Two Japanese robots are now happily hopping on an asteroid [Updated]

Saturday update: More than 24 hours after they were released by the Hayabusa2 spacecraft to fly down to the surface of the asteroid Ryugu, the Japanese Space Agency has finally provided an update on the fate of the two tiny robots. And they’re doing quite well indeed.

“We are sorry we have kept you waiting!” the space agency, JAXA, tweeted. “MINERVA-II1 consists of two rovers, 1a & 1b. Both rovers are confirmed to have landed on the surface of Ryugu. They are in good condition and have transmitted photos & data. We also confirmed they are moving on the surface.”

Then, the rovers shared some pictures, including these two.

This dynamic photo was captured by Rover-1A on September 22 at around 11:44 JST. It was taken on Ryugu’s surface during a hop. The left-half is the surface of Ryugu, while the white region on the right is due to sunlight. (Hayabusa2 Project) pic.twitter.com/IQLsFd4gJu

— HAYABUSA2@JAXA (@haya2e_jaxa) September 22, 2018

Just knowing that two tiny robots are now hopping merrily around an asteroid with almost no gravity makes our own world seem a little bit merrier.

Original post: Japan’s Hayabusa2 spacecraft hasn’t garnered much attention in the western world, but on Friday night the 609kg vehicle attempted something rather amazing. The spacecraft descended from its station-keeping orbit 20km above a small asteroid down to just 60 meters, and there it deployed two miniature rovers bound for the surface.

Each weighed only about a kilogram, and after separating from the main spacecraft they approached the asteroid named Ryugu. Japanese mission scientists think the rovers touched down successfully, but are not completely sure. Communication with the two landers stopped near the moment of touchdown.

This is presumably because Ryugu’s rotation took the rovers out of view from the Hayabusa2 spacecraft, but scientists won’t know for sure until later Friday (or Saturday morning, in Japan) when they attempt to download images from the rovers. And thus we are left with a suspenseful situation.

Sampling the rock

Hayabusa2 launched from Earth back in November, 2014, aboard a Japanese H-IIA rocket, and arrived in the vicinity of Ryugu in June of this year. The innovative mission will spend the rest of this year and nearly all of 2019 at Ryugu. In addition to this rover landing attempt, the spacecraft will also try to sample the asteroid and bring some of the material back to Earth.

This is a daring sample maneuver. It will see the spacecraft deploy an impactor, which in turn will fire a 10-millimeter projectile with a mass of 5 grams into the surface. This should create a small crater and, about two weeks later, allow Hayabusa2 to return and collect a pristine interior sample from the asteroid. If all goes well, the spacecraft will depart the asteroid in December 2019 and return to Earth about a year later, landing in a remote part of Australia.

One of the purposes of Thursday night’s rover landing attempt is to gather images of and data about the surface of Ryugu in preparation for the sampling attempt. If they survived the landing, the two 7cm-tall, cylinder shaped rovers will “hop” across the surface and replenish their power with solar cells.

Discovered in 1999 by astronomers in New Mexico, Ryugu is a near-Earth asteroid that orbits the Sun every 16 months, roughly between the orbits of Earth and Mars. It measures about 920 meters across, and its relative proximity to Earth makes it a good candidate for a sampling mission like Hayabusa2.

The spacecraft is so named because of a previous Japanese mission, Hayabusa, that explored the asteroid Itokawa about a decade ago. It returned a small amount of material, about 1,500 grains of rock, from the surface of the asteroid. Hayabusa2 was built after learning from the original mission, and seeks to study its asteroid in greater depth, return a greater amount of material, and deliver insights about the origins of the Solar System.