Senate appropriators are proposing to allocate $1 billion to NASA next year for the construction of new lunar landers to take humans to the surface of the Moon — roughly $2.4 billion short of what the agency requested. The shortfall threatens to delay NASA’s ambitious plan of landing the first woman on the Moon by 2024.

Today, the Senate Appropriations Committee released 12 funding bills for next year, laying out proposed budgets for the federal government. The newly released legislation would allocate a total of $23.5 billion to NASA, an increase over last year’s NASA budget but roughy $1.75 billion less than the $25.2 billion the administration had asked for.

The Trump administration has been calling for increased funding to NASA over the next five years to help fund the agency’s Artemis program, an initiative to send the first woman and the next man to the surface of the Moon. Originally, NASA had planned for the first Artemis landing to occur in 2028, but the administration challenged the agency to move that up to 2024. NASA has been clear that a sizable budget increase is necessary to meet the tighter deadline, particularly for the new human lunar landing system.

In April, NASA awarded three companies — SpaceX, Blue Origin, and Dynetics — with contracts to develop vehicles that could be used to transport people down to the surface of the Moon. The initial awards were small, worth a combined $967 million for all three companies. To help accelerate the development of these vehicles, the president’s budget request for NASA called on Congress to provide nearly $3.4 billion for the human lunar landers in 2021. Ultimately, the agency plans to select two of the three companies to build out their vehicles for Artemis, with the final decision occurring early next year.

However, Congress seems reluctant to give NASA the full amount it has asked for. In July, the House released its proposed funding bill for 2021, which only provided $628.2 million to further develop lunar landers. When testifying in front of the Senate Appropriations Committee in September, NASA administrator Jim Bridenstine made it clear that the money would guarantee that the space agency would miss the 2024 deadline.

“We’re very grateful for that, I want to be clear,” Bridenstine said of the appropriation. “I will also tell you that that that’s not enough to achieve the 2024 moon landing. I’m glad that they did it; it shows strong bipartisan support that we all agree we need to go to the Moon. But again, the longer the program goes, the more I worry that it becomes at risk.” NASA has not yet released a statement on the Senate bill out today.

The actual federal budget has yet to be finalized. But now that both the House and the Senate have released their proposed budget bills, it’s likely that the final compromised funding for landers will fall somewhere between $600 million and $1 billion. Of course, that money just covers how much NASA will invest in those vehicles. It’s possible the companies could add more of their own funds to accelerate the development of their vehicles in an attempt to make a landing in 2024. But that date is still considered a long shot, even if more funding materializes.

Even more uncertainty lies ahead for Artemis as president-elect Joe Biden prepares to take office. The Biden transition team hasn’t released any details about its space policy, and the fate of the Artemis program under Biden is uncertain. Meanwhile, Bridenstine has said that he does not plan to remain in his position under the new administration, even if asked to stay. There is also turmoil over the transition process, as the General Services Administration has yet to acknowledge Biden’s win, blocking government money being used for the transition. 

Despite all this uncertainty surrounding NASA’s future, it still seems that agency will likely get some money for a lunar lander next year, just less than what the agency had hoped.