PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov
Contact: Mary A. Hardin
FOR IMMEDIATE RELEASE
March 18, 1997
JPL NAMED A PARTNER IN NEW MISSIONS TO STUDY EARTH
Small, lower-cost spacecraft to study the distribution
of Earth's forests and the
variability of its gravity field have been competitively selected
by NASA for development under a new Office of Mission to Planet
Earth program, called Earth System Science Pathfinders (ESSP).
NASA's Jet Propulsion Laboratory has been named a partner in the
gravity mission and in an alternate atmospheric chemistry
mission.
JPL will conduct the mission design and instrumentation on
the Gravity Recovery and Climate Experiment (GRACE), led by Dr.
Byron Tapley of the University of Texas at Austin. GRACE employs
a satellite-to-satellite microwave tracking system between two
spacecraft to measure the Earth's gravity field and its time
variability over five years. Such measurements are directly
coupled to long wavelength ocean circulation processes and to the
transport of ocean heat to Earth's poles. GRACE includes major
international cooperation with participation from Dr. C. Reigber,
co-principal investigator from GeoForschungsZentrum (GFZ) in
Potsdam, Germany.
JPL has also been selected as a partner in a proposed
mission to better understand how atmospheric circulation controls
the evolution of key trace gases, aerosols and pollutants over
time. This mission was chosen as an alternate, should one of the
primary missions encounter serious cost, scheduling or technical
problems in its early development phases. Called the Chemistry
and Circulation Occultation Spectroscopy Mission (CCOSM), this
project would be led by Dr. Michael Prather of the University of
California at Irvine.
The first mission to fly as part of the Earth System Science
Pathfinders program is the Vegetation Canopy Lidar (VCL) mission,
led by Dr. Ralph Dubayah of the University of Maryland, College
Park. The mission seeks to provide the first global inventory of
the vertical structure of forests across Earth using a multibeam
laser-ranging device. VCL will enable direct measurement of tree
heights, forest canopy structures and derived parameters such as
global biomass, with at least 10 times better accuracy than
existing assessments.
"These exciting missions will deliver their first science
results in a little over three years, remarkably fast for such
capable spacecraft," said William Townsend, acting
associate administrator for the Mission to Planet Earth program
at NASA Headquarters, Washington, DC. "At the same time, they
will cost-effectively complement NASA's Earth Observing System
(EOS) program by addressing emerging research questions that will
further expand our scientific knowledge of the Earth.
"Science value per dollar was the top criteria in this
selection," Townsend added. "We also spent a great deal of
effort validating the realism of the proposers' cost
estimates and their technical readiness. For all of these
reasons, the alternate mission should be considered a very real
option should one of the selected missions unexpectedly
encounter major difficulties."
"It also is important to note that the three selected
missions collectively address all four major science research
priorities of the U.S. Global Change Research program: land
cover change, atmospheric chemistry, and both seasonal and long-
term climate change," said Dr. Ghassem Asrar, Earth Observing
System chief scientist at NASA Headquarters.
The ESSP selections were made from a group of 12
proposals that were evaluated in the second phase of a rigorous,
two-phased selection process that began less than
eight months ago with a July 1996 announcement of opportunity.
This original announcement generated 44 proposals, which were
initially reviewed for scientific
merit. The review resulted in 12 proposals that met the
requirements for the second phase of the ESSP evaluation.
As with NASA's Discovery program of small, focused space
science-oriented spacecraft, the underlying philosophy of ESSP is
to achieve maximum science value while complementing existing or
planned flight missions. In the "principal investigator" (PI)
mode for implementing ESSP, the single PI and his or her team are
ultimately responsible for developing the flight mission hardware
from selection to a launch-ready condition within 36 months, with
minimal direct oversight from NASA. The PI and mission team are
responsible for accomplishing the stated scientific objectives
and delivering the proposed measurements to the broader Earth
science community and general public as expediently as possible.
The laser mapping technique to be used by VCL, which was
pioneered by NASA in aircraft experiments several years ago,
should help resolve a major uncertainty in the scientific
understanding of the global carbon cycle, particularly the role
of terrestrial ecosystems in sequestering the atmospheric carbon
dioxide produced by industrial activities and automobile
exhausts. At the same time, the multibeam VCL lidar instrument
will generate a vast array of reference points for future surveys
of land topography, including the planned NASA-Department of
Defense Shuttle Radar Topography
Mission in 1999-2000. VCL measurements should also have
practical commercial applications in forestry management.
The total mission life-cycle cost to NASA of VCL is $59.8
million, including the launch vehicle. VCL will be launched in
spring 2000 on a Pegasus launch vehicle. Industrial partners in
VCL include CTA Space Systems, McLean,VA; Fibertek Inc., Herndon,
VA; and Omitron Inc., Greenbelt, MD, with participation by
scientists at NASA's Goddard Space Flight Center, Greenbelt, MD,
and several U.S. universities.
GRACE will provide a framework for studying the
gravitational signatures of gigantic, continent-sized underground
water reservoirs, or aquifers. It also will
provide a never-before-available perspective on global ocean
circulation and the time variability of Earth's overall external
shape, or geoid. This fundamental data set could
enable great improvements in existing ocean radar altimetry data
sets, and retrospective improvements of seasonal to inter-annual
climate change estimates.
Through an innovative teaming arrangement, GRACE's
German partner, GFZ, will provide mission operations and a
Russian booster for a spring 2001 launch, greatly reducing the
direct total cost to NASA, which is $85.9 million. In addition
to JPL, other partners include Loral Space Systems, Palo Alto,
CA, and Dornier of Germany to build the spacecraft.
The Chemistry and Circulation Occultation Spectroscopy
Mission would make at least 18 months of measurements of the
vertical distribution of more than 30 diagnostic trace gases and
aerosol properties. Such data will provide never-before-available
chemical and physical boundary conditions from which to model the
behavior of the chemistry of Earth's atmosphere, such as the
mixing of pollutants in the lower atmosphere. Measurements to be
acquired by CCOSM will be used in conjunction with general
atmospheric circulation models to assess the effectiveness of the
Montreal Protocol (i.e., the banning of chlorofluorocarbons and
other potentially harmful gases) on controlling the depletion of
atmospheric ozone.
In addition to JPL, partners in CCOSM include Lockheed-
Martin Infrared
Imaging Systems, Lexington, MA, and Spectrum Astro Inc., Gilbert,
AZ.
In addition to the funding support for the science team
associated with each mission, NASA has set aside 10 percent of
the annual budget for the ESSP program to support innovative use
and analysis of the observations resulting from the ESSP
missions. The intent is to utilize these funds to support
science data analysis and research investigations through an open
solicitation and peer review process once data from the ESSP
missions become available. NASA intends to solicit another set of
ESSP missions in the fall of 1998.
The ESSP program is a new element of NASA's Office of
Mission to Planet Earth, a long-term, coordinated research
enterprise designed to study the Earth as a global
environmental system.
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3/18/97 MAH
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