NASA/Kim Shiflett

NASA is planning to return to the moon within five years, thanks to a directive handed down by Vice President Mike Pence in March. However, if it is to put astronauts back on the lunar soil, it's going to need a lot more cash.

On May 14, the White House requested an additional $1.6 billion to top up the proposed $21 billion in funding for the agency over the 2020 fiscal year. On Wednesday, the House Committee on Appropriations, which controls the government's purse, left that additional request out of NASA's spending plan, Quartz reports.

The White House had proposed the additional funding come from unused cash from an aid program, the Pell Grants Program, designed to help low-income students get to college. The chair of the committee, Rep. Nita Lowey called it an "unconscionable proposal," according to Quartz.

A press release from the Committee on Wednesday revealed the funding bill was approved and NASA would be funded to the tune of $22.32 billion. That total includes $7.16 billion for science programs and $5.1 billion to fund NASA's long-in-development Orion crew vehicle for space exploration and the Space Launch System (SLS), NASA's next-gen rocket.

There is a silver lining: The bill provides a $1.3 billion step-up from the $21 billion originally requested by the agency, but that additional cash will not be funneled into lunar lander development and instead go into other NASA programs unrelated to the moon mission.

NASA's original roadmap had astronauts returning to the moon by 2028, off the back of successful launches of the SLS. However, the vice president accelerated that roadmap with an announcement in March, bringing the deadline back to 2024. NASA has been scrambling to come up with a roadmap that will put astronauts -- including the first female -- back on the moon for the first time since 1972.

Without the additional funds being driven into moon-specific programs, the fate of the accelerated return to the lunar surface hangs in the balance.

NASA administrator Jim Bridenstine is set to make an announcement regarding the lunar mission's Gateway on Thursday at 11 a.m. PT. You can watch the teleconference online at NASA.