Japanese Asteroid Probe Deploys Micro-Robot

BOULDER, Colorado -- Japan's Hayabusa spacecraft has deployed a micro-rover designed to explore asteroid Itokawa and is on track to attempt a first sampling of the object in a week's time.

Taking some 12 hours to descend closer and closer to the asteroid -- starting at roughly 4,600 feet (1.4 kilometers) altitude from the center of Itokawa -- the spacecraft reached a hovering distance over the space rock. The craft then released a small robot toward Itokawa's surface. There was no immediate word on the condition of the robot after deployment.

After release of the robot, Hayabusa began propelling itself to a higher altitude above the asteroid.

Ejected by the Japanese space probe during the close encounter was the MIcro/Nano Experimental Robot Vehicle for Asteroid, or MINERVA for short.

The tiny 1.3 pound (591 grams) device is a hopping lander, outfitted with cameras to take images up-close of the asteroid's rocky surface. In addition, a target marker was also deployed, falling onto the asteroid. That hardware will assist in Hayabusa's landing on the body in order to carry out sampling operations.

Surface imagery

The MINERVA robot is an ultra-small lander equipped with three small color cameras. Close-up observations of rock minerals can be done by the onboard cameras. Imagery of more distant regions of the surface can be obtained as well.

Attached to the top and the bottom of MINERVA are a set of six thermal sensors. These devices can measure the surface temperature of the asteroid. Hayabusa scientists hope to be able to tell whether the surface of asteroid Itokawa is rich in sands or rocks, relying upon on the variation in temperature data collected by the sensors.

Engineers handling the Hayabusa spacecraft have clarified the issues that led to the cancellation of a November 4 landing rehearsal.

At that time, an onboard navigation computer detected anomalous information during the practice run. The problem resulted in an abort command being transmitted to the probe by Earth controllers, thereby stopping the rehearsal.

Mission officials are now prepared to carry out a landing at the "Muses Sea" site, performing sampling tasks on both November 19 and another touchdown on November 25, according to the web site of the Institute of Space and Astronautical Science (ISAS), a space science research division arm of the Japan Aerospace Exploration Agency (JAXA).

Strangely familiar

Space experts are eagerly awaiting more data from the probe. The impressive set of images already sent back from the spacecraft are helping discern the body's true makeup...perhaps even adding more mystery to what's known about asteroids.

"Clearly, asteroid Itokawa does not resemble the classic picture of a heavily cratered chunk of rock," said planetary scientist, Clark Chapman, an expert on asteroids at the Southwest Research Institute here.

"There are essentially no craters visible at all. Instead, there are rocks and boulders covering much of the body. And then there are the remarkable flat areas," Chapman told SPACE.com. He added that those flat areas on the object don't seem flat - so much as smooth - and seemingly curve around the shape of the asteroid.

"For people like me, who were involved with the asteroid Eros, investigated by NASA's Near Earth Asteroid Rendezvous (NEAR)/Shoemaker mission a few years ago, Itokawa looks strangely familiar," Chapman explained.

When you back away from Eros and look at the whole body, Chapman continued, it has the classic look of a cratered body. "But Itokawa is too small to hold any of those large craters," he said.

Dealing with a real mystery

So one might think that, because Itokawa looks like Eros at the same absolute scale, scientists would understand what's going on?

"The truth is that many of us are baffled by both Eros and Itokawa," Chapman said.

"Several scientists have tried to explain Eros by invoking processes that would rearrange Eros' fairly deep regolith (uppermost covering) and fill in any craters...say after a jolt from a large impact," he said.

However, the fact is that Itokawa has no gravity at all to speak of. "So it doesn't seem that such ideas can be right," Chapman noted. "I think we are dealing with a real mystery...revealed both by NEAR Shoemaker for Eros and by Hayabusa for Itokawa."

Some images already dispatched from Hayabusa suggest that Itokawa might be composed of two large chunks, smashed together, Chapman advised. "In this sense, it looks a bit like a classic 'rubble pile'... a configuration that we think is common among asteroids."

Chapman said it will be exciting to see if the little MINERVA, which is designed to hop around Itokawa "like a Mexican jumping bean", will be successful and return good pictures and temperatures.

Return samples

Hayabusa and ground teams are preparing for a historic attempt to gather and return asteroid specimens to Earth.

Imagery taken by Hayabusa has been used to pick touchdown locations on asteroid Itokawa.

Japan's Hayabusa roared off into space from Japan's Kagoshima Space Center on May 9, 2003. The spacecraft arrived at its asteroid target on September 12 of this year.

Plans call for the probe's return capsule carrying asteroid specimens to return to Earth in June 2007, landing by parachute in a remote desert spot in Woomera, Australia.