The wonders of NASA — Mars rovers, astronaut Instagram feeds, audacious missions probing distant galactic mysteries — have long enthralled the American public. And, it turns out, the accomplishments have won the agency the public’s trust: Polls have consistently shown NASA to be the second-most trusted government institution, behind only the Centers for Disease Control and Prevention.

The public, however, probably has less appreciation for the work NASA has done on its home planet. NASA’s $2-billion-a-year earth-science program has long tracked global-scale environmental conditions on Earth, including climate change.

But with the election of Donald Trump, there was immediate concern — inside NASA and among the fans of its valued work on global warming — about the future of the agency’s earth-science program. Within hours of Trump’s acceptance speech on Nov. 9, an internal email from a senior official in the Earth Sciences division at NASA’s Goddard Space Flight Center circulated within NASA acknowledging worry that “funding may now be exposed to severe reductions.”

The last month is not apt to have eased that alarm.

Trump’s most visible advisor on space policy has been Bob Walker, a former House Science committee chairman who is now a space-policy lobbyist pressing to move “Earth-centric” and “heavily politicized” climate science out of NASA altogether. And Christopher Shank, who was chosen by Trump to lead the transition at NASA, is a seasoned strategist who has expressed strong skepticism about the severity of global warming.

Should Trump come to take a dim view of NASA’s research on climate change, he’s likely to have no shortage of support in Congress. The last few years have seen intensifying moves against the Obama administration’s investments in climate science in hearings led by the Texas Republicans Sen. Ted Cruz and Rep. Lamar S. Smith, whose views on NASA and climate parallel those of Walker — built around the notion that NASA needs to focus on outer space, not back on Earth.

As Smith put it in 2015, “There are 13 other agencies involved in climate-change research, but only one that is responsible for space exploration."

NASA’s Earth Science Division, if less well known to the public, has regularly seen its budget fluctuate with turnover in the White House. Under Ronald Reagan, there were substantial investments in what was then called the Earth Observing System. George H.W. Bush, building on a 1987 report by astronaut Sally Ride, funded a program that came to be known as the “Mission to Planet Earth.”

George W. Bush reversed course, and reduced resources for the program (his administration was eventually exposed for trying to suppress NASA research on global warming). Most recently, though, the division’s budget was greatly restored by Barack Obama. A core argument of Walker and congressional critics of NASA earth science, that budgets have ballooned and reduced resources for other NASA science programs, has no basis, said Arthur Charo, who has tracked NASA science budgets for the Standing Committee on Earth Science and Applications from Space of the nongovernmental National Academy of Sciences.

He said a careful look at programs, adjusting for inflation, shows no evidence of such a pattern. “There is a mythology that earth science has undergone dramatic growth and that this growth has occurred at the expense of other divisions in the Science Mission Directorate,” he said. “Both assertions are false.”

The Trump transition office declined requests for interviews and Walker did not reply to email messages.

Piers J. Sellers is the director of the Earth Sciences Division at NASA’s Goddard Space Flight Center, and the former astronaut is a climate scientist himself. ProPublica spoke with him recently. Sellers declined to discuss the politics surrounding NASA during a presidential transition, but said the agency has a unique position in the world in clarifying global environmental risks and that part of its mission deserves support.

“We’re doing our best to provide the least dangerous options to getting from here to a safe future,” he said. “That’s our job as U.S. government scientists. NASA has the greatest capability to see what’s going on and has a pretty strong capability to model what’s going on into the future, as well.”

Some of NASA’s most vital earth-science work has been done at a tiny climate research hub, the Goddard Institute for Space Studies. The center occupies the upper floors of a century-old building in upper Manhattan best known for Tom’s Restaurant, the cash-only corner diner famed because its facade was featured in the sitcom “Seinfeld.”

The institute was led for decades by James E. Hansen, the climate scientist who stepped ahead of most peers in the hot summer of 1988, famously telling a Senate panel it was “99 percent certain” that human-generated greenhouse gases were driving global warming. A decade ago, Hansen defied muzzling efforts during the George W. Bush administration and irked defenders of fossil fuels with his warnings of calamitous warming. He retired in 2013 to focus on activism aimed at curbing emissions of greenhouse gases linked to warming.

The institute has produced one of the four most important records of global temperature trends and, under Hansen’s successor as director, the TED-talking, Twitter-savvy climatologist Gavin A. Schmidt, has continued to refine climate simulations and communicate warnings about unabated warming.

Schmidt declined to be interviewed for this story, citing what he described as selective quoting in recent coverage of possible threats to earth science under the Trump administration. But he’s shown no signs of dread in his personal Twitter flow, on Thursday night posting this provocative two-parter:

It's as if they really believe that the science is ordered up by politicians & changes as often as their principles.

Newsflash: It doesn't

— Gavin Schmidt (@ClimateOfGavin) December 9, 2016

On Wednesday, in an appearance at a space law conference in Washington, D.C., Walker, Trump’s advisor, stuck with his vision of stripping “Earth-centric” science out of NASA and “transferring the programs, lock, stock and barrel, to another agency,” according to an article by Jeff Foust in Space News.

It could be argued that the core work done at Goddard — particularly its climate modeling — is redundant, for the United States has two other major climate modeling centers, and there are more than 30 worldwide. But Richard Betts, the head of the climate impacts division at Britain’s Met Office, said in an interview that the Goddard Institute’s modeling stands out because of NASA scientists’ longstanding familiarity with the information coming from NASA-built satellites.

Decades ago, John R. Christy, the director of the Earth System Science Center at the University of Alabama, Huntsville, co-developed with NASA a method for tracking the temperature of the lower atmosphere from satellites, cutting out some of the uncertainties that come with surface measurements. He has long held skeptical views on the severity of global warming, and has been a featured witness of Republicans resisting steps to cut greenhouse gases. But in an interview Thursday, Christy expressed concern about plans to move Earth-focused science out of NASA.

“NASA has a very good track record of putting things in space that work, and that provide data,” he said. “NASA does that soup to nuts kind of work.” He added, “Undoing that would be disruptive to the mission we have of trying to characterize the planet with as much accuracy as we can.”

He also noted that, with or without human-caused global warming, from California to sub-Saharan Africa, the forces driving megadroughts and other climate-system threats are still poorly understood. “There’s so much that needs to be known and the perspective from space is just absolutely essential,” he said.

What happens to NASA next?

In his victory speech on Nov. 9, Trump pledged to listen to people with differing views, so perhaps he’ll reach out beyond Walker in weighing next steps for NASA to people like David Titley, a retired Navy rear admiral and former Oceanographer of the Navy, who has written a comprehensive overview of the value NASA earth science provides to society, including to national security.

Or perhaps he could turn to former President George W. Bush. While funding for NASA earth science dropped on his watch, his administration’s 2006 NASA Strategic Plan made clear that NASA was an appropriate venue for such research: “Earth science is science in the national interest. While scientific discovery from space is inherent in the Agency’s mission, NASA’s programs in earth science also are central.”

Sellers, in the email to his Earth Sciences Division team a month ago, managed to summon some confidence, even defiance.

“We have an excellent record of achievements and can make a solid case for stable support,” wrote Sellers (his email was provided to ProPublica by someone else at NASA).

“We will never give up on this.”