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Europa Clipper illustration
A Europa mission can cost much less than earlier estimates, while also helping solve a number of other issues facing NASA, from the future of outer solar system exploration to utilization of the SLS. (credit: NASA/JPL)

A generational opportunity for Europa


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Europa’s time has come. In recent years, a remarkable set of scientific, technical, and political factors have converged, all compelling us to explore this enigmatic moon of Jupiter. NASA finds itself presented with a generational opportunity to perform the reconnaissance and initial exploration of one of the most promising astrobiological targets in our solar system. NASA should request a new start for a flagship mission to Europa before this opportunity passes us by.

Europa is no longer a problem for NASA to solve; it has itself become the answer to problems vexing the space agency.

Europa has intrigued scientists since the late 1970s, when the Voyager spacecraft first glimpsed its strangely fractured surface. The Galileo spacecraft, despite its crippled main antenna, confirmed the existence of water and an iceberg-like disjointed surface in the 1990s, but raised more questions than it answered: there is probably water in liquid form, but what is the exact extent of it? What is its chemistry? Is Europa habitable now or in the past? What could live there? Is anything living there?

The scientific rationale for Europa is strong. The National Research Council’s two planetary science decadal survey reports demonstrate the consensus of the scientific community about the importance of its exploration. The first decadal survey, “New Frontiers in the Solar System: An Integrated Exploration Strategy,” ranked Europa as the most important planetary flagship mission destination for 2003–2013. The second decadal survey, “Visions and Voyages for Planetary Science,” ranked a Europa flagship as a close second behind a Mars sample caching rover (which, crucially, NASA is pursuing in its Mars 2020 concept). NASA’s own strategic objectives of searching for past or present life clearly support Europa as a destination.

But decades-long scientific consensus does not a mission make. Drastic cuts to NASA’s Planetary Science Division in 2013 seemed to bury any prospects for a mission in the near future. The lure of Europa is powerful, however, and recent events have resurrected the dream for this generation. Europa is no longer a problem for NASA to solve; it has itself become the answer to problems vexing the space agency.

The most obvious problem is the near-term collapse of outer planets exploration. After the planned end of the Cassini and Juno missions in 2017, NASA will no longer have any spacecraft among the outer planets (New Horizons will be far beyond Pluto at that point.) Requesting a new start for a Europa mission now will help ensure the continuity of crucial engineering expertise in navigation and operations for such distant spacecraft. This issue has not gone unnoticed; it prompted Robert Braun and Noel Hinner to declare that NASA will soon go “radio dark” in the outer solar system for the first time since the 1970s. Europa, particularly as the first in a series of new program of outer planets exploration, would minimize this darkness, which at this point is unavoidable.

Europa finds itself with another unusual opportunity: ardent bipartisan support from key members in Congress.

The second, and more interesting, problem that a Europa mission helps solve is related to the Space Launch System (SLS). It’s no secret that the planned flight rate of the SLS is too low. Crewed missions are expensive and will be infrequent, leaving the SLS to launch at a planned rate of once every three to four years. Steve Squyres, the chairman of the NASA Advisory Council, has stated repeatedly that such a flight rate is unprecedented in NASA history and raises questions of safety and preservation of institutional knowledge. But aside from human missions, what other program could uniquely utilize the power of the SLS? The answer is outer planets exploration, which would benefit immensely from the SLS’s capability to launch heavy payloads directly to the outer planets, avoiding the time-consuming process of multiple Earth/Venus flybys. No other science program within NASA benefits so readily from the SLS, and Europa—which has at least one highly developed, mature mission concept ready to go—can demonstrate the utility of the SLS while ushering in a new era of systematic outer planets exploration.

Of course, a mission to Europa should not come at the expense of our hard-won capabilities at Mars or other areas of planetary exploration. A small increase to the Planetary Science Division budget—to a minimum of $1.5 billion per year—would support a reduced-cost flagship mission to Europa by the early 2020s, with peak funding coming in the years immediately after the 2020 Mars rover funding itself peaks. The Europa Clipper spacecraft concept, developed by the Jet Propulsion Laboratory (JPL) and the Applied Physics Laboratory (APL), is a good example of a mid-size flagship mission that fits within this small budget increase. The Clipper, which would orbit Jupiter and fly by Europa 45 times in a 3.5-year prime mission, requires less fuel and radiation shielding which reduces mass and operational complexity. The vast majority of scientific goals defined in the planetary science decadal survey would be met. And the estimated cost—approximately $2 billion—is less than half the original estimate of the most recent Europa orbiter concept.

Proposing to increase the budget of a federal program in the current economic climate normally enters the realms of fantasy, but in this regard, Europa finds itself with another unusual opportunity: ardent bipartisan support from key members in Congress.

Increased political support, consistent scientific consensus, a reduced cost flagship concept, and the realization that Europa offers a powerful solution to difficult programmatic problems at NASA combined to form a potent argument for Europa.

“I look forward to working with my colleagues in Congress to ensure that a Europa mission has the full support of the federal government,” said Representative John Culberson (R-TX) in a press release put out by The Planetary Society in December. Rep. Culberson sits on the Commerce, Justice, and Science Subcommittee of the House Appropriations Committee, and is a vocal advocate for a flagship-class mission to Europa. Also on the committee, though on the other side of the aisle, is Rep. Adam Schiff (D-CA), who is himself a strong supporter of planetary exploration. Together, they form the core of a bipartisan group of lawmakers who support Europa and planetary science. The Senate lacks a similar focus on Europa, but there is also no anti-Europa contingent there, either. And if the Europa Clipper concept is selected, major contributions from APL would likely solidify political support from Maryland and other states with contributing research centers. There is no doubt: if NASA were to propose a reduced-cost flagship mission within an increased Planetary Science Division budget, Congress would provide the necessary funds.

Increased political support, consistent scientific consensus, a reduced cost flagship concept, and the realization that Europa offers a powerful solution to difficult programmatic problems at NASA combined to form a potent argument for Europa. What was needed was a spark to clarify the potential to the White House and NASA. That spark, ironically, came in the form of water.

The recent detection of water plumes emanating from the moon’s south pole has become the catalyst needed to crystallize all other arguments for Europa. The plumes, which an orbiting spacecraft could fly through, greatly reduce the cost of the initial reconnaissance of Europa’s water. Though it has yet to be confirmed, the discovery has reignited interest in the public and the NASA and White House administrations. NASA has already demonstrated a dramatic reversal in policy with its $15 million request for low-cost Europa mission concepts in the FY2015 budget request.

Europa commands strong public interest. After a brief burst of attention from Arthur C. Clarke’s 2010 in the 1980s, the search for life on Europa once again captured the imagination of moviegoers in the 2013 film Europa Report. National Geographic used the plume discovery to feature Europa on the cover of its July 2014 issue. Last week, a Reddit AMA (Ask Me Anything) with NASA’s Chief Scientist Ellen Stofan, Bill Nye The Science Guy, and JPL Europa Study Scientist Robert Pappalardo garnered an astonishing 2,000 questions within 30 minutes and became the top post on the immensely popular website that day. A recent public event by The Planetary Society on Capitol Hill drew a standing-room only crowd eager to hear about the possibility of Europan exploration.

To summarize: Europa is one of the most important destinations in planetary science and falls directly within major strategic goals of NASA; the detection of plumes has reignited public and administrative interest; a mission to Europa would reinvigorate the exploration of the outer planets and provide an additional application for the SLS in between more expensive and infrequent human missions; the exploration of Europa is popular with the public, as evidenced by decades of attention from popular culture and response to events both virtual and physical; and a mission to Europa has powerful bipartisan Congress and requires only a small increase in the budget for the Planetary Science Division.

This truly is a generational opportunity: any mission to Europa would require years to build, fly, and operate. Rarely do we see such a remarkable convergence of factors pointing towards a single destination for exploration. But this opportunity to finally explore Europa will not last forever. NASA must act decisively before it passes us by; Europa will be there in the future, but we may not.


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