NASA satellites often continue to provide important Earth observations long after the end of their originally planned and funded mission lifetimes (Box 2.1). The biennial NASA Earth Science Senior Review is tasked with evaluating the scientific value of missions that are currently or will soon be operating beyond their planned lifetime. The Senior Review also evaluates mission performance with respect to the health of the instruments and spacecraft, cost, and relevance to national interests.2 The first Senior Review in 2005 reviewed 12 extended missions and recommended continuation of 10 and termination of 2.3 The most recent review, in 2011, evaluated 12 extended missions, with all receiving “very high marks for Scientific Merit, Scientific Relevance, and Scientific Product Maturity.”4 All 12 missions were recommended for continuation, but with reduced funding for 2 missions owing to the degradation of some measurements.
Finding: The NASA Senior Review process is working well and provides a fair and open decision pathway for considering extended-life missions in a cost-effective way.
The 2007 decadal survey made its recommendations for new measurements and missions based on the assumed success of NOAA and NASA missions—sometimes referred to as “foundational” missions—that were already in development with launches expected in the early part of the decade following the survey release. These included the Ocean Surface Topography Mission (OSTM), OCO, Glory, Aquarius, NPP, Landsat Data Continuity Mission (LDCM), and Global Precipitation Measurement (GPM) missions.5 In the years following the release of the survey, NASA continued to focus much of its implementation efforts on completing these foundational missions (Table 2.1).
The successful launch of OSTM in 2008 was followed by two successive disappointments, the launch failures of OCO and Glory, in February 2009 and March 2011, respectively.6 These launch failures resulted in the loss of key observations of carbon dioxide (OCO), aerosols (Glory), and total solar irradiance (Glory). Subsequently, NASA authorized a replacement mission for OCO, OCO-2, which originally was scheduled for a 2013 launch but now has an uncertain launch date following the loss of Glory, which used the same Taurus XL launch vehicle as OCO. In June 2011, Aquarius/Satélite de Aplicaciones Científicas (SAC)-D, a mission partnership between NASA and the Space Agency of Argentina (Comisión Nacional de Actividades Espaciales) to measure sea-surface salinity, was successfully launched. Aquarius is the first dedicated satellite mission for observing the global salinity field needed for climate studies. Preliminary
2 The Senior Review process defines national interests as covering applied and operational (non-research) uses, including “operational uses, public services, business and economic uses, military operations, government management, policy making, nongovernmental organizations’ uses, etc.” See Appendix 2, “National Interest Panel Report,” in G. Hurtt (chair), A. Barros, R. Bevilacqua, M. Bourassa, J. Comstock, P. Cornillon, A. Dessler, G. Egbert, H.-P. Marshall, R. Miller, L. Ritchie, et al., NASA Earth Science Senior Review 2011, submitted to Dr. Michael Freilich, Director, Earth Science Division Science Mission Directorate, June 30, 2011, available athttp://www.science.nasa.gov/media/medialibrary/2011/07/22/2011-NASA-ESSR-v3-CY-CleanCopy_3x.pdf. The particular implementation of the Senior Review that is employed by NASA’s Earth Science Division is consistent with that recommended in the National Research Council report Extending the Effective Lifetimes of Earth Observing Research Missions (The National Academies Press, Washington, D.C., 2005).
4 See NASA, NASA Earth Science Senior Review 2011, 2011, p. 5.
5 The GPM mission consisted of two spacecraft—a core spacecraft and a low-inclination orbiter.
6 The two failures were attributed to the Taurus XL launch vehicle, thus creating significant uncertainty in the planning for launch vehicles for future missions for many years into the future (see in Chapter 3 the section “Access to Space”).