The Space Reviewin association with SpaceNews

MSL model
A full-size model of the Mars Science Laboratory rover was on display at the annual AAAS meeting last month in Boston. (credit: J. Foust)

The end of the golden age of Mars exploration?

By all accounts it should be the best of times for scientists and other advocates for the exploration of Mars. The planet is under unprecedented study by spacecraft, including three orbiters—NASA’s Mars Odyssey and Mars Reconnaissance Orbiter and ESA’s Mars Express—as well as NASA’s twin Mars Exploration Rovers, whose 90-day missions have now lasted over four years each. All these spacecraft have returned data that has helped scientists reshape our understanding of the Red Planet, in particular the key issue of water on the planet both in its past and today. Moreover, another spacecraft, Phoenix, is en route to Mars, and will land in the planet’s northern polar regions on Memorial Day weekend. And perhaps the most sophisticated Mars spacecraft ever, the nuclear-powered Mars Science Laboratory (MSL), is under development for launch next year.

But for many of these scientists and enthusiasts, the future of Mars exploration after MSL is not nearly as bright. The next NASA mission after MSL won’t launch until 2013, and the future after that is even murkier. NASA is also planning to shift funds from Mars research to other areas of its science programs, including other planetary missions, much to the consternation of researchers who have spent years or decades studying the Red Planet. With no firm date for human exploration of Mars—only a passing reference to it in the national space exploration policy—some are left to wonder whether the current golden age of Mars exploration is coming to an end.

Reborn lander, giant rover

The next two NASA missions to Mars take very different approaches to studying the planet. Phoenix, scheduled to land on Mars on May 25, lives up to its name: it is based on hardware originally developed for the Mars Surveyor 2001 mission that was cancelled after a similar spacecraft, Mars Polar Lander (MPL), crashed on the surface in December 1999. Phoenix is carrying instruments designed to study the history of water on Mars and determine the habitability potential of the ice-rich soil in the planet’s polar regions.

“We’re now pushing the state of the art, the envelope, in performance in almost all of the ways that MER was a success,” Richard Cook, MSL project manager, said.

Phoenix, unlike the Mars Exploration Rovers, is a fixed lander with a relatively short mission. MSL, by contrast, returns to the rover approach, but on a much bigger scale than Spirit and Opportunity. MSL is about five times heavier than the current rovers, forcing NASA to abandon the airbag approach used for those missions in favor of an intricate “sky crane” that will lower the rover directly onto the surface. The rover is designed to last two years—compared to the 90 days of the Mars Exploration Rovers—and travel 20 kilometers, carrying a sophisticated suite of experiments that may help scientists understand whether Mars was habitable early in its history.

“We’re now pushing the state of the art, the envelope, in performance in almost all of the ways that MER was a success,” Richard Cook, MSL project manager, said during a press briefing about Mars exploration during the annual meeting of the American Association for the Advancement of Science (AAAS) last month in Boston.

While Phoenix was designed to be a relatively low-cost mission, MSL is not: its total development cost now exceeds $1 billion, driven up by some technical difficulties. One of those is the recent discovery that the spacecraft’s heat shield will have to be designed after the material originally planned for use, SLA, was deemed unsuitable for MSL. Cook said in an interview that while SLA had been used successfully on previous Mars missions, the much larger size of MSL created turbulent flow at the edge of the shield that increased heating in areas, causing the SLA material to ablate unpredictably. NASA instead will use a different substance, called PICA, for the heat shield; the material is also being considered for the heat shield of the Orion crew exploration vehicle. The change will add another $25–30 million to the cost of the mission, he said.

An uncertain future

NASA had originally planned to follow up the flagship MSL in 2011 with an inexpensive orbiter, part of the Mars Scout family of low-cost missions that includes Phoenix. However, in December of last year NASA announced the mission would be delayed until 2013 after the agency discovered an “organizational conflict of interest” after the two finalists—both proposing missions to study the Martian upper atmosphere—had submitted studies that would be used to pick the winning proposal. Reconstituting the review team to eliminate the conflict of interest would take enough time that it would not allow the mission to be developed in time to meet the 2011 launch window.

Mars advocates got another setback in February, when NASA released its fiscal year (FY) 2009 budget proposal. The five-year annual average for the Mars program in the budget proposal—$350 million—was far less than the $620 million/year planned for 2009–2012 in last year’s budget proposal. The budget included no money for any specific missions beyond the Mars Scout mission. But NASA did offer the Mars community something of interest: a proposal to perform a Mars sample return mission—something of great interest to scientists who would like to be able to study Mars samples in terrestrial labs—around the end of the next decade.

“By removing any semblance of a continuous exploration program,” Braun wrote, “NASA’s 2009 budget request puts the Mars program on a path towards irrelevance.”

These cuts energized the Mars science community. In a letter distributed to members of the Mars Exploration Program Analysis Group (MEPAG) shortly after the budget proposal’s release, and in a later op-ed in the March 3 issue of Space News, Robert Braun, an aerospace engineering professor at Georgia Tech, warned of the long-term consequences of NASA’s shifts in funding. Braun said that the funding cut flies in the face of language in the conference report that accompanied the final fiscal year 2008 appropriations bill, which called for continuing a program of at least one mission per launch window, including a “science orbiter” in 2013 and another rover mission in 2016.

“By removing any semblance of a continuous exploration program,” Braun wrote in his Space News op-ed, “NASA’s 2009 budget request puts the Mars program on a path towards irrelevance. The budget requested is simply inadequate to complete the next steps in this remarkable exploration program.”

In a speech last week at the Lunar and Planetary Science Conference (LPSC) in Houston, Griffin defended the decision to de-emphasize Mars in favor of other planetary work. He noted that a recent “report card” on NASA’s planetary sciences program by the National Research Council (NRC) gave the agency’s Mars program an A, while its outer planets program got a D and its research and analysis program—which provides grants to scientists to study the data collected by the agency’s numerous missions—a C. “We have rebalanced the planetary science portfolio accordingly,” Griffin concluded in his prepared remarks.

That rebalancing did not sit well with many of the scientists present at Griffin’s speech. According to one account of the question-and-answer session that followed, several people asked why the Mars program was being penalized financially for the shortcomings of other science programs. One person noted that if his child came home with a report card with an A, a C, and a D, he would ask for all A’s, not to lower one grade to raise another. Others expressed concern about those who specialized in Mars research who could be hurt by a loss of funding.

Griffin, though, was unswayed, saying that Mars research was not being eliminated but instead, he was “returning things to lower levels,” according to the account of the session. As for the report card, Griffin said that given the limited resources available, he couldn’t afford to get an A in everything. Griffin, a golfer, used an analogy: if his putting was poor, he wouldn’t spend all his time on the driving range.

Last week the space subcommittee of the House Science and Technology Committee took up the issue of the future of Mars exploration during a hearing on the science aspects of the 2009 NASA budget proposal. In his testimony, Steve Squyres, the Cornell University professor who is the principal investigator for the Mars rover mission, expressed concerns about the cost of the proposed sample return mission versus the planned level of funding in the budget proposal. The budget includes $68 million to start studies of such a mission, a tiny fraction of the overall cost, and NASA recently chartered a study at the request of the Office of Management and Budget to examine the costs of such a mission.

“One problem is that $68 million in the period from FY’09 to FY’13 is far short of the investment that would be needed to support launch of MSR [Mars Sample Return] by 2018 and 2020,” Squyres wrote in his prepared statement. “In order to launch the first element of the mission in 2018, our study concluded that a technology investment of hundreds of millions of dollars—not just $68 million—would have to be made by four or five years before the 2018 launch.”

Fitting a Mars sample return mission in the current projected budget, Squyres concluded, requires either slipping the mission beyond 2020 or canceling other missions planned for 2013 and 2016.

The overall cost of an MSR mission—$3.5 billion, as projected by NASA—is also an area of concern. “That number is less than twice the probable cost of the Mars Science Laboratory, for a mission that appears to be much more than twice as complex,” Squyres wrote. “We concluded that the full cost of MSR will exceed $3.5 billion by an amount comparable to an entire flagship mission.”

“Putting this together, our study concluded that the President’s FY’09 budget request will support NASA’s planned Mars missions in 2013 and 2016 only if MSR is slipped well beyond 2020. Alternatively, we concluded that MSR could be carried out by 2020 only if both the 2013 and 2016 missions were eliminated,” he concluded, adding that the consequences of eliminating the 2013 and 2016 missions would be “severe” to the overall science program. “There would be a lack of continued progress toward key goals of the NRC Decadal Survey, and a loss of scientific balance. Of perhaps still greater concern is the loss of technical and scientific know-how that could occur as a result of the very long hiatus between landed missions.”

Breaking that steady stream of missions worries some scientists, who value the current approach that allows them to build upon previous successes. “There is a concern,” Charles Elachi, director of JPL, said at the AAAS meeting. “There is a lot of discussion in the community regarding whether we should go straight to a sample return, which is a very expensive and time-consuming mission but also has a lot of scientific value versus a program of continuous discovery, answering questions and bringing new questions.”

“In my mind, the big difference in the Mars program has been this continuous investigation and the permanent presence of these robotic scientific stations,” Elachi added. “I hope the program will continue doing that.”