A unique space mission has launched. Objective? Planetary defense

Developed as part of ESA’s (European Space Agency) space security program, the Hera mission has launched. She went into space on a SpaceX Falcon 9 from Cape Canaveral Space Force Station in Florida, USA. Her solar panels were deployed about an hour later. Now The probe is set to conduct the first detailed study of a binary asteroid, 65803 Didymos, which is orbited by a smaller object, Dimorphos. And it is the latter that the probe will focus on because its orbit was changed by NASA’s Double Asteroid Redirection Test (DART) mission in 2022.

Hera’s mission plan

But Dimorphos is not Hera’s only target. The spacecraft will also conduct demanding technology experiments in deep space, including deploying two shoebox-sized “CubeSats” to approach the target asteroid, maneuvering in ultra-low gravity to obtain additional science data before final landing. The main spacecraft will also attempt to “autonomously” navigate around the asteroid based on visual tracking.

ESA, together with NASA and other partner agencies, observes the sky to identify and track hazardous asteroids. But what can be done to stop the incoming object, if it can be done at all? NASA’s DART mission was created to help answer this question. On September 26, 2022, the DART spacecraft performed the first asteroid deflection in human history by intentionally colliding with Dimorphos, which orbits the larger, mountain-sized asteroid Didymos, changing its orbit.

Based on observations from Earth, DART managed to shorten the orbital period of Dimorphos around Didymos by 33 minutes, almost 5% of its original value, while also throwing a plume of debris thousands of kilometers into space. However, there remain many unknowns about this event that scientists must resolve to help transform this asteroid deflection impact method into a well-understood and reliably repeatable planetary defense technique. How large was the crater left by the DART impact? Has the entire asteroid been transformed? After reaching the asteroid Didymos in two years, the mission will conduct a close-up “crash site survey” to gather all the missing knowledge.

Not just asteroids

Hera will perform the most detailed exploration of a binary asteroid system to date. Although binary systems make up 15% of all known asteroids, none of them have yet been studied in detail. In addition, The Dimorphos asteroid is the smallest body ever visited by a space mission. Moreover, Didymos is also unique in that it rotates extremely fast, bringing it close to the limits of its structural stability considering its dimensions. It is also worth emphasizing that as many as approximately 100 European companies and institutes from 18 ESA member states were involved in the development of the Hera mission. At the heart of the probe is, among other things, an innovative autonomous navigation system developed by Polish engineers from the international technology group GMV, one of the largest companies in the European space sector.

Along the way, Hera will benefit from Mars’ gravitational assistance while exploring the Martian moon Deimos, using its instruments for scientific purposes for the first time. Arrival at Didymos is expected for fall 2026, when the asteroid mission will enter its main science and technology demonstration phase. She will work there for six months. ESA itself plans to launch a similar Ramses mission soonwhich is scheduled to encounter the asteroid Apophis during its close approach to Earth in 2029.