ESA’s Hera asteroid mission for planetary defence seen with one of its two solar wings added, during its continuing test campaign at the ESTEC Test Centre in the Netherlands.

Watch the solar wing being deployed in this video clip.

The van-sized spacecraft, left, is powered by a pair of solar array wings, made up of three panels each, provided by Leonardo in Italy plus Beyond Gravity in Switzerland.

One of these 5-m-long wings was added for Hera’s ‘cold deployment check’ – a manual unfolding process to confirm that the wing fits correctly. Because the solar wings have been designed to operate in weightlessness they were supported by a frame during this test deployment.

Hera is Europe’s contribution to an international planetary defence experiment. Following the DART mission’s impact with the Dimorphos asteroid last year – modifying its orbit and sending a plume of debris thousands of kilometres out into space – Hera will return to Dimorphos to perform a close-up survey of the crater left by DART. The mission will also measure Dimorphos’ mass and make-up, along with that of the larger Didymos asteroid that Dimorphos orbits around.

Near the end of Hera’s current test campaign this solar wing deployment will be repeated, this time as a ‘hot deployment check’ where the deployment is commanded through and implemented by the spacecraft itself, as it will occur in space.

Hera is scheduled for launch in October 2024, to rendezvous with the Didymos and Dimorphos asteroid system. The spacecraft’s onboard thrusters – seen here covered with red tags at each corner of its hull – will manoeuvre it through deep space to reach its destination just over two years later.

The facing side of the spacecraft was open during the deployment test because the team was still working inside it, finalising the installation of test sensors. Since then Hera has been sealed and its antennas fitted, allowing mechanical testing to proceed.

Operated for ESA by European Test Services, the ESTEC Test Centre is the largest facility of its kind in Europe, providing a complete suite of equipment for all aspects of satellite testing under a single roof. Hera will be on view to attendees of the ESA Open Day at ESTEC on Sunday 8 October.

To find out more about Hera and planetary defence, watch our Incredible Adventures of the Hera Mission series.