

They monitor the thickness of ice caps and sheets, the surface levels of lakes and oceans, the size of glaciers. They measure the amount of surface radiation and atmospheric water vapor, the depth of snow packs, the level of carbon dioxide in the atmosphere.

The climate sensors placed on U.S. weather satellites are our windows on a warming world.

But, because the Pentagon, NASA, and the National Oceanic Atmospheric Administration are scaling back a joint project to replace aging weather and climate satellites, scientists may soon be flying with one eye closed, and the fight to save the Earth will suffer a setback.

Instead of six new satellites, the agencies will launch just four, leaving enough room for weather forecasting equipment, but either eliminating or reducing the quality of seven essential climate sensors that scientists say are necessary for tracking climate change and studying global warming.

The problem is acute because a pair of 40-year-old satellites - one measures global vegetation and the other collects wind data for forecasting hurricanes and El Ninos - are reaching the end of their useable lives with no clear plan to replace them.

Admittedly, the satellite replacement program has been mismanaged. The project is $6 billion over budget and more than 18 months behind schedule. But it must be completed in full. To pull the plug now would, as the director of Climate Science Watch, a program of the Government Accountability Project, be "criminal negligence."

It's part of a dangerous trend at NASA, where the focus has shifted toward putting a human on Mars, while the space agency's budget for science missions has declined 30 percent in the past six years. For NASA, and for the Bush administration, it is both scientifically and morally bankrupt to fail to employ adequate resources toward identifying and solving the real and immediate threat of global climate change.

To put it bluntly, NASA should concentrate on ensuring our future on Earth before spending billions so that humans can go mucking about on another planet.