Japan Lands Two Tiny Rovers on Asteroid Ryugu

Japan Lands Two Tiny Rovers on Asteroid Ryugu

The Japan Aerospace Exploration Agency (JAXA) has landed two tiny rovers on the asteroid Ryugu as part of its Hayabusa2 asteroid sample return mission.  The rovers, MINERVA-II1 A and B, weigh 1.1 kilogram (~2.4 pounds) each and can hop across the asteroid’s surface to obtain data that will help JAXA determine the best sites to obtain samples for return to Earth.

JAXA launched Hayabusa2 in December 2014.  It is a follow-on to the Hayabusa mission that returned 1,500 grams of asteroid Itokawa in 2010.

Hayabusa2 arrived at Ryugu on June 28, 2018 after a nearly four year journey.  It will orbit the asteroid for about 18 months before heading back to Earth with samples in a capsule that will be ejected and land in Australia in 2020.

Hayabusa2 carries several landers. The first two, twin MINERVA-II1 rovers (A and B), landed yesterday after being released from the Hayabusa2 spacecraft about 60 meters (~200 feet) above the surface.  JAXA released a photo taken by Rover 1A while it was hopping from one location to another and by Rover 1B during its journey down to the surface.

This JAXA photo of the rovers before launch shows their size.

The small rovers, MINERVA-II1. Rover-1A is on the left and Rover-1B is on the right. Behind the rovers is the cover in which they are stored. Caption and Image credit: JAXA.

Rover-1A  carries four cameras and Rover-1B has three so stereo images of Ryugu’s surface can be created.  The rovers also carry temperature probes, an accelerometer, optical sensors and a gyroscope.  They communicate back to Earth through Hayabusa2.  They were developed by JAXA’s Institute of Space and Astronautical Sciences (ISAS) along with academic and industry partners.

Ryugu has very little gravity, so hopping must be done carefully.  Each rover remains “airborne” for about 15 minutes with each hop, moving approximately 15 meters (~50 feet) each time.  Ryugu is quite small — just 1 kilometer (0.6 miles) in diameter.

Artist’s illustration of the MINERVA-II1 Rovers A and B on Ryugu. Credit: JAXA

The first Hayabusa mission also carried a MINERVA rover, but it did not successfully reach the surface.

In addition to MINERVA- II1 A and B, Hayabusa2 is carrying MASCOT, built by Germany’s DLR and France’s CNES, which is scheduled to land on October 3, 2018 (Central European Summer Time).  Then MINERVA-II2, a 1 kilogram (~2.2 pounds) rover, will be deployed next year and a Small Carry-On Impactor made of copper that will be dropped onto the surface at a velocity of 2 kilometers per second (~1.2 miles/second) to create a crater.  JAXA has a video of a 2014 test of what that will be like.  The crater will allow access to material that is below the surface and the test will generate data for planetary collision science.

A device on Hayabusa2 itself will collect the samples. The first of three attempts is scheduled for late October 2018. The other two are next year.

Hayabusa2 is scheduled to leave Ryugu in November-December 2019 with the sample return capsule landing near Woomera, Australia in December 2020.

NASA launched its own asteroid sample return mission in September 2016.  OSIRIS-REx got the first glimpse of its target, asteroid Bennu, last month.  It will arrive there on December 3 and orbit the asteroid for several months to identify two possible sites from which to get samples.  One eventually will be selected and the sample will be obtained in July 2020.  It will take three years for the spacecraft to get back to Earth, with the sample return capsule landing in the Utah desert in September 2023.

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