From the January 2006 issue

Hayabusa update

It's a waiting game for the plucky Japanese probe.
By | Published: January 23, 2006
South Pole of Itokawa
Hayabusa captured this image of Itokawa’s south pole in late October 2005. The smooth, partially shadowed area in the center is Muses Sea, where the probe touched down in an attempt to collect a surface sample.
The daring Hayabusa mission to collect samples from asteroid Itokawa is now hovering above its target, unable to hold its attitude or even maintain constant communication with Earth. This situation has kept the mission team from identifying the cause of Hayabusa’s malfunction, which complicates any measures controllers take to stabilize the craft’s attitude.

Last month, the Japanese Aerospace Exploration Agency (JAXA) opted to delay the craft’s departure from the asteroid until spring 2007, which puts off return of possible samples until June 2010. A bright spot: Hayabusa has enough propellant to keep its ion engines running for the trip’s duration.

Before Hayabusa’s cameras returned their first clear images of Itokawa in September 2005, scientists assumed small near-Earth asteroids would have surfaces showing little geological variety. Images of Itokawa’s boulders, towering rock splinters, and smooth regions quickly overturned that notion.

Itokawa was scientists’ first glimpse of a “naked asteroid.” Other near-Earth objects visited to date have been coated with a thick layer of fine soil pulverized by eons of micrometeorite impacts. So, on two counts, Itokawa’s surface is like nothing planetary scientists have seen before.

Hovering 2.5 miles (4 kilometers) above Itokawa, Hayabusa’s cameras snapped this view October 22, 2005. What’s notable about the surface is the near total lack of impact craters. On closer inspection, a few areas seem to show partially filled, or “reclaimed,” impact craters.
Questions remain about whether the probe actually collected asteroid samples. Between a power failure, lost data, leaking fuel, and communication troubles, scientists have been unable to verify that all worked according to plan when Hayabusa made its November 25, 2005, touchdown on the asteroid’s surface. The only way to know what really happened is to look inside the sample-return capsule. And for that to happen, of course, Hayabusa must make the journey back to Earth.

Still, the mission has given planetary scientists a wealth of information and pioneered technologies that will be used in space missions to come, such as its ion drive and its ability to autonomously rendezvous and land. Over the next year, even as controllers scrutinize their data to work out a plan for stabilizing the craft, planetary scientists will study the data Hayabusa returned and work to understand what makes Itokawa tick.

Either way, for Hayabusa, the best is yet to come.