SORCE
September 2001 Project Summary
THE EOS SORCE mission is scheduled for a launch date of July 31,
2002. LASP is currently under contract with NASA GSFC for all the
phase C/D/E activities to accomplish the SORCE mission (excluding
launch vehicle procurement, which NASA is providing within the cost
cap). Orbital Sciences Corporation is under contract with LASP to
provide the S/C bus, S/C systems integration and test, and launch
services interface and launch support. The launch vehicle has been
procured through NASA. A Pegasus, launched in campaign mode, from
KSC, is on schedule.
Overall, the SORCE Program is still on schedule, but schedule slips
may be imminent due to the replacement, and retesting of diodes
and power converters on the SORCE GCIs (generic channel interfaces)
and the SORCE instruments. No descopes are required at this time.
SORCE managers and engineers attended the SORCE Delta Gyro Review
at Goddard Space Flight Center October 1st and 2nd, 2001. SORCE
is pleased with the outcome of the review, as SORCE has the "go
ahead" to fly in a "gyroless" mode.
Progress made on the SORCE program at LASP during the month of September
2001 includes the completion of the SURF calibration for SOLSTICE
A and the completion of the SOLSTICE And TIM Thermal Cycle. The
SOLSTICE B was successfully shaken on October 1st and 2nd. The MU
(microprocessor unit) bugs continue to be ironed out. Parallel testing
efforts for the SORCE instruments have proceeded in a remarkably
smooth manner. This is due to the combination of LASP's upgraded
class 10000 clean room facilities, the improved and enlarged MOBI
thermovac tank, commendable scheduling efforts, and the professional,
innovative, and dedicated efforts of the SORCE scientists, engineers
and students. The nearly complete instruments can be viewed through
the clean room windows, and the work is impressive. Also see our
web site, http://lasp.colorado.edu/sorce/index.htm
for more information and illustration.
SORCE Red Team activities continue to evolve, and the final detail
of the Red Team agreement between SORCE/NASA/Orbital and the Aerospace
Corporation are underway. As always, SORCE schedules are monitored
on a daily basis to meet the varying needs of the SORCE program.
While slack continues to dissipate, new solutions to difficulties
are created daily and incorporated into the agenda for SORCE.
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The top
concerns for SORCE include: 1) Diminishing slack in the instrument
integration schedule, 2) Late flight MU delivery resulting in
late test of flight software, 3) Reduction of slack for SIM characterization
and calibration, 4) Replacement of diodes and Interpoint power
converters on the SORCE GCIs and instruments, 5) Decreasing contingency
funds. Rescheduling, additional personnel, double shifting, efforts
to expedite parts, and rebudgeting have addressed these concerns.
Orbital
News
Progress has been good at Orbital Sciences Corporation, manufacturer
of the SORCE spacecraft bus. Orbital has verified the full core
avionics path and has sent commands from MAESTRO through the CEU
and APE to the PRE and has received appropriate telemetry during
the process. Orbital also successfully completed the crossstrapping
risk mitigation test and the hardware interface verification between
the 2 CEUs, (central electronic unit) and the APE (attitude power
electronics). Orbital has received both flight star trackers and
has received the software update for the EDU(engineering development
unit) tracker. The EDU tracker has been tested on the Flat Sat
(flat satellite). In addition, Orbital has loaded the flight software
build 3.0 to the bus to match the Flat Sat. Three of the four
RWA's (reaction wheel assemblies) have been integrated to the
bus. Orbital has also completed bench test (actuation) and integration
of the solar array pin pullers. In addition, Orbital attended
the Xcvr TRR (transceiver test readiness review). Subsequently,
one unit had a vibration failure: rework and retest have both
been successfully completed, and both units are currently in thermal
vacuum test. Orbital has added staff to the I&T (integration
and test), Flat Sat and SE (systems engineering) teams, and the
development of the BPT (bus performance test) is underway. Planning
and scheduling for double shifting begins the first of October
2001.
SORCE
Science News
In July, SORCE received news that NASA was going to "turn
off" UARS. This decision would have had major negative impact
on the SORCE science, and would have severely compromised the
relation of the SORCE ultraviolet irradiance to the time period
of UARS. If UARS were discontinued the following effects would
take place.
1) The long - term record of ozone and ozone change would not
have the required continuous and long-term record of solar forcing.
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