If you Google “Hayabusa” you will likely find a few articles about a mission plagued by problems and will leave you with the impression that the engineers at JAXA are a bunch of bumbling goons. What you will find less of is the fact that a sample-return mission is just about the most difficult types of missions any organization can attempt. As a matter of fact, only 4 sample-return missions (other than Apollo) have ever been successfully executed in history. Two Lunar missions by the Soviets with Luna 20 and 24 and much later, two American lead missions Genesis and Stardust which collected space dust and cometary particles. It is worth noting also that only two of those missions actually included landing on the surface of another body, grabbing some samples and then returning home. So for JAXA to even attempt such a bold mission without having even 1% the robotic mission experience of the USA and the Russians is all by itself an accomplishment.
So what were the failures? Well, there is a long list of issues including: a Solar Flare that destroyed solar cells aboard the craft, two reaction wheels that control movement failed, two attempts to fire pellets at the surface failed (to kick up the samples into the collection cannister) and finally a whole litany of communication errors, fuel leaks and telemetry issues which put the mission in serious doubt of ever returning to Earth. To make a long story short — the probe did touch-down on the surface of asteroid Itokowa. The first such mission ever intentionally designed to do so (NASA did have an impromptu touch down on 433 Eros in 2000, but that was more a controlled crash). Despite the pellet failures, mission specialists think that the very act of touching down was likely to kick up enough dust to collect some materials in the collection canister. After much wrangling with a seriously debilitated spacecraft they managed to get Hayabusa on make-shift trajectory back to Earth, very much later than planned… but home just the same.
With fingers crossed, the sample package is to parachute down in South Australia on or around June 13th at which point it will be shuttled back to Japan and hopefully they will find something contained within. Even if it is just a few particles, it will still be the only samples of asteroid particles un-altered by the extreme heat of a natural Earth entry (aka: a meteor) and only the 3rd time in history a probe landed on another world and returned a piece of it back to Earth for study. Not bad for the new kids in space.
Pictured at top is a frame from the trailer “Hayabusa Back to Earth” in anticipation of the potentially successful sample-return mission. It appears to be a 3-D render based on actual images returned from the mission. The second is an actual image with the shadow of the spacecraft as it maneuvered to a close encounter with its target. The third image illustrates what touch-down may have been like for Hayabusa. You can see the large amount of theoretical dust kicked up by the thrusters which may be JAXA’s best hope for actually having captured particles in the sample-return canister.