Sky-high expectations

When the scorched and dented pod from Hayabusa crashed into the Australian outback in June 2010, there was an outpouring of national pride in an epic space journey and a scientific effort that no other nation had previously attempted - much less achieved. Hayabusa landed on a 500-meter-long asteroid named Itokawa that is tumbling through our solar system - overcoming a series of mechanical problems en route, including a malfunctioning gyroscope and a fuel leak - and managed to gather microscopic particles of space dust from the surface. It then completed the journey home to deliver its priceless payload to the scientists of the Japan Aerospace Exploration Agency (JAXA).

The lessons learned on a flight that traversed, in total, 1 billion km - and which lasted seven years, one month and four days - have significantly benefited our understanding of our solar system and the origins of our planet, said Dr. Makoto Yoshikawa, who took over the role of lead scientist on the project in 2006, and who is today the mission manager for Hayabusa-2.

Now, it is the turn of the second craft to bear that name to get off the ground and find the answers to the scientists' ever-growing list of new queries.

Structure of asteroid

"I would say that the most important thing we learned from the first Hayabusa mission was about the structure of the asteroid," Yoshikawa told DW. "The asteroid is made up of fragments of rocks - a 'rubble pile' - and we never knew that before."

Yoshikawa said that the scientists did not know that there were craters on the surface, or that there were lots of boulders, and this all came as a surprise to them.

Once back on Earth, JAXA scientists told that the craft's recovery chamber contained around 1,500 minute particles - each less than 100 micrometers in diameter. These particles have been shared with experts around the world and are being studied to see what they can teach us about the formation of the universe.

Tests have already revealed LL-type chondrite with elevated levels of iron, which is not found on the surface of Earth. Further tests measured the presence and levels of isotopes, the structure of crystals within the rock fragments, the abundance of atoms, the presence of organics and noble gases, and identified other trace elements.

The successful project was named by the influential Science magazine as one of the most remarkable scientific breakthroughs of the year. Hayabusa also made the cover of the magazine twice.

Expectations sky-high

This means that expectations are high for Hayabusa-2.

The target this time is classified as a C-type asteroid, meaning that its rocks will contain more organic matter and water. Presently known only as 1999-JU3, it has a similar orbit to Itokawa and occasionally comes relatively close to Earth. More spherical than the previous target, the asteroid is around 920 meters long.

As with the first Hayabusa, the improved craft, which is scheduled to be launched in late 2014, will use an ion engine to reach 1999-JU3 in June 2018. According to the project schedule, Hayabusa-2 will remain with the asteroid for around 18 months, carrying out a series of tests, before leaving for Earth, where it will arrive in late 2020.

Arguably the biggest innovation from the first Hayabusa project will be the manner in which particles of space dust are recovered from the asteroid.

"When the craft arrives, it will release a small box containing an explosive device before maneuvering to the far side of the asteroid, to stay out of the way of the blast," said Yoshikawa. "The explosion will send a 2 kg copper sphere into the surface of the asteroid to make a crater, maybe 50 cm deep and as much as 3 meters wide."

Hayabusa-2 will then briefly touch down in the crater to collect material that was below the surface.

"Material on the surface has been weathered by solar light and radiation, so we want to gather particles that have not been exposed to that weathering process," he said.

First in space exploration

"Nothing like this has ever been attempted before and our aim is to gather grains of around 0.1 gram," said Yoshikawa. "Ideally, we would love to be able to gather a few grams of dust, but we will not necessarily need that much as our analyzing techniques are very advanced now."

The most critical part of the entire operation will be the delicate touch-down on the asteroid - any error of judgement could fatally disable the craft, Yoshikawa emphasizes - but he is confident that the expedition will be another success for JAXA.
"The solar system was born 4.6 billion years ago, but before that there was a molecular cloud," he said. "We believe that cloud contained the material that became life on our Earth and that is what we are looking for."