When ESA’s Hera asteroid mission for planetary defence touched down at its Florida launch site in its Antonov An-124 transporter, the mission’s two shoebox-sized CubeSats travelled with it. This is the moment the Milani and Juventas CubeSats made it down to the ground on the morning of 3 September.

The two CubeSats have since undergone functional testing – to check no damage was sustained from their travels – then been fuelled, and are now integrated into the main spacecraft, in readiness for a planned launch by SpaceX Falcon 9 from Cape Canaveral Space Force Station in early October.

Seen left is the Milani CubeSat in its container, produced for ESA by Tyvak International in Italy, with the Juventas CubeSat from GomSpace in Luxembourg to the right.

The Milani CubeSat hosts a multispectral imager to map surface mineralogy as well as a dust surveyor. Juventas carries a radar instrument, to perform the first radar probe of an asteroid’s internal structure, along with a gravity-detecting gravimeter.

The CubeSats have been stowed in their ‘Deep Space Deployers’ on Hera’s top-side Asteroid Deck, which will stow them safely until they are ready to be deployed one at a time in the vicinity of the mission’s target Didymos binary asteroid.

About Hera

Hera is ESA’s first mission for planetary defence. Due for launch in October this year, Hera will fly to the Didymos binary asteroid system in deep space to perform a close-up survey of the Dimorphos moonlet in orbit around the primary body. The Great-Pyramid-sized Dimorphos is already historic, as the first Solar System object to have its orbit changed by human activity, by the 2022 impact of NASA’s DART mission.

Hera is intended to gather crucial missing data about Dimorphos for scientists, to turn DART’s grand-scale experiment into a well-understood and potentially repeatable planetary defence technique. To increase its yield of data, Hera carries with it ESA’s first deep space CubeSats, carrying additional instruments and planned to fly closer to the asteroid’s surface than the main spacecraft, before eventually landing.