Keep Watching the Ice
Meet the satellites bringing data to the discussion of global warming
- By Ben Iannotta
- Air & Space magazine, September 2006
(Page 5 of 7)
The new ICESat operating plan has made the job of steering and controlling the spacecraft more complicated for the staff and students at the University of Colorado’s Laboratory for Atmospheric and Space Physics in Boulder. LASP officials had assumed they would settle in to a pattern of routine monitoring from the lab’s cozy mission operations center. But during a teleconference in 2003, NASA managers outlined the new operating scenario to the LASP staff. “When we went to that telecon we went, ‘Whoa! They’re going to correct a manufacturing defect with an operational workaround,’ which
wasn’t unheard of,” says veteran satellite controller Jack Faber, an operations engineer who also teaches satellite control at the University of Colorado. “The bottom line was LASP is going to have to do a lot of work.”
The satellite is steered not by rockets but by electric-powered reaction wheels, which spin at differing rates to create a predictable torque that changes the direction in which the satellite points.
Since ICESat studies the changes in glaciers, volcanoes, and river basins that might be off its orbital track, LASP controllers must be ready to turn it to face targets of opportunity. Now that ICESat is run intermittently, the controllers have to work harder during the limited time. Controllers must upload aiming commands approximately once a week instead of once a month, as was the original plan.
ICESat’s laser campaigns are intense affairs in which controllers closely monitor the temperature of the laser subsystems for signs of trouble. Each time the satellite comes into range of a ground station, controllers have about 12 minutes to send commands and download the all-important temperature readings.
On one sunny afternoon at LASP, ICESat has risen above the horizon north of Alaska and into range of the Svalbard ground station in the Norwegian Arctic.
Faber and Chris Bunch, a 22-year-old mechanical engineering student, are ready to make contact with the craft, and Bunch is twirling a pen nervously in one hand.
Faber’s graying beard and jeans may look typically Boulder, but he’s anything but casual about running the operations center. He once famously booted the LASP director out of the control center for being distracting during the critical moments after a satellite launch.