Technicians working to assemble the James Webb Space Telescope.Credits: Chris Gunn/NASA

The world’s most expensive telescope is the latest victim of the coronavirus pandemic that has been sweeping the planet. The James Webb Space Telescope was supposed to launch in March 2021, but the viral outbreak has threatened to delay this project and others – including the agency’s goal to send astronauts back to the Moon, and possibly a major mission to Mars this July.

Last week, NASA halted work on the US$8.8-billion James Webb Space Telescope, the flagship successor to the Hubble Space Telescope. Webb had been going through final assembly and tests in Southern California — a region now locked down by the state’s governor to keep people from spreading the coronavirus. “The decision was made to ensure the safety of the workforce,” NASA said in a 20 March statement.

Engineers have been racing to finish Webb, which is the most complicated space telescope ever built. After launch, it is meant to unfold like a flower and expose its 6.5-metre primary mirror, which will stare at distant planets and galaxies for clues to the early and modern Universe.

The observatory is fully assembled inside a clean room at Northrop Grumman Aerospace Systems in Redondo Beach, California. Technicians had been working to put it through a final round of tests — intended to shake the entire telescope in order to recreate the stresses it will experience as it rides a rocket to space. The work had been mostly on track until NASA pulled its employees because of coronavirus concerns.

“Delaying launch is absolutely the right thing to do, if it will keep the people working on the mission safe,” says Zachory Berta-Thompson, an exoplanet researcher at the University of Colorado Boulder. “We astronomers can continue to be patient.”

Nobody knows how long the delays might last. Webb is ultimately slated to launch from the Kourou spaceport in French Guiana, which is itself temporarily closed because of coronavirus concerns. Each delay now will push the launch date later — meaning that NASA will continue to have to spend time and money on the telescope as it also tries to develop future missions.

The hold-up adds to a long list of woes for Webb, which has experienced years of delays and cost overruns.

The Mars question

NASA faces an even tighter deadline with its Mars mission. The rover, named Perseverance, is slated to blast off between 17 July and 5 August — a window during which Earth and Mars are temporarily aligned in the best way for spacecraft to travel between them. If it misses the launch window, the mission must wait two years to try again. The European Space Agency has already delayed a Mars rover it planned to launch in July, in part because of how the coronavirus has affected its employees’ ability to work on the mission.

Perseverance will drill and collect pencil-thin samples of rocks from Mars’s Jezero crater region, which future missions are expected to pick up and return to Earth.

So far, NASA is pushing ahead with Perseverance. Engineers are working on it at NASA’s Kennedy Space Center in Florida, which remains open despite the coronavirus outbreak. They are doing “heroes’ work” in keeping the mission on track for a July launch, said Thomas Zurbuchen, NASA’s head of science, in a 20 March virtual town-hall meeting. Earlier this month, they attached some of the final equipment to the body of the six-wheeled rover.

Given the travel disruptions, NASA is considering using some of its own aeroplane fleet to transport key staff from the Jet Propulsion Laboratory in Pasadena, California, to Florida for the final weeks of preparation. "Depending on the phase, this could be about 10 or so people per week, or less," NASA spokeswoman Alana Johnson told Nature. Internally, NASA is calling this plan Perseverance Airlines, Zurbuchen said.

Another likely coronavirus casualty is NASA’s plans to send astronauts to the lunar surface by the end of 2024. That self-imposed deadline was already hugely ambitious, given that the agency is still working on a heavy-lift rocket and crew capsule for the mission. Now, work on those has halted at NASA facilities in Mississippi and Louisiana, which are closed because of the coronavirus. NASA’s Ames Research Center in Northern California, which is working on a lunar rover destined for the Moon’s south pole, is also closed.

NASA missions that are already operating in space continue as planned, with staff running them remotely. They include Hubble and the OSIRIS-REx mission, which is expected to pick up a sample from the surface of the asteroid Bennu as early as August.

The European Space Agency announced on 24 March that it has temporarily turned off science instruments on four Solar System missions, to reduce the number of people needed in its control operations centre in Darmstadt, Germany, where one employee has tested positive for the coronavirus. The missions are Solar Orbiter, which launched last month and is on its way to the Sun; two Mars missions, the ExoMars Trace Gas Orbiter and Mars Express; and the Cluster satellites, which are investigating Earth's magnetism.

One US astronaut and two Russian cosmonauts are slated to launch to the International Space Station on 9 April. Like all visitors to the station, they will be in quarantine for two weeks before launch, to be sure they aren’t carrying any infections.