Illustration of the imagined asteroid explorer "HAYABUSA2," which is expectd to return samples from asteroid 1999JU3.Akihiro Ikeshita
In an ambitious quest to learn more about the building blocks for life, Japan is preparing to launch an ambitious mission to retrieve samples from a primitive asteroid, the same type of object that may have smashed into early Earth, delivering water and organics.
The mission, slated to launch in 2014, is a follow-on to Japan's troubled, but ultimately successful Hayabusa 1 probe, which managed to snare some microscopic bits of dust from an asteroid known as Itokawa and return them to Earth in June 2010.
That mission helped resolve a long-standing question about the connection between asteroids and a particular group of meteorites that have been recovered on Earth.
Hayabusa 2 is going after a bigger question -- whether the ingredients for life arrived on asteroids similar to 1999 JU3, the target of Japan's new mission. Unlike Itokawa, known as an S-type asteroid, 1999 JU3, an older, carbonaceous or C-type asteroid, is believed to be rich in hydrated minerals and organic matter.
"We're not saying that we can find the origin of life on Earth," Hokkaido University's Shogo Tachibana, a lead scientist for the Hayabusa mission, said in an article published in this month's Physics World. "Rather that asteroids preserve the history of the very early solar system."
C-type asteroids aren't usually found near Earth. They mostly orbit between Mars and Jupiter in the main asteroid belt. The asteroid 1999 JU3, however, travels close enough to Earth to be reached by a relatively small spacecraft.
Like its predecessor, Hayabusa 2 is designed to land on the asteroid, fire small projectiles into its surface and collect samples released from the impacts. Scientists hope things will go smoother for the new probe. Hayabusa 1, launched in 2003, suffered from engine failures, fuel leaks and communications problems before returning its sample cache back to Earth in June 2010. Because the projectiles didn't fire, scientists weren't sure they had even captured any samples until they opened the canister five years later.
"When we looked with a high-resolution microscope, we saw a lot of very small particles in the capture chamber," Tomoki Nakamura, with Tohoku University in Japan, said at the American Geophysical Union conference last year.
A more robust Hayabusa 2 will repeat the sample-collecting, but add a 5-pound, copper-tipped projectile to blast a small crater into the asteroid as well, exposing more pristine material from deeper inside the body.
"We can get fresh samples that are less weathered by the space environment or heat," noted Hayabusa scientist Yasuhiko Takagi, with Japan's Aichi Toho University.
"Minerals and seawater which form the Earth, as well as materials for life, are believed to be strongly connected (to) the primitive solar nebula in the early solar system. We expect to clarify the origin of life by analyzing samples acquired from a primordial celestial body," Takagi wrote in a paper presented at the conference.
Hayabusa 2 should arrive at the asteroid in June 2018 for an 18-month mission. After carefully mapping the surface, Hayabusa is expected to release a small rover, named Minerva 2, and a German-built lander named Mascot. It would then touch down on the surface of the asteroid twice, deploying small, finger-sized projectiles that would raise small clouds of debris for collection.
Before leaving in December 2019, the probe would release the larger impactor, which is designed to explode above the asteroid's surface and carve out a small crater. Hayabusa 2 would then attempt to touch down for a third time in or near the crater and retrieve subsurface materials as well.
If all goes well, Hayabusa 2 would return its samples to Earth a year later.
"Hayabusa's exploration to Itokawa provided us a lot of new information and we were quite surprised to know the nature of this small S-type, near-Earth asteroid," scientists with the Japan Aerospace Exploration Agency wrote in a paper posted on NASA's Lunar and Planetary Institute website.
"We expect that the exploration of the small C-type near-Earth asteroid by Hayabusa 2 will give us another surprise and our understanding (of) the solar system will be advanced much," they said.