Rover Curiosity is a star, but can it help fund future of Mars exploration?

The steady stream of enticing photographs from the rover Curiosity may be wowing scientists and the public, but NASA is facing serious budgetary constraints on the future of Mars exploration.

NASA's Mini Cooper-sized rover Curiosity has spent the past week wowing the mission's scientists, engineers, and the public with each new set of photos it sends and each indication that everything on the one-ton, pencil-necked robot is working virtually flawlessly.

Given all the good news, you'd think that the Mars exploration program is hale and hearty.

Instead, the agency is in the final stages of a major overhaul of its robotic exploration effort at Mars. In the past, such overhauls have come after spectacular failures – after the loss of the Mars Observer orbiter in 1993 and again after the loss of two more missions in 1999.

This time, it's coming as the world celebrates the initial success of the most daring attempt at a Mars landing yet on a mission that begins the hunt for evidence that Gale Crater, with its imposing three-mile-high central summit, could once have supported life.

The reason for the overhaul?

"It's purely budgetary," says Bruce Jakosky, a researcher at the University of Colorado in Boulder and the lead scientist on the final mission on the current Mars agenda, the MAVEN orbiter.

The White House proposed a $4.91 billion science budget for NASA for fiscal 2013, which starts Oct. 1. That's a 3 percent cut over last year's spending. Within that broad category, however, the administration sought $1.19 billion for planetary-science, a 20 percent cut. And the Mars program garnered a $360.8 million request, a cut of 38.5 percent.

The conundrum is largely one of the agency's own making, says Roger Launuis, a former historian at NASA and now curator of planetary exploration programs at the Smithsonian Institution's Air and Space Museum in Washington.

The James Webb Space Telescope, the successor to the highly successful Hubble Space Telescope currently on orbit, has seen its price tag expand from a 1997 estimate of about $500 million to build and launch to nearly $9 billion today. Its launch date has shifted by more than four years to a planned launch in October 2018, according to the Government Accountability Office.

For all its success and promise, Curiosity also overshot its budget. Since 2008, the cost for the now-$2.5 billion mission grew by $881 million. Technical challenges during development delayed its launch by two years.

Given the current budget climate, Congress appears unwilling to offset the overruns, Dr. Launius says. Nor has the Office of Management and Budget been inclined to tuck anything extra into NASA's budget to ease the squeeze.

The change forced the agency to withdraw from a joint program of high-profile Mars missions for 2016 and 2018 undertaken with the European Space Agency.

Some hold that if Curiosity snags the ultimate prize, evidence for organic compounds in the rocks it analyzes, "then the science community, which is already energized, will make a very strong case that, given what we've built up, the capability that we've produced, it would be just tragic, foolhardy, to not continue this as recommended by the National Academy of Sciences," says Scott Hubbard, the first head of NASA's Mars Exploration Program and now a consulting professor at Stanford University in Palo Alto, Calif.

The latest decadal survey from the Academy, a blueprint for the next 10 years of planetary exploration, gives a Mars sample return mission – in which rock or soil samples are brought back to Earth for more sophisticated examination – its highest priority among big-ticket missions, with some cost caveats.

But historians note with some irony that success in spaceflight rarely, if ever, begets more money, while disasters tend to rally the troops. President Nixon, arguably facing a less drastic budget picture than President Obama, nevertheless shut down the Apollo program at the height of its success and nearly ended NASA's human spaceflight effort altogether.

Success and loosened purse strings "are not closely linked," says John Logsdon, a space-policy specialist and professor emeritus at George Washington University in Washington.

What Mars advocates hope to see, he says, is "that the public reaction to this success could result in a slight modification of priorities" that would restore some money to the Mars program.

"I hope they are right," he adds. "We're not talking about a lot of money in the short term."

Where Curiosity's success might well become a factor is in deliberations affecting budgets beyond fiscal 2013, he says.

For now, however, NASA is making plans based on the FY 2013 request.

In June, the agency held a three-day meeting with Mars researchers to weigh options for a scaled-down Mars Exploration Program. And the agency is putting the final touches on a new blueprint for Mars exploration that foresees a launch as soon as 2018.

The team at NASA developing the recommendations aims to turn in an outline of its results by the end of the month, says Doug McCuistion, current director of the Mars Exploration Program. A full written report is expected this fall.

The goal, Mr. McCuistion says in an interview, is to have a plan set for consideration in the budget President Obama will present to Congress in January for fiscal 2014.

The team conducting the overhaul, the Mars Program Planning Group, has been working hard to preserve the goal of a sample-return mission while looking for ways to weave its way more deeply into the human-exploration program for the red planet, with an eye for developing technologies and research objectives that will benefit both.

Based on the June meeting and a status report the planning group presented to members of the NASA Advisory Committee in late July, the group is considering several paths.

For instance, the agency could loft an orbiter mission either as a communications satellite around Mars to support existing and future missions, as some sort of technology demonstration mission, or to conduct further science investigations. An orbiter mission of some sort would fit into the funding stream envisioned in the FY 2013 budget, with some adjustments within other NASA accounts.

If Curiosity finds it's organics, NASA could follow the orbiter up with a mission to the surface in 2020 or 2022 to collect and store samples for later return or conduct further studies of the organics.

No organics? NASA could send rovers to several sites to explore additional options for returning samples. Or it could hold off until 2022 or 2024 to pursue a full out sample-return mission – one that might require two launches.

Some Mars researchers say they worry that if the Mars program becomes too intimately tied to human exploration of Mars, the program may suffer the same fate as the lunar science missions that emerged from President George W. Bush's Vision for Space Exploration.

NASA lofted a high-profile, two-in-one mission – the Lunar Reconnaissance Orbiter and the crater-crashing LCROSS – and more recently the GRAIL lunar-gravity mission. But with the Obama administration's shift in emphasis to destinations for humans beyond the Earth-moon system, lunar missions have fallen by the wayside, these researchers argue.

But as McCuistion sees it, Mars has legs.

Humanity has fixed its gaze on the red planet for millenniums, and considered its prospects as a habitable world for generations.

From "popular culture to scientific discovery, it's been one of the most interesting and highly recognized 'other worlds,' " he says. As an ultimate destination for human exploration, "Mars ranks right up there. Nobody's ever lost sight of the excitement of getting humans to Mars. I think that will not change."

But he adds, political will plays a key role.

"It is a long-term commitment. The nation, through Congress and multiple administrations, has to make a commitment to doing that," he says.

With planning nearly complete for Mars Exploration Program 3.0, the MAVEN mission's Dr. Jakosky takes an upbeat view.

"I don't see MAVEN as the last mission" in the Mars Exploration Program, he says. "I see it as the next mission."