The Hera mission, from the European Space Agency, will go to 2 asteroids, to help protect Earth against asteroid impacts.
Source: European Space Agency (ESA)
Developed as part of ESA’s Space Safety programme and sharing technological heritage with the Agency’s Rosetta comet hunter, Hera lifted off on a SpaceX Falcon 9 from Cape Canaveral Space Force Station in Florida, USA, on 7 October at 10:52 local time (16:52 CEST, 14:52 UTC) with its solar arrays deploying about one hour later.
The automobile-sized Hera will carry out the first detailed survey of a ‘binary’ – or double-body – asteroid, 65803 Didymos, which is orbited by a smaller body, Dimorphos. Hera’s main focus will be on the smaller of the two, whose orbit around the larger asteroid was changed by NASA’s Double Asteroid Redirection Test (DART) mission, demonstrating asteroid deflection by kinetic impact, in 2022.
Hera will also perform challenging deep-space technology experiments including the deployment of twin shoebox-sized ‘CubeSats’ to fly closer to the target asteroid, manoeuvring in ultra-low gravity to acquire additional scientific data before eventually landing. The main spacecraft will also attempt ‘self-driving’ navigation around the asteroids based on visual tracking.
The mission’s launch and journey into deep space is being overseen from ESA’s European Space Operations Centre in Darmstadt, Germany.
“The underlying idea of a planetary defence mission based on one spacecraft impacting an asteroid with a second that gathers data goes back two decades, with a significant contribution made by the late Prof. Andrea Milani, a pioneer in asteroid risk monitoring whose name has been lent to one of Hera’s two onboard CubeSats.”, said Ian Carnelli, mission manager.
On 26 September 2022, the DART spacecraft performed humankind’s first asteroid deflection by intentionally crashing into Dimorphos, the Great-Pyramid-sized moonlet of the larger, mountain-sized asteroid Didymos, shifting its orbit.
Based on observations from Earth, DART succeeded in shrinking the orbit period of Dimorphos around Didymos by 33 minutes, nearly 5% of its original value, while also casting a plume of debris thousands of kilometres in space.
But many unknowns remain about the event, which scientists need to resolve in order to help turn this ‘kinetic impact’ method of asteroid deflection into a well understood and reliably repeatable planetary defence technique. How big was the crater left by DART’s impact, or did the entire asteroid undergo reshaping? What is the mineralogy, structure and precise mass of Dimorphos?
With a cube-shaped main body measuring approximately 1.6 m across and flanked by twin 5-m solar wings, the Hera spacecraft is ESA’s own contribution to this international planetary defence collaboration. Once it reaches the Didymos binary asteroid in two years’ time, the mission will perform a close-up ‘crash scene investigation’ to gather all the missing knowledge needed.
Around 100 European companies and institutes across 18 ESA Member States have been involved in developing the Hera mission. OHB System AG led the industrial consortium, including responsibility for the overall spacecraft design, development, assembly and testing.
The Milani CubeSat, developed for ESA by Italian industry led by Tyvak International, will survey the mineral makeup of Dimorphos and its surrounding dust, while the Juventas CubeSat, produced by a Luxembourg-led consortium under GOMspace, will perform the first subsurface radar probe of an asteroid. Late in its six-month asteroid survey, Hera will also test out an experimental self-driving mode that will allow it to navigate around the asteroids autonomously based on monitoring of surface features.
The arrival at Didymos is foreseen for autumn 2026, when the asteroid mission will enter its main science and technology demonstration phase.
The spacecraft will pass through Mars to get a gravitational impulse and study the Martian moon Deimos.
