U.S. fleet of climate satellites is shrinking

Shrinking satellites
Meanwhile, the list of delayed, downsized and canceled satellites is a long one:

• NASA’s Earth Observing System was conceived in the 1980s as a 15-year program that would collect comprehensive data about the planet’s oceans, atmosphere and land surface. It was originally intended to send three generations of spacecraft into orbit at five-year intervals, but budget shortfalls limited the project to only one round of launches.
• Landsat, a series of satellites that have provided detailed images of the ground surface for more than 30 years, is in danger of experiencing a gap in service. Landsat 7, launched in April 1999, is scheduled to be replaced by a next-generation satellite in 2011. But if the existing satellite fails before that date and NASA has not developed a contingency plan, scientists, land managers and others who depend on Landsat images could be out of luck.
• The launch of a satellite designed to measure rainfall over the entire Earth, the Global Precipitation Measurement mission, has been pushed back to 2012. But the satellite it is designed to replace, the Tropical Rainfall Measuring Mission, can’t possibly last that long. That means there will be a period of several years when scientists have no access to the accurate global precipitation measurements that help them improve hurricane forecasts and predict the severity of droughts and flooding.
• In December, scientists working on the Hydros mission received a letter canceling their program. They were developing a satellite that would measure soil moisture and differentiate between frozen and unfrozen ground, an increasingly important distinction since melting of the Arctic permafrost has accelerated over the past several decades. The satellite also would have improved drought and flood forecasting.
• Last month Scripps’ Valero was notified that the Deep Space Climate Observatory, a project he has led for more than seven years, would be canceled. The spacecraft has already been built, but NASA is reluctant to spend the $60 million to $100 million it would cost to launch and operate it.

“It would be a tremendous return in science on the dollar,” Valero said.

The observatory would have provided valuable information about how clouds, snow cover, airborne dust and other phenomena affect the balance between the amount of sunlight Earth absorbs and the amount of heat energy it emits. And because it would have hovered between Earth and the sun at a distance of roughly a million miles, it would have been able to observe the entire sunlit surface of the planet constantly. Such observations could greatly enhance scientists’ understanding how much the planet has warmed in recent years and help them predict how much warmer it will get in the future.

Four- to seven-day forecasts at risk
Finally, a new generation of weather satellites being developed jointly by NASA, the Department of Defense and the National Oceanic and Atmospheric Administration has gone so far over budget that federal law requires a review of whether it is worth continuing. Even if the program does survive, the first spacecraft in the National Polar-Orbiting Operational Environmental Satellite System can’t be launched until at least 2010, and probably 2012.

The current generation of polar-orbiting weather satellites is critical to weather forecasting because it offers a complete picture of the planet every six-hours. That detailed coverage is especially important for developing four- to seven-day forecasts, because it gives meteorologists the ability to track weather systems as they evolve in both time and space.

Weather forecasts could be compromised if the launch of the final satellite from the previous generation of polar orbiters, scheduled for late 2007, fails. The chances of a satellite failing on launch are typically about 10 percent.

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