Impactor blasts bits of asteroid into a sample collection cone.
JOHN TIMMER – 2/22/2019, 2:05 PM
Today, in an extended Twitter thread and ensuing press conference, JAXA’s Hayabusa2 team announced that everything had gone well in gathering an asteroid sample for eventual return to Earth. While we don’t yet know about the material it obtained, the Japanese spacecraft has successfully executed all the commands associated with the sample recovery.
Hayabusa2 has been in space since 2014, and it slowly made its way to an orbit 20km above the surface of the asteroid Ryugu. In late 2018, the spacecraft made a close approach to the asteroidand released two small, solar-powered robots that have been hopping on the surface since. This week has seen the first of what are intended to be several sample-gathering attempts.
The procedure for this is pretty straightforward: Hayabusa2 snuggles up to the asteroid and shoots it. The probe has a sample-gathering “horn” that it can place up against the asteroid’s surface. Once it’s in place, Hayabusa2 can fire a bullet into the asteroid’s surface, blasting material loose that will be gathered by the horn and stored for return to Earth. JAXA, the Japanese space agency, calls its gun a “projector” but admits that the thing it fires is a bullet. JAXA has a webpage that describes some on-Earth testing of the whole system.
This obviously requires Hayabusa2 to leave its orbit at 20km and approach the asteroid. Approach is done rather cautiously, with an initial speed of 145 meters/hour, slowing to 36m/hr during the final steps, which means covering 20km took a significant chunk of time. The team monitoring Hayabusa2, however, has confirmed that all the commands planned during the approach were executed appropriately, which indicates that Hayabusa2 now carries the first of several asteroid samples.
The initial samples will be the surface material, which has been exposed to radiation and high energy particles possibly since the formation of the Solar System. But Hayabusa2 also carries a heavier bullet that’s intended to blast off the surface material to expose material that’s remained protected for billions of years. Ryugu is thought to be rich in water and organic matter, and it could provide a time capsule for the study of these starting materials prior to their incorporation into planets and moons.