TES NEWS, Volume 4, Number 3, August 1995

Mars Global Surveyor TES Update: Looking good for April 1996, September 1997

by Greg Mehall, TES Systems Engineer, ASU

The last couple of months have been very productive as work on the Mars Global Surveyor (MGS) Thermal Emission Spectrometer (TES) continues at the Hughes Santa Barbara Research Center (SBRC) in Goleta, California. We remain on pace for an April 1, 1996, delivery to the spacecraft contractor, Lockheed Martin Astronautics, in Denver, Colorado.

The SBRC employees that are part of the TES team are working diligently on our agressive schedule. We are lucky to have many of the same people working on the MGS TES that designed and built the first TES for the Mars Observer mission. Many of these people are working extra hard to ensure timely completion of the schedule milestones. As the ASU system engineer, I have been spending most of my time in Santa Barbara. My interactions with the SBRC employees have shown me their devotion to delivering a quality instrument to Dr. Philip Christensen of ASU.

While our schedule has been a busy one, there still has been time for some fun. In June, Dr. Christensen came to SBRC and gave a lunchtime seminar about the Mars Global Surveyor mission and the investigations of Mars that he hopes to do with the TES instrument. This kind of interaction between ASU and SBRC has kept the project fun to work on, and is the main reason for the enthusiasm I have seen among the employees working on the project at SBRC. Working on the MGS TES instrument is a unique opportunity for the employees at SBRC to contribute to the scientific discoveries that will be made with TES once it reaches Mars.

Another exciting development came recently from our work with the Mission Operations people at the Jet Propulsion Lab (JPL) in Pasadena, California. At JPL, they are designing the aerobraking portion of MGS's mission, which takes place between arrival at Mars in September 1997 and the beginning of the mapping phase in January 1998. We are extremely excited that we will be able to turn on TES and observe Mars during the aerobraking period, allowing us to study Mars much earlier than expected. The observations we can make during this time will be unique because we can obtain data at different times of the day and at different resolutions than we can get once the mapping phase begins. The observations during this period will also reduce the risk of not getting any TES data, in the event that the spacecraft does not survive to the start of the mapping phase in 1998. This issue of obtaining data as early as possible became a critical concern after the loss of Mars Observer.

Plans for TES integration with the MGS spacecraft, scheduled for April 1996, continue to move forward. In June, Steve Silverman (TES Project Engineer at SBRC) and I went to the "MGS Spacecraft Assembly, Test and Launch Operations, Preliminary Design Review," held at Lockheed Martin in Denver. The meeting reviewed the preliminary design for integrating TES and other instruments with the spacecraft and its subsystems. This meeting was critical for seeing how TES will be connected to MGS and it's computers. The meeting also reviewed plans for testing and calibrating TES after it is on the spacecraft in Denver, an important phase of preparation for launch because we need to find out things such as whether there are vibrations or electromagnetic fields that might cause interference that can mess up the spectra obtained by TES.

As for fabrication of the new TES itself, work is progressing on schedule. We are almost ready to integrate the TES electronics module, which will run all of the uplink, downlink and controls of the TES. The electronic module consists of seven multi-layered electronic boards that have a lot of high reliability, space-qualified electronic components. These boards are now assembled and are nearly through with "board level testing." After the boards complete this testing, engineers will add the final bonding, radiation shielding, and coatings. Then the boards will be mounted into their mechanical housings (fabricated by the ASU Machine Shop) and the integration of these modules will begin in early August, a month ahead of schedule.

Assembly of the TES mechanical and optical components is also on schedule. All of the components on the aft optics plate have been installed and are currently being aligned. This is the part of TES that will generate the thermal infrared spectra that scientists will use to study the composition of the martian surface and atmosphere. The initial alignment of the aft optics plate components should be completed by mid-August. The full electronics module and optical/mechanical integration should occur in September if we continue to proceed with no major problems.

We are very excited about recent developments with TES; things are going very well. For more information, look to the November 1995 issue of TES News for my next update on the MGS TES. At that time, we will be almost done putting TES together, and will be moving toward the time where we test and calibrate the final, space-qualified instrument.

Back to Contents of TES News August 1995