Wednesday, November 16, 2005

Hayabusa on Mission to Discover Origins of the Solar System

by Geoff Counihan (Class of '05)

The Japanese launched the Hayabusa spacecraft on May 9th 2003 from their Kagoshima launch site. The spacecraft was meant to rendezvous in mid summer 2005 with the near earth asteroid Itokawa and bring back samples to earth in June 2007. Since asteroids are left over material from the formation of the solar system, these samples hopefully will help us determine what elements comprised the early solar system.

Itokawa is a 600-meter long potato shaped asteroid, which named after Hideo Itokawa, an early Japanese rocket scientist. The goal of the mission is to land on the surface of the asteroid, bring back samples from the surface, and to parachute them into Woomera, Australia. This will let scientists study the minerals that compose the asteroid and better understand the early composition of the universe. In addition to this primary objective, the mission is also to prove the electric propulsion engines, an autonomous navigation system, the sample collection system, and re-entry equipment.

During Hayabusaís flight two of the three reaction wheels, and the solar panels were slightly damaged by solar flares. This delayed the arrival to the asteroid until September 2005. These problems have required the scientists to rely more on Hayabusaís chemical propellant thrusters to maintain control of the spacecraft. It has also caused the scientists to be much more concerned about fuel conservation.

Since September, Hayabusa has been circling a few miles from Itokawa and has been collecting data on the asteroid. The entire surface has been examined with cameras and x-ray spectrometers to map the terrain and identify mineral composition. It has also been taking detailed pictures to identify the best landing site. There are two possible locations both generally smooth ñ almost all the rest of the asteroid is covered in jagged rocks and rough terrain. These two potential sites are now being thoroughly examined to determine which is best for Hayabusa.

On November 4th the Hayabusa ran into trouble during its practice landing session in preparation for the planned landings on November 12th and 25th. Scientists shut down the practice mission due to unusual signals from the spacecraft and have not yet rescheduled a landing.

When Hayabusa does land on Itokawa, it will release an ultra small Micro/Nano Experimental Robot Vehicle for Asteroid, known as MINERVA. MINERVA is a hopping robot lander with three, color cameras. Two of which are for stereoscopic close ups, and one is for distance. An interesting fact about the design of this 1.3 lb. lander is that it will hop around on the asteroidís surface transmitting data back to the hovering spacecraft.

During the landing, the Hayabusa will shoot a marker into the landing area that will reflect light back to the spacecraft. Then it will use a laser ranging device to descend to the asteroidís surface. Once there it will quickly sample the surface, launch MINERVA, and take off.

The most difficult part of the mission is clearly landing on the asteroid and gathering samples. The communication lag from the asteroid to earth is 10 minutes, meaning that the spacecraft will have to make most of the important decisions alone, without direct control from the scientists on earth.