The rovers that hopped across Ryugu

HIBOU, OWL and MASCOT: how tiny robots explored an asteroid where gravity is too weak for wheels.

Published 2026-10-23

Ryugu is less than a kilometer across, so its gravity is extremely weak.^[3] Wheels would barely grip, so Hayabusa2 carried robots designed to hop.^[5]

HIBOU and OWL

On September 21, 2018, Hayabusa2 released the MINERVA-II-1 container from an altitude of about 55 m. It deployed two small rovers, HIBOU (Rover-1A) and OWL (Rover-1B), which dropped independently to the surface.^[5] Hayabusa2 was the first spacecraft to deploy operating rovers on an asteroid.^[5]

MASCOT

On October 3, 2018, Hayabusa2 deployed MASCOT (Mobile Asteroid Surface Scout), built by the German Aerospace Center (DLR) with the French space agency CNES.^[5] It carried an infrared spectrometer, a magnetometer, a radiometer and a camera. Running on a non-rechargeable battery, it operated for about 16 hours, as planned.^[5]

MASCOT's magnetometer showed that Ryugu has no magnetic field at the scale of its boulders.^[5] Its radiometer design was later used on NASA's InSight Mars lander.^[5]

ROVER-2

A third rover, ROVER-2 (MINERVA-II-2), was built by a university consortium led by Tohoku University and carried four mechanisms for short hops.^[5]

Try it yourself

Real asteroid science starts with looking closely: rocks, minerals, meteorites and magnified grains. Our young explorer's science kit picker suggests hands-on kits for budding planetary scientists.

Numbered citations link to the sources list on the Ryugu overview page.