At $2.5 billion and counting, the Curiosity rover is one of NASA’s costliest projects ever. And landing it was an unprecedented engineering challenge: taking a vehicle twice as long and five times as heavy as its predecessors, and slowing it from 13,200 mph to a soft landing in the space of seven minutes.

So it’s a hell of a neat trick that NASA just pulled off, and it’s sure to generate a lot of amazing video.

And yet, Houston — and Washington — we have a problem. By the end of the year, the Congressional Budget Office warns, federal debt will approach 70% of GDP, near the post-World War II high. In 25 years, CBO projects, health care and retirement outlays will consume nearly as large a share of the economy as the entire federal government does today.

This is why we can’t have neat things.

True enough, NASA’s $18 billion 2012 budget isn’t, by itself, what stands between us and our fiscal day of reckoning. But the federal government’s terrifying balance sheet argues for eliminating every nonessential line item. Curiosity’s mission is to test Martian soil for microbial life. If it’s there, says NASA’s James Green, then we’ll “have to rethink our place in the universe.” Rate the debate

Helping us “rethink our place in the universe” is not, I submit, one of the essential functions of the federal government.

Common sense dictates that if we’re going to spend tax dollars on scientific research, it’s better spent where it can benefit human beings. We spend over three times as much on interplanetary “bridges to nowhere” than on cancer research.

What benefits the American taxpayer gets from NASA’s foraging for new frontiers are, says economist and former NASA researcher Robin Hanson, “mostly like the pyramids … national prestige and being part of history.”

Wonderful things, to be sure, but they’re luxury goods in an age of austerity.