Goddard Earth Sciences Update 15 September 2000
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
GODDARD EARTH SCIENCES UPDATE
SEPTEMBER 15, 2000
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Dr. Vincent Salomonson, Earth Sciences Director
Goddard Space Flight Center
Greenbelt, MD 20771 (301) 614-5634
********************************************************************************
Goddard Earth Sciences Update” is a weekly bulletin to keep management
apprised of the latest accomplishments of Goddard’s Earth Sciences
Directorate. This newsletter is also accessible at
http://www.gsfc.nasa.gov/
Please forward comments or suggestions to: Lynn Chandler (301) 614-5562 or
Debra. L.Chandler.1@gsfc.nasa.gov
********************************************************************************
In this Issue: A Constellation of Microsatellites Promises to Help in a Range
of Geoscience Research
============================================================================
The technique of atmospheric limb sounding by radio occultation was
first developed in the 1960s and since used to study planetary atmospheres.
Applying this technique to the Earth’s atmosphere using the Global
Positioning System (GPS) as a source and a receiver in low-Earth orbit was
suggested as early as 1988, but was not tested until April 1, 1995, when a
proof-of-concept, low-cost experimental satellite known as
MicroLab-1 was launched into low Earth orbit to test the technique.
Now a full, near-operational satellite constellation mission is
under development: A joint Taiwan-U.S. scientific satellite project began
formally with the signing of a bilateral Cooperative Agreement in December
1997. Named ROCSAT-3/COSMIC, the project consists of a constellation of
eight low- Earth-orbit micro-satellites to be launched in late 2002. Each
of the micro-satellites will carry an advanced GPS (Global Positioning
System) receiver. The satellites will conduct atmospheric vertical
profile soundings for meteorology and ionospheric research using GPS radio
signals received minutes before a GPS satellite gets occulted by the Earth
from the line-of-sight of any of the micro-satellites. Each day
ROCSAT-3/COSMIC will produce approximately 4,000 globally uniform,
all-weather soundings of atmospheric radio refractivity, which can be
converted to information about the
atmospheric temperature and humidity profiles. Additional ionospheric data
will be obtained by an on-board Tiny Ionospheric Photometer and a tri-band
beacon transmitter. Also, the routine GPS tracking of the COSMIC satellite
orbits will provide new data for improving the solution of Earth’s gravity
field.
The total cost of COSMIC including the pre-launch spacecraft
development, launch, plus the first two years of post-launch operation is
estimated to be roughly $100 million. Because of COSMIC’s scientific,
technical, and educational merits, the National Science Council of Taiwan,
Republic of China, has committed approximately $80 million for
the project. The remaining 20% will be funded by the participating U.S.
agencies, including NSF, NASA, NOAA, Navy and Air Force. COSMIC will be
jointly implemented by UCAR and Taiwan’s National Space Program Office,
with the participation of JPL, U.S. Naval Research Laboratory, the
University of Arizona, Florida State University, and the University of
Texas. COSMIC represents the third space mission of Taiwan, and is also
named ROCSAT-3 (Republic Of China, SATellite mission #3) in Taiwan.
Reference: Kuo, Y. H., B. F. Chao, and L. C. Lee, A Constellation of
microsatellites promises to help in a range of geoscience research, EOS,
Trans. Amer. Geophys. Union, 80, 467-471, 1999.
****************************************
For further information contact:
Dr. Benjamin Fong Chao, 926
(301) 614-6104
chao@bowie.gsfc.nasa.gov
****************************************
