Under the President’s proposal, $493 million would be spent on the Europa mission through 2021 versus the $2.1 billion needed to keep the mission on track to launch in 2022.

In political terms, pushing the mission’s launch out a dozen or more years may be the equivalent of postponing it forever. For the mission to fly, it would need continuous support from at least two more Presidential administrations and as many as six to eight new Congresses. It’s hard to imagine any mission sustaining support for that long. It’s also hard to imagine how NASA could keep a high caliber engineering and science team together for what might be fourteen or more years (with a possible six or seven additional years of flight following launch to arrive at Europa). On a very practical engineering level, many of the technologies available to design into a mission today will be obsolete and no longer available by the late 2020s. The mission design would need to be continuously tweaked to substitute new technologies.

Why might the President’s budget officials be opposed to the Europa mission? The explanation given in the proposal document is that launching a Europa mission before the late 2020s would lead to an unbalanced planetary program that would not support the program laid out in the last Decadal Survey. This statement assumes that the cap on the total planetary budget would remain fixed at around the $1.5 billion proposed for this year.

Here are the possible explanations I’ve been able to think of for the Administration’s lack of support for the Europa mission (the first two are consistent with the explanation in the budget document):

Delaying the Europa mission prevents a bulge in spending requirements. For the rest of this decade, NASA’s new mission spending is dominated by the expensive Mars 2020 rover. The budget proposal also shows sharp budget increases late in the decade for the Discovery and New Frontiers programs. Launching the Europa mission by 2022 as mandated by Congress would require either greatly increasing overall planetary funding or cannibalizing other programs. (Note: I would like to see a much larger planetary budget.)

The budget officials (and perhaps NASA’s senior managers) prefer cheaper Discovery and New Frontiers missions to the Flagship Europa mission. Experience has shown that large Flagship mission are more likely to have large cost overruns that play havoc with NASA’s budget. Countering this, the generous money that Congress has provided the mission so far as matured the design much more than is typical at this stage of development. That maturity makes cost overruns less likely.

Europa isn’t Mars, and studying and eventually getting humans to Mars is NASA’s current overriding goal.

Pure politics. Several of the Congressional leaders who are strongly backing the Europa mission and planetary exploration in general are highly conservative politically. While they favor spending more money on planetary missions, they also want to cut funding for missions for NASA to study the Earth, especially climate change. Essentially proposing to push out the launch of a Europa mission to forever may be part of a hardball negotiating tactic to trade more funding for the Europa mission for also fully funding the President’s generous proposed budget for Earth science missions.

At the moment, we are left with the Europa mission as a formally approved mission on NASA’s books with an engineering and science team, a selected suite of instruments, and no target launch date. The interesting politics will be whether or not Congress forces the addition of the many hundreds of millions of dollars into NASA’s planetary budget over the next several years needed to launch as early as 2022 without cannibalizing other planetary programs. (For more on this, see this previous blog post.)

The Europa mission isn’t the only areas in which the Administration and Congress disagree on NASA budget and policy. While outside the scope of this blog post, they also disagree on the amount that should be spent on Earth science (as noted above), developing commercial launch capabilities, and developing the Orion and Space Launch System programs.

Outside of these areas, though, there is a consensus on spending levels, and the final budget is likely to be similar to the proposed budget.

SpacePolicyOnline has a very good summary of the overall NASA budget and areas where the Administration and Congress are likely to disagree. For the planetary program, Casey Dreier at The Planetary Society has good commentary on the proposed planetary budget.

Budget Details

Each budget proposal comes in two parts. The first proposes spending for the next fiscal year (FY17 in this case) and is the starting point for the eventual law allocating funding for the next year. The second part projects notional funding for four additional years (FY18 to FY21 in this case). These notional budgets are not acted on by Congress, but provide agencies with guidance for future years. For agencies like NASA whose projects typically take several years to implement, these notional budgets take on particular importance. The agency cannot issue multi-year contracts that are inconsistent with the notional out year budgets. These creates a problem if, for example, Congress provides generous funding for the Europa mission next year but the notional budgets are inconsistent with the necessary multi-year contracts.

The numbers for the following charts come from NASA’s budget documents except as noted.