Too few. The Aquarius mission, launched in June 2011, is one of NASA's recent success stories. But a National Research Council report says that with many older missions failing, U.S. Earth-observing systems are facing a rapid decline.
The ability of U.S. scientists to monitor changes in the planet's climate, natural hazards, and land surface continues to deteriorate, warns a report
from the U.S. National Academies' National Research Council (NRC) that was released today. Aging satellites are being replaced too slowly, the report
concludes, and by 2020 the country may have only 25% of its current observing capacity.
The new panel was asked to review progress since the NRC's decadal survey of NASA's Earth-observing satellite missions was completed in 2007. That
survey cautioned that the U.S. observation program was at risk. NASA has attempted to uphold the priorities outlined in the decadal survey, the
committee notes. But the observation network has suffered as long-running missions end and new missions are lost, delayed, or canceled.
NASA has had some notable successes in keeping with the vision, the report notes. The Ocean Surface Topography Mission, launched in 2008, measures sea
surface heights to help understand ocean circulation, climate change, and sea level rise. The Aquarius mission, launched in June 2011, has produced its
first monthly maps of global ocean salinity. In addition, the National Polar-Orbiting Operational Environmental Satellite System Preparatory Project,
launched in October 2011 to improve short-term weather forecasts, is bridging a data gap until the National Oceanic and Atmospheric Administration's
(NOAA's) Joint Polar Satellite System program gets under way in 2016.
"NASA headquarters has been doing a very good job with a difficult situation," says oceanographer Antonio Busalacchi, director of the Earth System
Science Interdisciplinary Center at the University of Maryland, College Park, and a member of the NRC committee issuing the new report. "But given
extenuating factors, the [vision of the] decadal survey will not be in place by 2020."
The biggest extenuating factor is a lack of money. The decadal survey had assumed that the administration's Earth science budget would be restored to
2002 funding levels of $2 billion per year; instead, since 2007the budget has never risen above $1.5 billion. That shortfall has made it impossible to
execute the recommended program, the report notes. But the network has also been weakened by lost satellites, failed launches, and a lack of
medium-class launch vehicles to deliver the satellites to space. (The only currently produced medium-class launch vehicle, the Taurus rocket, failed in
three of its last four launches, including the 2009 Orbiting Carbon Observatory and the 2011 Glory launches.)
And "mission creep"—escalating costs as scientific requirements for missions expand during development—has also taken its toll. To bring mission
costs down, the committee recommends considering mission cost caps. At the same time, the committee recommends considering missions as part of a total
package, rather than considering the scientific benefits and costs of each mission in isolation. "Individual missions may have a reduction in science
capability, but for the greater good," Busalacchi says.
The survey had also assumed that several environmental satellites managed by NOAA would have complemented the fleet operated by NASA. But, with NOAA
facing its own budget cuts, those missions didn't materialize.
Rather than pointing the finger at NOAA, Busalacchi says, the committee is hoping that its report highlights the urgent need for an overarching
national strategy of Earth observation. The responsibility for developing such a strategy, he adds, is "above NASA, and above NOAA. It's at the [White
House] Office of Science and Technology Policy level. The course we are on is obvious, and it's not sustainable."