Want to know about the technology on the space station?

Steve Husty, a senior software engineer who works for NASA on the portable computer systems used on the International Space Station, has written to correct us on aspects of our story about the failure of computers aboard the International Space Station. In the process he's provided us with an interesting explanation of the technology on the space station which we've published below.

I felt compelled to respond to your report about the ISS C&C (command & control) computers failing write up.

You stated:

NASA hasn't said what the problem machines are but all a strong body of evidence points to IBM Thinkpads featuring older Intel processors, when the project began around two years ago these machines used 486 chips.

The IBM Thinkpad laptops to which you refer, called PCS (Portable Computer System) are used throughout the station. They are indeed 486 based laptops. However, they are running Sun's Solaris OS for x86, and the OpenWindows WM, and a custom application that provides a graphical interface to the various on-board systems.

It is not unusual for a project of this size and scope to be using technology that seems dated to the man-on-the-street. The project in fact is much older than two years. The deployment and assembly phase is only two years old at this point, but the station has very old roots. Design requirements and specifications need to be fixed, even though technology marches on, the program must to stick to its requirements. At the time this computer was selected, it met the requirements adequately to perform its intended function.

You also stated:

Subsequent emails from our readers revealed these machines were involved in far more than playing space invaders. It seems the laptops were running most of the main functions on board the station, including the communications functions that have failed.

This is blatantly false. Your readers have misinformed you. The PCS runs its own applications, which have very little to do with the actual main function operations in a module. PCS provides a graphical interface to the station's systems and a crew commanding capability for most of the station's functions. It is however, not required to maintain the station's functions. The laptop's processor is not involved in the calculation, monitoring or execution of the station's processes. The PCS's processor is dedicated to running its OS and its applications - which, as I stated, are secondary to the actual operation of the station's built-in computers. We get copies of the crew logs, and one of the things they are most impressed with is the (continued) operation of the PCS.

The ISS is a very complex machine, which will only continue to grow and evolve. To be sure, there are going to be system hiccups, shutdowns and glitches. NASA, its contractors and subcontractors and the international partners really are working hard to make the station successful. As such, their failures are sure to attract attention.

The computers that crashed (the C&Cs) and the PCS laptops are not the same computers and that the latter, while important are not responsible for running the station's operations. ®