NASA/ESA spacecraft preps for worst-case scenario as it swoops past Sun

The NASA/ESA Solar Orbiter - the most complex scientific laboratory ever to have been sent to the Sun - is approaching the closest point to our active and unpredictable Sun. The European Space Agency is preparing for any potential complications that could arise during this close encounter - called perihelion.

"It’s our worst-case scenario. If Solar Orbiter were to experience some major issue on board, and then we were unable to reestablish communications," says flight controller Daniel Lakey.

As the spacecraft swoops past the Sun, ESA’s ESOC mission control centre is running a series of highly complex operations. According to the agency, there's a looming risk that the spacecraft could auto-reset into a safe mode, a state where only the most basic functions are reactivated.

A safe mode during perihelion would be particularly bad because of the severe impact on science operations during this busy period, the agency said on Tuesday.

During perihelion, the Solar Orbiter has less power available as the intense heat requires the spacecraft to tilt its solar arrays away from the Sun to avoid damage. A quick recovery from any potential safe mode is imperative to prevent a loss of scientific data or, in the worst case, a total power outage.

According to ESA, when in safe mode, the top priority for a spacecraft is to point its communication antenna towards Earth and reestablish communication as soon as possible. What makes this situation more challenging is the spacecraft's reliance on a back-up antenna that has limited movement capabilities, This prevents several potential complications, but it also means the whole spacecraft must rotate to point the antenna in certain directions.

For such scenarios, the solution is a contingency operation known as 'strobing'. It involves the spacecraft performing a controlled roll to maintain its heat shield towards the Sun while attempting to establish a connection with Earth.

Recent tests conducted by the ESOC teams have successfully demonstrated their preparedness for a strobing recovery, should the Solar Orbiter find itself in such a situation. The tests confirmed that the teams could detect the spacecraft's emergency beacon and identify its status in the event of a safe mode with malfunctioning star trackers.

What keeps you up at night? For us, it’s thinking about new ways that our missions could go wrong – and how to solve them!As @ESASolarOrbiter swoops past the Sun, we’ve been practicing how to recover the spacecraft if it were to lose sight of Earth.https://t.co/0mKNoiaZbu

— ESA Operations (@esaoperations) April 2, 2024