Pocket-sized probe to measure asteroid gravity in space.

The European Space Agency (ESA) has completed vacuum and vibration tests for its Gravimeter for Small Solar System Objects (GRASS) asteroid probe, which is designed to measure surface gravity on the Dimorphos asteroid. GRASS, which is the size of a mobile phone, will be hitching a ride to Dimorphos aboard a cubesat named Juventas, which is part of ESA's Hera mission for planetary defense. GRASS will launch about the Hera mission in October 2024, if all goes according to plan.