Under the direction of the Bush administration, NASA is cutting its Earth science program by $3.1 billion over the next five years, with the money directed toward renewed efforts to send people to the moon in preparation for a manned Mars mission. Last year, the agency dropped the phrase “to understand and protect our home planet” from its mission statement.

Knowing more about Mars is a worthwhile scientific endeavor. It can’t, however, come at the expense of critical research about our own planet and the dangers it faces from climate change.

Lawmakers must ensure that NASA continues to devote resources to studying Earth. Reinserting understanding the home planet in the agency’s mission would be a good first step.

Sen. Susan Collins plans to send a letter to the president making these points. She sent a similar letter to NASA last year.

The National Academies of Science last week warned that the ability to monitor and understand environmental events such as patterns of drought, hurricanes, volcanoes and retreating glaciers was at “great risk” because NASA was cutting back on Earth observing work. By 2010, the number of operating Earth-observing instruments on NASA satellites will be cut nearly in half under current budget constraints.

Much of the research funded by NASA is done at the country’s universities. Cutting funds for this research will eliminate opportunities for graduate students and university researchers, further eroding U.S. leadership in science and engineering, the National Academies warns.

University of Maine researcher Gordon Hamilton and graduate student Leigh Stearns use NASA satellite data to measure glaciers around the world. Ms. Stearns calculated that three of Greenland’s largest glaciers were moving three times faster than expected. Accelerating toward the ocean at 14 kilometers a year, the glaciers dump vast amounts of meltwater into the sea, which could cause a significant rise in sea level and change ocean currents and salinity.

The satellite they rely on, Terra, is aged and NASA has no plans to replace it. As professor Hamilton explained via e-mail from Antarctica, long-term measurements and observations are critical to understanding climate change. Scientists now have about 30 years of satellite data, the minimum for seeing patterns. Breaks in the data because of malfunctioning or nonexistent satellites would set back current research efforts.

Professor Hamilton also points out that the NASA mission statement and its research priorities were developed with a lot of input from the scientific community. Now, without such input, the priorities and mission have been changed.

Lawmakers can fix this by first restoring the agency’s mission statement and second ensuring the agency devotes adequate funds to Earth research.