Missions Selected to Study Earth's Forests, Gravity Field
3/18/97
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RELAYED TEXT STARTS HERE:
Headline: Missions Selected to Study Earth's Forests,
Gravity Field
Source: Florida Today
Date: 3/18/97
Copyright 1997: FLORIDA TODAY
NASA NEWS RELEASE: 97-46
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).
The Vegetation Canopy Lidar (VCL) mission, led by Dr.
Ralph Dubayah of the University of Maryland, College Park,
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 structure, and
derived parameters such as global biomass with at least
ten times better accuracy than existing assessments.
The Gravity Recovery and Climate Experiment (GRACE), led
by Dr. Byron Tapley of the University of Texas at Austin,
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 through Dr. C. Reigber as Co-Principal
Investigator from GeoForschungsZentrum (GFZ) in Potsdam,
Germany.
A proposed mission to better understand how atmospheric
circulation controls the evolution of key trace gases,
aerosols and pollutants over time has been selected as an
alternate, should one of the selected missions encounter
serious cost, schedule or technical problems in their
early development phases. Called the Chemistry and
Circulation Occultation Spectroscopy Mission (CCOSM), the
mission would be led by Dr. Michael Prather of the
University of California at Irvine.
"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 Mission to Planet Earth 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. This 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 their team are ultimately responsible
for developing the flight mission hardware from selection
to a launch-ready condition in 36 months, with minimal
direct NASA oversight. The PI and their 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 lifecycle 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
dataset could enable great improvements in existing
ocean radar altimetry datasets, and retrospective
improvements of seasonal to interannual 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.
Other partners include Loral Space Systems, Palo Alto, CA;
the Jet Propulsion Laboratory, Pasadena, CA, and Dornier
of Germany to build the spacecraft.
CCOSM 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.
Partners in CCOSM include Lockheed-Martin Infrared Imaging
Systems, Lexington, MA; Spectrum Astro Inc., Gilbert, AZ;
and the Jet Propulsion Laboratory.
In addition to the funding support for the science team
associated with each mission, NASA has set aside ten
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 annother 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.