To hear some NASA officials tell it, the U.S. National Polar-orbiting Operational Environmental Satellite System (NPOESS) platform can do it all. Not only can it host payloads that have been flying on separate civilian and military weather satellites since the early years of the space age, but it also can be calibrated precisely enough to provide research-quality climate data, accommodate a land imaging sensor and even carry a greenhouse-gas monitoring instrument that previously was supposed to fly on a mission dubbed Glory.

Pretty soon they’ll be saying NPOESS can wash the dishes and cure the common cold to boot.

Hyperbole? Sure. But it is no exaggeration to say that some U.S. government officials are stretching the limits of credibility in their efforts to justify throwing everything but the kitchen sink onto the NPOESS satellites.

Their motivation is not hard to see. NASA, armed with a presidential mandate to begin preparing for human missions to the Moon and Mars, without major funding increases, is looking to cut spending wherever it can. That makes programs such as Earth science and aeronautics, which do not contribute directly to U.S. President George W. Bush’s exploration vision, increasingly attractive targets to those wielding the budget knives.

Luckily, Congress does not seem to be buying many of the claims being made about NPOESS’ qualities as a super satellite, but at least some of this skepticism is driven by parochial considerations.

More telling is the recent National Research Council report “Earth Science and Applications from Space: Urgent Needs and Opportunities to Serve the Nation,” which questioned the feasibility of using NPOESS as a dumping ground for NASA’s Earth science measurements. The report further noted that NASA has few if any missions in the pipeline to replace the Earth Observing System satellites that originally were supposed to compile a 15-year data record with the goal of differentiating between natural and human-induced global climate changes.

With NASA realigning itself for Moon and Mars exploration, the time has come for an open and inclusive national policy debate about the agency’s future role in Earth science. House Science Committee Chairman Sherwood Boehlert (R-N.Y.) hit on the crux of the issue during an April 26 hearing on NASA’s Earth science program: If not NASA, then which agency, and with what money? Voicing skepticism about NASA’s put-everything-on-NPOESS strategy, Boehlert said he had not seen a realistic plan or funding profile for doing that.

The NPOESS satellite platform no doubt will be highly capable — it has to accommodate the different monitoring and data needs of the U.S. Air Force and the National Oceanic and Atmospheric Administration (NOAA). But it remains to be seen whether it can handle additional sensors that may have different requirements in terms of satellite orbits, operations and data distribution.

NASA and the White House nonetheless already have decided to rely on NPOESS as the host platform for the operational land imager, heir apparent to the Landsat thematic mappers that have documented land-use changes throughout the world since the 1970s. That plan is risky because of both technical issues and the fact that that there is a very strong chance that the first NPOESS satellite will not launch before the existing Landsat satellites stop returning worthwhile data.

There also are issues inherent in placing research instruments aboard operational satellites, and these are not limited to sensor calibration and data handling. What is the likelihood, for example, that NOAA and the Air Force would be willing to delay an NPOESS satellite launch to wait for a first-of-its-kind research instrument that has fallen behind schedule? The answer, of course, is that it is not even remotely likely.

Although widely viewed as an operational agency, NOAA also has an important institutional research function; fundamentally there is no reason why it cannot assume NASA’s role in environmental and climate change research. In fact, it could be argued that NOAA, given its Earth focus and weather satellite responsibilities, is the more appropriate agency to handle that mission.

But that case has to be made and subjected to scrutiny against the alternatives in a public policy forum. For NASA simply to say — as its recent actions suggest — that it doesn’t want to pay for Earth science research anymore just doesn’t cut it.

Also lacking is any kind of realistic plan for transferring NASA’s Earth science responsibilities to NOAA — assuming that is fairly judged to be the best course to take. And along with such a plan has to come funding, a budget that cannot be raided readily to cover cost overruns on another program or to shift money to higher-priority efforts.

The House Science Committee and the National Research Council have fired what should be taken as the opening salvo in a national debate that has been brewing ever since President Bush announced his exploration vision in January 2004.

It is time for NASA, NOAA and the White House to get involved in earnest. Earth science is of vital importance to the nation and the world. It should not be an afterthought or an add-on to an already complex program.