![]() ![]() The GRASS gravimeter of the #HeraMission has recently undergone a successful environmental test campaign. The Hera probe will be able to characterize even more changes like this and turn “the kinetic impact experiment into a well-understood and in principle repeatable method of planetary defense,” according to Hera system engineer Hannah Goldberg. One of the most significant impacts of DART’s collision with the asteroid was that it reduced Dimorphos’ orbital period around Didymos by 32 minutes. While the asteroid may be small compared to other planetary objects measuring at 160 meters in diameter, it is the same size as Egypt’s Great Pyramid of Giza. The Hera mission is particularly interesting as it will mark the first probe to rendezvous with a binary asteroid and will be the smallest planetary object a spacecraft has ever visited. “As the measurements are made during the free fall of Juventas over Dimorphos, that will follow a bent trajectory before the impact, it will measure the gravity field from several different positions and therefore may reconstruct the mass distribution of the asteroid.” ![]() By measuring the small displacements of these beams and the mass, it is possible to reconstruct the gravity in three dimensions,” continued Carrasco. “GRASS has two small masses attached to two beams placed orthogonally to each other that rotate at around one revolution per minute. The gravimeter can detect the slightest motion, with the sensitivity equivalent of a single micrometer, or a thousandth of a millimeter. The GRASS instrument is the size of two smartphones stuck together. ![]() “It will be in the final falling phase that GRASS will start working to measure the gravitational attraction of the asteroid and thus picturing its mass distribution while it falls, lands, and sits still on the surface of the asteroid,” Carrasco told NSF. During this descent, GRASS will record the impact on the asteroid, subsequent bounces, and any shifts in surface gravity over time from the influence of Didymos, ESA explains. “It may be small, but GRASS is packed with complex mechanical parts and electronics,” Jose Carrasco, the chief executive officer at EMXYS said.Īfter Hera completes the subsurface radar imaging campaign of Dimorphos, Juventas will be released and gradually fall onto the surface of the asteroid. The payload was developed by the Royal Observatory of Belgium (ROB) and Spain-based EMXYS, which was responsible for manufacturing its electronics and mechanical integration. See AlsoĮSA describes the gravimeter as the size of two smartphones stuck together, shaped like the letter L. The payload is carried in one of Hera’s two cubesats, Juventas, which itself is the size of a shoebox. The tiny GRASS payload, which has a mass of just under 400 grams, is designed to measure the expected gravity levels and the precise mass of the Dimorphos asteroid. At 160 m in diameter it is about the same size as #Rome’s #Colosseum /JoPXy1SUjo GRASS is designed to measure such miniscule gravity levels as the #Dimorphos asteroid #HeraMission will deliver it to is the smallest planetary object ever to be visited by spacecraft. This follow-up mission forms part of the asteroid impact and deflection assessment, an international collaboration focused on experimenting with kinetic impact as a means of planetary defense against near-Earth objects (NEO) through DART and providing accurate data from the impact through Hera. GRASS is one of the core parts of Hera that will work with the other instruments to provide a clearer picture of the impact made by DART, and is scheduled to launch in October 2024, for a December 2026 rendezvous with Dimorphos. Hera will complete the first post-impact survey of the asteroid that NASA’s Double Asteroid Redirection Test (DART) collided with in September 2022, and the gravimeter for small solar system objects (GRASS) is the small device that will be carried by Hera to measure the minuscule gravity levels of Dimorphos, the orbiting moonlet of the 65803 Didymos binary system. A tiny instrument that can measure the gravity levels of an asteroid has completed its ground tests, pushing the European Space Agency’s (ESA) Hera mission closer to launch.
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