Jan. 24, 2000
Status 24 January 2000 The Terra Project is hoping to re-start the orbit ascent burns next Monday, January 31. A final decision on how and when to proceed is expected later this week after the results of some new tests have been analyzed. Spacecraft engineers have concluded that unexpected behavior of several thrusters during the January 11 burn taxed the spacecraft attitude control system, and short test burns are scheduled for today and tomorrow to gain more insight into Terra's "attitude problem". One test being performed is reorientation of the solar array during the burn to minimize torque around the pitch axis. Meanwhile, the countdown continues toward acquisition of the first "science" data from MISR this Wednesday, January 26. The initial camera output will be "dark" data, since the cover is still closed. Instrument activities for Wednesday have been scheduled to occur during contacts with the spacecraft from 6:48 AM - 7:45 AM PST and 8:11 AM - 8:51 AM PST (with later contacts available if necessary), and include the following: *Putting MISR in the "pre-memory load" configuration. This will turn off the cameras and optical bench heaters. The instrument will begin to cool down, and the "outgassing" phase will officially come to a close.
*Uploading the flight software. This will be followed by a read-out of the computer's memory to verify that the load took place correctly. MISR's computer will then be commanded to "jump" from the current set of operating instructions to the new software instructions.
*Commanding MISR to "global" mode. This is the most commonly used science operating configuration of the instrument. It turns all the cameras back on, but science data and other engineering information will now be provided over the "high rate" data channel.
*Commanding the optical bench and focal plane heaters to their normal operating set points. For the optical bench this is 5 degrees Centigrade, and for the focal planes is -5 degrees Centigrade. Because the "thermo-electric" coolers will not be turned on until Thursday, January 27, the focal planes will initially not get as cold as the set point and are expected to run at perhaps 7 degrees C. Intensive preparations for these events by the MISR team and others who work closely with us are happening at three locations: *The EOS Operations Center at the Goddard Space Flight Center in Maryland. This is where the instrument sequence planning and command and monitoring activities are taking place.
*The MISR Science Computing Facility at JPL in California. Data analysis plus development and checkout of core components of the data processing software are concentrated here, along with instrument engineering support.
*The Atmospheric Sciences Data Center at the NASA Langley Research Center in Virginia. This is our data conduit and is where the majority of MISR data will be processed, distributed, and archived once the mission enters the "operational" phase. Daily coordination meetings are occurring between all three of these centers, and everyone is working hard to make sure our systems are ready. Checkout of spacecraft navigation data and other ancillary information needed for processing the science data is already underway. You can see earlier status reports by checking the "News" link of the MISR web site at
http://www-misr.jpl.nasa.gov.
David Diner