Hayabusa's Rocky Journey Ends with a Spectacular Return

Image of asteroid Itokawa taken by the Hayabusa probe.
JAXA

A Japanese space capsule, released by the Hayabusa asteroid probe, returned successfully to Earth today, with a spectacular, fiery show. The return marks the end of the seven year Hayabusa mission. The mission is returning from a nearby asteroid, named Itokawa, with a capsule perhaps filled with material collected from the asteroid itself. [Video of reentry and full description of mission below the fold.]

The Hayabusa mission was run by the Japanese Aerospace Exploration Agency (JAXA). The mission was plagued by several challenges, yet the probe was still very successful. The probe used ion engines to help it reach Itokawa, an asteroid about 500 meters long. On its way however, the probe suffered severe damage to its solar panels due to a very large solar flare (in fact, it was the largest solar flare in recorded history!). The damage resulted in lower power production, meaning that the probe's ion engines, which rely on electric power, would be weaker.

The probe ultimately arrived at Itokawa in 2005, sending back valuable data and images. Using the new information and the photographs, it was evident that the asteroid was composed of just small chunks of rock coalesced together by gravity. Despite its large size, the asteroid therefore had a very low density.

When the probe ultimately made its descent near the asteroid, it hovered about 10 meters above the surface for 30 minutes without landing. This perhaps may or may not have been enough to collect some dust in the capsule that returned today. However, since the probe had never been to stay for this long near the hot Sun-lit side of the asteroid, the spacecraft eventually heated, and entered safe mode, ascending away from the asteroid.

As the scientists at JAXA regained control, they decided to make another attempt at collecting samples from the surface of the asteroid. This process did not perform completely as expected, but scientists are hoping that some particles from the asteroids were collected.

Afterwards, the probe returned back to Earth, heading for the Australian outback. Before the return of the capsule, the capsule detached from the rest of the probe, which burned up in the atmosphere. (This can be seen in the video below. The magnificent flare is the probe burning up, while the moving dot seen afterwards is the return capsule.) Only the capsule returned to the ground, with the help of a parachute. Eventually the capsule will be transported to Japan, where JAXA scientists will discover if there are particles recovered from Itokawa. Even if tiny, small particles smaller than grains of sand were collected, they would be immensely valuable. As some of the only few pieces of space matter returned by a robotic mission, they could contribute greatly to scientific research.




So why is collecting a sample from an asteroid so important and valuable? Asteroids contain rocky materials preserved from the formation of the Solar System. Carrying out research of the materials found in asteroids can give us valuable insight about how the Solar System began. This type of information simply cannot be collected on the Earth.

Animation of asteroid Itokawa taken by the Hayabusa probe.
JAXA