Much, and more, has been made of a letter released yesterday in which 49 former NASA astronauts, engineers and scientists admonish the space agency for taking a high-profile stance on climate change: namely that it’s happening due to human activity, and that it could have catastrophic consequences for the planet.

The crux of the letter is this:

As former NASA employees, we feel that NASA’s advocacy of an extreme position, prior to a thorough study of the possible overwhelming impact of natural climate drivers is inappropriate. We request that NASA refrain from including unproven and unsupported remarks in its future releases and websites on this subject.

The letter raises several issues that I would like to address.

First of all, that these men and women are skeptical about human-caused climate change is not surprising. I know a number of them and have interviewed several of them during the last five years in which I have covered NASA. Many, such as Walt Cunningham, Larry Bell and Harrison Schmitt, are well known skeptics.

What these men and women are not is climate scientists. Most are not even scientists in the sense that they have pursued scientific research during their careers, in any discipline.

What these men and women are are heroes. They are the space program’s greatest generation, which built the spacecraft that landed on the moon, first ventured into the heavens and laid the groundwork for the space shuttle and International Space Station programs. Many of them are also deeply unsatisfied with the current state of human spaceflight.

But this, again, does not make them experts in the field of climate change.

Secondly, let’s address their central assertion, that NASA’s viewpoint on climate change is an extreme one, and that man-made emissions of carbon dioxide are not having a significant warming effect on the planet.

It is true that there is vigorous debate in the scientific community about how significant warming will be in the coming century, but there is almost no disagreement among climate scientists that the planet is, and will continue to warm due to human emissions of greenhouse gases. A recent study of warming by previously skeptical scientists, in fact, found that the planet has continued to warm in accordance with scientific predictions.

Finally there’s the issue of NASA’s reputation.

The signatories of the letter are clearly upset with the political advocacy of James Hansen, who is probably the most prominent climate scientist in the United States, and heads NASA’s Goddard Institute for Space Studies. Hansen is in the habit of saying controversial things, such as climate change being a moral issue on par with slavery.

The letter writers say:

At risk is damage to the exemplary reputation of NASA, NASA’s current or former scientists and employees, and even the reputation of science itself.

This, I think, is a valid point. With a significant fraction of the U.S. public skeptical of climate science, a high profile position taken by the agency does hurt its reputation and could cost its science programs’ funding in the future.

But what is NASA to do? Many of its satellites are providing climate scientists the data they use to make their findings. Is the space agency to deny its own data?

Ultimately I believe this is probably part of a campaign to force Hansen out. Hansen has successfully resisted previous efforts to keep him quiet.