Washington • Kay Behrensmeyer was supposed to be preparing for a three-week expedition to Kenya. Instead, she spent Thursday packing her research permits, her fossil-collecting supplies, and maps she’d spent weeks compiling and annotating by hand into a Fed-Ex box, which she shipped to a junior colleague on the project. Behrensmeyer, curator of vertebrate paleontology at the National Museum of Natural History, wasn’t going anywhere. The federal government was shut down.

In research labs and at field sites across the world, the week-long government shutdown has ground scientific progress to a halt. Thousands of scientists are among the hundreds of thousands of federal employees and contractors who must stay at home without pay. The furlough is expected to persist into the new year, which would mean a rocky start to 2019 for American science.

“It’s distressing, dispiriting, deflating,” said Behrensmeyer, who has spent two years planning this trip. She was supposed to leave on Saturday, but was instructed not to go when it became clear that the Smithsonian would run out of stop-gap funding before a budget agreement was reached.

The partial shutdown, caused by President Donald Trump's rejection of a bipartisan spending deal that did not allocate billions of dollars for a U.S.-Mexico border wall, also curtailed scientific operations at the National Oceanic and Atmospheric Administration, the Agriculture Department, the National Science Foundation and the U.S. Geological Survey. Furloughed government scientists are prohibited from checking on experiments, performing observations, collecting data, conducting tests or sharing their results.

If the budget impasse extends into the new year, scientists say, it could harm critical research.

“Any shutdown of the federal government can disrupt or delay research projects, lead to uncertainty over new research, and reduce researcher access to agency data and infrastructure ... Continuing resolutions and short-term extensions are no way to run a government,” said Rush Holt, chief executive of the American Association for the Advancement of Science, in a statement.

Alice Harding, an astrophysicist at Goddard Space Flight Center who is among roughly 15,000 furloughed NASA employees, worries about missing rare astronomical phenomena — starbursts proceed with or without a federal budget. Just days before the government closed, she and her colleagues at the Fermi space telescope observed a pulsar flashing in an unprecedented way. She scrambled to get a follow-up observation using NASA’s NICER instrument in her last days at work.

"But if the government ends up shutting down for more than a week, we won't get a second one," Harding said.

Crucial research windows will slam shut on Earth, too. A crop-eating pest called the brown marmorated stink bug emerges only in the spring. Scientists must prepare for the insects' annual debut, and missing it would set researchers back an entire year, the Entomological Society of America warned. "A lot of incredible science happens in our government every day," said Robert K.D. Peterson, the organization's president, in a statement. "But when the government shuts down, even partially, that work is derailed."

In Alexandria, Virginia, the National Science Foundation headquarters is closed. About 1,400 employees are furloughed, a spokesperson said. "Ongoing operational and administrative activities will be minimal unless the suspension of these activities will imminently threaten the safety of human life or the protection of property," the agency said in a statement.

The NSF is a funding agency, and its closure will have a massive effect on research if the shutdown lasts for an extended period. Review panels, which convene to approve or reject scientific grant proposals, were not scheduled in the final week of 2018. Should the shutdown extend into 2019, panels in January will have to be canceled and rescheduled, disrupting the flow of science. The NSF does not distribute grant payments to scientists during a shutdown.

The U.S. Antarctic Program remains operational "for the foreseeable future," according to a statement from Kelly Falkner, director of the NSF's office of polar programs.

The National Institute of Food and Agriculture, part of the Agriculture Department, is running on a skeleton crew. Only four of the 399 NIFA staff, according to the USDA shutdown plan, report to work during a shutdown. As at the NSF, the NIFA grant program tends to be quiet during the final week of the year — but January is a critical time in its grant review process.

The Agriculture Department's in-house body of scientists, the Agricultural Research Service, shrinks by 82 percent to just over 1,100 people. Those exempt from the furlough will maintain laboratories, greenhouses and care for research animals; there are time-sensitive data to collect as well as crops and cells to tend. The USDA shutdown plan allows studies involving human subjects to continue. The Agriculture Department did not respond to a request for comment on Thursday, perhaps because the USDA shutdown plan furloughs all but two of the 58 people who work in its communications office.

Federal science agencies are "basically closed for business today," said Rep. Eddie Bernice Johnson, D-Texas, the likely next chair of the House Science Committee, in a Dec. 22 statement. "As I've noted in previous shutdowns, as our competitors in other countries surge ahead in their R & D investments, we have basically shut down a large chunk of our federal science and technology enterprise."

Smithsonian museums and the National Zoo, supported by prior-year funds, remained open as scheduled this week. But if the shutdown continues into the new year, the museums and zoo will close on Jan. 2. All research will cease, but employees who feed and care for animals at the zoo and the Smithsonian Conservation Biology Institute are exempted.

“It’s like being put in the penalty box and not being told when you can come back out on the ice,” said Nick Pyenson, curator of fossil marine mammals at the National Museum of Natural History and author of “Spying on Whales.” Smithsonian scientists cannot communicate with collaborators. Researchers in the field — who are spread across the world — must return home. “That’s really frustrating.”

Thousands of atmospheric scientists are scheduled to converge in Phoenix starting Jan. 6 for the annual meeting of the American Meteorological Society. Hundreds of those scientists work in the federal government, mainly in agencies like NOAA, which includes the National Weather Service, and NASA. More than 800 of the presenters and speakers on the docket are federal employees. If the shutdown continues, those scientists will not attend.

This meeting is where scientists hatch new ideas for lifesaving methods and warnings, said Dan Sobien, the president of the National Weather Service Employees Organization. "Any delay in that research could someday cost someone their life, and that person could be you or me," Sobien said. Not having NWS meteorologists there to collaborate "will likely cost many more lives than the absence of any border wall, anywhere."

Keith Seitter, the executive director of the American Meteorological Society, said the effect of the shutdown on future advances is impossible to calculate, "but we know that it is significant."

"The interactions that occur at these meetings foster new science and new services across the enterprise that greatly benefit all of society," Seitter said. "Having one of those sectors not represented at the meeting greatly impedes progress" on saving lives, supporting the economy and building an understanding of the environment.

At least 26 events at the meeting will be affected or wholly canceled because of the federal scientists' absence, including events like a "town hall" style session on global weather models, where NOAA scientists hope to talk with colleagues about progress, challenges and ideas surrounding its new forecasting system. The United States has fallen behind in weather forecasting over the past couple of decades, outpaced by the United Kingdom and Europe in technology and computing power.

The student and early-career branch of the conference will be severely affected — many of the mentors for that group are federal employees in NOAA or NASA. A managing meteorologist at one of the National Weather Service offices, who wished to remain anonymous to speak openly about the shutdown, said the opportunities for young people to meet and interact with professionals are scant outside of conferences like these.

"You are removing a large body of people whom they can meet as future mentors, giving them exposure to what federal agencies do," the manager said. "It's hard to recruit talented people, and AMS and [the National Weather Association] are our two biggest opportunities to interact with these bright young people who are our future workforce."

More generally, the manager added, "the entire weather enterprise is impacted" when a whole sector is absent.

If the shutdown lasts into the second week of 2019, it could also weaken the winter meeting of the American Astronomical Society, which organizers bill as "the Super Bowl of astronomy." AAS's executive officer, Kevin Marvel, said that two of the meeting's seven invited speakers and roughly a third of its 3,100 participants are federally funded scientists who would be unable to attend if funding is not restored.

"There could be a lot of empty poster boards, missing oral talks," Marvel said. "It's just going to be a mess."

The conference is the biggest annual gathering of astronomers in the United States and offers an important chance for researchers to meet with federal officials who operate their field's most important instruments, such as the Hubble Space Telescope and the National Radio Astronomy Observatory.

"Without the government scientists that make the missions go and make the telescopes operate," Marvel said, "you're missing a big component of what makes the meeting valuable."

Much astronomical research will go forward despite the lapse in federal funding. Operations staff for ongoing space missions are deemed essential, and observing time at ground-based telescopes is awarded far enough in advance to allow for several weeks of uninterrupted research. Facilities like the National Radio Astronomy Observatory have implemented short-term cash management measures to continue normal operations during the shutdown.

But a prolonged closure could stretch these temporary measures to their breaking points, scientists said. Even though instrument operators are allowed to stay on the job, without working scientists they won't have new targets for their telescopes.

For a time, it seemed as though the shutdown might also put a damper on two high-profile space events: the OSIRIS-REx spacecraft's arrival into orbit around its target asteroid, Bennu, on Dec. 31; and the New Horizons probe's historic encounter with a faraway space rock called Ultima Thule, the most distant object ever explored by humans, early on New Year's Day. Though NASA scientists and engineers who operate the missions are considered essential and able to work, the people who run its vaunted publicity operation - which includes NASA TV and its 30 million follower Twitter account - were among those furloughed without pay.

Alan Stern, a Southwest Research Institute scientist and the principal investigator for New Horizons, said the absence of publicity from the agency would be "incredibly disappointing."

But on Friday, NASA Administrator James Bridenstine announced that last-minute arrangements had been made to allow for coverage of both missions.