October 5, 2012
Asteroid Fragments May Offer Insight Into Origins Of Planets
Alan McStravick for redOrbit.com - Your Universe Online
The year was 1998. The Red Hot Chili Peppers had just parted ways with Dave Navarro. The world was introduced to Britney Spears. And the movie Armageddon bested all other films at the box office.
Why should a near-Earth asteroid, discovered 14 years ago have any relevance today? Why should you care?
The discovery of Itokawa occurred in the first year after the LINEAR project was enacted. LINEAR went on to discover an estimated 231,082 objects in space. Of those, 2,423 were near-Earth asteroids. The distinction that the asteroid Itokawa bears that its 2,422 cousins don´t is that Itokawa is only the third planetary body from which we have been able to draw samples and then return them to Earth, and the first asteroid from which we´ve been able collect samples.
The samples were gathered by the Japanese mission Hayabusa. Hayabusa — a Japanese word that means ℠falcon´ — is a joint venture between Japan´s Institute of Space and Astronautical Science (ISAS), NASA and Australian space agencies. The cooperative project set out to collect from Itokawa a sample of loose material from its surface known as regolith. In September of 2005, Hayabusa arrived at Itokawa and spent the next several months surveying and capturing samples from the asteroid.
Much like a scene out of 1998´s top-grossing film, the Hayabusa had to approach Itokawa very carefully. Initially, the spacecraft remained at a distance of about 12.5 miles from what is referred to as the “gate position”, so called because, much like an aircraft at an airport terminal, this is a position the craft comes to before loading or unloading cargo. From here, and without the benefit of human control, the craft utilized automated optical navigation, a method that was necessary because of the communication delay between Earth and the craft.
Despite the malfunction of Hayabusa´s collection mechanism, the two touch-and-go maneuvers still managed to allow the craft to collect thousands of grains of regolith grains.
These tiny pieces of rock — only about 50-100 micrometers in size and smaller than the diameter of a human hair — were brought back to Earth in 2010, landing safely in the Australian Outback. From there, the samples were sent to 11 different research teams for analysis. Dr. Henner Busemann and his team at University of Manchester´s School of Earth, Atmospheric and Environmental Sciences (SEAES) were among the 11 teams chosen. They were selected because SEAES has the most sensitive system in the world for analyzing the rare gases xenon and krypton.
The remnants from the formations of planets, scientists still know relatively little about asteroids. The Hayabusa mission is part of a continuing effort to understand how they form and evolve. Busemann´s team hopes to find out how rapidly and by what processes the asteroid´s surface is being changed. They also want to understand whether asteroids like Itokawa might have delivered material to Earth early on in its history.
Aside from the records achieved with this mission, the work done will help to provide insight into the early history of our Solar System and the formation of the planets more than 4.5 billion years ago.
"Meteorites are samples of asteroids that fall to Earth, and we've learnt a lot by studying them,” said Busemann.
"However, these grains are unique because we know which of the millions of asteroids they came from and they haven't been exposed to the Earth's environment. We stand to learn a huge amount about how asteroids formed and evolved."