WASHINGTON (CN) – As NASA astronauts floated outside the International Space Station to make repairs Wednesday, a congressional committee on Earth weighed the gravity of the station’s future.

A Senate Commerce, Science and Transportation subcommittee met Wednesday with newly appointed NASA head William Gerstenmaier and Paul Martin, the agency’s inspector general.

It was the first of two hearings scheduled to consider NASA’s long-term plans for low-Earth orbit activities and what the commercial prospects for the space station will be by 2025, when federal funding for the feat of human engineering ends.

Last December, President Donald Trump issued a directive to NASA to “lead an innovative and sustainable program of exploration with commercial and international partners to enable human expansion across the solar system and bring back to Earth new knowledge and opportunities.”

With plans for human travel to Mars by the 2030s on the agenda, Gerstenmaier told lawmakers the International Space Station must remain a fully functional component of scientific study.

But in order to preserve the station – which is the size of a football field – the need for a partnership between the government and commercial industry is imperative, since the craft’s maintenance costs alone run roughly $4 billion annually.

A transition report from NASA to Congress delivered in March – late, according to deadlines set out in the bipartisan NASA Transition Authorization Act of 2017 – said the space station can run at its current capacity through 2028.

Though the satellite’s longevity extends a few years beyond the 2025 funding cutoff, NASA’s inspector general Paul Martin said the federal budget for 2019 shows zero investment in transitioning the International Space Station into a quasi-commercial weigh station for future space travelers.

Martin questioned the efficiency of relying on commercial ventures to shore up funding.

“It is unlikely a private entity can assume a station’s operating cost of $1.2 billion in 2024. Such a business prospect requires robust demand from the commercial market and the scant commercial interest in this over the last 20 years gives us pause at the agency’s current plans,” Martin said.

The savings for the federal government by ceasing its funding to the station may also be a pipedream, Martin said.

“For crew and cargo transportation plus ongoing civil infrastructure costs, even if many activities transition from one to the other, any assumption that ending direct federal funding would free up $3 billion to $4 billion in 2025 for use on other NASA initiatives is wishful thinking,” he said.

Plotting a course through the space station’s transition will remain a focus of the committee. Though another hearing on budgetary concerns is not yet on the books, the subcommittee’s chairman Sen. Ted Cruz, R-Texas, emphasized not decommissioning the space station prematurely as was done with the space shuttle program in 2011.

“The program was phased out before an alternative was established. It created a gap for the national space program and made NASA reliant upon Russia to get to and from the ISS,” Cruz said.

From 2006 to 2018, NASA has paid increasingly large sums to Russia for use of its shuttle services. The cost went from $21 million to over $80 million, a $60 million increase in 12 years.

Commercial delivery systems costs will be nearly 2 ½ times more than what the space shuttle would have cost, Cruz said.

Gerstenmaier said NASA is eager to work with Congress since keeping a “continuous presence” in human space flight is critical to the agency’s core mission.