WASHINGTON — Senators preparing a new NASA authorization bill want to ensure that the agency’s long-term focus remains human missions to Mars even as it plans flights to the moon.

At a July 25 hearing by the Senate’s space subcommittee, titled “Destination Mars – Putting American Boots on the Surface of the Red Planet,” key senators made clear that development of a “Gateway” facility in cislunar space, or human missions to the surface of the moon, should not be a distraction to human Mars exploration.

“While the moon will provide a great testing ground in preparation for the journey to Mars, we must remain vigilant and ensure that we limit costly delays that could push a crewed Mars mission in the 2030s out of reach,” said Sen. Ted Cruz (R-Texas), chairman of the space subcommittee, in his opening remarks. “Mars is today the focal point of our national space program.”

That view had bipartisan support. “We need to help NASA lift its gaze past the moon and understand how the work we do in space closer to Earth will serve us in our quest for Mars,” said Sen. Ed Markey (D-Mass.), ranking member of the subcommittee.

Both Markey and Sen. Bill Nelson (D-Fla.) criticized NASA for not yet providing a “roadmap” document required by a 2017 NASA authorization act outlining its plans for eventual human missions to Mars. That report was due to Congress last December.

“We don’t have this roadmap yet. It’s seven months overdue. But, anyway, NASA is moving on major acquisitions like the development of a large lunar lander. What gives?” Nelson said. “Let’s see the program for going to Mars and how all of this fits in. We need to make sure we’re making smart choices about the priorities.”

None of the four witnesses at the hearing were from NASA, but they were largely sympathetic to the senators’ desire to maintain a focus on Mars. “Putting humans on Mars has been my dream as long as I can remember,” said Dava Newman, a professor at the Massachusetts Institute of Technology and former NASA deputy administrator. “We’ve been stuck in low Earth orbit for too long.”

Chris Carberry, chief executive of advocacy group Explore Mars, cited language in that 2017 authorization bill calling for a report to study the feasibility of a 2033 human mission to Mars. “If this deadline it to be achieved, we cannot allow ourselves to postpone critical decisions. Otherwise, we will have little hope of seeing American boots on the ground in the 2030s,” he said.

Asked by Cruz what is needed in a future NASA authorization bill to make a human Mars mission in the 2030s feasible, most focused on stability for the agency. “One of the most important things is constancy of purpose,” said Peggy Whitson, a recently retired NASA astronaut who holds the U.S. record for cumulative time in space. “We need to have a vision that lasts more than one administration. We have to have a budget line that will support those goals and objectives that we are striving to reach.”

Tory Bruno, president and chief executive of United Launch Alliance, echoed that, with a particular focus on launch. “From the standpoint of the launch industry, this is a flat marketplace,” he said. “It’s essential that we have a healthy industrial base.” Earlier in the hearing, he said the government should “prevent U.S.-taxpayer-funded payloads from being sent overseas to be launched on foreign vehicles from foreign launch pads.”

The committee billed the hearing as the first in a series as it prepares a new NASA authorization bill. The second hearing, scheduled for Aug. 1, will be devoted to NASA science programs, particularly the search for life beyond Earth. NASA Administrator Jim Bridenstine is expected to testify at a later hearing, yet to be formally announced.