If all goes according to plan, GRASS will launch the Hera mission in October 2024. The European Space Agency (ESA) wants to place a small mobile phone-sized satellite on an asteroid to measure gravity.

ESA has completed vacuum and vibration tests of the Gravimeter for Small Solar System Objects (GRASS) asteroid probe. GRASS is designed to measure gravity on the surface of the asteroid Dimorphos, with which the NASA spacecraft is traveling. DART GAME met him last year as part of his assignment. Dimorphos is about 525 feet (160 meters) in diameter and roughly the size of NASA’s Vehicle Assembly Building (VAB) at Kennedy Space Center in Florida. When it comes to buildings, VAB is huge. It is one of the largest in the world by area. When it comes to planetary bodies, Dimorphos isn’t that big. In fact, it is the smallest object in the Solar System ever visited by a human spacecraft.

Therefore, measuring gravity would be a difficult task, as the gravity of an object like an asteroid is many times lower than that of a planet. “Obviously, the true performance of the gravimeter cannot be demonstrated directly here on Earth, but our lab tests combined with numerical simulations have shown that we have achieved high enough sensitivity to detect such low gravity,” ROB’s Özgyur Karatekin said in a statement. Said. ESA.

GRASS was developed by the Royal Observatory of Belgium (ROB) and EMXYS in Spain. The probe, the size of a video game controller, weighs just 0.7 pounds (330 grams) and requires only half a watt of power; this is slightly more than the average basic calculator. GRASS will use two rotating blades to measure gravitational fluctuations on the surface of Dimorphos caused by the parent asteroid Didymos. The rotation of the wings is affected by even the smallest changes in the environment, allowing GRASS to achieve accuracy within a thousandth of a millimeter, which is less than a millionth of Earth’s own gravity.

Final tests were completed at ESA’s Mechanical Systems Laboratory; where the probe was placed inside a thermovacuum chamber and exposed to extreme temperatures to simulate a space-like environment. The probe’s small instruments must also withstand the harsh conditions of launching a rocket, so to test this, GRASS passed a series of vibration tests to simulate its upcoming launch into orbit.

GRASS will hitchhike to Dimorphos with a cube satellite called Juventas, which is part of ESA’s Hera mission to protect the planet. “After the DART collision, Hera will collect close-up data on the asteroid Dimorphos to turn this kinetic experiment into a well-understood and in principle repeatable method of protecting the planet. GRASS surface gravity measurements will help researchers know the exact mass of the asteroid and the main Hera spacecraft conducted by the asteroid. radio science experiments,” said Hera systems engineer Hannah Goldberg.

Upon arrival, Hera will deploy Juventas, who will gradually descend to the surface of the Dimorphos as soon as she completes her primary imaging mission. GRASS will then touch the surface of Dimorphos. GRASS will measure its impact on the asteroid, as well as any probe bounce in its deceleration path. And no matter where or how it lands, task managers will be ready.

“We have to assume that Juventas can land on Dimorphos at any angle, so potentially the solar panels will be prevented from producing more power. Instead, GRASS will run on Juventas’ internal battery for up to 20 hours,” he said.

Now that GRASS has passed its own rigorous testing, it will be fully tested again before being integrated into Juventas. Jose Carrasco runs GRASS at EMXYS. “We are very pleased with its durability during the testing campaign. We will now perform a full integrity test to ensure it was not damaged during testing, and then it will be handed over to GomSpace in Luxembourg for onboard integration. Juventus,” said Carrasco.

If all goes according to plan, GRASS will launch the Hera mission in October 2024. The spacecraft will reach its asteroid targets in two years. Source