GLAST Update 22 June 2008
What is GLAST doing now?
We’re almost two weeks into the mission now, and things continue to go well, thanks to coordinated efforts across the team. Over the weekend, the spacecraft onboard attitude control software was further tested, with more challenging pointing sequences, autonomous repoints (once the instruments are activated and configured, they can request the spacecraft to change its orientation to keep a gamma-ray burst location detected onboard within the LAT field of view. This is similar to what is done on the Swift satellite), and rehearsals for Targets of Opportunity (TOOs — quick-response repointing of the observatory via ground command — which we expect to do for GLAST only under extraordinary conditions, but we want to be ready!). With such complex maneuvers, there have been a few interesting hiccups, all of which have been quickly understood and addressed. Everything continues to function in a very stable manner, and it has been great fun watching the observatory move from baby steps to sophisticated, graceful motions.
Operating a spacecraft
Jack Leibee, one of my colleagues at Goddard, is the Mission Manager for GLAST (he is also the Systems Manager). I asked him to write a few thoughts from his perspective about what it’s like to operate a satellite like GLAST:
Getting ready to operate a spacecraft, once it is in orbit, is a very demanding task. For the last year and a half, we have been testing between the GLAST Operations Center and the spacecraft to verify that all commanding procedures are correct, as well as confirming that we have all the tools necessary (e.g. plotting and displaying observatory data) to monitor the performance of GLAST. We conducted well over 300 hours of this type of testing, while GLAST was on the ground, executing around 400 command procedures. We also conducted 10 simulations, where we had all the folks who are going to support the mission execute the activation command procedures with a GLAST simulator. In some of the pre-launch tests, the Simulation Director inserted anomalies (e.g. a component fails) to test the operations team ability to respond: figure out what happened, why it happened, and how to recover back to normal operations.
During launch and ascent to orbit, we watched the spacecraft telemetry in the Mission Operations Center. We also saw the spacecraft react to separation from the rocket by pointing to the Sun and deploying the solar arrays (needed to provided power to the spacecraft.) Over the next 10 days we have been turning on spacecraft components and checking out the spacecraft (e.g. Slewing (moving) the spacecraft to look at different points in the sky) to verify it meets requirements. This is all in preparation for the instrument turn on of the LAT and GBM in just a couple of days.
It has been an exciting and rewarding time for all of us as we see the results of everyone’s hard work and dedication.
In addition to regular status updates, you’ll be able to read about the GLAST Education and Public Outreach activities, as well as reports from other scientists working on GLAST from around the world about their hopes and expectations as the instruments are powered on and checked out. Please check back regularly.