Dr. Neil deGrasse Tyson is an astrophysicist who has become one of the best informal educators in the nation – possibly the best, when it comes to space science.

That expertise does not necessarily carry  over into other fields, such as politics, however. Dr. Tyson’s call for doubling the size of NASA’s budget to 1% of Federal spending, which inspired a public petition, was naive at best.

Making “percent of Federal spending” a figure of merit for any agency, including NASA, is a flawed idea. Space programs should be funded (or not funded) on their own merits, on the basis of an entitlement.

No other Federal program is funded on a “percentage” basis. To ask that NASA be funded on such a basis suggests that its budget level cannot be supported on its merits, which is a dangerous thing for NASA’s supporters to suggest. It would be even more dangerous if the idea of percentage entitlements caught on. There are probably 200 special-interest groups that would suggest their program should have 1% of the Federal budget, most of them with far more political clout than NASA. There’s no way NASA would come out on top.

That would be true even if times were good economically, but times are not good. To suggest doubling the size of NASA’s budget in today’s economic climate suggests that Dr. Tyson is out of touch politically.

It wouldn’t be the first time he has appeared out of touch. In 2004, Dr. Tyson was one of the members of the Aldridge Commission on space policy, which declared that human spaceflight would “remain the providence [sic] of government” – in a report issued shortly after SpaceShip One became the first private craft to be piloted into space.

In fairness, Dr. Tyson may not have fully read the entire report and realized what he was signing. Others apparently did not. Dr. Paul Spudis, a lunar scientist and another member of the Commission, has  defended that statement, saying it only applied to human spaceflight beyond Earth orbit. The text of the written document  does not support that claim, however.

A more fundamental question might be why astrophysicists and planetary scientists are asked to decide policy on human spaceflight. This seems to come from the popular misconception that spacecraft are developed by “rocket scientists.” But, of course, spacecraft are not developed by scientists. They are developed by engineers. We don’t expect geologists to design trucks or be experts on trucking policy. We don’t expect oceanographers to know how to design ships or run a shipping line. And we don’t ask meteorologists to design a jet fighter or run the Air Force. Why, then, do we expect astronomers and planetary scientists to be experts on what sort of human spaceflight capabilities the United States should develop?