AO-51
Encyclopedia
AO-51 is the in-orbit name designation of a LEO
amateur radio
microsatellite
(AMSAT
) of the OSCAR
series; formerly known as ECHO. It was launched on June 29, 2004 from Baikonur Cosmodrome
, Kazakhstan
on a Dnepr launch vehicle. It is in sun synchronous
low Earth orbit
.
AO-51 contains an FM repeater with both a 144 MHz (V band) and 1.2 GHz (L band) uplinks and 435 MHz (U band) and 2.4 GHz (S band) downlinks. Additionally it contains a digital subsystem that transmits telemetry on 70 cm and provides a complete PACSAT BBS that can be configured on both V and S band uplinks. There is also a 10 meter PSK uplink.
AO-51 has four VHF receivers, two UHF transmitters, six modems, 56 channels of telemetry. The two UHF transmitters are connected to four antennas, two in right-hand circular polarization and two in left-hand circular polarization.
The AO-51 FM satellite is easily workable with an amateur radio VHF dual band hand-held radio, as long as you know when the satellites footprint
is within reach. Transatlantic contacts have been made without much effort, as long as the satellite is approximately mid-Atlantic so that the edge of the satellites footprint
is within reach on either continent.
It's always good practice to check the AO-51 Schedule before trying to transmit during a satellite pass to ensure that the sat is in the correct mode and not being tasked for emergency comms.
As of May 2011 the satellite has problems with the battery. By September, a work around for the battery issue was found, bringing the repeater back in use. On November 29, 2011, the AO-51 Command Team announced that AO-51 has ceased transmission and is not responding to commands.
Low Earth orbit
A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...
amateur radio
Amateur radio
Amateur radio is the use of designated radio frequency spectrum for purposes of private recreation, non-commercial exchange of messages, wireless experimentation, self-training, and emergency communication...
microsatellite
Miniaturized satellite
Miniaturized satellites or small satellites are artificial satellites of unusually low weights and small sizes, usually under . While all such satellites can be referred to as small satellites, different classifications are used to categorize them based on mass .One reason for miniaturizing...
(AMSAT
AMSAT
AMSAT is a name for amateur radio satellite organizations worldwide, but in particular the Radio Amateur Satellite Corporation with headquarters at Silver Spring, Maryland, near Washington DC. AMSAT organizations design, build, arrange launches for, and then operate satellites carrying amateur...
) of the OSCAR
OSCAR
OSCAR is an acronym for Orbiting Satellite Carrying Amateur Radio. OSCAR series satellites use amateur radio frequencies to facilitate communication between amateur radio stations. These satellites can be used for free by licensed amateur radio operators for voice and data communications...
series; formerly known as ECHO. It was launched on June 29, 2004 from Baikonur Cosmodrome
Baikonur Cosmodrome
The Baikonur Cosmodrome , also called Tyuratam, is the world's first and largest operational space launch facility. It is located in the desert steppe of Kazakhstan, about east of the Aral Sea, north of the Syr Darya river, near Tyuratam railway station, at 90 meters above sea level...
, Kazakhstan
Kazakhstan
Kazakhstan , officially the Republic of Kazakhstan, is a transcontinental country in Central Asia and Eastern Europe. Ranked as the ninth largest country in the world, it is also the world's largest landlocked country; its territory of is greater than Western Europe...
on a Dnepr launch vehicle. It is in sun synchronous
Sun-synchronous orbit
A Sun-synchronous orbit is a geocentric orbit which combines altitude and inclination in such a way that an object on that orbit ascends or descends over any given point of the Earth's surface at the same local mean solar time. The surface illumination angle will be nearly the same every time...
low Earth orbit
Low Earth orbit
A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...
.
AO-51 contains an FM repeater with both a 144 MHz (V band) and 1.2 GHz (L band) uplinks and 435 MHz (U band) and 2.4 GHz (S band) downlinks. Additionally it contains a digital subsystem that transmits telemetry on 70 cm and provides a complete PACSAT BBS that can be configured on both V and S band uplinks. There is also a 10 meter PSK uplink.
AO-51 has four VHF receivers, two UHF transmitters, six modems, 56 channels of telemetry. The two UHF transmitters are connected to four antennas, two in right-hand circular polarization and two in left-hand circular polarization.
The AO-51 FM satellite is easily workable with an amateur radio VHF dual band hand-held radio, as long as you know when the satellites footprint
Footprint (satellite)
The footprint of a communications satellite is the ground area that its transponders offer coverage, and determines the satellite dish diameter required to receive each transponder's signal...
is within reach. Transatlantic contacts have been made without much effort, as long as the satellite is approximately mid-Atlantic so that the edge of the satellites footprint
Footprint (satellite)
The footprint of a communications satellite is the ground area that its transponders offer coverage, and determines the satellite dish diameter required to receive each transponder's signal...
is within reach on either continent.
It's always good practice to check the AO-51 Schedule before trying to transmit during a satellite pass to ensure that the sat is in the correct mode and not being tasked for emergency comms.
As of May 2011 the satellite has problems with the battery. By September, a work around for the battery issue was found, bringing the repeater back in use. On November 29, 2011, the AO-51 Command Team announced that AO-51 has ceased transmission and is not responding to commands.
Two-Line Element Set (TLE)
1 28375U 04025K 10319.48348090 .00000056 00000-0 29545-4 0 8243
2 28375 098.0749 304.4752 0084701 358.8875 001.2111 14.40709462335298