Soichi Noguchi, the Japanese astronaut currently onboard the ISS, installed a new data converter for MAXI. MAXI has two channels for the data telemetry. One is the “low speed line”, or, if you are familiar with the space flight tech, MIL-STD-1553B, which is robust and reliable, but the bandpath is limited. The other is called “medium speed line”, which is in fact a wired ethernet similar to what you find in your office, and should be able to transmit mega bits per second. GSC can transmit the essential science data over the low speed line, but SSC relies heavily on the medium speed line. Due to a misunderstanding in a network protocol, combined with the design feature of MAXI data processor, the transmission over the ethernet was never smooth. We had to modify the header in the ethernet packets, and had to filter out broken or illegal ethernet frames which can occur in a crowded LAN. Since a few months after the launch, we used a laptop computer already present in JEM as a filtering bridge, but it was not stable either. Several times we had to reboot MAXI to recover the communication over the medium speed line.
With the latest shuttle flight, a new device “Armadillo” specifically designed for this job was transported from the ground, and Soichi installed it in the network. Now MAXI seems to be happily sending out data in the medium speed line.
