A few minutes before 8:00am (Denver time) on Sunday, June 13, the troubled seven year journey of the Japanese Space Agency's Hayabusa spacecraft ended in a fiery atmospheric reentry near Woomera, Australia. Hayabusa's successful landing marks the first time any spacecraft has returned to Earth after visiting an asteroid (Itokawa in 2005).
The Hayabusa mission now enters the next stage in its life cycle: laboratory analysis of dust and regolith samples collected from the asteroid. If such samples were actually collected, the tiny grains would instantly become the most valuable bits of matter on the Earth.
Space is a dusty place...
Never before have scientists studied pristine asteroid samples in a controlled laboratory setting. All prior asteroid samples came from meteor fragments surviving their own fiery plunges without the protection of a spacecraft hull. While the inner layers of some meteors survive relatively intact, researchers have no way of determining exactly where the fragments originated.
Tons of space dust accretes onto the Earth every day, and most of the dust comes from asteroids. Spikes in dust accretion data over the past tens of millions of years typically follow large asteroid impacts in the main belt, such as the Baptistina impact around 160 million years ago.
A mission about context
Asteroids and space dust therefore serve as important clues in a cosmic detective story. Context is critical to any detective's investigation, and the Hayabusa mission provides better context for its valuable cargo of dust than random daily dust or meteor accretions onto the Earth. Inquisitive scientists hope these leftovers of early solar system planet formation will reveal more clues about the past, present, and future of planetary evolution.
Unfortunately, Hayabusa's primary sample collection procedure didn't work correctly when the spacecraft landed on asteroid Itokawa five years ago. Immediately after landing in November, 2005, tiny explosive projectiles should have kicked regolith into the sample containment system... but these projectiles probably didn't fire. Mission controllers hope that the landing itself kicked up enough pebbles and dust for some fragments to reach the sample containment system. Soon we will finally know what actually happened.
Random dust kicked up during landing provides poor sample context as well because any captured material may have accreted onto the asteroid from other asteroids or been heavily modified by impact processes. Far better context would be achieved by human detectives actually visiting an asteroid, but the demands of an asteroid sample return mission involving human explorers far exceed our current technological capabilities (though lessons learned during missions like Hayabusa help).
Calling Geraldo Rivera...
Stay tuned for more details as researchers peek inside Hayabusa's sample containment system over the coming days. Will Al Capone's vault contain treasure this time or will it be empty again?