We tracked RAX-2 during six passes this past week but unfortunately were unable to communicate with the MHX 2400, RAX’s backup radio. We attempted direct communication with the radio, which if the radio were turned on, should work independently of the flight computer. Given the silence and previous work with the UHF radio, this indicates that both radios are inactive and the silence is caused by an upstream anomaly on the flight computer or power system. We didn’t have time to work with the 150 ft dish to hunt for onboard electrical activity this week, so that will be saved for a later date. A big thanks to Bryan Klofas and our colleagues at SRI International for supporting the work at the dish!
We’re off to California this week to visit SRI International and use their high-gain antennas for RAX debugging. We’ll first try to communicate with RAX’s backup radio, the 2.4 GHz MHX 2400, using the 60 ft dish. If we can’t communicate with the spacecraft, then we’ll hunt for electrical activity onboard using the 150 ft dish. With this tracking work, we hope to diagnose the silence of the primary UHF radio.
RAX-2 has remained silent on it’s UHF frequency since April 20, 2013. Since there haven’t been any transmissions over UHF, even when listening with high-gain antennas at SRI international, the next step is to attempt to diagnose where the failure has occurred. There is a backup Microhard S-band radio onboard, and we are attempting communication with that system this month. Although the cease in operations was unexpected, RAX-2 fully completed its planned one-year mission and has provide unprecedented measurements of ionospheric irregularities.
RAX-2 stopped transmitting beacons over the weekend and is not responsive to normal commands. The cease in normal operations happened mid-day on Saturday, April 20, and the cause of the issue is currently under investigation. Over the next few days, we will be recording the spectrum during passes and sending up some custom commands in an attempt to determine the cause.
RAX-2 has been operating on-orbit for 540 days, has completed its scientific goals, and has surpassed it’s planned one-year scientific mission. We’ll be posting updates on the status as we investigate over the next few weeks.