Understanding the complex, changing planet on which we live, how it supports life, and how human activities affect its ability to do so in the future is one of the greatest intellectual challenges facing humanity. It is also one of the most important for society as it seeks to achieve prosperity and sustainability.
The decades of the 1980s and 1990s saw the emergence of a new paradigm for understanding our planet—observing and studying Earth as a system of interconnected parts including the land, oceans, atmosphere, biosphere, and solid Earth. At the same time, satellite observing systems came of age and produced new and exciting perspectives on Earth and how it is changing. By integrating data from these new observation systems with in situ observations, scientists were able to make steady progress in the understanding of and ability to predict a variety of natural phenomena, such as tornadoes, hurricanes, and volcanic eruptions, and thus help mitigate their consequences. Decades of investments in research and the present Earth observing system have also improved health, enhanced national security, and spurred economic growth by supplying the business community with critical environmental information.
Yet even this progress has been outpaced by society’s ongoing need to apply new knowledge to expand its economy, protect itself from natural disasters, and manage the food and water resources on which its citizens depend. The aggressive pursuit of understanding Earth as a system—and the effective application of that knowledge for society’s benefit—will increasingly distinguish those nations that achieve and sustain prosperity and security from those that do not. In this regard, recent changes in federal support for Earth observation programs are alarming. At NASA, the vitality of Earth science and application programs has been placed at substantial risk by a rapidly shrinking budget that no longer supports already-approved missions and programs of high scientific and societal relevance. Opportunities to discover new knowledge about Earth are diminished as mission after mission is canceled, descoped, or delayed because of budget cutbacks, which appear to be largely the result of new obligations to support flight programs that are part of the Administration’s vision for space exploration. In addition, transitioning of many of the scientific successes at NASA into operational capabilities at NOAA and other agencies has failed to materialize, years after the potential and societal needs were demonstrated, even as the United States has
announced that it will take a leadership role in international efforts to develop integrated, global observing systems.
The Committee on Earth Science and Applications from Space affirms the imperative of a robust Earth observation and research program to address such profound issues as the sustainability of human life on Earth and to provide specific benefits to society. Achieving these benefits further requires that the observation and science program be closely linked to decision support structures that translate knowledge into practical information matched to and cognizant of society’s needs. The tragic aftermath of the 2004 Asian tsunami, which was detected by in situ and space-based sensors that were not coupled to an appropriate warning system in the affected areas of the Indian Ocean, illustrates the consequences of a break in the chain from observations to the practical application of knowledge.
The committee’s vision for the future is clear: The nation needs to rise to the grand challenge of effectively enhancing and applying scientific knowledge of the Earth system both to increase fundamental understanding of our home planet and how it sustains life and to meet increasing societal needs. This vision reflects and supports established national and international objectives, built around the presidential directives that guide the U.S. climate and Earth observing system initiatives. Realizing the vision requires a strong, intellectually driven Earth sciences program and an integrated in situ and space-based observing system—the foundation essential to developing knowledge of Earth, predictions, and warnings—as well as better decision-support tools to transform new knowledge into societal benefits and more effectively link science to applications. The payoff for our nation and for the world is enormous.
EARTH OBSERVATION TODAY
The current U.S. civilian Earth observing system centers on the environmental satellites operated by NOAA;1 the atmosphere-, biosphere-, ocean-, ice-, and land-observation satellites of NASA’s Earth Observing System (EOS);2 and the Landsat satellites, which are currently managed under a cooperative arrangement involving NASA and the U.S. Geological Survey (USGS). Today, this system of environmental satellites is at risk of collapse. Although NOAA has plans to modernize and refresh its weather satellites, NASA has no plan to replace its EOS platforms after their nominal 6-year lifetimes end (beginning with the Terra satellite in 2005), and it has canceled, descoped, or delayed at least six planned missions, including the Landsat Data Continuity “bridge” mission.3
These decisions appear to be driven by a major shift in priorities at a time when NASA is moving to implement a new vision for space exploration. This change in priorities jeopardizes NASA’s ability to fulfill
See discussion at the NOAA Web site at <http://www.nesdis.noaa.gov/satellites.html>.
EOS is composed of a series of satellites, a science component, and a data system supporting a coordinated series of polar-orbiting and low-inclination satellites for long-term global observations of the land surface, biosphere, solid Earth, atmosphere, and oceans. See “The Earth Observing System,” at <http://eospso.gsfc.nasa.gov/>.
In accordance with congressional guidance and the Land Remote Sensing Policy Act of 1992 (PL 102-555), the Commercial Space Act of 1998 (PL 105-303), and the U.S. Commercial Remote Sensing Policy (April 25, 2003), NASA and the Department of the Interior/USGS initially planned to continue the Landsat-7 data series by implementing a Landsat Data Continuity Mission (LDCM) that would procure data from a privately owned and commercially operated remote sensing system. Following an evaluation of proposals, NASA declined to accept any offers and canceled this plan in September 2003. Per guidance from the White House Office of Science and Technology Policy, NASA then agreed to transition Landsat measurements to an operational environment through the incorporation of Landsat-type sensors on the National Polar-orbiting Operational Environmental Satellite System (NPOESS) platform. NASA also agreed to further assess options to mitigate the risks to data continuity prior to the first NPOESS-Landsat mission, including a “bridge” mission. Unless otherwise specified, the committee’s reference to cancellation of the LDCM is to this bridge or “gap filler” option, which would have launched a free-flying instrument to avoid a gap in data continuity between the already-degraded Landsat 7 and the launch of the first NPOESS-Landsat satellite in late 2009 or early 2010.
its obligations in other important presidential initiatives, such as the Climate Change Research Initiative and the subsequent Climate Change Science Program. It also calls into question future U.S. leadership in the Global Earth Observing System of Systems, an international effort initiated by the current Administration. The nation’s ability to pursue a visionary space exploration agenda depends critically on its success in applying knowledge of Earth to maintain economic growth and security at home.
Moreover, a substantial reduction in Earth observation programs today will result in a loss of U.S. scientific and technical capacity, which will decrease the competitiveness of the United States internationally for years to come. U.S. leadership in science, technology development, and societal applications depends on sustaining competence across a broad range of scientific and engineering disciplines that include the Earth sciences.
As a result of the recent mission cancellations, budget-induced delays, and mission descopes, the committee finds the existing Earth observing program to be severely deficient. The near-term recommendations presented below describe the minimum set of actions needed to maintain the health of the NASA scientific and technical programs until more comprehensive community recommendations are made in the final report of the survey. They address deficiencies in the current program at NASA and some of the emerging needs of NOAA and the USGS. The committee’s recommendations address issues in six interrelated areas:
Canceled, descoped, or delayed Earth observation missions;
Prospects for the transfer of capabilities from some canceled or descoped NASA missions to NPOESS;
The adequacy of the technological base for future missions;
The status and future prospects of NASA Earth science Explorer-class missions;
The adequacy of research and analysis programs to support future programs; and
Development of baseline climate observations and data records.
ACTIONS TO MEET CURRENT CRITICAL NEEDS
Proceed with GPM and GIFTS
Recently, six NASA missions with clear societal benefits and the established support of the Earth science and applications community have been delayed, descoped, or canceled. Two of these missions should proceed immediately:
Global Precipitation Measurement (GPM). The Global Precipitation Measurement mission is an international effort to improve climate, weather, and hydrological predictions through more accurate and more frequent precipitation measurements. GPM science will be conducted through an international partnership led by NASA and the Japan Aerospace Exploration Agency (JAXA). Water cycling and the availability of fresh water resources, including their predicted states, are of critical concern to all nations, and precipitation is the fundamental driver of virtually all water issues, including those concerned with national security. GPM is the follow-on to the highly successful Tropical Rainfall Measuring Mission, which is nearing the end of operations.4 It is an approved mission that has been delayed several times by NASA.
The committee recommends that the Global Precipitation Measurement mission be launched without further delays.
Atmospheric Soundings from Geostationary Orbit (GIFTS). The Geostationary Imaging Fourier Transform Spectrometer (GIFTS) will provide high-temporal-resolution measurements of atmospheric temperature and water vapor, which will greatly facilitate the detection of rapid atmospheric changes associated with destructive weather events, including tornadoes, severe thunderstorms, flash floods, and hurricanes. The GIFTS instrument has been built at a cost of approximately $100 million, but the mission has been canceled for a variety of reasons. However, there exists an international opportunity to launch and test GIFTS.
The committee recommends that NASA and NOAA complete the fabrication, testing, and space qualification of the GIFTS instrument and that they support the international effort to launch GIFTS by 2008.
Three other missions—Ocean Vector Winds, Landsat Data Continuity, and Glory—as well as development of enabling technology such as the now-canceled wide-swath ocean altimeter, should be urgently reconsidered, as described below.
Evaluate Plans for Transferring Needed Capabilities to NPOESS
Instruments on the following three canceled missions may be either reinstated as independent NASA missions as originally planned or replaced with appropriate instruments for flight on the National Polar-orbiting Operational Environmental Satellite System (NPOESS). This latter approach has both advantages (e.g., transfer of research capabilities to operational use) and disadvantages (e.g., decrease in instrument capability, gaps in data continuity).
Ocean Vector Winds. Global ocean surface vector wind observations have enhanced the accuracy of severe storm warnings, including hurricane forecasts, and have improved crop planning as a result of better El Niño predictions. Such observations are achievable from proven space-borne scatterometer systems. However, NASA has canceled the Ocean Vector Winds mission, a previously planned follow-on to the active scatterometer currently operating on the QuikSCAT mission, which has already exceeded its design life. NOAA is currently planning to use a passive microwave sounder, CMIS (Conical Scanning Microwave Imager/Sounder), which will be launched on NPOESS, to recover ocean wind measurements. Tests of the feasibility of this technique are underway based on use of a similar instrument on the Navy’s Windsat satellite.
Landsat Data Continuity. For more than 30 years, Landsat satellites have collected data on Earth’s continental surfaces to support Earth science research and state and local government efforts to assess the quality of terrestrial habitats, their resources, and their changes due to human activity. These data constitute the longest continuous record of Earth’s surface as seen from space. The Land Remote Sensing Policy Act of 1992 directs NASA and the USGS to assess various system development and management options for a satellite system to succeed Landsat 7. The president’s budget for NASA for FY 2006 discontinues plans for launch of this satellite system and instead directs NASA to assume responsibility for providing two Operational Land Imager (OLI) instruments for delivery to NPOESS (the second OLI is to be delivered 2 years after the first).
Glory. Glory carries two instruments—the Advanced Polarimetric Sensor (APS) and the Total Irradiance Monitor (TIM). Part of the framework of the president’s Climate Change Research Initiative, Glory was developed to measure aerosol properties (via the APS) with sufficient accuracy and coverage to quantify
the effect of aerosols on climate. Aerosol forcing is one of the most important sources of uncertainty in climate prediction. Glory would also monitor the total solar irradiance. Measurements of total solar irradiance are needed to understand how the Sun’s energy output varies and how these variations affect Earth’s climate. TIM would ensure continuity of this important time-series should the irradiance monitor on the Solar Radiation and Climate Experiment (SORCE) satellite fail prior to the launch of NPOESS.
The committee recommends that NASA, NOAA, and the USGS commission three independent reviews, to be completed by October 2005, regarding the Ocean Vector Winds, Landsat Data Continuity, and Glory missions.5 These reviews should evaluate:
The suitability, capability, and timeliness of the OLI and CMIS instruments to meet the research and operational needs of users, particularly those that have relied on data from Landsat and QuikSCAT;
The suitability, capability, and timeliness of the APS and TIM instruments for meeting the needs of the scientific and operational communities;
The costs and benefits of launching the Landsat Data Continuity and Glory missions prior to or independently of the launch of the first NPOESS platform; and
The costs and benefits of launching the Ocean Vector Winds mission prior to or independently of the launch of CMIS on NPOESS.
If the benefits of an independent NASA mission(s) cannot be achieved within reasonable costs and risks, the committee recommends that NASA build the OLI (two copies, one for flight on the first NPOESS platform6), APS, and TIM instruments and contribute to the costs of integrating them into NPOESS. APS, TIM, and the first copy of OLI should be integrated onto the first NPOESS platform to minimize data gaps and achieve maximum utility.
The reviews could be conducted under the auspices of NASA and NOAA and USGS external advisory committees or other independent advisory groups and should be carried out by representative scientific and operational users of the data, along with NOAA and NASA technical experts.
Develop a Technology Base for Future Earth Observation
Much of the recent progress in understanding Earth as an integrated system has come from NASA’s EOS, which is composed of three multi-instrumented platforms (Terra, Aqua, and Aura) and associated smaller missions.7 Initial plans, made in the 1980s, called for three series of each of the platforms to ensure a 15-year record of continuous measurements of the land surface, biosphere, solid Earth, atmosphere, and oceans. However, by the late 1990s, budget constraints and other factors led NASA to abandon plans for follow-ons to the first series of EOS satellites. Knowledge anticipated from analysis of EOS long-term data records depends now on a precarious plan to use instruments on the nation’s next generation of operational weather satellites—NPOESS, scheduled for launch in 2009, and a new GOES series, scheduled for
launch in 2012—foreign missions, and the occasional launch of small Explorer-class missions. In fact, aside from several delayed Explorer-class missions, the Ocean Surface Topography Mission (a follow-on to the current Jason-1 mission), and the Global Precipitation Measurement mission, the NASA program for the future has no explicit set of Earth observation mission plans.
The committee’s final report will include a prioritized list of new Earth observing missions and capabilities. In the meantime, a healthy scientific and technological base for future missions must be maintained.
Enabling technology base. The paucity of missions in active planning mode undercuts the observational capability for which a strong enabling technology base is essential. Particularly disturbing is the absence of development activities for identified measurement capabilities that have been extensively studied, vetted within the community, and endorsed by NASA. For example, interferometric synthetic aperture radar (InSAR) technology now exists in Europe and Canada to monitor small changes in Earth’s surface that might presage a volcanic eruption or an earthquake, but development of L-band technology will be required to overcome the limitations of current instruments for observing in vegetated areas. Radar interferometry (wide-swath altimetry) was also being developed to monitor coastal currents, eddies, and tides, which affect fisheries, navigation, and ocean climate, but a planned mission was canceled. Finally, the European Space Agency plans to launch in 2008 a mission to measure winds in the atmosphere using an ultraviolet laser, but in the United States active remote sensing techniques for such measurements are not yet at a comparable level of technology readiness.
The committee recommends that NASA significantly expand existing technology development programs to ensure that new enabling technologies for critical observational capabilities, including interferometric synthetic aperture radar, wide-swath ocean altimetry, and wind lidar, are available to support potential mission starts over the coming decade.
Reinvigorate the NASA Earth Explorer Missions Program
NASA developed its Earth System Science Pathfinder (ESSP) program as “an innovative approach for addressing Global Change Research by providing periodic ‘Windows of Opportunity’ to accommodate new scientific priorities and expand community participation in NASA Earth science activities. The program is characterized by relatively low to moderate cost, small to medium sized missions that are capable of being built, tested and launched in a short time interval.”8 ESSP missions were intended to be launched at a rate of one or more per year.
ESSP missions provide a mechanism for developing breakthrough science and technology that enables future societal benefits and for ensuring that human capital is maintained for future missions. For example, the Gravity Recovery and Climate Experiment (GRACE) mission measured time-varying gravity changes up to 100,000 times smaller than those measured previously and provided the first measurements of variations in groundwater storage at continental scales.9 New ESSP missions within this program need to be initiated on a frequent basis to fuel innovation,10 and missions must be launched soon after selection to keep the
See information on the Earth System Science Pathfinder program at <http://earth.nasa.gov/essp/>.
See M. Cheng and B.D. Tapley, 2004, “Variations in the Earth’s Oblateness During the Past 28 Years,” JGR-Solid Earth 109(N9): B09402. Also see “GRACE Science Papers” on the GRACE home page at <http://www.csr.utexas.edu/grace/publications/papers/>.
This approach corresponds to the original intent of the Earth System Science Pathfinder program, which solicited proposals every 2 years for satellite measurements that were outside the scope of approved Earth science missions. Proposals were solicited in all Earth science disciplines, from which two missions and one alternate were selected based on scientific priority and technical readiness.
technology from becoming obsolete. Some of the missions now being planned may not be launched until nearly 10 years after they were selected.
The committee supports continuation of a line of Explorer-class missions directed toward advancing understanding of Earth and developing new technologies and observational capabilities, and urges NASA to:
Increase the frequency of Explorer selection opportunities and accelerate the ESSP-3 missions by providing sufficient funding for at least one launch per year, and
Release an ESSP-4 announcement of opportunity in FY 2005.
Strengthen Research and Analysis Programs
The committee is concerned that a significant reallocation of resources for the research and analysis (R&A)11 programs that sustain the interpretation of Earth science data has occurred either as a result of the removal of the “firewall” that previously existed between flight and science programs or as an unintended consequence of NASA’s shift to full-cost accounting. Because the R&A programs are carried out largely through the nation’s research universities, there will be an immediate and deleterious impact on graduate student, postdoctoral, and faculty research support. The long-term consequence will be a diminished ability to attract and retain students interested in using and developing Earth observations. Taken together, these developments jeopardize U.S. leadership in both Earth science and Earth observations, and they undermine the vitality of the government-university-private sector partnership that has made so many contributions to society.
Strengthen Baseline Climate Observations and Climate Data Records
The nation continues to lack an adequate foundation of climate observations that will lead to a definitive knowledge about how climate is changing and will provide a means to test and systematically improve climate models. NASA and NOAA should enhance their observing systems to ensure that there are long-term, accurate, and unbiased benchmark climate observations.
The committee recommends that NASA, NOAA, and other agencies as appropriate accelerate efforts to create a sustained, robust, integrated observing system that includes at a minimum an essential baseline of climate observations, including atmospheric temperature and water vapor, spectrally resolved Earth radiances, and incident and reflected solar irradiance.
Finally, as recommended in previous National Research Council reports, an expanded set of long-term, accurate climate data records should continue to be produced to monitor climate variability and change. A climate data and information system for NPOESS is needed that will make it possible to assemble relevant observations, remove biases, and distribute and archive the resulting climate data records. A
corresponding research and analysis effort is also needed to understand what these records indicate about how Earth is changing.
The committee recommends that NOAA, working with the Climate Change Science Program and the international Group on Earth Observations, create a climate data and information system to meet the challenge of ensuring the production, distribution, and stewardship of high-accuracy climate records from NPOESS and other relevant observational platforms.
Today the nation’s Earth observation program is at risk. If we succeed in implementing the near-term actions recommended above and embrace the challenge of developing a long-term observation strategy that effectively recognizes the importance of societal benefits, a strong foundation will be established for research and operational Earth sciences in the future, to the great benefit of society—now and for generations to come.