[meteorite-list] MUSES-C Update - February 25, 2003

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:10:01 2004
Message-ID: <200304022341.PAA13211_at_zagami.jpl.nasa.gov>

http://www.isas.ac.jp/e/new/release/2003/03_03.html

MUSES-C Monthly Report No. 3
ISAS
February 25, 2003

>From January to early February, MUSES-C underwent a thermal vacuum test for
its flight model, the final important checkpoint before launch. As the main
feature of the explorer is that it uses ion engine propulsion, the test
focused on the large-output power equipment that is needed to run the ion
engine. The test was separated into two rounds. In the first round, we
verified the temperatures of and the validity of thermal control for the
individual on-board instruments by connecting the ion engine's acceleration
power to a simulated load. Verification of the temperature rise in the
bottom equipment, another main target of the test, was also made successful
by simulating approaching and landing sequences to the asteroid surface,
where the temperature is estimated to be about 100Ει. In the second round,
the first such experiment in the world, the flight model's ion engine was
actually activated and run up to ion acceleration. It was different from
the first round of the test in that the real engine itself was the load to
the acceleration power. MUSES-C employs the cluster-type ion engine
configuration. Fortunately, we could also confirm that each engine head ran
normally.

Although attracting little attention, power-constrained thermal control is
one of the new technologies applied to MUSES-C. In conventional satellites
and explorers, there is no guarantee that the heaters will not all start at
once, with power consumption consequently shooting up to maximum when the
temperature falls below the lower limit. In MUSES-C, since a constant
amount of power must be secured for the ion engine, a new control logic has
been defined for the computer to limit the maximum power consumption by the
heaters. Even when the electromagnetic valve for chemical propulsion causes
a momentary peak-power hike, the power-constrained thermal control system
responds by shutting down the heater power source for an instant. This is a
good example of new technologies used not only for major demonstration but
also for minor refinement. MUSES-C will be transported to the launch site
in Uchinoura in mid-March after pre-launch alignment, inertia data
measurement, and the final function test finishing by the end of February.
Received on Wed 02 Apr 2003 06:41:31 PM PST