QRZ Logbook

Friday, August 5, 2011

ARISSat-1 launched from ISS, missing UHF antenna

After a 4-hour delay due to issues with a missing UHF antenna, Sergei Volkov, RU3DIS, and Alexander Samokutyaev deployed ARISSat-1 from the Pirs module of the ISS last Wednesday.

While preparing to deploy ARISSat-1, the spacewalking cosmonauts noticed only one antenna protruding from the bird when there should have been 2, one for 2 meters (VHF), the other for 70cm (UHF).

Controllers in Moscow and Houston decided to postpone the deployment to evaluate the issue as the cosmonauts continued with their remaining scheduled spacewalk duties.

Later in the spacewalk, controllers gave the go-ahead for Sergei and Alexander to send ARISSat-1 into space, gently nudging it aft and nadir of the station in order to eliminate the possibility of collision with the station later.

The images posted are actual screen captures taken by ground stations listening for ARISSat-1's SSTV signal. You can see the helmet of Sergei Volkov and a pre-loaded image of the ARISSat-1 logo. Live cam images are captured at various times which will allow for stations on the ground to get a near-real-time static image of what ARISSat-1 is seeing over 200 miles high. If the satellite goes into darkness, the logo images are transmitted.

In addition to SSTV, voice and BPSK at various times. While in the sunlight, it will transmit on high power and near-continuous transmission. While in eclipse, it will go into power-saving mode, transmitting intermittently.

It's not yet known the full extent of the damage to the UHF system (designed to be a linear transponder), however, hams are reporting they are making successful contacts with it.

For now, here are the modes of operation:
  • 145.950 MHz FM Downlink: FM transmissions will cycle between a voice ID as RS01S, select telemetry values, 24 international greeting messages in 15 languages, as well as SSTV images.
  • 435 MHz - 145 MHz Linear Transponder: The linear transponder will operate in Mode U/V (70 cm up, 2 meters down). It is a 16 kHz wide inverting passband and the convention will be to transmit LSB on the 435 MHz uplink and receive USB on the 145 MHz downlink.
  • 145.919 MHz/145.939 MHz CW Beacons: The CW transmissions will be call sign ID RS01S, select telemetry and call signs of people actively involved with the ARISS program.
  • 145.920 MHz SSB BPSK-1000 Telemetry: When the CW2 beacon on 145.919 MHz is active, this indicates that the BPSK-1000 format is being transmitted. If the CW1 beacon on 145.939 MHz is active, the backup of BPSK-400 format is being transmitted.
ARISSat-1 is also known as "KEDR", which translates to "Siberian Pine" in Russian. It was Cosmonaut Yuri Gargarin's callsign during his flight which made him the first human being in space. ARISSat-1 was launched to coincide with the 50th anniversary of Gargarin's historic flight. Its callsign is RS01S.

Check out AMSAT's "how-to" page for information on how to operate ARISSat-1.

No comments:

Post a Comment