Amateur radio satellite AO-51 remembered

Dozens of messages were posted to the Amsat-bb after the news of the amateur radio satellite AO-51‘s end of mission was received. Many remembered their contacts, several thanked the Operating Team. Many noted that AO-51 was the satellite that brought them into this part of our hobby. Continue reading

AO-51 End of Mission

AO-51 on Launch Platform

It is with a heavy heart I report that AO-51 has ceased transmission and is not responding to commands. The last telemetry data indicated that the third of six batteries was approaching failure to short, and observations indicate the voltage from three cells is insufficient to power the UHF transmitters. The IHU may continue to be operative. Initial tests with the S band transmitter were also not positive, although more attempts are in order. We have tried leaving the satellite in an expected state where if voltages climb high enough, the 435.150 transmitter may possibly be heard.

The command team will regularly attempt communications with the satellite over the coming months (and years). There is always the possibility that a cell will open and we could once again talk to our friend while illuminated. Thanks to all who helped fund, design, build, launch, command, and operate AO-51. It’s 7 year mission has been extraordinary. Please support AMSAT’s Fox-1 project, and other AMSAT projects worldwide with your time and money.

For the AO-51 Command Team,

73, Drew KO4MA
AMSAT-NA VP Operations


AMSAT Bulletin Board (AMSAT-BB)

AO-51 Current Status

AMSAT-NA VP Operations Drew Glasbrenner KO4MA reports on Friday’s IHU crash on the Amateur Radio satellite AO-51.

Sometime between 1815 and 1945Z November 25, AO-51’s IHU crashed. This happened after a few days of intermittent and unpredictable operation.

Mark N8MH and I reset the satellite and started the repeater back up around ~2030Z, and lowered the output power to about 300 milliwatts. Battery voltage was low, around 4.9v, with cell 1 less than 1 volt. This is very troublesome, as the impending third cell failure will likely end our continuing operations, particularly if it fails shorted as the others have.
We’ve also observed the transmitters cutting off around 4.7 to 4.6 volts prior to the last reset, in eclipse.

We’ll do what we can, but her days are short. Let me ask once again for more reports, especially from the US operators, to the webpage. The command stations monitor this for changes in the operation of AO-51, and while worldwide participation is good, few US operators post to it.

Please support the several satellite programs worldwide, such as AMSAT-Fox, AMSAT-UK FUNcube and UKCube, AMSAT-ZL Kiwisat, AMSAT-DL P3E, and others.


VI6CHOGM on Amateur Radio Satellites

VI6CHOGM, celebrating the Commonwealth Heads of Government Meeting in Perth Oct 28-30, will be active on the amateur radio satellites SO-50 and AO-51.

Adam VK2YK writes:

Below are the passes this weekend that I’ll be active on with the special event callsign VI6CHOGM. All dates and times are in UTC.

Friday 28 OCT 11
SO-50 – 0530
SO-50 – 0710
AO-51 – 0714
AO-51 – 0852

Saturday 29 OCT 11
SO-50 – 0559
AO-51 – 0636
SO-50 – 0739
AO-51 – 0812

Sunday 30 OCT 11
SO-50 – 0627
AO-51 – 0733
SO-50 – 0808
AO-51 – 0912

Hope to hear you on the birds this weekend. Check out for more info on freqs being used.


Adam VK2YK

AO-51 operations update



AO-51 operations update

AO-51 Control Station, Mark Hammond, N8MH wrote a status update on this satellite. Mark noted that since the failure of the first cell on the six-cell battery the ground controllers have been limited to simple commands for basic configurations.

Mark said that ground control stations have evolved basic control
and management techniques of AO-51 which allow them to set power levels manually, change uplinks/downlinks. Additional features such as telemetry collection/storage, and the BBS are not functional at this time. If the satellite resets during eclipse these basic functions must be restored manually by a ground station.

Ground stations have discovered there is a second cell in the battery showing problems. Mark noted, “We think it will be the next cell to go with the probable result that our limited manual mode of operation probably will no longer be an option, and the mission might be considered over.”

AO-51 is currently transmitting on:

Downlink: 435.150 MHz FM (LHCP) and using a
Uplink: 145.880 MHz FM

The power level is just under 1 watt (about 980 mW). Controllers expect to keep this configuration until further notice.

Keep up with the latest AO-51 Control Team News on-line at:

The current scenario of AO-51 is one reason we need to keep moving AMSAT and satellite development/building/launching moving forward!!

We have learned a lot already with ARISSat-1, and FOX looks promising.
AMSAT needs the support of its users now more than ever!

Mark Hammond, N8MH
AO-51 Control Station

AO-51 Having a difficult time

AMSAT Vice-President of Operations Drew Glasbrenner, KO4MA reported
the AO-51 Command Team is having a difficult time trying to restore
AO-51 to operation.


The current situation is the satellite will not retain the upload of
the flight software across eclipse. The batteries are in very poor