"Culberson's" Europa mission: How can mission proritization be done so unilaterally?

Question

According to Marcia S. Smith of SpacePolicyOnline.com in "NASA Gets Big Boost in Final FY2016 Appropriations Bill" news article:

Planetary Science. Funding for planetary missions is \$1.631 billion, an increase of \$270 million above the request and \$193 million more than FY2015. It includes \$175 million for a mission to Jupiter's moon Europa, a priority of House Appropriations CJS subcommittee chairman Rep. John Culberson (R-TX). He added substantial funding for the mission in FY2013 (\$75 million) and FY2014 (\$80 million) although NASA did not request any. For FY2015, NASA requested \$15 million and Congress provided \$100 million. For this year, NASA requested \$30 million. Not only did Congress add \$145 million to that figure, but it directs NASA to build a lander as well as an orbiter. It reiterates that it wants the mission launched in 2022. NASA has been envisioning a later launch date to match the projected funding levels in the President's budget request.

Now, don't get me wrong, I'm all for an advanced Europa mission, but deciding so unilaterally, by a single congressman that happens to chair the House Committee on Appropriations Subcommittee on Commerce, Justice, Science, and Related Agencies, seems wrong to me. Countless advanced missions are proposed each year and compete for attention of the statesmen and budgetary support, and which ones succeed and which ones don't shouldn't be decided on by lone policymaker's wits.

It might backfire, and having watched the two day Exoplanets Program Analysis Group (ExoPAG) meeting that just ended today, it appears it already has. This unilateral budget increase for a single specific mission has been a subject of some ridicule, and Culberson's "vision" of focusing on Europa as one single world with highest likelihood of harboring life was corrected with the dioptric power of exoplanetology snark - that surely Earth-analog exoplanets have the highest likelihood of harboring life besides the Earth itself. I'm not going to comment if I agree or not (Enceladus! oops), that's not the point of my question, which is simply:

Is Culberson within his rights to unilaterally bypass all the mission prioritization and selection processes set in place so the scientific community and the society at large decide which ones to support, to what extent and when based on merit, feasibility, benefit, cost and other criteria that might apply? Can a single well-seated policymaker come up with and self-approve his own policy?

Please note that I'm not seeking an open discussion. I expect answers to be substantiated with verifiable sources of information, perhaps there's a precedent that I'm not aware of, but I also welcome some conjecture if you want to comment on this from your own perspective, as long as you first answer the question.

Answer 1

Any lawmaker involved in writing a bill is entitled to change the bill in any way he or she sees fit. That change alone cannot be enacted by that single representative, but must be voted on by the entire Congress.

In general, the process of inserting one's own pet project into such a bill is known as an "Earmark". Usually this is done to benefit one's home location, but can be used to support any project that the congressmen wishes.

In fact, NASA Earmarks have a long history. For instance, the Office of Inspector General did a report on NASA's earmarks in 2006.

It's also worth noting that the President can specifically request NASA to earmark money for some project. The two most notable examples are Kennedy's 1960 request to get a man to the Moon, and less famously President Bush's 2004 exploration program. These are usually done in concert with NASA missions.

In fact, the NASA Europa Exploration mission as a part of the Planetary Sciences Decadal Survey, published in 2011. Initially it was allocated \$75 million, presumably over a period of time, \$15 million being a part of the first year. It has since grown every time it has passed through Congress. And in fact, the mission has been approved by NASA for continuing studies, in a mission concept phase. This mission is a Jupiter orbiter concept, which makes frequent close approaches to Europa, an anticipated 45 times in the primary mission.

As for the lander bit specifically, it is within Congress's rights to do so, and part of the appropriation they have for the mission has been devoted to studying a lander. There is evidence that NASA has been interested, such as NASA inviting ESA to send a lander with the Europa mission. In my personal opinion, making such a change to the mission is not wise, but not completely unreasonable either. Europa has received considerable attention in the past, far more than Titan had when the Huygen's probe landed on it. At a later date, if it becomes clear that NASA cannot include the lander, then they can return to Congress to explain why, nothing is set in stone yet. It is still worthwhile to explore such concepts.

Lastly, NASA would prefer to pick their own missions, at least according to this Washington Post article in 2006. They prefer to have Congress set the priorities, and perhaps a very general budget, and let NASA figure out the specifics themselves. In this instance, it seems that NASA laid out the missions that it would like to do, and a particular Congressman took it into his own hands to prioritize one of them. Granted the Europa mission is one of the higher priority missions on the list, and as it was extra money allocated to NASA, and not taken from another pile of money allocated to them, I'm sure they aren't complaining about it too much.