The Senate still has to pass its own version of the bill, and that version could differ substantially. But as is, the House bill's appropriations for NASA's budget would mean a big boost for the search for life on other planets and moons — and a substantial cut for the study of our own planet.
The bill appropriates the same amount for NASA's total 2016 budget ($18.53 billion) as President Obama's request did in February, a bump of $519 million compared with last year. However, it allocates the money a little differently than Obama would.
There's more money for studying other planets — but less for studying our own
The Republican-controlled committee wants to cut about $265 million from NASA's Earth science program, which at this point isn't a big surprise.
In a hearing last month, Lamar Smith (R-TX) — chairman of the House Committee on Science, Space, and Technology — criticized "a lack of balance" in Obama's budget request, in particular citing "the disproportionate increase in the Earth Science Division."
The big underlying issue here is climate change. Smith and many other Republicans don't believe humans are causing it, and though NASA's Earth science program also studies a variety of other topics, the fact that it conducts climate research makes it a target.
The bill doesn't specify where all $265 million in cuts would come from, but it does eliminate the Thermal-Infrared Free-Flyer — an imaging spacecraft that NASA hopes to launch in 2019, when Landsat 7 (a satellite that currently provides new photos of Earth's surface) will run out of fuel.
NASA administrator Charles Bolden criticized the cuts in a statement Tuesday. "The House proposal would seriously reduce our Earth science program and threaten to set back generations worth of progress in better understanding our changing climate, and our ability to prepare for and respond to earthquakes, droughts, and storm events," he wrote.
Good news for a mission to Europa
Meanwhile, the bill provides a nearly $200 million boost to planetary science (which refers to the study of planets other than Earth). Most strikingly, it would give a huge boost to NASA's uncrewed mission to Jupiter's moon Europa, and directs it to launch in 2022, accelerating the timeline by a few years.
John Culberson (R-TX) — chairman of the subcommittee responsible for drafting the bill — has long been a big proponent of a mission to Europa, and the Houston Chronicle's Eric Berger reports that he's pushing for more money so the probe can include a lander. This would give us a much better chance of determining whether Europa's ice-capped oceans might be home to extraterrestrial life.
The bill would also create an "ocean worlds exploration program" within NASA, specifically devoted to exploring places like Europa, as well as Jupiter's moon Ganymede and Saturn's moon Enceladus. All these icy moons are believed to be home to liquid oceans, and probing them might be our best bet for finding life elsewhere in the solar system.
The bill also provides a bit of money for a pair of older missions: the Opportunity rover, on Mars, and the Lunar Reconnaissance Orbiter, orbiting the moon. It costs money simply to continue operating and collecting data from these probes, and Obama's request provided none, making some observers worry that they might be terminated.
There are several other slight changes to NASA's planetary science program in the bill — such as boost in funding for production of plutonium-238, necessary to fuel deep-space missions to the outer solar system where solar power isn't abundant. Casey Dreier of the Planetary Society has a great explanation of these changes here.
NASA's "rocket to Mars" gets a boost
When it comes to NASA's human spaceflight programs — which ultimately eat up more of the agency's budget than science — the bill allocated about $200 million more than Obama's proposal.
The biggest bump is the extra $493 million the bill would devote to NASA's Space Launch System (SLS), a gigantic rocket currently in development that the agency wants to eventually use for a human mission to Mars. There've been some doubts that NASA would be able to complete SLS given current levels of funding, so this is good news for the program. Funding for the Orion capsule, which would be paired with SLS as part of a Mars mission, is the same as in Obama's request.
On the other hand, the bill dictates a $244 million cut to NASA's Commercial Crew Program — a partnership between NASA and private companies that will see SpaceX and Boeing begin to ferry astronauts up to the Space Station and back starting in 2017.
This program was intended to allow NASA to delegate the relatively routine transport to and from low Earth orbit to private companies, in order to focus on a more ambitious mission to Mars. But NASA has previously said that cuts to this program will force it to renegotiate existing contracts with SpaceX and Boeing, and could mean substantial delays.
So what happens next?
Sometime next month, the Senate Appropriations Committee will likely pass its own version of the bill, and the two versions will eventually be reconciled.
It's hard to say exactly what that bill will look like, but Dreier is hopeful that it will reduce the big cut to Earth science. Among others, Barbara Mikulski (D-MD) — the ranking Democrat on the Appropriations Committee — says she plans to make it a priority:
#ClimateChange is damaging MDs shores and the Chesapeake Bay, costing billions in tourism and causing farmers heavy losses— Barbara Mikulski (@SenatorBarb) May 18, 2015
That's why I'm fighting to put funds in the fed checkbook for NASA's Earth Science program and #climate research at NOAA and NSF— Barbara Mikulski (@SenatorBarb) May 18, 2015