WASHINGTON — The number of U.S. satellites watching Earth is expected to plummet by 2020, and weather forecasting, including hurricane tracking, could suffer as a result, a new report warns.
The study, released last week by the nation's top science advisors, estimated that the fleet of science satellites operated by NASA and the National Oceanic and Atmospheric Administration would "decline precipitously" from a peak of 110 probes last year to fewer than 30 in 2020.
The drop is a result of several factors, including budget problems and rocket accidents, and scientists said the United States risked blurring its vision of Earth if it did not act quickly to replace satellites expected to die during the next eight years.
"Consequences are likely to include slowing or even reversal of the steady gains in weather forecast accuracy over many years and degradation of the ability to assess and respond to natural hazards," investigators with the National Academies said.
These satellites track a broad range of environmental markers, including the thinning of ice sheets and changes in cloud cover and temperature.
But budget problems, both internal and external, are expected to prevent the agencies from maintaining the size of the current fleet.
No major funding increases are planned for NASA and NOAA, which get about $17.7 billion and $5 billion each year, respectively, and cuts could be coming, given Washington's newfound push for austerity.
Officials with NASA and NOAA, though acknowledging the challenges, said the satellites would remain effective.
"We are committed to continuing to advance the United States' Earth-observing research capability and the benefits these activities provide to our nation and abroad," NASA spokesman Dwayne Brown said in a statement.
But several weather experts said they were already concerned.
One major loss in recent years was the 2009 malfunction of a satellite named QuikSCAT, which measured the speed and direction of ocean winds, helpful for hurricane forecasters.
Efforts to replace QuikSCAT have stalled, and meteorologists said its absence had forced them to rely on less accurate instruments.
"This has had a big impact at looking at winds," said Shuyi Chen, a meteorology and oceanography professor at the University of Miami.
She said that the failure to replace QuikSCAT had made it tougher to find tropical depressions — the first step in a storm's evolution into a hurricane — and that the meteorology community was concerned about the slow pace of launching a replacement.
"The worry is that we have no planned missions on the horizon," Chen said.
NOAA has all but abandoned attempts to replace QuikSCAT and instead is drawing data from a similar satellite operated by India's space agency.
Another obstacle cited in the National Academies report was the potential loss of the Cosmic network of six satellites, which uses GPS data to help gather information about temperature and water vapor.
"It has a demonstrable impact on hurricane forecasting," said Rick Anthes, an atmospheric scientist and one of the report's coauthors.
These satellites will reach the end of their design life this year, and a planned replacement network of 12 satellites won't be launched until at least 2015.