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'Lost in Space' missions

— "Never send a human to do a machine's job": It's one of my favorite quotes from Agent Smith in "The Matrix," and it also turns out to be a pretty close paraphrase of a space exploration dictum from engineer Gentry Lee, a veteran of NASA's Mars missions.

University of Maryland physicist Robert Park would agree with that dictum as well. He's a longtime critic of human space exploration, contending that robots can do the job more cheaply, more safely and more capably. That's why he's no fan of the international space station, as seen in this in-depth look at space station science.

So what would he spend the money on instead? He didn't hesitate to give three examples of robotic missions that could yield big payoffs but have been sidelined by NASA due to the agency's cost crunch:

The Deep Space Climate Observatory, a.k.a. DSCOVR, a.k.a. Triana, a.k.a. GoreSat. This satellite would continuously monitor Earth in several wavelengths to learn about our planet's absorption of solar energy, and the effect on global climate. The $100 million spacecraft has been built and is ready for launch, but the mission has been mothballed. Park said sending DSCOVR to the L1 gravitational balance point is "the most important thing we could be doing in space right now."

Park pressed for the mission to proceed in a New York Times op-ed piece earlier this year, and several other articles have bemoaned DSCOVR's descent into limbo. Park told me that determining the root causes of global warming is "the most important question facing mankind, and we've built the device to do it."

He suspects the problem may have something to do with the satellite's parentage: DSCOVR was the latest incarnation of a mission suggested by Vice President Al Gore back in 1998. At the time, the satellite was criticized as little more than a 24/7 source of pretty space pictures - an "ideological playtoy," in the words of Rep. Dana Rohrabacher, R-Calif. This timeline from NASA Watch makes it sound as if politics figured more prominently than science in the mission's genesis.

In any case, with the Republicans in charge of the White House as well as Congress, the prospects for "GoreSat" have definitely dimmed.

The Terrestrial Planet Finder, or an equally powerful space telescope by another name. The TPF would actually be a set of telescopes flying in formation, with their observations combined through a trick known as interferometry. Such a telescope could spot planets like Earth orbiting distant stars, and perhaps even conduct a chemical analysis of those planets' atmospheres to look for telltale signs of life.

"We are now in a position where we have the capability to build a real space telescope," Park said.

This PDF file from NASA estimates the cost of the TPF at about $1 billion, but the cost almost certainly would be more than that. The most recent plan called for the mission to be phased in as two chunks, with completion due in 2020 or so. There are big questions about the technological hurdles facing the project. But for astrobiologists, the TPF (or something like it, such as the European Space Agency's Darwin probe) is a must-have tool in the hunt for Earthlike planets.

Unfortunately for astrobiologists, their favorite pursuits were hard-hit in the latest NASA budget, and projects like the TPF were put on the back burner. There's a ray of hope, however: The House's version of the NASA budget bill adds $10 million to keep the TPF project alive for the next fiscal year.

The Europa orbiter would take a closer look at Europa, a mysterious moon of Jupiter that is thought to harbor a salty sea of liquid water beneath its globe-girdling crust of ice. The Galileo spacecraft found evidence for such an ocean - but the orbiter would carry radar-sounding equipment and other instruments that could delve more deeply into the mystery.

The mission went through several incarnations, one of the most recent being the nuclear-powered Jupiter Icy Moons Orbiter. NASA has shelved the idea for now, but Park says there's a "good chance" that a Europan ocean may actually contain some sort of extraterrestrial life. The House budget bill provides $15 million to fund preparations for an eventual Europa orbiter. You can traced the ups and downs of the Europa mission through this threaded discussion at UnmannedSpaceflight.com.

So those are Park's three top picks. "We ought to be getting on with it," he said. "Instead, we're squandering our resources on God knows what."

Would you agree with this list? Do you think sending people to the moon, Mars and beyond is more important? (Most of the people who have participated in our unscientific Live Vote say no.) Should it be all of the above? None of the above? Are some missions too good for NASA, or more appropriately funded by the private sector? Feel free to weigh in with your comments below.