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Hayabusa 2 arrives at asteroid Ryugu

Hayabusa-2 approaching asteroid 162173 Ryugu (1999 JU3).

Artist’s concept of Hayabusa 2 approaching asteroid 162173 Ryugu (1999 JU3). Image Credit: JAXA

After a journey of about 2 billion miles (3.2 billion kilometers), the Japan Aerospace Exploration Agency’s (JAXA)  Hayabusa 2 spacecraft rendezvoused with its target, the asteroid Ryugu. This latest milestone marked a critical point in a mission designed to investigate these tiny remnants from the formation of our solar system.

Asteroid Ryugu photographed at a distance of 40 meters on June 24, 2018. Image Credit: JAXA, University of Tokyo and collaborators

Asteroid Ryugu photographed at a distance of 40 meters on June 24, 2018. Image Credit: JAXA, University of Tokyo and collaborators

Rendezvous was confirmed at 9:35 a.m. JST on Wednesday, June 27 (8:35 p.m. EST, Tuesday, June 26).  Hayabusa 2 is maintaining a current distance from the tiny world of some 12.4 miles (20 kilometers) and the status of the vehicle is normal. The spacecraft will remain at Ryugu for a year and a half, departing the asteroid in December 2019 and returning to Earth in December of 2020.

Hayabusa 2 is the successor of JAXA’s Hayabusa  (MUSES-C) mission which explored the asteroid Itokawa and returned to Earth in June of 2010. Hayabusa 2 launched on December 3, 2014 from the Tanegashima Space Center on an H2A rocket. While Hayabusa 2 is similar in configuration to its predecessor, improvements have been made to its ion propulsion system and its onboard instruments.

The spacecraft will use a small carry-on impactor (SCI) to create a small crater on the asteroid’s surface. This should allow the spacecraft to sample “fresh” underground materials to compare with samples taken from the asteroid’s surface. Hayabusa 2 also carries with it a trio of small MINERVA-II rovers and a small lander called MASCOT.

During its stay at Ryugu Hayabusa 2 is scheduled to make three sampling runs, two from the unaltered surface and the third from inside the crater made by the SCI. A sampling run will begin will the spacecraft being commanded to move towards the selected are of the asteroid. At an altitude of 328 feet (100 meters) Hayabusa 2 is planned to enter into an autonomous mode and release a target marker to land in the designated area.

At 98 feet (30 meters) the spacecraft should position itself over the target and then slowly approach the surface until it touches down. Hayabusa 2‘s sampling horn will cover the target area, and a projectile will be fired into the surface, ejecting material back up through the horn and into one of three sample storage containers, which will then be sealed. The spacecraft is then slated to lift off from the surface and resume its scientific operations.

Asteroid Ryugu (originally named 1999 JU3) is a C-type (carbonaceous) asteroid and is expected to be rich in organic compounds. While originally thought to be spherical,  recent imagery has shown it to be roughly diamond-shaped.

“The shape of Ryugu is now revealed. From a distance, Ryugu initially appeared round, then gradually turned into a square before becoming a beautiful shape similar to fluorite (known as the ‘firefly stone’ in Japanese),” said project manager Yuichi Tsuda. “Now, craters are visible, rocks are visible and the geographical features are seen to vary from place to place. This form of Ryugu is scientifically surprising and also poses a few engineering challenges.”

The mission team is planning to conduct exploratory activities near the asteroid, including scientific observations of Ryugu and surveying the asteroid for potential sample collection sites.

“The Project Team is fascinated by the appearance of Ryugu and morale is rising at the prospect of this challenge. Together with all of you, we have become the first eyewitnesses to see asteroid Ryugu. I feel this amazing honor as we proceed with the mission operations,” Tsuda said.




Jim Sharkey is a lab assistant, writer and general science enthusiast who grew up in Enid, Oklahoma, the hometown of Skylab and Shuttle astronaut Owen K. Garriott. As a young Star Trek fan he participated in the letter-writing campaign which resulted in the space shuttle prototype being named Enterprise. While his academic studies have ranged from psychology and archaeology to biology, he has never lost his passion for space exploration. Jim began blogging about science, science fiction and futurism in 2004. Jim resides in the San Francisco Bay area and has attended NASA Socials for the Mars Science Laboratory Curiosity rover landing and the NASA LADEE lunar orbiter launch.

Reader Comments

James Lunar Miner

“While Hayabusa 2 is similar in configuration to its predecessor, improvements have been made to its ion propulsion system and its onboard instruments.”
– Jim Sharkey

Yep! High ISP electric propulsion systems can enable propellant efficient, and thus low mass and reduced cost, spacecraft and missions that are capable of exploring and returning samples from various asteroids. High ISP electric propulsion systems are nifty!

“IES (Ion Engine System) has been modified to account for the aging effect during extended support periods. The thrust level of IES was increased by 25%, using the same Xe microwave discharge ion engine system.”

And, ” IES (Ion Engine System): Xe microwave discharge ion engine system; Maximum thrust 28 mN, Isp=2800 s; 4 thruster heads on gimballed stage; 3 operative at once (4/3 redundant)”

“Hayabusa-2, Japan’s second Asteroid Sample Return Mission”

See also:
“Electric-Powered Lunar Space Tug Could Facilitate Future Moon Missions” By Elizabeth Howell 6/14/2017

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