The discovery that a salty sea once covered party of the surface of Mars will have lasting effects on the future exploration of the Red Planet, according to scientists and policy experts inside and outside NASA.
Space agency officials said the briney find by the Opportunity rover has singled out its Meridiani Planum landing site for future robotic exploration and given a timely boost to President George W. Bush's recently state vision of eventually sending humans to take a more personal look around.
During a Tuesday announcement of the finding, NASA Administrator Sean O'Keefe said the ancient sea has "profound implications" for future investigations in which the space agency plans to send "more sophisticated robotic capabilities" to Mars.
"And it's in due course that human explorers will follow," O'Keefe said.
No easy path
The giant step is still years away, with many political hurdles to cross.
"My sense is that this is going to bolster the space vision plan, but how it plays out in dollars and cents is still up in the air," said George Whitesides, executive director of the National Space Society, of sending people to the Red Planet. "From a policy perspective, though, this couldn’t have come at a better time."
The water announcement was delivered in the same week as a meeting of the Commission on the Implementation of United States Space Exploration Policy, which begins today in Atlanta, Georgia.
Appointed by Bush, the commission is tasked with recommending actions that will help NASA meet the President's space vision to return humans to the Moon, then eventually send people to Mars and beyond, while at the same time closing out the space shuttle program.
"It strengthens the case for Mars as one of the main targets for the space vision," said committee member Neil deGrasse Tyson, an astrophysicist and director of New York City's Hayden Planetarium, of Opportunity's finding. "I'm not even worried about Mars right now."
The strong case NASA scientists have built for water in Mars' past using rover data, starting first with evidence of groundwater then moving on to a shallow salty sea, is a microcosmic version of the track the entire space vision must follow, Tyson told SPACE.com. It was incremental steps, he added, that made the Apollo mission to put humans on the moon such a success. And as a successor to the successful 1997 Mars Pathfinder mission, the current Mars Exploration Rover (MER) mission has already emulated that pattern.
But it must be followed up with human missions in the same way.
"So to go to the Moon, it's not just to hop around, it's to test certain capabilities that can then be used for Mars, " Tyson said. "And Mars is just a destination, it's a step among many steps in the vision."
Tyson also said that the way NASA has kept the Mars water case in the public eye through science and press briefings could, if duplicated in future missions, protect the larger space vision from succumbing to the whim of partisan politics over time by periodically focusing the effort on results.
NASA officials and scientists yesterday repeatedly stressed that additional missions, each more ambitious than the previous, will be needed to continue telling the story of Mars' watery past and to find out if life ever existed there.
Leading toward future missions
O'Keefe said Opportunity's discovery would contribute to the planned constant reshaping of the Bush vision, which is based on making exploration decisions that evolve as science and technology progress.
"It certainly would have an impact," he said, adding that now there will be "all kinds of ideas" about objectives for the next mission that couldn't be imagined a few months ago.
At the moment, Opportunity's Meridiani Planum site is the prime target for NASA's next Mars rover mission, the Mars Science Laboratory, a nuclear-powered robot five times larger than the MER rovers. It is expected to launch in 2009.
NASA officials are also preparing the Mars Reconnaissance Orbiter, the next spacecraft aimed at the red planet, for an August 2005 liftoff. It would orbit Mars. One task that only now is on its to-do list is to search for more areas with rock outcroppings and soil patches that match those found by Opportunity — other spots that might be sea-worthy.
Ultimately, NASA officials and many scientists are eager to send a robot to Mars early in the next decade to gather rocks and return them for study in terrestrial labs. Many scientists say that if there was ever microbial life on Mars, finding its remains will require examining the rocks in labs back home. That mission got an emotional boost yesterday with Meridiani Planum as its working target.
"If you have an interest in searching for fossils on Mars, this is the first place you'd want to go," said Ed Weiler, NASA associate administrator for space science.
For some, sending humans to Mars is mostly about being bold. But many geologists would like to actually go there on the grounds that the history of the red planet's geology, and its biology if any, will only become clear after scientists set foot in red dust.
Not everyone agrees that rapidly increasing complexity is a good thing, however.
The Mars Science Laboratory rover, which would abandon the tried-and-true airbag landing scheme of both Pathfinder and the current MER rover mission, has drawn some criticism from scientists.
Bob Craddock, science advisor for the undersecretary for science at the Smithsonian Institution, told SPACE.com that while the success of the MER missions and their findings highlight the need for future red planet robots, it need not mean a shift away from what already works.
"In fact, I would argue that we need to send even more robotic missions identical to the MER," he said yesterday, adding that NASA's intrepid use of the same basic Mariner spacecraft bus led to an enormously successful phase of exploration in the 1960s.
"The delivery system for Pathfinder and MER is now three-for-three," Craddock points out. "It's proven technology. The MER findings are unprecedented. Instead of reinventing the wheel for each successive mission, which is both risky and costly, NASA needs to look for ways of utilizing the technology it has in hand."
Whatever missions fly next, public and political support will be crucial in keeping Bush's space vision alive, which means keeping federal funding flowing into NASA.
"The vision must sustain public support longer than a presidential election cycle or political cycles in general, as well as economic cycles," Tyson said in an interview earlier this year.
Yesterday, Tyson said he does not expect Opportunity's success to affect some of the more critical aspects of space policy, such as NASA's budget for the 2005 fiscal year, any more than its success to date already has.
"I think it’s a success story from the beginning right on to the current moment, and right up until the dust blots out the last light on the solar panels," he said of the twin rovers Spirit and Opportunity. "A secure success story for NASA."
SPACE.com's Senior Science Writer Robert Roy Britt contributed to this report.