As the longest-ever US government shut down stretches on, more scientific research is being disrupted, including observations from NASA’s only flying telescope.

SOFIA, the Stratospheric Observatory for Infrared Astronomy, is an observatory built onto a Boeing 747. Its mobility, and the fact that it can fly above much of the water vapor in the atmosphere, makes it an important asset for researchers studying distant stars and galaxies.

The government shutdown means the resources and staff needed to get SOFIA in the air have been furloughed, and the observatory has been grounded.

“We know we’ve lost flight opportunities in [the current proposal cycle], and I apologize to the [investigators] who are going to suffer because of this,” Harold Yorke, director of SOFIA science mission operations at the Universities Space Research Association, said at the annual American Astronomical Society (AAS) meeting last week, according to SpaceNews.

SOFIA’s annual schedule runs in cycles, with researchers submitting detailed proposals in the summer, jockeying for flight times. Towards the end of the year, they find out whether or not their proposal was accepted—a success few are able to achieve, according to Jonathan Tan, a galactic astronomy professor at Chalmers University of Technology in Sweden.

“Roughly one-in-four or one-in-five [proposals] are successful in getting time,” Tan said in a phone interview. “So 80 percent of people have to try again the next year or give up.”

Tan himself regularly uses SOFIA to observe massive stars—10 to 100 times the mass of the sun—in our galaxy under the SOMA project, which stands for SOFIA Massive Star Formation Survey.

This survey is designed to study to formation of massive stars and Tan said that the flying infrared telescope is crucial to the kind of observations he needs to make. Shorter wavelengths don’t escape the dense gas and dust particles surrounding a forming star, he said, so longer infrared wavelengths are the only way to see inside. But these wavelengths get absorbed by water vapor in the atmosphere, making them much harder to read from the surface of the Earth, making SOFIA the ideal observatory for this work.

“It wouldn't be possible from the ground,” Tan said.

Rectifying the situation isn’t just a matter of rescheduling the flights once the shutdown ends, explained Matthew Hankins, a postdoctoral astronomy researcher at CalTech who has also used SOFIA on previous work. Due to the fact that the telescope is on a moving airplane, there are a lot of careful logistics that go into planning a flight and ensuring the telescope will be pointed at the right spot at the right time, Hankins said.

“If even one leg on a flight was lost, then it’s very difficult to reschedule,” Hankins said. “They’ll likely wind up bumping those operations to the next cycle—an entire year later from when the person was expecting.”

These kinds of delays happen when, say, inclement weather interrupts one leg of a flight. In this case, the government shutdown has disrupted weeks worth of flights, and the next cycle of proposals has already been approved. Hankins said this creates a lot of uncertainty as to when, if ever, the missed flights can be made up.

While postponing research by a year or two is an inconvenience for established scientists, Tan said it can be much more damaging for early-career scientists, whose research funding may depend on collecting and publishing data now, not later. Some observations can only be made at a certain time or place—such as when an asteroid passes in front of a particular star—meaning some experiments may never have the chance to be recreated.

Amid an unprecedented government shutdown, researchers have no idea how, or if, their projects will be able to continue.