Image courtesy GRACE Science Team NASA, German Aerospace Center,
University of Texas Center for Space Research, and GeoForschungsZentrum Potsdam.
The first image released from the Gravity Recovery and Climate
Experiment (GRACE), a joint NASA-German Aerospace Center mission,
graphically illustrates the sensitivity of the mission’s twin spacecraft
to changes in Earth’s gravity.
Color gradations in the image measure changes in the distance
between the GRACE spacecraft as they orbit overhead approximately 220
kilometers (137 miles) apart. Such variations are caused as the
spacecraft fly over Earth’s uneven gravity field, for example, when
GRACE travels over mountain ranges or undersea trenches. Earth’s largest
spatial features (those covering the largest areas of Earth) have been
removed from this image so that such smaller features can be
highlighted. GRACE’s extremely sensitive microwave ranging
instrumentation is capable of measuring variations at the micron, or
millionth of a meter, level.
The data for this and similar images will be processed by the GRACE
science team to produce precise maps of Earth’s gravity field.
Preliminary maps of Earth’s geoid, or mean gravity field, are expected
to be available to researchers in the spring of 2003.
For more information, read:
NASA’s First Gravity Mission Image Depicts a Bumpy Ride
GRACE fact sheet
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This image originally appeared on the Earth Observatory. Click here to view the full, original record.