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Parkes 64m Radio Telescope Listens for AO-40
With our attempts to restore AO-40 we have received today significant support from Parkes Observatory in Australia. http://www.parkes.atnf.csiro.au/
The Parkes Observatory is operated by the Australia Telescope National Facility (ATNF) which is part of Commonwealth Scientific and Industrial Research Organisation (CSIRO).

From here were received the live pictures of Apollo 11 Moon landing, 1969. See above homepage of Parkes.

The radiotelescope has a diameter of 64 metres and the system noise figure is approx. 25 K.

From about 6:00 UTC, a 4 MHz wide spectrum with center frequency of 1097 MHz was scanned with high level technique in order to find the LO frequency of the AO-40 L1 receiver. A band of approx. +/- 20 kHz around the actual LO frequency was examined intensively. Three hours were needed to prepare the setup for AO-40 and to search.

Unfortunately nothing was heard which could be a signal of AO-40!!

The fact that nothing was heard of the L1 receiver s LO does not lead to the conclusion that AO-40 is completely dead. The receivers of Parkes are not really fitted for frequencies below 1.25 GHz, and naturally one does not know how good the L1 receiver s LO is shielded or how much of the signal would go through the antenna to the outside world. During the next days more research follows.

The L1 command receiver is continuously switched on, and it would have been good news if we had such a confirmation that the 10 V power source for the L1 receivers is still functioning. All receivers and also the IHU are supplied with the 10 V source.

All command stations are continuing to send commands to the satellite in order to switch the batteries.

I would like to say a great thank you on behalf of AMSAT-DL to Brett Dawson, VK2CBD and the team of Parkes observatory, especially to Dr. John Reynolds (Officer in Charge) and John Sarkissian (Operations Scientist).

Peter Guelzow, DB2OS
President AMSAT-DL

AMSAT-DL Oscar 40-sida



AO-40 update

Hej! Hr r en rtt fin frklaring p Oscar 40 lget,Vi hller tummarna!! 73 Hkan

The problem is, that the Main Battery clamps the bus voltage down toabout 14V or even less, from its nominal 24V.

As Stacey described, this is obviously due to several battery cells in the main battery, which failed shortened in some sort of domino effect.

It happened so fast, that we were not able to completely isolate the main battery and use only the aux battery. At the moment both batteries are in parallel.. this will not damage the AUX battery, but it prevents it from charging.

The extremely low battery (and bus) voltage is a problem, because the transmitters and other electronics were not designed or may not work at these low voltages..

The IHU and receivers should still work, but without telemetry it is hard to predict what the current situation really is..

Since the solar panels pump all their energy into the remaining cells of the main battery, they will indeed get very hot.. Our hope now is (and that s what is to be expected) that these cells will ventall their electrolyte and dry out. When that happens, the cells should fail high resistance and our bus voltage should come up..

Thus, the improving sun angle should help in speeding up this process.But again, we yet do not know how long this will take.. but chances not bad for this to happen..

73s Peter, DB2OS

Klla: amsat


Inget resultat från K-bandsändaren

Frn AMSAT-BB mailinglista lser vi fljande:

AO-40 K-band; no result
Short binary programs (typically 40 bytes) were sent to AO-40 today (Jan 31) to turn the K-band transmitter ON, from 2145-2300 utc. The sequence was also repeated several times during the session. Charlie Suckling G3WDG reported that nothing was heard on K-band.

Utver detta finns senaste info frn ANS, se lnk i rutan nedan.

Senaste nyhet frn ANS

Klla: AMSAT-BB / James G3RUH


Senaste uppdatering 27/1

Senaste uppdatering angende batteriproblemen:

Initial attempts today at recovering the S2 beacon on AO-40 have so far not been successful. However, these will be repeated many more times from multiple locations in the days ahead. We have a good fix on ALON/ALAT and we are spinning at 3.5 RPM, so we have quite a few days/weeks before the squints become problematic due to the mystery effect. Currently, the mystery effect is working for us to improve solar angle. Attempts will also be made in the next few days to bring the K-Tx on line and search for its signal. The command team has a series of simple machine code commands that, if heard, should activate transmitters, switch receivers, switch batteries, etc. without having to load the flight software into the IHU-1.

By way of review, the command team had been watching the main battery for a number of months and noting that its behavior, while not alarming, was not fully as expected. In particular, there were voltage fluctuations with
spin under relatively light power loads. When panels 1-6 received sunlight their 1/2 complement of solar cells would often lead to a voltage dip, which would pop back up when the fully arrayed panels were in the sunlight. This suggested that perhaps one cell in the 20 cell main battery
might be weakening. On Sunday, we noted that the battery was not maintaining its set voltage and this led to the safety software shutting off the passbands. Some minor adjustments were made to the solar array voltage offsets and this helped some, but we stayed in passband off mode to
study the matter further. It appears that at this time we may have acquired a second bad or shorted cell, though we are analyzing this further. During eclipse on orbit 1487, at approximately 1930 utc on 2004-01-26 the battery voltage hit the extreme low voltage trigger. This caused safety resets of the battery and solar array set points and the
auxiliary battery was tied in to the main battery. This all appears to have happened benignly, and when I got AOS at MA=8, about an hour and a half later on the following orbit, I noted that the extreme low voltage flag had been set ,as well as the other changes noted. Voltages on both
batteries at this time were similar to other post-Sunday values, as were the charge currents. At this voltage level, the auxiliary battery was considerably undercharged. We appeared to be in a stable, though not fully nominal mode, and I was in the process of noting the status of things to the command team to decide on the next course of action when, at 00:39:59 utc the battery voltage suddenly dropped from its post-Sunday level of 25.5
to 26.5 volts, down to 18 volts. This was accompanied by an expected increase in charge current. The safety software shut off the S2 Tx at the next MA change, and I brought it back up manually twice, noting that the voltage was relatively stable at about 14 volts with heavy charge
current. After letting things sit for a few minutes, a third attempt to start the S2 Tx was not successful.

Our current best understanding is that we suffered a catastrophic failure of the main battery which is clamping the buss voltage at a low level. Accordingly, we have been concentrating our efforts on trying to connect the auxiliary battery to the main buss and disconnect the main
battery, placing it on trickle charge for further analysis. If we can manage just 10 volts on the main buss to activate the IHU-1 we should be able to accomplish this with the simple machine codes noted above, and the
voltages should come up to levels where the S2 will function.

If you examine the telemetry during this time, 10 minutes after the low-voltage event , the temperature of heat pipe 4 + X + Y takes a 34.2 deg.C apparent increase in temperature over a span of 14 seconds (1 block interval), and continues to rapidly increase almost to the top of the
scale. Given the timing of this change, 10 minutes after the low-voltage event , its rapidity, the thermal inertia of the large, circumferential heat pipes, etc… it is difficult to believe that this is real. Most importantly, this heat pipe sensor sits in a benign area at the apex of panels 1 and 6, near the high-gain end of the spacecraft. There are no batteries or BCR s in this region, only the controller for the liquid rocket motor (which was powered off!), and the L1 receiver, which shows no accompanying change in temperature. All of the BCR s and batteries are much closer to heat pipes 1 and 2 at the omni end of the spacecraft. Therefore, this may represent a failure of the software/hardware due to low voltage, rather than a real temperature increase. However, this will be studied further. No other telemetry anomalies have been noted but we continue to look.

–W4SM for the AO-40 Command Team

Ls artikel p DL0-sidan

Klla: W4SM


Uppdatering 29 jan

Senaste nytt angende Oscar 40:

Initial attempts to turn on the K-tx with short machine code commands did not result in a detectable signal, but this will be repeated. Several additional cycles with the S2 have been repeated as well without result. These attempts always terminate with transmitter off commands, and simple commands to try to switch the battery to the aux. mode.

Our hypothesis remains that we have a battery failure clamping the voltage low. We re looking at the spacecraft physical and electrical layout and even the flaky heatpipe reading to see if we can come up with a more detailed failure point explanation.

If our theory is correct, the remaining cells of the main battery are taking quite a beating as the BCR s try unsuccessfully to bring them up to the set point voltage of about 28 volts. We expect that more than 6 amps are flowing through the remaining cells in the main battery and this
current will increase by about 30% as the solar angles improve. We only need for one of these cells to lose enough electrolyte to open and we could be back in business. I ll repeat my comment from before that time is
an unknown here and days or weeks without result do not mean ultimate failure.

I will be out of town for two days on an unavoidable business trip, but will update the bulletin board when I return on Sunday. The command team will continue to try to regain the S2 and K Tx s and report any successes here.

–W4SM for the AO-40 Command Team

Klla: W4SM


Batteriproblem på AO-40

Oscar 40 har ftt ngot problem med batterierna s passbandet r avstngda just nu. Problemet undersks:

On orbit 1486, the main battery voltage ran lower than expected. This was due in part to usage and high solar angle as mentioned previously, but even after the passbands were shut off automatically the voltages did not come
back up as expected, in spite of apparently positive battery charge currents. At the beginning of the eclipse on orbit 1486 at MA =225, the battery voltage rapidly dropped just below the S2 Tx cutoff voltage of 24.0
volts and the S2 Tx shut down. to protect the battery and IHU s. The eclipse ended at about MA=237, approx. 55 minutes later. We expect the S2 Tx to start back up as programmed at MA =2 (as I type this), though it has
been known to be balky before on restarts and could require manual cycling.

The command team is investigating this anomaly to determine if the main battery may have developed a single bad (shorted) cell or if there is a problem with the battery set voltage, solar array set voltages, or other
problem. Until we sort this out the passbands will be off for one or more orbits. If the battery charge or array set points are wrong, they can be changed. If we have one bad ( shorted ) cell we can reset charge/trigger points to account for this, and we have the completely redundant auxiliary battery, if needed. We hope to be able to work through this and correct things without too much down time.

We ll update you here as soon as we know more.

– –W4SM for the AO-40 Command Team

Klla: W4SM