Space Ho!
It looks like the six German-made, Russian programmed computers on the International Space Station (ISS) are back up and running after a few days of tense troubleshooting trying to discover the reason why they wouldn’t reboot properly. The computers which control the ISS’s navigation and command and control systems shut down last Wednesday, and there was trouble rebooting them. ( A good time line and incident details can be found at CBS News Space Place.)
These problems had been preceded by problems on Tuesday, where a computer crash prevented the ISS from immediately taking over gyroscopic control as planned from the docked shuttle Atlantis. During the computer rebooting sequence, a false fire alarm on the Russian segment of the ISS was sounded. Later Tuesday night, gyroscopic control was handed back to the ISS computers, although the reason for the computer crash on was not understood. However, only one out of the three navigation and one out of the three command and control computers were working after the successful reboot.
Early Wednesday morning, while astronauts were outside working on retracting a solar array wing, the two remaining computers crashed, and none of the computers would reboot – a first in ISS history. If the computers could not be rebooted, the ISS would potentially have to be abandoned. Making the troubleshooting a bit harder was that the Russian Federal Space Agency Roskosmos does not have its own satellites which can communicate with the ISS, forcing Russian space engineers to wait until the ISS is within line-of-site of Russian ground stations to downlink the needed telemetry to perform troubleshooting.
By yesterday afternoon, the computers were back up and working. There was a belief that there was a problem with the quality of power supply to the computers, possibly caused by the addition of new solar arrays. Russian astronauts used jumper cables to by-pass the computers’ surge protectors, and lo and behold, the computers booted up as normal. While this solution points to the source of the problem, the reasons why remain a mystery. NASA’s space station program manager Michael Suffredini probably summed it up best when he said, “As the station gets bigger, this potential [for problems] continues to grow. I think we’re going to find system sensitivities as we change the space station.”
There are a number of interesting aspects to this story. First, while the computers (and software) were designed to be redundant and independent, the power supplies to them don’t appear to be so. I bet that this issue is going to get a hard look in the next few weeks by NASA and Roskosmos.
Second, this episode will likely mean more consideration for possible unintended consequences to not only the computers but other systems and their interfaces aboard the ISS as it continues to be constructed. Even after all these years in space, surprises can still occur and nothing up there can be seen as ever being easy.
Third, the folks who are working on the Mars program are likely trying to figure out whether there is something they now need to be worried about. A mission to Mars could last well over two years, and any computer problems on that little voyage could spell big trouble.
Fourth, reliable computers are really, really important in space. This crash was not by any means the first, nor will it likely be the last. In 2001, during the shuttle Endeavour’s visit to the ISS, all three of the ISS command and control computers shut down, which was apparently caused by a bad hard drive.
Finally, having a really good tool kit around with lots of patch, jumper cables and spare parts about is priceless. While it often appears to be, not every computer problem is a software problem
