Having already disrupted operations at NASA, the coronavirus outbreak was set to affect the agenda of the European Space Agency (ESA) as well, which has now suspended four upcoming Solar System science missions due to a further reduction of on-site personnel.

Most employees at ESA have already been working from home during the past few weeks as a preventive measure. Nevertheless, the agency has now decided to increase restrictions as an employee tested positive for COVID-19 at its mission control in Darmstadt, Germany.

As a result, the instruments and data collection on some space probes are being temporarily stopped. This includes the Cluster mission, which uses four probes to investigate Earth’s magnetic environment, the ExoMars Trace Gas Orbiter and Mars Express, which investigate the red planet, and the Solar Orbiter mission.

“Our priority is the health of our workforce and we will, therefore, reduce activity on some of our scientific missions, especially on interplanetary spacecraft, which currently require the highest number of personnel on-site,” ESA’s director of operations, Rolf Densing, said in a statement.

The four missions will now enter a so-called hibernation mode, an option frequently used that allows spacecraft to function autonomously without any assistance from Earth. They can remain in this state for several months but doing so will have a “negligible impact” on the missions, according to Densing.

The European Space Agency had recently postponed the launch of its joint Mars rover mission with Russia’s Roscosmos until 2022, in part due to travel restrictions resulting from the pandemic. Meanwhile, NASA also delayed several of its upcoming missions and closed down some of its facilities.

“It was a difficult decision, but the right one to take. Our greatest responsibility is the safety of people, and I know all of us in the science community understand why this is necessary,” says Günther Hasinger, ESA’s Director of Science. “This is a prudent step to ensure that Europe’s world-class science missions are safe.”

ESA’s temporary reduction in personnel on-site will also allow it to concentrate on maintaining spacecraft safety for all other missions involved, in particular, the Mercury explorer BepiColombo, which is on its way to the innermost planet in the Solar System and will require some on-site support around its scheduled Earth flyby on April 10.

The challenging maneuver, which will use Earth’s gravity to adjust BepiColombo’s trajectory as it cruises towards Mercury, will be performed by a very small number of engineers and in full respect of social distancing and other health and hygiene measures required by the current situation.