Mars beckons space age explorers, much as the New World lured Christopher Columbus. NASA answers the siren call again Saturday -- launching the $2.5 billion nuclear-powered Mars Science Laboratory, nicknamed Curiosity.
It is the most ambitious and complex robotic rover built to explore the Red Planet. The goal: find elements that could prove whether life ever existed on Mars.
An Atlas V rocket hoisted the rover, officially known as Mars Science Laboratory, into a cloudy late morning sky from Space Launch Complex 41 at Cape Canaveral Air Force Station, just south of the launch pads from which space shuttles left for 30 years, and before them, Apollo moon missions.
Curiosity is set for a nearly nine-month trip to the Red Planet. Getting there is only the start; when the spacecraft plows into the thin Martian atmosphere, that's where the spacecraft designers will be tested.
Curiosity weighs one ton and is much too heavy to land on airbags like NASA's previous rovers, Spirit and Opportunity. So it will be slowed by a heat shield and parachute, then gently lowered to the planet's surface on cables suspended from a rocket-powered sky crane. It is the first time this design is being used, and mission managers have openly confessed they're uneasy.
Mars is a harsh mistress. Of 38 missions we earthlings have sent there since the beginning of the space age, NASA counts 24 failures. The Russians have never yet had a full success.
This mission, if it succeeds, will answer questions for NASA scientists who are planning to send humans to Mars, some day. How would a manned mission work?
"The key is pre-deploying spacecraft and rovers -- getting infrastructure in place to make the most of the time we have to explore the planet," said Bret Drake of NASA's Human Space Flight Team.
Drake said we just won't know enough to go to Mars for another 30 years. It would take 180 days to get to Mars, 180 days to get back, and the astronauts would spend 500 days exploring the planet. The logistics are daunting. Problems like protecting astronauts from the radiation found in interplanetary space have yet to be solved.
Astronaut Mike Gerhardt is testing concept rovers and systems that could be used by explorers on Mars. A 900 day mission? He would go in a heartbeat.
"Once you get there, think how exhilarating it would be," he said. "You would be discovering a new planet."
Getting to Mars is time-consuming partly because of the way our planets orbit. Rice University's Dr. Patricia Reiff jokes she thinks sometimes Mars doesn't want us there.
"Even though it is relatively close to Earth, its orbit is one and a half astronomical units, where we are at one," she said. "Because the orbits are so nearly the same we only line up every two years, so we only have a good opportunity to fly to Mars every two years. That just makes it tricky navigationally."
The failures are legendary -- including the latest, Russia's Phobos-Grunt spacecraft, which is currently stuck in Earth orbit after it launched earlier this month. Phobos-Grunt was an ambitious mission to land a robotic probe on one of Mars's moons, Phobos ("Grunt" is Russian for "ground"), and scoop up soil to return to Earth. Scientists were thrilled with the prospect of testing samples in labs around the world. Now engineers are talking about when the doomed spacecraft will crash back to Earth, probably in late December or early January.
Curiosity, hopefully, will avoid Phobos-Grunt's fate. If all goes well, it will land on Mars on Aug. 6, 2012.