--Michael King, EOS Project Scientist
On March 18, Mr. William Townsend, acting Associate Administrator for the Office of Mission to Planet Earth, announced the selection of winning proposals for end-to-end science missions known as Earth System Science Pathfinders (ESSP). Under the terms of the competition, these ESSP proposals included not only instruments and data analysis, but also spacecraft, launch vehicle, and satellite command and control systems, and were cost capped at $60 M for the first mission and $90 M for the second mission. These principal investigator-led missions are to be developed from approval to launch in just 3 years (for the first mission) with little direct NASA oversight, and are expected to yield exciting new science that complements, but does not duplicate, NASA Earth Observing System (EOS).
The Vegetation Canopy Lidar (VCL) mission, led by Prof. Ralph Dubayah of the University of Maryland, College Park, will provide the first global inventory of the vertical structure of forest canopies across the Earth using a multibeam laser-ranging lidar system. Through demonstration flights from aircraft Dubayah has already demonstrated the ability of penetrating the vegetation canopy so that not only the distribution of tree top height can be determined but also the surface topography beneath the forest understory, even in thick rainforest environments.
The Gravity Recovery and Climate Experiment (GRACE), led by Prof. Byron Tapley of the University of Texas, Austin, employs a satellite-to-satellite laser tracking system between two spacecraft to measure the Earth's gravity field (geoid) and its time variability over five years. Such measurements of the Earth's geoid are crucial for accurate long-wavelength ocean circulation processes and to the transport of ocean heat from the equator to poles, as is measured by radar altimetry missions such as TOPEX/Poseidon and Geosat Follow-on Jason-1. GRACE involves significant international participation by co-principal investigator Dr. C. Reigber from GeoForschungs Zentrum (GFZ) in Potsdam, Germany.
In addition, a backup mission was selected in the event that one of the selected missions runs into cost, schedule, or technical difficulties. Called the Chemistry and Circulation Occultation Spectroscopy Mission (CCOSM) and led by Prof. Michael Prather of the University of California at Irvine, this mission is aimed at better understanding how atmospheric circulation controls the evolution of key trace gases, aerosols and pollutants over time. It is based on Fourier transform spectroscopy techniques and would measure limb emission and solar scattering and transmission during sunrise and sunset events.
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 the July 1996 release of the ESSP Announcement of Opportunity (AO). The original announcement generated 44 proposals which were subsequently evaluated on the basis of scientific merit.
The total mission lifecycle cost to NASA of VCL is $59.8 M, including launch vehicle, and will be launched in Spring 2000 from a Pegasus launch vehicle. GRACE has an innovative teaming arrangement with GFZ which includes the provision of mission operations and a Russian booster for a Spring 2001 launch, reducing the direct costs to NASA, which will be $85.9 M. Finally, NASA has set aside 10% of the annual budget for the ESSP program to support innovative data analysis and research investigations resulting from data acquired during these missions, funds which will be allocated later based on a rigorous peer review process following launch of these missions.
On February 6 President Clinton submitted his budget for fiscal year 1998 (which begins October 1, 1997). This budget includes $1.417B for Mission to Planet Earth. Furthermore, due in large part to efforts by the administration as well as both parties of Congress over the past summer, the proposed budget represents both balanced and sustainable funding for NASA over the next five years. The final budget must still await hearings in the House and Senate authorization and appropriations committees over the next 6 months.
Data gathering is continuing for a biennial review of MTPE that should be held in Spring 1997. This review is an important element in periodically assessing the MTPE program status and direction in response to increased scientific understanding, evolving technology, new opportunities in the commercial, international, and operational arenas, and budget constraints. This review will focus both on progress made in MTPE/EOS since the National Academy of Sciences' Board on Sustainable Development review in July 1995, and will further consider (i) balance in the research & development program between basic and applied research, airborne science, modeling, and global observations, (ii) implementation strategies and scientific priorities for EOS Chemistry-1, (iii) ground system architectures for operation of future MTPE/EOS missions after the early release of software needed to support TRMM and EOS AM-1, (iv) strategies for the insertion of new technology through programs such as the New Millennium Program (NMP) and the instrument incubator program, (v) plans and opportunities for international, interagency, and commercial partnerships both in space-based and validation activities, and (vi) strategies for implementation of NASA-led missions.
Finally, I am happy to report that ASTER (Advanced Spaceborne Thermal Emission and Reflection radiometer) and CERES (Clouds and the Earth's Radiant Energy System) have been delivered to Lockheed Martin Missiles and Space, King of Prussia, Pennsylvania, for integration on the AM-1 spacecraft. These are the first two of five instruments that will fly on AM-1, still scheduled for launch in June 1998.