NASA officials announced plans to build a new rover that would follow Curiosity and Opportunity on the Red Planet's surface in 2020, potentially to collect soil or rock samples that could later be sent back to Earth.
The objectives are not yet set, nor are the tools the rover would wield, said John Grunsfeld, head of NASA's Science Mission Directorate in Washington. But Grunsfeld's remarks Tuesday raised the hopes of planetary scientists that NASA would be focusing its efforts on the complex and costly task of retrieving a piece of Mars.
"Collecting a cache of samples is difficult — it requires a very capable vehicle," said Steve Squyres, lead scientist for the Mars exploration rover mission, which put Opportunity on the planet in 2004. "The vehicle that John Grunsfeld just described for launch in 2020 is fully capable of doing that job."
The announcement electrified many of the roughly 18,000 researchers attending the American Geophysical Union's fall meeting this week in San Francisco.
Before Curiosity landed on Mars this summer, NASA was unsure of its future direction in exploring the solar system. Big-budget missions to Mars seemed politically unpalatable after Curiosity's $2.5-billion price tag, and no other major missions had been scheduled, even as the next launch window in 2018 approached.
But the rover's dramatic landing and early scientific exploits have rejuvenated enthusiasm for Martian exploration.
That has given a boost to NASA's Jet Propulsion Laboratory, home of the Mars exploration program and the expected lead on the new rover program.
The new rover, estimated to cost $1.5 billion, promises to provide a "shot in the arm" for the local economy, said Rep. Adam B. Schiff (D-Burbank), whose district includes JPL in La Canada Flintridge.
Mars missions make up a significant share of JPL's projects. Over the last decade, Curiosity alone employed about 3,000 staffers and brought in 4,000 others from outside the lab.
Rather than reinventing the rover all over again, Grunsfeld said NASA would base designs for the new machine on Curiosity's tried-and-true architecture.
The mission would use the same landing method as the spacecraft carrying Curiosity did, a complex sequence involving a heat shield, a parachute and a hovering platform that lowered the rover to the surface by cable before hurling itself away.
It would even use spare parts collecting dust in Curiosity's proverbial closet.
There are advantages to building a rover along the lines of the Mars Science Laboratory, as the Curiosity mission is officially known, said David Paige, a UCLA planetary scientist working on the Messenger mission to Mercury.
Engineers have worked out the kinks from that mission. They've proved that the landing system — which inspired NASA's popular online video, "Seven Minutes of Terror" — can work without a hitch.
They can also tap the same scientists and engineers that made the previous landing mission a success, said Fuk Li, head of the Mars Exploration Directorate at JPL.
"They're capitalizing on the investment that's already been made," Paige said.
It's unclear what the rover would do on the Martian surface, Grunsfeld said. One idea is for the rover to collect and store soil and rock samples. That would only be the first step; a far more complex mission would be to bring them back to Earth.
The Planetary Science Decadal Survey, which publishes long-term goals for exploring the solar system, touted a sample-storing mission as a top priority over the next decade. But this would involve a major technological leap: NASA would have to find a way to protect the samples, launch them from the Martian surface and safely carry them home.
President Obama has set a goal of sending astronauts to Mars orbit sometime in the 2030s. Grunsfeld said a robotic sample-return mission would help provide a road map for a manned mission.
Another option would be to forget the sample cache, and instead outfit the rover with the most advanced tools possible and send it to another tantalizing spot on the Martian surface.
There already are some well-researched options: Curiosity's scientists agonized over which of several tempting landing spots to choose.
Some scientists, however, pointed out that there were other interplanetary spots — Saturn's moon Titan, or the ice-covered oceans of Jupiter's moon Europa — that could harbor the ingredients for life but have been neglected in recent years.
"What about the rest of the solar system?" said UCLA astronomer David Jewitt. "Sure, Mars is one place in the solar system, but there are many other really exciting places we ought to be going as well."
If the project goes ahead — it is contingent upon Congress agreeing to fund NASA at the level the Obama administration has requested for the next five years — it would be the seventh NASA mission either being operated or planned.
Curiosity and Opportunity currently roam the surface of the Red Planet. The Mars Reconnaissance Orbiter and Odyssey satellites circle above them. The MAVEN orbiter, set to launch in 2013, will study the planet's upper atmosphere, and the 2016 InSight mission will probe the planet's insides.
The European Space Agency also has spacecraft orbiting Mars and plans to send a rover to the Red Planet in 2018.