A sample return mission to primitive bodies has the potential to revolutionize our understanding of pristine materials essential to understand the conditions for planet formation and emergency of life. Japanese asteroid explorer "Hayabusa" arrived at the small asteroid "Itokawa" whose size is only about 500m and showed us the mysterious world. Hayabusa made it possible for us to see exact nature of a very small asteroid approaching to the earth. JAXA is now working on a mission named Hayabusa-2. This is a mission to retrieve samples of surface from an asteroid to the earth. JAXA consideres to mount "Crackup installation" on Hayabusa-2 that Hayabusa didn't have. It will be separated above target asteroid 1999 JU3 and explodes there after Hayabusa-2 hides behind the asteroid. Then an impactor of approximately 2 kg hits the surface of the asteroid and it will make a crater of several meters in diameter. After that, it tries to collect materials inside of the crater. Preparing for that, Hayabusa-2's Small Carry-on Impactor (SCI) underwent a test in October, 2013.
In other words, Hayabusa-2 will collect materials of underground not only the ones on the surface. By doing that, the spacecraft will try to collect less altered materials. An artificial crater that can be created by the device is expected to be a small one with a few meters in diameter, but still, by acquiring samples from the surface that is exposed by a collision, we can get fresh samples that are less weathered by the space environment or heat.
Hayabusa-2 applies a method to throw a metal projectile against the asteroid with high speed to create an artificial crater. Through the test in October 2013, JAXA scientists confirmed the accelerating part of the projectile while aiming to verify if its speed, configuration, and thrown direction precision met the design when the pyrotechnics, which were comparable to those of actual ones for the flight, were ignited to set off the projectile.
Hayabusa-2 Small Carry-on Impactor undergoes test. Credit: JAXA/NihonKohi
JAXA confirmed that the test results were very impressive as the speed and configuration were almost as designed, and the direction precision was also good as the SCI precisely hit a target that was 100 meters away. The scintists were able to successfully complete the performance confirmation test of the SCI pyrotechnic part.
JAXA scientists investigating the material after SCI collision test. Credit: JAXA/NihonKohi
Asteroid 1999 JU3 is one of the Near Objects (NEO) that come close to the Earth's orbit. This asteroid is about 900 meters in size and its rotation period is about 7.6 hours. The albedo of the surface is low, estimated about 0.06, and its approximate shape and spin axis inclination have been estimated.
After arriving at the target asteroid, Hayabusa-2 will observe using a variety of remote-sensing instruments. The spacecraft will carry the German/French lander on board through the international cooperation. It will be released from Hayabusa-2 and will land on the asteroid, then perform observations of the surface of asteroid in detail. Furthermore, the spacecraft will create an artificial crater by the impactor.
Hayabusa-2 is scheduled for launch in December 2014. It should arrive at the asteroid in mid 2018, staying around there for one and half years before leaving the asteroid at the end of 2019 and returning to Earth around the end of 2020.
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