HOUSTON, TEXAS--A committee of the National Research Council is insisting that the cost of two of the largest planetary missions it is recommending for NASA in the coming decade must be slashed or they can't fly. But even that unusual fiscal discipline will likely not be enough, say observers here at the annual Lunar and Planetary Science Conference. The committee's Planetary Science Decadal Survey  was released here late yesterday. The self-imposed austerity was necessary to squeeze planetary scientists' ambitions into the relatively optimistic budget projections of last year; today's federal spending realities will likely require even more slicing into planetary ambitions.
In a sharp departure from the past, the decadal survey committee went to an outside contractor, Aerospace Corporation of El Segundo, California, for independent, rigorous estimates of the cost of missions it is recommending for the next decade. For the previous survey, the committee made its own cost estimates, some of which missed the mark. Most infamously, the previous survey estimated that the Mars Science Laboratory rover (now called Curiosity) would cost under $650 million. After growing mission ambition and multiple technical problems, Curiosity currently clocks in at a cost of $2.3 billion.
The new independent cost estimations gave the survey committee "sticker shock," says Steven Squyres of Cornell University, the chair of the committee. Outside estimates always come in above estimates made by the groups of planetary scientists proposing the missions, sometimes well above. In the large-mission category, the committee's highest priority for the decade 2013-22 is the Mars Astrobiology Explorer-Cacher (MAX-C). The survey estimated its cost at $3.5 billion in fiscal year 2015 dollars. Advocates proposing the mission had pegged the cost at $2.2 billion. That jump was too much for the committee. "MAX-C would take up a disproportionate share of NASA's planetary budget," the report says. Unless the price tag can be whittled down to $2.5 billion, the report says, the mission to explore for signs of life and collect sedimentary rocks for later return to Earth should be delayed or canceled.
The committee's other large-mission recommendations got similarly austere treatment. The next highest priority, also life-related, is the Jupiter Europa Orbiter mission. It would take a close look at the ice-covered jovian moon, which could harbor life in its subsurface ocean. But at a whopping projected cost of $4.7 billion, it should be flown only if NASA's budget for planetary science grows and the mission cost can be shrunk so that no other missions would be affected, the report says. And the third priority, the Uranus Orbiter and Probe mission, should be downscaled or canceled if it grows above its $2.7 billion estimated cost. The lowest cost and lowest priority large missions recommended were a Venus Climate Orbiter at $2.4 billion and a spacecraft to orbit Saturn's ice-spewing moon Enceladus at $1.9 billion.
Among proposed medium-size missions, the committee found a better match between ambition and budget. With a maximum allowable cost of $1 billion, the selected missions span the solar system and, not incidentally, all the subgroups of the planetary community. The missions would: return a sample from an icy comet, probe gas giant Saturn, explore the surface of fiery Venus, return a sample from a huge impact basin on the moon, visit asteroids orbiting the sun with Jupiter, repeatedly fly by Jupiter's radiation-soaked volcanic moon Io, and plant a network of geophysical observatories on the moon. Unlike its predecessor, the committee declined to prioritize the seven missions.
The 1300 planetary scientists gathered here suffered sticker shock when Squyres presented the costs of their hoped for missions. It only got worse when James Green, head of NASA's planetary science division, pointed out that the president's requested 2012 budget—which he must follow for planning—roughly cuts in half the funding the committee had allotted for new missions in the coming decade. Squyres noted that the report contains directions on how to accommodate smaller budgets than assumed: downscale, delay, or cancel large missions from the top priority down to the lowest until something fits in the available budget. Given the president's budget, he noted, that could mean no large missions at all in the next decade. Alternatively, he added, planetary scientists could get behind the decadal survey and lobby for more funding.