MESSENGER Shipped to Goddard for Prelaunch Tests
Less than six months from its scheduled launch to Mercury, NASA's MESSENGER spacecraft is set for the next round of tests to
prepare it for the first orbital study of the innermost planet.
Engineers prepare the MESSENGER spacecraft for a vibration test. Conducted on a shake table, the
test checks the spacecraft's structural integrity by simulating the rough ride atop a launch vehicle. MESSENGER's mirrored solar panels are folded
in on the sides of the spacecraft; the long post in the center is the folded boom for MESSENGER's Magnetometer instrument.
MESSENGER was shipped today from the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, MD, where it was designed and built,
to the environmental testing facilities at NASA's Goddard Space Flight Center in Greenbelt, MD. The 20-mile delivery capped nearly four years of
detailed design, assembly and testing on one of the most complex spacecraft APL has ever built. With features ranging from a lightweight
composite structure and miniaturized instruments to a heat-radiation system and protective ceramic-fabric sunshade, MESSENGER (short for MErcury
Surface, Space ENvironment, Geochemistry, and Ranging) is well equipped for a 5-year cruise through the inner solar system and a yearlong study
of Mercury starting in July 2009.
"We're sending a spacecraft to orbit a planet where the sun is 11 times brighter than what we see on Earth and temperatures can climb past 800
degrees Fahrenheit," says MESSENGER Project Manager David G. Grant, of APL. "This is an incredible engineering and scientific challenge that no one
has ever tried before, and the team is doing all it can on the ground to make sure MESSENGER succeeds at Mercury."
This week engineers finished the first of MESSENGER's "shake and bake" tests, checking the spacecraft's structural strength atop large vibration
tables at APL. Over the next 10 weeks at Goddard the team will check MESSENGER's balance and alignment; put it before speakers that simulate the
noise-induced vibrations of launch; and seal it in a large thermal-vacuum chamber that duplicates the extreme heat, cold and airless conditions of
space. In March, MESSENGER will be sent to Kennedy Space Center/Cape Canaveral Air Force Station, FL, and prepared for its May 2004 launch aboard a
Boeing Delta II rocket.
"Each part of the spacecraft has passed individual vibration and environmental tests, and under tougher conditions than we expect they will see
at Mercury," says James C. Leary, MESSENGER mission systems engineer at APL. "Now we're looking at MESSENGER as a whole system. By the time it launches
MESSENGER will have been thoroughly tested."
Carrying seven scientific instruments - including a camera, laser altimeter, magnetometer and several spectrometers - the solar-powered MESSENGER
will image Mercury globally for the first time. It also will gather data on the composition and structure of Mercury's crust, its geologic history,
the nature of its thin atmosphere and active magnetosphere, and the makeup of its core and polar materials. While cruising to Mercury the spacecraft
will fly past the planet twice - in 2007 and 2008 - snapping pictures and gathering data critical to planning the orbit study.
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