It seemed like a good idea at the time. Back in 2010 President Obama wanted to distance himself from the space exploration programs of George W. Bush and his predecessors. Humans had been to the Moon, and while they would one day go to Mars, the president reasoned, they needed a more realistic near-term destination. He chose an asteroid.

“By 2025 we expect new spacecraft designed for long journeys to allow us to begin the first-ever crewed missions beyond the Moon into deep space,” Obama said at Florida’s Kennedy Space Center, during the one space policy speech he has given as president. “So we’ll start by sending astronauts to an asteroid for the first time in history.”

An asteroid offered a couple of key benefits. It was new—no human had visited one before. And with a shallow gravity well, it didn’t require expensive landers and ascent vehicles to get onto and off its surface. But there were also problems. Even after searching for a couple of years, scientists couldn’t find a suitable asteroid that came close enough to Earth for astronauts to reach it in a timely manner, and the Orion vehicle NASA was building could only support a crew for 21 days in deep space.

After studying the problem, NASA engineers concluded they didn’t have the tools or the budget to mount a human mission to an asteroid. They couldn’t even come close to the 2025 date. So NASA kludged a solution that became known as the asteroid retrieval mission, or ARM.

Under this plan the agency would send a robotic spacecraft out into the Solar System, grab an SUV-sized boulder off the surface of an asteroid, and bring it back to the vicinity of the Moon. Astronauts would then visit it in 2025. Technically, this still met Obama’s goal. But it was an unhappy solution for most involved, and it wasn’t clear how this brought the agency much closer to its ultimate destination of Mars.

Changing launch dates

It is now the last year of Obama’s second term in office, and it appears NASA may be quietly backing away from the asteroid mission. This week, as the agency’s chief financial officer, David Radzanowski, discussed the president’s budget in a conference call with reporters, he let slip a seemingly huge piece of news. The robotic spacecraft NASA planned to grab an asteroid boulder would not launch in 2020, as originally planned, but some time in the early- to mid-2020s.

The agency’s notional launch date had changed to 2023, Radzanowski said. But he then cautioned reporters not to focus on that date. It could be earlier than that, he said, adding: “Don’t get fixated that there’s a delay at this point in time.”

But it is difficult to see 2023 as anything but a three-year delay. Michele Gates, the asteroid mission’s program manager, has regularly given presentations that show the robotic mission launching in December, 2020, reaching the target asteroid in 2022 and performing several experiments before dragging a boulder back to the vicinity of the Moon by 2025. If the robotic mission’s launch date slips three years, astronauts probably could not visit the boulder before 2027 or 2028, at the earliest. Asked directly about this apparent discrepancy, Radzanowski said a crew visit to an asteroid by 2025 remained a possibility.

Ars reached out to one space industry veteran who listened to Radzanowski’s presentation for clarification. This politically connected analyst, who did not want to damage his reputation with NASA, offered a blunt explanation for Radzanowski’s asteroid comments: “Oh come on, these poor guys are just trying to get through one more budget release with a shred of dignity intact knowing it’s all in the crapper next year.”

That seems an all too realistic possibility. Congress has been lukewarm in its support of the asteroid mission, at best. Many scientists who study asteroids have said it doesn’t contribute much to their field of work. And it doesn’t seem likely a new president will embrace a “near-term” mission that won’t be completed during his or her administration.

One former senior NASA official who has retained contacts within the agency’s Washington DC headquarters said NASA is unlikely to go to bat for the asteroid mission with the next president. “Nobody believes in the ARM mission,” this source told Ars. “When the boss says go make this happen, you have to jump. That’s part of the deal. But deep in their hearts, is anybody really sold on ARM? I don’t think so.”

It is also perhaps telling that the president’s budget request only allocates $66.7 million for formulation of the ARM mission in the fiscal year 2017 budget. That seems like a relatively low amount for what is the agency’s flagship human mission, the first actual exploration mission using its proposed Orion spacecraft and Space Launch System rocket. By contrast, the agency’s new budget requests $90 million to begin developing a habitat scheduled to be built near the Moon in the late 2020s. That higher amount seems to represent a pivot toward a higher-priority mission.

Solar electric propulsion

To be fair, the asteroid retrieval mission will demonstrate a handful of key spaceflight technologies, most notably solar electric propulsion. This mode of propulsion uses solar energy to power a spacecraft’s engines and therefore requires far less propellant than a conventional space vehicle.

Although solar propelled vehicles move slower, they are seen as key cargo delivery vehicles to stage provisions at Mars for eventual human missions. However, this technology could be tested in other ways. For example, last year NASA’s Advisory Council voted unanimously to recommend that the agency repurpose the asteroid mission to retrieve a sample from the Martian moon Phobos.

One council member, former Goddard Space Flight Center Director Thomas Young, articulated the council’s feeling at that time. “What we really should be saying is terminate ARM, take the $1.25 billion and apply it to the technology to get people to Mars," he said. "That’s the cold hard facts of what we’re saying.”

Publicly, NASA almost certainly is not going to abandon the asteroid mission while President Obama is in office. However, until this year, it has never asked Congress for this large of an appropriation to be spent directly on the ARM mission. It will be most interesting to see how Congress responds to this request.