An artist's conception shows the Jupiter Europa Orbiter with the Jovian moon Europa in the foreground.
11:35 a.m. ET March 8:
Planetary scientists would love to have some samples collected on Mars for delivery back to Earth, and they're itching to get a closer look at Europa, a moon of Jupiter that may harbor a hidden ocean and perhaps life as well. But they might be stymied during the decade to come, due to the federal government's tightening financial circumstances.
The Mars and Europa missions are the top priorities for flagship robotic missions emerging from a big-picture scientific assessment known as the Decadal Survey. Over the past couple of years, the survey's organizers have received input from more than 1,600 planetary scientists, and the final results were released today in the form of a National Research Council report titled "Visions and Voyages."
The whole idea of the survey is to let scientists weigh in on NASA's priorities for exploration over the coming decade. Two big-ticket missions — the Mars Astrobiology Explorer-Catcher, or MAX-C, and the Jupiter Europa Orbiter — rose to the top:
- MAX-C, proposed for launch in 2018, would gather up rocks and soil from a promising area of the Red Planet and have the stuff ready to blast into Martian orbit, where it could be picked up for eventual return to Earth. Such a mission would lead to the first opportunity to examine fresh material from Mars, which could hold clues to the existence of past or present life on Mars.
- The Jupiter Europa Orbiter is proposed for launch in 2020 and would reach the Jovian system in 2025 or so. The spacecraft would focus on Europa and two other moons of Jupiter that may have subsurface oceans of water, Callisto and Ganymede. Ice-penetrating radar could determine how close liquid water is to the surface of those moons, and detailed chemical analysis of Europa's top layer could conceivably turn up signs of life.
The only problem is, doing these sorts of things costs money. A lot of money. The report notes that the mission to Jupiter and Europa is projected to cost $4.7 billion, and MAX-C's projected cost is $3.5 billion. It suggests that MAX-C would have to be cut back to $2.5 billion, and that the Jupiter Europa Orbiter mission should proceed in the 2013-2022 time frame "only if changes to both the mission and the NASA planetary budget make it affordable without eliminating any other recommended missions."
The exploration situation could get even tougher due to the budget-cutting mood in Washington. If there's less money than projected for planetary exploration, NASA should consider not only cutting back on the scope of those flagship missions, but delaying or canceling them, the report says.
This illustration shows one of the concepts for Europe's ExoMars rover at left, and NASA's MAX-C collection rover at right.
The future of NASA's robotic exploration is further complicated by the fact that both MAX-C and the Jupiter Europa Orbiter are being considered in cooperation with the European Space Agency. MAX-C would be complemented by ESA's ExoMars rover, and the Europeans have been willing to sign up as partners in the Europa study effort. Shifts in cost and scope could affect the character of international cooperation in robotic space exploration.
What's more, NASA has other types of programs to think about: The International Space Station is likely to be in operation well into the 2013-2022 period, and Congress wants the space agency to spend billions on the development of a next-generation heavy-lift rocket for human spaceflight. Meanwhile, the Decadal Survey's report on astrophysics — released last August — has rolled out a separate wish list with pricey items, including a $1.6 billion space telescope to probe dark energy and identify Earthlike planets.
Game plan for future missions
The survey's chairman, Cornell University astronomer Steve Squyres, discussed the 400-page report in depth today during the Lunar and Planetary Science Conference in Texas. He laid out a game plan for matching the aspirations of planetary scientists with the available budgets:
- See if MAX-C and ExoMars can be combined into a one-rover sample collection mission to Mars. He said an analysis of the mission requirements suggested that such a mission could be done for $2.5 billion, even if NASA had to do it alone.
- If MAX-C's cost to NASA can't be brought down to $2.5 billion, the mission should be taken off the table. "There's no Plan B," said Squyres, who heads the science team for the wildly successful Mars rover missions. The Jupiter Europa Orbiter would become the prime focus for flagship missions, but the cost would have to be reduced. "It is a fabulous mission, but at 4.7 [billion dollars] it is an intractable problem that needs to get fixed," Squyres said.
- If neither of those two missions can be done in the 2013-2022 period, consider sending an orbiter and atmospheric probe to Uranus. Cost of that mission, which would be the first to focus exclusively on an ice giant planet, is estimated at $2.7 billion, "so it ain't cheap either," Squyres said.
- The next priorities would be the Venus Climate Mission (at $2.4 billion) or the Enceladus Orbiter (at $1.9 billion). "If you can't afford any of those, you've got no flagships at all," Squyres said.
Under that scenario, big-ticket missions would go by the wayside for the next decade, leaving NASA with medium-class missions such as Juno, a solar-powered Jupiter orbiter with a cost of $1 billion; and lower-cost efforts such as the GRAIL lunar probes, which carry a price tag of $375 million. Squyres said those types of programs should not be cut back. The scientists also endorsed the Mars Trace Gas Orbiter, a NASA-European mission that would be launched in 2016 to delve into the mystery of Martian methane.
Wide array of future flights
The report suggests seven candidates for future medium-class missions, which would be selected through NASA's New Frontiers program. Such missions could bring a sample back from the surface of a comet, explore the lunar south pole, analyze Saturn's atmosphere, explore the Trojan asteroids that share Jupiter's orbit, land on the surface of Venus, observe the Jovian moon Io, or distribute sensors around the moon to study lunar seismology.
On another front, the decadal report recommends setting aside 6 to 8 percent of NASA's planetary science funding for technology development and urges the federal government to restart production of plutonium-238. That radioisotope is used to power missions heading for the outer solar system, where solar power just isn't enough to keep a spacecraft warm and working.
Squyres urged the researchers assembled in Texas to contact their representatives in Congress and voice their support for the exploration plan.
Jim Green, the director of NASA's Planetary Science Division, said that tough economic times may lie ahead, and the scientific community's backing would be critical in the years to come. "The decadal report transcends Congress, transcends changes in administration, and is our guiding light that moves us forward, year after year after year," he said.
Correction for 11:35 a.m. ET: An earlier version of this report incorrectly suggested that Green called on scientists to contact members of Congress. That call actually came from Squyres.
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