Today is a big day for humanity. We have bombed an asteroid, finally exacting revenge for what the asteroids did to the dinosaurs. There’s a valid scientific reason, too. The Japanese Hayabusa 2 spacecraft is collecting material from the asteroid Ryugu, and blasting it with a massive kinetic projectile is a good way to expose material from deep below the surface.
Japan Aerospace Exploration Agency (JAXA) launched the spacecraft in 2014, and it took more than two years for it to reach Ryugu more than 186 million miles (300 million kilometers) from Earth. After meeting up in deep space, Hayabusa 2 began mapping the surface of Ryugu to develop a plan of attack.
Hayabusa 2 has a sampling arm designed to gently touch the surface of Ryugu. To get material into the sampling arm, the probe carries a few 5-gram tantalum slugs it can fire at high speed. Earlier this year, Hayabusa 2 successfully fired off one of its two bullets to help it scoop up a few fragments of the asteroid.
JAXA confirms Hayabusa 2 has now dropped the bomb on Ryugu — the bomb, in this case, is the 5.5-pound (2.5kilogramsm) Small Carry-on Impactor (SCI). The SCI is actually a self-contained launching platform with a shaped HMX explosive charge that propels the impactor at 2 kilometers per second. Hayabusa 2 deployed the SCI and then moved to a safe location on the other side of the asteroid before JAXA launched the SCI at the surface. Images from the probe confirm the SCI hit Ryugu, blasting material into space.
[SCI] The deployable camera, DCAM3, successfully photographed the ejector from when the SCI collided with Ryugu’s surface. This is the world’s first collision experiment with an asteroid! In the future, we will examine the crater formed and how the ejector dispersed. pic.twitter.com/eLm6ztM4VX
Hayabusa 2 will wait a bit before it heads back to the impact site, but JAXA hopes it will find a crater several meters across. The floor of the crater should have pristine asteroid regolith that hasn’t been bombarded by radiation for uncountable eons. It’s as close as we can come to getting a sample of the early solar system. Hayabusa 2 will eventually descend to the surface in order to collect a sample from the crater. It also carries another small tantalum bullet to excavate another surface sample.
Hayabusa 2 isn’t collecting pieces of Ryugu to keep them in deep space. The probe has a sample-return container, which JAXA plans to launch back to Earth in the coming months. It might contain as much as 100 milligrams of asteroid material when it gets here in late 2020.