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are
working on visualization techniques to present the final
real data from SORCE via the Web.
Work
is continuing on the SORCE web page, with small changes
occurring daily. As the launch date nears, the data collection
and science will be a prominent feature on the site. The
web page will also meet the needs of the non-technical curious
person, and public educators teaching at many levels. The
July Steamboat SORCE Science Working Group Meeting summary
can be found on SORCE's web page. This summary will also
be appearing in the July-August issue of The Earth Observer,
the EOS Project Science Office bi-monthly publication.
Orbital
Sciences Activity -
The solar array panel illumination tests were successfully
completed at the end of July, and the solar arrays were
removed to prepare for the Thermal Vacuum Testing. Additional
preparations included thermocouple installation (218 total!),
thermal blanket installation, and instrument module taping
and bagging.
After
a few minor delays, unrelated to instrument or spacecraft
performance, the SORCE spacecraft went into the Thermal
Vacuum Chamber on Friday, August 2. Following one last final
inspection and photos, the chamber doors were closed on
Tuesday afternoon, August 6, and the spacecraft was turned
on in preparation for the vacuum pump-down. When the pump-down
reached 10-5 Torr, the spacecraft was turned off and the
"bake-out" process began. The chamber was heated
to 50° C or 122° F to bake-out any contaminants
in the chamber before beginning any thermal tests. At the
same time, the tank pressure reached 10-6 Torr, where it
remained for the entire 3-week duration of the thermal vacuum
testing. This created a very special environment simulating
space. The vacuum pump will remain active at all times during
the thermal testing phase. After
several limited performance tests (LPTs) in the hot environment
to evaluate and measure instrument and spacecraft functionality
and performance, the next step was to follow the same procedure
to test in cooler temperatures. More LPTs were run at the
cold temperatures, before switching back to a hotter environment.
This transitioning between various survival temperatures
is similar to what will be happening to the spacecraft once
SORCE is launched into orbit. The vacuum chamber exposes
the spacecraft to the most extreme minimum and maximum temperatures
it will encounter. Aliveness tests, which take about 15
minutes, are run after reaching all cold and hot |
SORCE
in the Thermal Vacuum
Chamber prior to testing.
plateaus,
checking the functionality of all moving mechanisms. The
thermal vacuum tests also include a series of comprehensive
performance tests (CPTs), which can take up to 18 hours
each.
Different
stimulation sources (tungsten and mercury bulbs, laser
diodes) are used in the chamber to simulate the sun exposure
to the instruments and to test the instrument reaction.
The instrument doors (shutters, filter wheels, prism positions,
etc.) are tested to make sure they are in working order
in all circumstances with a multiple of variables.
To
date, the testing has surfaced several interesting, but
minor issues. All of these present challenges have already
been or will be corrected by the end of September. At
no time during the thermal vacuum test have any thermal
limits gone outside of an acceptable range.
After
a thorough series of LPTs and CPTs on the spacecraft and
the instruments, the thermal vacuum tests are concluding
today, August 27. The chamber and spacecraft will be brought
to room equilibrium, the spacecraft turned off to avoid
electrical sparking, and the chamber will be vented with
nitrogen. Once the venting is complete, the chamber doors
will be opened and a post vacuum test inspection will
take place.
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