Where will the IMAGE satellite be assembled?

The Schedule of Pre-Flight Testing

At the August 1997 Mission Critical Design Review meeting, the layout of the payload was discussed by Jim Gaddy and specifically how the entire system was going to be tested before flight. One big requirement is that over 300 hours of test time have to be performed to avoid 'infant mortality' problems with new electronic components. There was some discussion over how many non-stop hours would be accepted, 80, 90, 100 hours, but 300 was decided by the IMAGE project as an acceptable goal. Also, this 300 hours would be the time the instrument component would be checked before delivery to Southwest Research Institute (SwRI) in January 1999. Each instrument will be subjected to its own set of tests after assembly, at the institution which hosts the instrument. Once each instrument is assembled on payload base plate, a whole new round of tests have to be performed to see how well the instruments work together without interfering with each other.

Once the instruments are delivered to SwRI, in February, 1999 the instruments will be assembled onto the upper deck of the payload bus in Building 178, a Class 1000 cleanroom, (less than one particle of dust bigger that 1 micron, per 1000 cubic foot of air) and tested to confirm that each instrument can execute all of its functions. By then, a series of test protocols have to be developed for each instrument with information specified about the expected ranges of proper operation. In March, 1999 the spacecraft will be checked to see how it operates under the electromagnetic interference expected from the RPI instrument. The SwRI EMI Facility will be used for this test. There is some discussion that such a test will not really tell us anything new because each instrument has, individually, been subjected to the same test under far more convenient conditions than a full-up spacecraft test. Avoiding this step would save time and money.

By the end of March, the spacecraft will be 'bagged' in a clean room for shipment to Lockheed Martin and by the second week of April it will be delivered. At Lockheed it will be unpacked and subjected to a variety of space-qualifying tests using the space environment simulator, vacuum, heat and vibration tests. Also, because the tests involve running each instrument and looking at the data it produces during each test, special 'Ground Support Equipment' (GSE) will have to be built to connect with the spacecraft to bypass the telemetry electronics on the ground. Even this equipment has to be specially designed and tested to make certain it is reading each instrument properly and able to upload commands properly.

Final Integration and Testing of IMAGE

All of the IMAGE 'Observatory' final integration and testing will be performed in June-August 1999 at Lockheed including a 'bake-out' to evaporate any gases from the hardware. It will be shipped in a truck and 'double bagged' and continuously purged with clean nitrogen gas to avoid contamination. The truck container will be braced to make certain that the walls never get closer than 4 inches to the spacecraft under worst case conditions. Every dimension of the truck cargo area has been measured to make absolutely certain that the payload with all of its wrappings can be easily inserted and removed from the vehicle with adequate wal, sealing and door clearances. It would be very embarrasing if the payload were 1/4 inch too wide for the satellite to clear the open doors!

By the end of August, 1999 it will be transported to the Western Test Range at the Vandenberg Air Force Base where the GSE equipment has been set up in one of the assembly hangars. The satellite will run through a series of Full Functional Tests including setting up a link between the Science and Mission Operations Center (SMOC) at GSFC and the GSE and a full test of the SMOC compatibility will be performed. The observatory will be located in a Class 10000 clean room with personel using anti-static garments, booties, caps, lint-free gloves and mouth covers. In a class 10000 cleanroom, the air is filtered so that there is less than one particle of dust bigger than 1 micron, per 10,000 cubic feet of air. Only essential personnel will be allowed to view the satellite under these conditions. The only access to the satellite will be through an umbilical cord carrying the power and telemetry lines. Also planned is a simulated countdown, launch and a sequence that follows the events during part of the first day in orbit. This will check how the satellite performs under launch conditions, verify the commanding sequences for powering up the spacecraft, and confirm that the spacecraft and all instruments continue to perform as designed.

A significant discussion in this session of the Mission of the CDR was who would be participating at Lockheed to do the testing, what support would be provided by Lockheed and what support is the responsibility of the IMAGE Program and its scientists. This has to be formally written up as a contract and statement of work to Lockheed so that everyone clearly understands the lines of responsibility, and who provides specific resources and a test protocal. Meanwhile, the SMOC has to be provided with spacecraft telemetry data during these tests to make certain that the command and data operations function correctly. During flight, the only difference would be that instead of an unbilical link to the payload at Lockheed and at Vandenberg, the SMOC would be in contact with the IMAGE CIDP via telemetry through the NASA Deep Space Network.


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