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Planetary defenders: after NASA’s DART comes ESA’s Hera, in which Romania plays an essential role

on 23 November 2021

The world will be watching the milestone launch of NASA’s Double Asteroid Redirection Test, DART, spacecraft on Wednesday, 24 November, intended to alter one small part of the Solar System forever.

DART will collide with the small moon of an asteroid in order to shift its orbit around its parent body – to test the concept of diverting threatening objects away from Earth. ESA will provide crucial ground station support to DART as it departs for deep space, helping relay signals from the ambitious mission immediately following launch.

Furthermore, one group of Europeans is following DART’s launch campaign particularly closely: the team developing ESA’s Hera spacecraft, designed to undertake a close-up survey of the consequences of DART’s collision. The concerned group also includes several Romanian teams that contribute to the first planetary defence mission.

DART will collide with the smaller body of the Didymos binary asteroid system in September 2022, striking at a speed of around 6.6 km per second. While the Didymos asteroid system will maintain its motion around the Sun unperturbed, the collision is expected to shift the orbit of the 160-metre-diameter Dimorphos around its 780-metre-diameter parent Didymos in a small but distinct way – just a fraction of one per cent – sufficient to be measured with Earth-based telescopes and radar.

But observing from across space will still leave multiple unknowns, such as the precise mass of Dimorphos, its makeup and its internal structure – as well as the size and shape of the crater left by DART. So, in November 2024 Hera will head towards the Didymos system, commencing its detailed ‘crime scene investigation’ of the two asteroids in late 2026.

By gathering data close-up, Hera will help turn DART’s grand scale impact experiment into a well-understood and repeatable deflection technique – ready to be deployed if an asteroid should ever be spotted heading Earthward.

The main Hera spacecraft will also deploy a pair of shoebox sized CubeSats to perform supporting observations: Milani will make spectral surface observations, while Juventas will undertake the first-ever radar soundings within an asteroid.

Scheduled to fly to the Didymos binary asteroid system with ESA’s Hera mission for planetary defence in 2024, the compact radar aboard the Juventas CubeSat will perform the first ever radar sounding inside an asteroid. Juventas will peer up to 100 m deep within the 160-m-diameter Dimorphos moonlet of the 780-m-diameter Didymos asteroid.

CubeSats are mini-satellites built up from standardised 10-cm boxes. Juventas is a ‘6-unit’ CubeSat, measuring 10x20x30 cm, while its quartet of radar antennas measure 1.5 m long each. So the test campaign includes a structural model of the Juventas CubeSat, to evaluate how the body of the miniature spacecraft might affect the radar signals.

Juventas is being led for ESA by GomSpace company in Luxembourg with GMV in Romania, with its radar developed by the Planétologie et d'Astrophysique de Grenoble group at the University Grenoble and Technical University Dresden, with Astronika in Poland constructing the antennas and EmTroniX in Luxembourg contributing the signal generation system.

Indeed, Romania will play an essential role in the HERA mission. Four companies and one research institution from Romania will contribute to the mission.  GMV Innovating Solutions — Romania will develop the navigation related component that is based on image processing from the Guidance, navigation and control  System (GNC) and the Fault Detection, Isolation and Recovery (FDIR). Additionally, GMV is responsible for the developing and production of the unit processing image. ATOS Romania through ATOS Convergence Creators will be involved in the ground testing system for the satellite and primary data processing. EFACEC Romania will carry out the Planetary Altimeter (PALT) manufacturing and testing, for both the hardware & software.

The National Institute for Research and Development for Optoelectronics - INOE 2000 will contribute to the PALT design, the testing functionality of PALT optics and the development of the optical ground support equipment.

Image credit: ESA-Science Office