concerning AO-40. The AMSAT-DL web page is reporting the following:
Plans have changed recently. We have found that there is a significant effect at perigee caused (we believe) by the satellite encountering an atmospheric induced change. This causes ALON to decrease by about 3 degrees each perigee (when the spin rate is at 2 rpm). In addition, ALON already reduces 0.7 degrees each perigee due to precession of the orbital plane -- so we were seeing nearly a 4-degree change each perigee pass, or about 5 degrees each day. Despite eclipses, the magnetorquer is a bit stronger than this effect and we are able to counteract and actually increase ALON by about 1 degree each perigee. Shifting ALON from 170 to 270 (at the 1-degree rate) was clearly going to take a very long time, even given that our assumptions could be extrapolated to different geometry. Meanwhile, perigee height is decreasing steadily due to solar perturbations. Because of these parameters the move from ALON 170 to 270 has been put on hold.
Instead, we are going to change ALON the other direction, taking it down to 90 and then through 0 and hopefully to 270 later in the year. There are a number of benefits of this plan:
- Firstly we can use the atmospheric effect to augment the magnetorquer and achieve a more rapid change in ALON;
- Second, communications will improve rapidly due to the improved ALON numbers;
- Third, as we approach ALON = 0, we are in a position to try limited transponder operation, which will surely be appreciated.
During this procedure, AO-40 will go into hibernation again. This is the name we've given to the state where the Sun sensor system cannot see the Sun, so the satellite cannot be magnetorqued by normal means. However, if the atmospheric effect continues to work as it evidently did during the previous hibernation, this period of poor Sun angle will be short lived. Also, at this time there is a possibility that the Sun will be nearly coaxial with the spin axis. The bottom of the spacecraft will be illuminated (not the top) reducing the effect of continuous, direct sunlight on the onboard cameras.
Expected Timetable
The following is our best estimate of the way things will evolve. The Sun angle will reach a point where the sensor will stop seeing the Sun in early April. Then we wait (perhaps) 4-6 weeks for the Sun angle reach a recovery point. By this time the ALON numbers should favor decent beacon communication. Although the Sun sensor will not give data, the temperature profile will provide Sun angle clues, as can be seen using recorded (historic) telemetry.
DATE ALON/ALAT SUN AZ/EL SA ILLUM Apr 05 146/0 280/5 -44 72% (lock loss) Apr 18 110/0 289/11 -79 19% Apr 25 90/0 294/14 -63 45% May 03 70/0 299/17 -39 77% The command team welcomes informed discussion as to why ALON is rapidly decreasing (the attitude vector direction changes clockwise as viewed from the orbit plane). This change only occurs close to perigee. The phenomenon is clearly observed, but is not explained.
Moe, AE4JY, has placed an updated version of his popular AO40Rcv telemetry program. The latest version, 1.10, is available at http://qsl.net/ae4jy/
ANS thanks AMSAT-DL for this information
Phase 3D/AO-40 Update - April 4, 2001
AO-40 Spinup Under Way
While using the onboard magnetorquing system to adjust AO-40's attitude, AO-40 ground controllers were able to bring the spin rate from nearly 18 RPM down to 1.8 RPM--the planned final value. Now, they're planning to raise the spin rate to 5 RPM to check excessive attitude change.
Citing what he called "some confusing results," AMSAT-DL President and key AO-40 project team member Peter Guelzow, DB2OS, said AO-40's attitude had changed faster than the experts believed possible.
Ground controllers theorized that the effects of drag at perigee were much higher than anticipated. The extra drag at perigee might have been caused by Earth's atmosphere ballooning outward in response to solar activity. As a result, it was decided to spin up the spacecraft to compensate for the too-rapid changes in attitude due to drag.
"This will give us additional breathing space," Guelzow said. Ground controllers have commenced a five-perigee magnetorquing sequence to raise the spin rate to 5 RPM. "In addition," Guelzow said, "preparations to test the arcjet thruster, as soon as accurate attitude is determined, are under way."
Further plans for orbit correction and commissioning of AO-40 will depend on how the arcjet tests go. If the arcjet tests are satisfactory, initial transponder operation could be attempted before summer.
AO-40's telemetry data stream halted briefly late last week. "Because of the recent very high solar activity, the AO-40 team at first thought that the IHU-1 had crashed," Guelzow said. It was later determined that a soft error had occurred and was corrected by the onboard EDAC, or Error Detection and Correction unit.
Phase 3D/AO-40 Update - March 18, 2001
To All Members of AMSAT-NA,
The following statement is addressed to those members of AMSAT-NA who have requested an explanation of the December 2000 incident that took place on P3D. This statement has been prepared and developed by Robin Haighton, VE3FRH, President of AMSAT-NA, with input and review from other AMSAT-NA members.
As you are aware, Phase 3D was launched on November 16, 2000 into an almost perfect geosynchronous transfer orbit (GTO) by an Ariane space launch vehicle (AR-507) from Kourou, French Guiana. Within a few hours of launch excellent telemetry was being received from the 2 meter beacon, and amateur radio stations worldwide started downloading data with great accuracy, due in part to the strong signal strength. The original plan was to use the 70cm beacon. However, for reasons not yet known, the 70cm transmitter signal was not heard.
Before the satellite could be regularly used for general amateur radio communications, it was necessary to carry out orbital changes, stabilize the satellite, open the solar panels, etc. The first changes to the orientation of the satellite were carried out using the onboard magnetorquing system. This worked well and after relatively few orbits the attitude of (now) AO-40 was 270/0, and ready for operation of the 400 Newton motor. Among the many components which comprise this motor system, there are several valves which control pressurizing helium and fuel. During construction of the satellite it was noted that one of the helium valves had a tendency to "stick" when operated. Both of these valves were sent back to the manufacturer for inspection and repair. Both valves were inspected and one valve was repaired, followed by return and re-installation into the system.
On the first attempt to fire the 400N propulsion system, it failed to operate, possibly due to a sticking helium valve. Before the second attempt, it was determined that the fuel tanks could be pressurized (by helium) to their correct pressure over a five minute period, and although this was about one-tenth of the normal helium flow rate, it was still adequate for the planned three minute motor burn.
On the second attempt to fire the 400N motor, all systems appeared to respond correctly at first. At the three minute mark the internal timer transmitted a signal for the main solenoid valve to close, which should have shut off the fuel to the motor. Telemetry shows that the signal was sent and received, but the motor did not shut off for two or three more minutes, placing AO-40 into a higher apogee orbit than was planned at that time.
To understand how this may have happened, it is necessary to be aware that the fuel for the 400N motor is made up of two components, hydrazine (MMH) and nitrogen tetraoxide (N2O4), with each component contained in two separate tanks, both of which could be pressurized by helium. Helium could also be applied to the solenoid motor valve, the output of which operates the two fuel valves which start (and stop) the fuel flow. These valves are actually part of the 400N motor and are located inside the motor itself.
On the solenoid motor valve there is an evacuation port that allows excess helium at the output port of the valve to escape when closing the valve. It is believed that this evacuation port was blocked and that the output port remained pressurized beyond the three minute mark of the motor operation -- thus the motor continued to burn for an extended period of time.
Between the fuel tanks and the 400 Newton motor there are fuel isolation valves which are pressure operated by the helium system. When the pressure in the helium manifold had been reduced to approximately 6 Bar (100 psi) the fuel isolation valves closed and prevented any additional fuel from entering the motor, stopping the burn. At this time it is possible that the main motor valves were still open, due to the trapped pressurized helium that had not vented at the solenoid motor valve.
Approximately twelve minutes after the motor shut down, a second anomaly occurred. This was detected when the motor solenoid valve changed from closed to open, possibly caused by fuel migrating in the lines between the isolation valve and the 400N motor. The motor could have also "burped" or "popped" as the fuel mixed and then ignited.
High pressure helium (180 Bar) is fed to the motor system via a high pressure on/off valve and a regulator valve -- reducing the pressure to a nominal 15 Bar level. It is then fed to the low pressure helium manifold. Because of the longer 400N burn, a program for testing the high pressure helium valve was written to "cycle" the valve (to insure proper functioning) and uploaded to AO-40.
On December 11, 2000, while cycling the helium valve, a sudden loss of signal from AO-40 occurred. It is believed that during this exercise the system became pressurized and that a leakage of fuel was the end result. Initial thoughts were that the spacecraft was completely dead and that chances of recovery were remote, with the possibility that AO-40 was in multiple pieces. However, with help from NORAD, it was determinedthat the satellite was in one piece, with a possibility of some recovery. At least two automatic resets passed without hearing from the spacecraft. It was decided to try and hear the general beacon on the S band (2.4 GHz) transmitter. On Christmas Day 2000 the second attempt to activate the S-band transmitter was successful, and since that day downlink telemetry has been recovered on a regular basis.
The following items have been found to be working; the 2 meter, 70cm, and 1.2 GHz receivers, the S-2 (2.4 GHz) transmitter, the magnetorquing system, the YACE camera, IHU-2 and the high-gain antennas. The following items are believed not to be working; the 2 meter and 70cm transmitters and the omni-directional antennas.
At the time of this bulletin (March 16, 2001) we still do not know the status of thearcjet motor - which is an important item, needed to position the satellite for future use. We do know that the satellite has lost mass, and we attribute this to the loss of bi-propellant fuel from the 400N motor. The satellite spin rate had increased as the overall weight decreased, but by using the magnetorquing system the spin rate is now nearly down to a usable 5 RPM. In addition, the heat pipe system (which became unusable at the higher spin rates) has now become effective again.
Soon AO-40 will be able to be reoriented so that the high-gain antennas will face the Earth, and the arcjet motor will be tested. Following the reorientation it will be possible to test the remaining systems on board the spacecraft and to determine which systems and bands will be available for future operations and under what conditions.
As we all learn more about the status of the satellite, additional bulletins will be posted on AMSAT-BB, and placed on theAMSAT-NA, AMSAT-DL and AMSAT-UK web sites. Meanwhile, all those involved in the recoveryof AO-40 are to be congratulated for their skills and perseverance, and may their hard work continue to bring us an operational satellite.
73,
Robin Haighton VE3FRH
President AMSAT-NAAO-40 is currently transmitting the following message in the A-Block MOTD:
Magnetorquing!! At Orbit # 172: ALON=212 / ALAT=45 / SPIN=5.8
ANS thanks AMSAT-NA for this information.
Phase 3D/AO-40 Update - March 11, 2001
The good news about AMSAT OSCAR 40 continues with this edition of ANS. The League is reporting the following in the current ARRL Letter:
Initial efforts to slow AO-40's spin rate have met with success. Peter Guelzow, DB2OS, of AMSAT-DL and the AO-40 team says magnetorqueing has been able to decrease AO-40's initial spin rate from almost 18 revolutions per minute.
The onboard magnetorqueing system (consisting of solenoid coils) uses the Earth's magnetic field to control the spacecraft's spin and orientation. Guelzow said that as soon as the spin is favorable, AO-40's attitude will be adjusted to improve communication with Earth. The onboard YACE camera was used to take some photographs "for a quick attitudedetermination," but he said the highly compressed digital photos were inconclusive. More pictures are planned once the spin rate is reduced.
The AMSAT-DL web site is reporting the following:
The spin rate is falling nicely. James Miller, G3RUH, provided the following information:
Expected
Measured
Orbit RPM SA RPM SA 157 16.93 38 16.73 38 158 16.18 37 15.87 37 159 15.43 36 15.20 35 160 14.70 35 14.66 34 161 13.95 34 13.91 33 162 13.22 33 12.99 32 163 12.50 33 12.11 30 164 11.80 31 11.36 28 165 11.11 30 10.74 27 166 10.41 29 9.82 25 The rate of reduction is -0.74 revolutions per perigee pass. In theory AO-40 could be down to 5 rpm in 11 orbits, or 8 days. In addition,the eclipse period is starting later (presently MA 0.5). The current magnetorqueing effort is performing very well and will be completedshortly. The attitude should then be approximately 206/30 and 10 rpm.With ALAT now out of the orbit plane, we can start changing ALON as well as controlling ALAT and further spin down.
The heat pipes appear to be functional again as the S-2 transmitter was running about 35-37°C in the last couple of weeks. Its temperature is now running at 19-20°C -- which means that the heat pipes are working again after the spin rate was lowered.
None of this analysis would be possible without the outstanding telemetry collation efforts of Paul, VP9MU, along with the efforts of a largely anonymous group of amateur radio satellite ground stations.
Thank you and 73!
Peter, DB2OSAO-40's orbital parameters (number 46) are as follows:
Satellite: AO-40Stay tuned to AMSAT News Service, the official source of AO-40 news and information.
Catalog number: 26609
Epoch time: 01063.46839262
Inclination: 5.4896 deg
RA of node: 217.4466 deg
Eccentricity: 0.8135323
Arg of perigee: 230.0708 deg
Mean anomaly: 25.1699 deg
Mean motion: 1.26955273 rev/day
Decay rate: 4.0e-07 rev/day^2
Epoch rev: 157
Checksum: 294
[ANS thanks AMSAT-DL and AMSAT-NA for this information]
Phase 3D/AO-40 Update - March 4, 2001
The month of March begins with good news about AMSAT-OSCAR 40.
The ARRL is reporting the following in the current ARRL Letter:
The sun began triggering AO-40's sun sensor as the satellite emerged from Earth's shadow on orbit 147. The news has boostedground controllers' optimism that they might be able to regain control over the satellite's spin rate and attitude sooner than had been predicted.
AMSAT-DL's Peter Guelzow, DB2OS, said this past week that as soon as the sensor unit delivers good sensor data, controllers will be able toreduce AO-40's spin and make it easier to adjust attitude. "This also willlead to an improvement in reception of the S-Band telemetry," he said.
For the past few weeks, AO-40 has remained in a semi-hibernation state, because the satellite's high angle has prevented the sensor from seeing sunlight. Controllers had planned to work around the sensor issue byusing a software routine.
Once ground controllers can get accurate AO-40 attitude data, they should be able to correctly aim AO-40's high-gain antennas for optimalreception on Earth. Ground controllers have been relying on telemetry from AO-40's S-band downlink -- but they are holding out hope that atleast some of the satellite's other transmitters will still function.
The next major step will be to bring AO-40 into an orientation where ground controllers can fire the onboard arcjet thruster -- using only gaseous ammonia and no electrical power. The test firing will allow checking out the guidance electronics and the arcjet valves.
Guelzow said plans call for optimizing the current orbit with a livearcjet firing. He said that several independent analyses -- including one done by the French space agency, CNES -- confirm that thecurrent orbit will be stable for many years, longer than the spacecraft's anticipated lifetime.
The AMSAT-DL web site is reporting the following:
Determination of AO-40's actual attitude is under progress. The YACE camera and IHU-2 have been turned on by ground controllers in order toreceive additional attitude information when AO-40 is close to Earth (at perigee). The first highly compressed images showing parts of theEarth's surface have already been downloaded as this edition of ANS is broadcast.
AO-40's orbital parameters (number 44) are as follows:
Satellite: AO-40When last listed, AO-40 ALON/ALAT was 226/-7.
Catalog number: 26609
Epoch time: 01060.32118714
Inclination: 5.5180 deg
RA of node: 218.3353 deg
Eccentricity: 0.8134782
Arg of perigee: 228.5693 deg
Mean anomaly: 26.7905 deg
Mean motion: 1.26955381 rev/day
Decay rate: 9.0e-08 rev/day^2
Epoch rev: 153
Checksum: 280
Moe Wheatley, AE4JY, has released Version 1.0 of AO40Rcv. More information is available at http://www.qsl.net/ae4jy/ao40rcv.htm
Stay tuned to AMSAT News Service, the official source of AO-40 news and information.
[ANS thanks AMSAT-DL, AMSAT-NA and the ARRL for this information]
Phase 3D/AO-40 Update - February 25, 2001
The month of February comes to an end with good news about AMSAT OSCAR 40.
The AMSAT-DL web site is currently featuring the following statement from Peter, DB2OS:
Dear All,
Lots of good news about AO-40!
The SEU (sensor electronic unit) is triggering the sun again after the end of eclipse on orbit 147. Telemetry channel #100 (analogue spin rate) is now showing a value of 49. This is the same value it wasshowing on orbit 89 when triggering was lost. Within a few orbits we should see that the second Sun sensor (SS2) also starts triggering,this should allow us to obtain attitude information and then re-start the magnetorquing efforts to spin-down the spacecraft.
One week ago the 3-axis sun sensors were turned on and they seem to be working nominally. It was planned to use the information fromthe 3-axis omni-directional sun sensors to obtain the necessary reference information for a new algorithm to spin-down the spacecraftwithout using the SEU information. The new software code, which will be patched into the operational programming, is almost ready to beuploaded, but due to the premature return of SEU data, this may no longer be necessary.
Analysis of the IHU temperature has revealed that the maximum Sun angle (with the lowest temperatures) was much earlier than anticipated.The temperature of the IHU reached its minimum exactly February 1, 2001 with a temperature of about -8.4°C. This is almost one monthearlier than originally thought. There is no explanation at the moment as to why this was premature.
The spin rate of around 17.5 RPM did not changed in the last few weeks, whatever it caused to increase has apparently stopped. Assoon as the SEU delivers good data, the magnetorquers will be used under control of the IHU to reduce the spin and make any possibleattitude changes easier. This should also improve telemetry reception on the S-band downlink.
The next milestone is to bring the spacecraft into a good orientation to fire the arcjet using no electrical power only gaseous ammonia only. This test firing will be used to check the arcjet control electronics and valves. Even without the arcjet burning, the thrust from the test firing will be enough to raise the perigee.
Several independent analysis (including the French space agency CNES) have confirmed that the current orbit will be stable for manyyears, more than the anticipated lifetime of the spacecraft.
The test firing should give us additional safety margin and a better feeling. However, it is later planned to optimize the current orbit witha full running arcjet. This is planned after testing of the 3-axis momentum wheels, which will be used to re-orient the spacecraftduring these maneuvers.
While the spacecraft was in hibernation, the command stations were in preparations for the next activities, watching the spacecraft telemetryand reporting healthy results.
AMSAT-DL expresses our appreciation thanks to Paul, VP9MU, for his outstanding service in gathering and archiving the AO-40 telemetryfrom different parts of the world. This is vital (additional) informationfor the command stations in their continuing effort to turn P3D back intonormal operation. We suggest everyone who is able to send captured telemetry to the AO-40 telemetry archive at ao40-archive@amsat.org
In summary, the spacecraft seems to be in very good shape, with no additional damage or other problems detected. The power budget is verygood and even during the poor Sun illumination it was not necessary to reduce power consumption by turning off the S-band transmitter for anypart of AO-40's orbit.
This is indeed a good sign for the next activities.
Stay tuned...
73,
Peter, DB2OS
AO-40's orbital parameters (number 40) are as follows:
Satellite: AO-40Stay tuned to AMSAT News Service, the official source of AO-40 news and information.
Catalog number: 26609
Epoch time: 01052.45100567
Inclination: 5.6046 deg
RA of node: 220.4851 deg
Eccentricity: 0.8134917
Arg of perigee: 224.8386 deg
Mean anomaly: 29.8566 deg
Mean motion: 1.26950859 rev/day
Decay rate: 3.0e-08 rev/day^2
Epoch rev: 143
Checksum: 280
ANS thanks AMSAT-DL and AMSAT-NA for this information
Phase 3D/AO-40 Update - February 18, 2001
If no news is good news then readers of ANS will be happy to learn that the month of February continues with on-going recovery effortsof AMSAT OSCAR 40.
The AMSAT-DL web site is currently featuring the following statement:
There is no spectacular news about AO-40. The spacecraft is still in a stable mode as the attitude drifts toward further improvements in early April. Times of best reception have varied as expected.
Joe Wheatley, AE4JY, has released version 0.4 of AO40Rcv. The main change is a TCP/IP-server feature that connects with W4SM's P3Tprogram. More information is available at http://www.qsl.net/ae4jy/ao40rcv.htm
Stacey Mills, W4SM, has also updated his P3T program, correcting a few malfunctioning sensors. More information is available at http://www.cstone.net/~w4sm2/software2/
ALON/ALAT is currently 248/-7, as last listed on the AMSAT-DL web page.
The AMSAT-UK web site is also featuring news of AO-40:
AO-40 continues in its attitude-induced limbo and there is no new news. As the attitude drifts - the optimum MA's to hear the spacecraft are nowearlier in the orbit. AO-40 is best heard between MA 2 and MA 14.
AO-40's orbital parameters (number 38) are as follows:
Satellite: AO-40Stay tuned to AMSAT News Service, the official source of AO-40 news and information.
Catalog number: 26609
Epoch time: 1046.15851798
Element set: 38
Inclination: 5.6690 deg
RA of node: 222.2686 deg
Eccentricity: 0.8134836
Arg of perigee: 221.7796 deg
Mean anomaly: 34.0600 deg
Mean motion: 1.26948856 rev/day
Decay rate: -8.3E-07 rev/day^2
Epoch rev: 135
ANS thanks AMSAT-DL, AMSAT-UK and AMSAT-NA for this information
Phase 3D/AO-40 Update - February 11, 2001
The month of February continues with on-going recovery efforts of AMSAT OSCAR 40.
The AMSAT-DL web site is currently featuring the following statement:
AMSAT OSCAR 40 is still in its seasonal limitations which will (naturally) end by April. If the announced de-spinning routine is successful, the (major) planned recovery efforts of AO-40 could begin earlier. Testing of this software routine is now underway.
The S-band middle beacon is operating nominally on 2401.323 MHz and can be heard best between MA-2 and MA-14. The MA numbers will slightly change due to changing attitude. Eclipses around perigee do not appear to have a negative influence on the satellite power budget according to received whole-orbit-data.
This year's AMSAT-DL Symposium will take place very soon and will have at least three lectures about AO-40:
AO-40 Telemetry ReceptionAMSAT-DL Journal editor DL6DBN and AMSAT-DL executives DJ4ZC and DB2OS are scheduled to attend.
AO-40 The Launch Campaign and History
AO-40 Now and in the Future
ALON/ALAT is currently 248/-7, as last listed on the AMSAT-DL web page.
The latest orbital parameters are as follows:
Satellite: AO-40The AMSAT-UK web site is also featuring news of AO-40:
Catalog number: 26609
Epoch time: 01033.57694040
Element set: 33
Inclination: 5.7772 deg
RA of node: 225.7720 deg
Eccentricity: 0.8134720
Arg of perigee: 215.7457 deg
Mean anomaly: 44.3265 deg
Mean motion: 1.26935859 rev/day
Decay rate: -4.4e-07 rev/day^2
Epoch rev: 119
Checksum: 287
AO-40's situation is stable with good battery conditions. If command stations are unable to change the attitude then the wait could last until April before favorable reception conditions return.
Before AO-40's launch, a long period was anticipated before full commissioning was expected to be completed. It now appears likely that this waiting period will be actually less than expected. The method of measuring the Sun angle with solar radiation is not a trivial activity.
There are still strong hopes that the ATOS motor can be used later to adjust the orbit to something more suitable to general communications.
Although optimism is certainly not a guarantee of future success, AMSAT continues to believe that there will be successful long-term amateur radio communication through AO-40.
AMSAT-UK wishes the command team the best of luck in their hard work.
Stay tuned to AMSAT News Service, the official source of AO-40 news and information.
ANS thanks AMSAT-DL, AMSAT-UK and AMSAT-NA for this information
Phase 3D/AO-40 Update - February 4, 2001
The month of February begins with command stations continuing their on-going recovery efforts of AMSAT OSCAR 40.
The AMSAT-DL web site is currently featuring the following statement:
AO-40 is currently like a ship on a sandbank at low-tide and in the fog. In the fog because of the high solar-angle (maximum of 77 degrees)where the onboard sun sensor(s) temporarily cannot see. At low-tide because the increasing solar-angle leads to less illumination (minimumof 23 percent) -- thus less energy is produced. AO-40 is stuck on a sandbank because the satellite cannot be maneuvered out of thissituation very easily. The 'de-spinning' software routine may help. This program should work without sun sensor data and will use on-goingmeasurements from the solar panels as an attitude indicator. Intensive work on this software is currently taking place.
Even if this routine doesn't work immediately, there is no reason to panic. The 'fog and low-tide' orbit will disappear with further seasonalSun movements around the spacecraft. By April the sensors will see the Sun again and active attitude control can be restarted. After loweringthe current spin rate, improving the Sun angle and repositioning AO-40's antennas, all further tests can be done.
Command stations G3RUH and W4SM have completed a long-term prediction of AO-40's new orbit. Even after last year's accident and theresulting decrease of perigee - AO-40's orbit will be fairly stable through this period.
ALON/ALAT is currently 248/-7, as last listed on the AMSAT-DL web page.
The AO-40 element set (number 30) is as follows:
Satellite: AO-40
Catalog number: 26609
Epoch time: 01027.28372779
Inclination: 5.8370 degrees
RA of node: 227.6036 degrees
Eccentricity: 0.8132970
Arg of perigee: 212.6216 degrees
Mean anomaly: 48.4646 degrees
Mean motion: 1.26933309 rev/day
Decay rate: -7.0e-07 rev/day^2
Epoch rev: 111
Checksum: 274
Stay tuned to AMSAT News Service, the official source of AO-40 news and information.
ANS thanks AMSAT-DL and AMSAT-NA for this information.
Back to Dxers Unlimited for February 10, 2001
Phase 3D/AO-40 Update - January 28, 2001
The month of January continues with command stations working in their on-going recovery efforts of AMSAT OSCAR 40.
The AMSAT-DL web site is currently featuring the following statement:
No news is good news. Due to limited command team access time to AO-40 (because of current orbit parameters), things have slowed down a bit. The spin rate is reported at 17.7 rpm. Whole Orbit Data (WOD) collections are in progress to recover telemetry data from orbit-phases where AO-40 cannot be heard properly. The latest measurements show stable battery-voltages and positive battery charging (except for eclipse times at perigee). [source: the AMSAT-DL web site]
ANS can report that discussions recently took place between AMSAT-NA President Robin Haighton, VE3FRH, and AMSAT-DL President Karl Meinzer, DJ4ZC, concerning the progress being made in the recovery of AO-40.
The current problem is the lack of accurate AO-40 attitude data.
Accurate data is not available due to the current off-pointing of the onboard Sun sensor (the sensor is simply not 'seeing' the Sun). Until accurate measurements can be made AO-40 will remain in a semi-hibernation state. When accurate measurements of attitude can again be made it will be possible to change the satellite's attitude, which will ultimately lead to correct pointing of AO-40's high-gain antennas.
If no commands are transmitted to the satellite it will take about 3 months before AO-40's attitude can be measured. However, the command team is currently working on additional measures in the hope that the attitude may be determined by other means (such as measuring the radiation falling on the solar cells). If any of these attempts are successful, then adjustments to the satellite's attitude will begin earlier.
On a more positive side there does not seem to be any additional damage to AO-40, at least since communication was re-established on Christmas day, although several systems remain to be tested including the arcjet motor. This motor is a critical item for making future orbit changes that will be required for satisfactory operation of the satellite. Another very positive item is that the magnetorquing systems appear to be working, which should also help make the needed (future) attitude adjustments.
Both AMSAT Presidents noted that when P3D was launched it was announced that it would take almost one year of commissioning efforts and orbital changes before the satellite would be considered fully operational. Thanks to the hard work of the commissioning and recovery teams, this time appears to be shortening. The unanswered question remains: what degree of functionality will AO-40 actually meet? This is the question the command team is working very hard to answer.
In summary, although optimism is certainly not a guarantee of future success, both Karl and Robin continue to believe that there will be successful long-term amateur radio communication through AO-40, with only the final nature of what these operations will actually be uncertain at the present time.
VE3FRH and DJ4ZC also noted that is very difficult to put out updated bulletins concerning the status of AO-40 on a frequent basis. The command team is involved in their employment and family life in addition to looking after AO-40, however, every (reasonable) effort is being made to report progress as soon as it happens.
ALON/ALAT is currently 248/-7, as last listed on the AMSAT-DL web page.
AO-40 element set number 28 is as follows:
Satellite: AO-40Stay tuned to AMSAT News Service, the official source of AO-40 news and information.
Catalog number: 26609
Epoch time: 01018.53756618
Inclination: 5.9258 degrees
RA of node: 230.0726 degrees
Eccentricity: 0.8133560
Arg of perigee: 208.4998 degrees
Mean anomaly: 11.7742 degrees
Mean motion: 1.26922670 rev/day
Decay rate: -1.63e-06 rev/day^2
Epoch rev: 99
Checksum: 299
ANS thanks AMSAT-DL and AMSAT-NA for this information
Phase 3D/AO-40 Update - January 21, 2001
The month of January continues with command stations working in their on-going recovery efforts of AMSAT OSCAR 40. The command team has determined the following:
* The V-band, U-band and the L-band (L1) receivers are working on the the high-gain antennas. The omni-directional antennas appear to be non-functional. The command team's conclusion is that damage has been sustained to the omni-directional antennas, antenna cables or antenna relays (or possibly all three).
* An attempt to command the V-band transmitter on the high-gain antennas has been done several times with no downlink signals detected. Telemetry may be indicating the transmitter is working, but with the current position of the satellite, V-band signals may not be receivable due to the assumption that the high-gain antennas may be pointing into space and not at Earth. Further tests will be conducted.
* No recent tests have been conducted on the U-band transmitter, but tests are planned once the current spin rate is reduced and the command team can confirm the heat pipes are working.
* The attitude control system is fully functional. Currently, a high spin rate (of about 17rpm) and an extreme sun angle (about 60 degrees) does not allow the sun sensor to provide accurate information. This explains why the indicated spin rate (via telemetry) is inaccurate. Without sun and attitude information the command team has suspended magnetorquing efforts, thus no further attitude or spin change has been attempted recently. Project leader DJ4ZC is developing a software algorithm which does not use sun sensor information. This software program will be tested and then used to try and reduce the spin rate and move the spacecraft to a better attitude.
In summary, once the sun angle and antenna pointing is improved, both the V-band and U-band transmitter tests can resume, along with suitable experiments of the ATOS (arc-jet) thruster and the momentum wheels.
ALON/ALAT is currently 248/-7, as listed on the AMSAT-DL web page.
Several stations, including AO-40 command station G3RUH have measured the frequency of the S-2 transmitter middle beacon as 2401.323 MHz. The beacon can be heard before perigee (between MA 245 and 256). Due to extremely high Doppler shift coupled with spin wobbling and fading, error-free telemetry reception will be difficult.
Moe Wheatley, AE4JY, has released an updated of his AO40RCV soundcard-demodulator. Data export and AFC have been improved, recorded sound files can be used and triggering up/down keys of (most common) transceivers for automatic doppler correction has been implemented. More information on AO40RCV is available at www.qsl.net
The current AO-40 orbital element set number 28:
Satellite: AO-40ANS thanks AMSAT-DL and AMSAT-NA for this information.
Catalog number: 26609
Epoch time: 01018.53756618
Inclination: 5.9258 degrees
RA of node: 230.0726 degrees
Eccentricity: 0.8133560
Arg of perigee: 208.4998 degrees
Mean anomaly: 11.7742 degrees
Mean motion: 1.26922670 rev/day
Decay rate: -1.63e-06 rev/day^2
Epoch rev: 99
Checksum: 299
Phase 3D/AO-40 Update - January 14, 2001
AO-40 Project Leader Karl Meinzer, DJ4ZC, has expressed confidence that, despite its problems, the satellite will be functional in the future -- although its mission likely will be different from the one planned prior to launch:
"Personally, I am optimistic and I believe that the command and engineering team stand a good chance of turning AO-40 into an extremely useful Amateur Radio satellite."
73, Dr. Karl Meinzer, DJ4ZC
This past week command stations continued working with the satellite in the on-going recovery efforts. No new information is available as this edition of ANS is broadcast, however, DJ4ZC will have a status announcement in the very near future.
The AMSAT-DL web site is currently featuring updated AO-40 orbital elements:
Satellite: AO-40AMSAT-UK's Richard Limebear, G3RWL, has put some thought into AO-40's future:
Catalog number: 26609
Epoch time: 01007.63378031
Element set: 23
Inclination: 6.0423 degrees
RA of node: 232.5105 degrees
Eccentricity: 0.8133763
Arg of perigee: 203.8825 degrees
Mean anomaly: 69.7775 degrees
Mean motion: 1.26906686 rev/day
Decay rate: -1.13e-06 rev/day^2
Epoch rev: 86
Checksum: 278
We know so far that the S-band transmitter and the L-band receiver are working and the IHU-1 is operational. If this is all what AO-40 will be, we could at least do some kind of 400 baud PSK digital communication via IHU-1. In addition, if the IF-matrix is functional (and telemetry shows it linked the S-band transmitter), SSB/CW via a linear-transponder will be possible. If AO-40 reaches such a state, we will get as much or more than AO-10 and AO-13 offered, only on more state-of-the-art frequencies.
Imagine if RUDAK and several other receiver and transmitter combinations can be turned on again.
I'll be patient and let the command-stations do their best to get as much as possible from AO-40. Also, I keep in mind that AO-40 is an experimental satellite, and from experiments we can learn.
Richard, G3RWL
ANS thanks AMSAT-DL, AMSAT-UK, AMSAT-NA and the ARRL for this information
Phase 3D/AO-40 Update - January 7, 2001
AMSAT-DL Vice President Peter Guelzow, DB2OS, provided ANS with the latest information about AMSAT OSCAR 40:
Dear All,
I know that many people are looking for more information and I can understand this, but please keep in mind that the recovery efforts are not easy and take a lot of time. Everyone involved in the recovery is indeed very busy and we all have our full time jobs and our families to consider in addition to the recovery efforts.
Due to the currently limited downlink capabilities, uploading of new commands and analyzing the results takes some time. So far, it has been determined that the L-band uplink receiver (on a high-gain antenna) is OK. Also, the VHF and UHF uplink receivers are OK and they seem to be working nominally. Since we know that the high-gain antennas are working, the V-band transmitter was switched 'on' for 1 MA count recently during a perigee pass over Australia (by command-station Graham Ratcliff, VK5AGR). Telemetry indicated a temperature rise but Graham could not detect any AO-40 telemetry signal on 2 meters. Unfortunately, the telemetry Gram was receiving on S-band at the time of this test was not error free and therefore some telemetry might be missing. The V-TX clearly needs to be tested again in the next few orbits.
Magnetorquing did commence and the results will be analyzed. Because of this action some additional FM wobbling may be noted on the S-band downlink when the magnetorquers are in action. If successful, the magnetorquing attitude control system will allow us to spin 'down' the spacecraft and adjust the attitude for a better sun and squint angle. Following this, it will take some time to evaluate the status of the various other systems and experiments, including the arcjet and momentum wheels.
However, there is a sign of a small leak, which we believe is also the reason for the higher spin rate we are seeing. The internal pressures of the propellant tanks are measured by discrete pressure transducers which are part of the PFA module. While the transducers could be damaged, it seems to be very unlikely. So for now the reason for the leak and the possible effects are under investigation and results will be reported when a final conclusion is made.
At the moment we clearly have priorities and the most important one is to bring AO-40 back into 'normal' mode as soon as possible. Depending on the outcome of these tests we can devise a new schedule that best exploits our currently known communications capability.
73, Peter, DB2OS
Following Peter's report, AMSAT-DL President Karl Meinzer, DJ4ZC, provided the following:
Greetings,
Since my report from late December, command stations have implemented the strategy which I had outlined. The first priority was to determine which command-uplink channels were available. This work was difficult, very time consuming (and for the satellite) somewhat dangerous due to the unknowns. The command stations did a magnificent job! Due to their combined efforts I can report the following findings:
1. After some blind transmissions to test the omni-antennas around apogee (that failed to produce a response), the scheduler was activated and programmed in such a way as to prevent lock-out. This strategy turned out to be very prudent and the scheduler-operation went smoothly and resulted in no additional anomalies.
2. The scheduler then took AO-40 through a number of modes, which allowed the P3D team to determine the following:
a. V, U and L-1 receivers work3. As Peter noted the V-band transmitter was operated for one MA-unit. It demonstrated a marked temperature increase, but no signal was heard. This was a quick-look test and this result should not be considered final. Further tests will be necessary (including the need to determine if the matrix was set properly). These tests will have to wait until the spin rate is reduced to ensure that the satellites heat-pipes will be able to handle the dissipation for extended periods.
b. V, U and L high-gain antennas work
c. U and L low-gain antennas do not work
d. the status of the V-band low-gain antenna has not been finally determined. Apogee blinds tests are in progress as I write this to accurately determine the status of this antenna
4. Magnetorquing was started to reduce spin and the first indications are a loss of around 0.5 rpm - roughly consistent with theoretical predictions. We can conclude that the system works. In order to use Earth-sensing data, a small additional program needs to be installed which stores data at apogee for later recovery when telemetry reception becomes available.
What's next?
During the next days the attitude control system should be returned to full functionality. It will be used to reduce the spin to a value consistent with heat-pipe operation and also with the requirements to change attitude. These changes are necessary for sun-angle constraints, communication access and also to reduce the effect of our ongoing mass-loss on perigee altitude. Newer model calculations show that the mass loss could be larger than my previous estimates; thus it would be prudent to use the resulting thrust to increase perigee altitude (right now it is decreasing it).
Once the spin/attitude situation is under control, we will continue the check-out of other systems (such as):
1. Determine the status of the V-band transmitter (controlled experiments)Present data so far indicates that although we have lost some systems in AO-40, there has been no further deterioration after the second incident. In particular, if ATOS and three-axis stabilization are still serviceable, AO-40 will still be able to produce a large fraction of the amateur radio service expected from it.
2. Determine the status of the U-band transmitter
3. Determine the serviceability of the ATOS (arcjet) to determine if it can be planned on for a strategy toward an improved orbit
4. Test the momentum wheels to determine if AO-40 can be put into a three-axis mode which would greatly reduce the impact of the loss of the omni-antennas
Personally, I am optimistic and I believe that the command and engineering team stand a good chance of turning AO-40 into an extremely useful amateur radio satellite.
73, Dr. Karl Meinzer, DJ4ZC
AO-40 command-station operator Stacey Mills, W4SM, has done a long-term calculation of AO-40's current orbit in the unlikely event that a malfunction within AO-40's propulsion system means that no further orbital maneuvers could take place. W4SM calculates the current orbit will be stable for a very long period.
Both the W4SM orbit calculation and the measured AO-40 beacon frequencies (during RF testing in Kourou) have been posted to the AMSAT-DL web site. See: www.amsat-dl.org/journal/adlj-p3d.htm
Stay tuned to ANS, the official source of information on AMSAT OSCAR 40.
ANS thanks AMSAT-DL and AMSAT-NA for this information
Phase 3D/AO-40 Update - December 31, 2000
The news received on Christmas day was what everyone wanted to hear -- AO-40 is transmitting again! Prior to this confirmation, the satellite had not transmitted any signals since December 13, 2000, which was shortly after the first burn of the 400-N motor.
On December 25, 2000 at 21:45 UTC command station ZL1AOX transmitted a L-band reset command which included an initialization block to switch 'on' one of the two S-band transmitters onboard AO-40. Just after the first attempt, AO-40's S-2 beacon was received by Ian, ZL1AOX. The S-band signal strength was S-5 to S-6, which compared to S-2 when the beacon was last heard last during testing in early December. AO-40's S-band transmitter produced a steady signal at ZL1AOX and from the doppler wobbling it was also clear that it was in fact coming from AO-40.
AMSAT-NA President Robin Haighton, VE3FRH, received the news with much relief:
"The excellent news of contact with AO-40 through the L-band uplink and S-band downlink has been received with joy and relief by AMSAT members around the world. AMSAT-DL issued a bulletin giving the news that everyone had hoped for on Christmas day, a fantastic gift to the Amateur Radio community."
VE3FRH also added the following comments:
"The command team has not stopped their investigation during the holidays. The AO-40 the team have now started to receive good telemetry data from the bird via the 2400 MHz S-band transmitter. However, copy is only available during the earliest part of each pass (typically MA 14-39) due to the offset of the antenna with respect to Earth. This restricts the amount communication that can take place during each pass. The data that has been recovered is being analyzed very carefully to try and determine a number of things," (such as):
* what actually happened and why did it happen?
* what telemetry functions are known to be correct and what telemetry data is suspect (and why)?
* what is the actual attitude of the spacecraft with respect to Earth and has the attitude changed?
* what is the spin velocity and has it changed?
* what is the current state of the batteries and are the battery chargers and regulators working?
* what happened to IHU-1 and IHU-2 and why?
* are all the antennas operational and what can be done next to improve communications?
* what risks are involved?
"When questions such as these (and others) are answered, it may be possible to determine the working capability of the spacecraft, and, if appropriate, to start to try operation on other bands. Much analysis work remains to be completed and I know that the command team will try to keep us all informed as and when they can answer the questions. Over the next week or two some critical decisions will be made, these decisions will be based on the results of the analysis and much discussion among the command team. Meanwhile, lets hope that the first week or two of the New Year will bring the same joy and relief to us all as the initial news of December 25th."
ANS earlier reported that on December 26th, ZL1AOX succeeded in loading IPS flight software and a minimal operational package into AO-40 and the satellite began sending telemetry (A blocks) that enabled initial analysis of the status of the spacecraft.
AMSAT-DL President Dr. Karl Meinzer, DJ4ZC, reviewed the received telemetry:
"A first (quick) look has revealed that some temperature sensors and possibly some current sensors have been lost by whatever incident caused the telemetry transmissions to stop. However, the power situation, in particular the battery voltages, look nominal.
We will now start a detailed analysis of the situation; the command stations will continue to follow a conservative philosophy with the primary target of not causing any additional damage along with retaining as much evidence as possible for the analysis of the incident."
DJ4ZC reported to ANS that recovery efforts of AO-40 will continue, mainly centered around housekeeping tasks designed to improve and stabilize the systems onboard the satellite. Several new software routines were successfully loaded that restored all Battery Charge Regulator functions and have resulted in a positive power budget. AO-40 has new flight software (with the exception of D-block programming and WOD routines which will be done later).
Command station G3RUH (James Miller) reported that commanding AO-40 on L-band frequencies was fairly easy, thus it appears the L-band receiver seems to be work nominally.
Recent telemetry instrumentation shows Helium pressure at essentially where it was following the first 400-N motor burn. Also, it appears that a few temperature and current sensors either failed and/or are showing incorrect values. The onboard sun sensors appear to be fine and are showing a solar angle that is near predictions.
Received spin rate telemetry is not accurate when compared to the actual spin as measured by the doppler wobbling of the S-band beacon. A substantial spin increase is noted and the P3D team is working to analyze and understand what has happened here.
As Peter Guelzow, DB2OS, reported to ANS; "the good news is that the spacecraft is now fully under control. During the next several days additional software will be loaded and the various uplinks will be verified."
AMSAT-DL's Frank Sperber, DL6DBN/AA9KJ, placed the following statement on the AMSAT-DL web site:
We wish you a happy new year which hopefully will bring back AO-40 to a substantial life. Thank you for your kind wishes and support. Both are very welcomed in these nervous times of AO-40's recovery. We'll try to keep you informed about the progress as best we can beside work and family.
Stay tuned to ANS, the official source of information on AMSAT OSCAR 40.
ANS thanks AMSAT-DL and AMSAT-NA for this information
New OSCAR Numbers Announced
ANS has received a copy of a letter sent to Dr. Turki Al Saud, the director of space research at the King Abdullaziz City for Science and Technology, the sponsoring agency of two of Amateur Radio's newest satellites, SaudiSat 1A and 1B.
The letter is written by AMSAT-NA (past) President Bill Tynan, W3XO:
In accordance with the request by AMSAT-NA President Robin Haighton, VE3FRH, that I be charged with the issuance of OSCAR numbers to qualifying Amateur Radio satellites (and) in response to a request for OSCAR numbers for SaudiSat 1A and 1B, which correspond to the provisions set forth in the following IARU document:
'Information For Perspective Operators of Satellites Utilizing Frequencies Allocated to the Amateur Satellite Service',
I do hereby designate SaudiSat 1A as Saudi OSCAR 41/SO-41 and SaudiSat 1B as Saudi OSCAR 42/SO-42.
Congratulations to all who worked on this project on the launch of these spacecraft. I am sure that the world's Amateur Radio community will very much appreciate having SO-41 and SO-42 available for use.
Sincerely,
William A. Tynan, W3XOSaudiSat 1A and 1B were launched September 26, 2000 aboard a converted Soviet ballistic missile from the Baikonur Cosmodrome. Currently, both satellites are in their commissioning stage, with initial housekeeping tasks underway. Each satellite will operate as a 9600 baud digital store-and-forward system as well as an analog FM (bent-pipe) repeater.
Congratulations from ANS!
ANS thanks AMSAT-NA's Bill Tynan, W3XO for this information
Phase 3D/AO-40 Update - December 24, 2000
The non-transmission problem with AO-40 continues.
The satellite has not transmitted any telemetry since December 13, 2000, which was shortly after the first burn of the 400-N motor.
AMSAT-DL's Peter Guelzow, DB2OS, informed ANS that the command-assist timeouts expected recently have all passed with no observations -- and command stations again tried to re-establish communication by sending blind commands. The command-assist watchdog timers are software timers programmed to cycle through various AO-40 receiver, transmitter and antenna systems.
The AO-40 command team was encouraged recently by information received from the North American Air Defense Command that indicated AO-40 was found to be in one piece with a radar cross-section as expected and that no other pieces were found by the radar sweeps.
AMSAT-DL President and P3D Project Leader Dr. Karl Meinzer, DJ4ZC, summarized recent command station events and activities performed on AO-40:
A large number of attempts have been made to hear AO-40 according to the pattern followed by command-assist. In addition the 70-cm downlink has been monitored with some large antennas. None of these attempts have resulted in anything heard from AO-40.
We are now assuming that the IHU is not running the regular spacecraft program and has either crashed or is nonfunctional. Thus, we have entered the part of our recovery strategy where we will try to reset the IHU and then uplink new software.
After reviewing our strategy we have concluded not to uplink the standard IPS routine (the regular spacecraft software), but to uplink short programs with the only objective to activate various downlink configurations. These programs will be uploaded after the IHU is reset.
The primary target is to establish communication. Once we have a downlink going, then and only then will we try to upload IPS again to put the satellite into a regular state.
A number of programs have been prepared to this end, and presently they are being debugged on a ground IHU. Once they work reliably as intended, we will start to uplink these modules. In view of the large number of options which need to be tried, this process may take (up to) several days. Work is continuing over the Christmas holidays - and I will report our progress.
So, for the moment, and in spite of the troubles we have with AO-40, I wish you a Merry Christmas and happiness in the new year (which should of course, include AO-40).
73's,
Karl, DJ4ZC
The following statement was taken from the AMSAT-DL web site:
Even during the Christmas days AO-40-command stations are active. It must be assumed the IHU-1 has crashed. Preparations of a special reset software have been completed to switch a transmitter and IF-matrix immediately to the V-band middle beacon without uploading the whole operational software.
Command stations have already started sending the reset commands to the spacecraft. So far, no success. Command stations will continue to reset and upload using different command receivers. Even if we do not have immediate success, there are still a couple of possibilities to try.
AMSAT-DL
Ken, N2WWD, released the following latest NORAD/Space Command Keplerian elements for AO-40:
1 26609U 00072B 00358.71368715 -.00000218 00000-0 00000-0 0 179
2 26609 6.1593 236.5032 8131813 196.8718 93.7933 1.26873926 676Ken reports these orbital elements have a "22 second along track difference when compared with NORAD set #16."
Stay tuned to ANS, the official source of information on AMSAT OSCAR 40.
ANS thanks AMSAT-DL, AMSAT-NA and the ARRL for this information
To Arnie Coro's Dxers Unlimited
To NY Transfer's Radio Havana Cuba