New Space and Tech

GRASS Instrument On Board ESA’s Hera Mission Ready For Final Integration

By Keith Cowing
Press Release
May 26, 2023
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GRASS Instrument On Board ESA’s Hera Mission Ready For Final Integration
Juventas CubeSat

The Gravimeter for Small Solar System Objects (GRASS) has successfully passed the test campaign at the Mechanical Systems Laboratory at the European Space Agency’s (ESA) ESTEC technical centre in the Netherlands.

The instrument will be the first to measure gravity directly on the surface of an asteroid and has been developed by EMXYS in collaboration with the Royal Observatory of Belgium (ROB).

The gravimeter will land on the surface of the asteroid Dimorphos on board Juventas CubeSat, part of ESA’s Hera planetary defence mission. The instrument is designed to measure an expected gravity level of less than one millionth that of Earth.

To demonstrate the readiness of the high-precision instrument, ESA has carried out a series of tests before final integration into the Hera Juventas cubesat. For this, GRASS was subjected to extreme temperature and space vacuum conditions inside a thermal vacuum chamber. After this, it was subjected to sustained agitation to mimic the violence of a rocket launch.

In words of José Antonio Carrasco, EMXYS CEO: “The GRASS gravimeter represents one more step in EMXYS expertise on producing space scientific payloads, in this case for operation not around Earth orbit, but in actual deep space. We are extremely pleased to have completed the testing phase of GRASS. Implementing an instrument of this unparalleled precision in such a reduced form factor has posed numerous technological challenges, both in mechanical and electronic design, for the Royal Observatory of Belgium and EMXYS. It is undoubtedly rewarding to see that GRASS has successfully passed the environmental tests and that it is finally ready to fly”.

The GRASS team had to design an instrument small enough to fit in Juventas, the size of a shoebox, along with the main radar instrument on the cubesat. The final design is only 330 grams in mass and requires only half a watt of power.

Once integrated into Juventas, GRASS will subsequently be tested as part of the overall nanosatellite.

About Hera Mission

In the world’s first test of asteroid deflection, Hera will perform a detailed post-impact survey of the target asteroid, Dimorphos – the orbiting Moonlet in a binary asteroid system known as Didymos. Now that NASA’s DART mission has impacted the moonlet, Hera will turn the grand-scale experiment into a well-understood and repeatable planetary defence technique. Demonstrating new technologies from autonomous navigation around an asteroid to low gravity proximity operations, Hera will be humankind’s first probe to rendezvous with a binary asteroid system and Europe’s flagship Planetary Defender.

SpaceRef co-founder, Explorers Club Fellow, ex-NASA, Away Teams, Journalist, Space & Astrobiology, Lapsed climber.