Japan’s Hayabusa Probe Arrives At Asteroid Ryugu — Wow!

Japan’s Hayabusa 2 spacecraft took these photos of the asteroid 162173 Ryugu at distances ranging from 150-206 miles away on June 17. Ryugu spins once every 7.6 hours. JAXA / Hayabusa 2

The Japanese asteroid sample return mission Hayabusa 2, which launched in December 2014, is pulling up to its target this week, the asteroid Ryugu. The asteroid, about a half-mile (900 meters) across, is shaped like a spinning top with several prominent craters and an equator-girdling ridge. The probe is still closing into Ryugu. In the last 12 hours it’s entered its gravity field earlier today stands just under 60 miles (~100 km) from the asteroid. It will arrive at its “home” location of 12.5 miles (20 km) from which it will begin its survey of Ryugu later this month.

Hayabusa 2 samples the crater floor after the blast, gathering fresh rocks shielded from the damaging effects of cosmic and solar radiation. Akihiro Ikeshita / JAXA

After a year-and-a-half-long survey, the spacecraft will depart on Dec. 2019 and deliver rock and dust samples to Earth via a return capsule in Dec. 2020. Hayabusa 2 will explore Ryugu in unique ways including blasting tantalum bullets at the surface to kick up debris that will be collected in a horn-shaped device. The probe will also launch an explosives-laden copper impactor to blast a small crater in the asteroid’s surface then collect material from within the crater. It sounds like a lot of trouble but the aim is to snatch a pristine bit of asteroid that hasn’t been weathered by solar radiation and cosmic rays.

UPDATE 6/21: These photos were made on June 18 from as close as 62 miles (100 km) and show a rich terrain. We can see individual large boulders plus a large, rocky mass about 490 feet (150 meters) across at the top of the asteroid. The belt-shaped ring of peaks around the equator are also brighter than their surroundings which may indicate either freshness or rock of a different composition. JAXA

During the blast, a small camera hovering nearby will take pictures; to protect its sensitive instruments from flying debris, Hayabusa 2 will “hide out” on the other side of the asteroid. It’s not unlike the way my friends and I would blow things up with gunpowder and firecrackers as kids.


Landing the MASCOT lander. Be sure to watch long enough to see how it moves itself around.

The spacecraft will also send off four small landers: the MASCOT lander will study the surface composition and properties, and three MINERVA landers snap photos and take temperature measurements. All the landers are built to make several hops across the surface to take measurements and photos from different locations. The ambitious schedule, borrowed from the Planetary Society, follows:

  • Late June: Hayabusa 2 approaches within 12.5 miles of Ryugu
  • Late July: Descends to 3.1 miles to perform medium-altitude observations
  • August: Descends to 0.6 mile to perform sensitive gravity measurements in preparation for a touch down to sample the surface
  • September-October: First touchdown with the four landers possibly being released

To follow the mission’s progress visit their Twitter site.

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