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Japan's Hayabusa 2 mission to an asteroid is delayed again

Paul Sutherland, Feature writer
Nov 27, 2014, 16:45 UTC, Updated Nov 30, 2014, 19:42 UTC

Sen—As the world celebrates the success of Europe’s Rosetta, Japanese space scientists are preparing to launch the latest mission to explore one of the minor bodies of the Solar System.

Their Hayabusa 2 spacecraft was originally due to blast off on Sunday 30 November from the Tanegashima Space Center. (Update: The launch, by a H-IIA rocket, has been postponed, for a second time, to 3 December at the earliest because of high winds. The earlier delay was due to a forecast of unacceptable cloud conditions.)

Its mission will be to rendezvous with an asteroid, land a small probe plus three mini rovers on its surface, and then return samples to Earth. It follows an earlier Japanese Hayabusa mission to an asteroid named Itokawa. 

Asteroids generally differ from comets, such as 67P/Churyumov-Gerasimenko which Rosetta is circling, because they don’t fizz with gas and dust. They seem to be chunks of material from the formation of the Solar System which never collected together to form planets.

Hayabusa 2’s target is a 1km-wide asteroid labelled 1999 JU3, after the year when it was discovered. It is a C-type asteroid, thought to contain more organic material than other asteroids, and so might again help scientists understand how the Solar System evolved.

The Japanese space agency JAXA intend for Hayabusa 2 to catch up with asteroid 1999 JU3 in 2018. It will land a small cube-shaped probe called MASCOT (Mobile Asteroid Surface Scout) developed by the German Space Agency (DLR) together with French space partners the Centre National d’Etudes Spatiales (CNES). 

The lander is able to move its centre of gravity so that it can tip itself over in order to move across the asteroid’s surface. The three small rovers, called Minerva-II, will also roam the asteroid, gathering data.

Hayabusa 2 also carries an impactor that will blast a 2-metre-wide crater in the asteroid’s surface, which will allow the spacecraft to collect fragments and bring them home for study in the laboratory. The spacecraft itself is designed to touch down briefly three times to gather samples.

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The German-French MASCOT lander is fitted to the Hayabusa 2 spacecraft. Image credit: DLR

The first Hayabusa kept space enthusiasts and scientists on the edge of their seats with its performance. Launched in May 2003, it reached the 500-metre long Itokawa in September 2005, then twice brushed its surface, allowing some surface grains to lodge in its collector. But a bid to blast out samples from the asteroid and to land a mini-probe called Minerva both failed.

Then fuel and power failures led scientists to fear that they had lost Hayabusa. But amazingly, they managed to regain control over the following months, and against all the odds, the probe was able to fire its capsule of precious asteroid dirt to a safe landing in the Australian Outback in June 2010.

Hayabusa 2 is the size of a small van, measuring 1.0 metres x 1.6 metres x 1.2 metres, and has two solar panels to provide power. In space it will be driven by an ion engine using xenon propellant 

The asteroid selected by JAXA is a “perfect specimen” according to Professor Humberto Campins, an international expert on asteroids and comets, at the University of Central Florida. He has said: “Based on our analysis, it should be rich in primitive materials, specifically organic molecules and hydrated minerals from the early days of our Solar System. If successful it could give us clues about the birth of water and life in our world.”

Scientists believe that learning more about objects such as 1999 JU3 will also help develop methods to deal with any cosmic debris, such as Near Earth Asteroids, that might be found on course to impact the Earth.

A number of other spacecraft have visited asteroids, including Rosetta which flew past 2867 Steins in 2008 and 21 Lutetia in 2010, en route to Comet 67P/Churyumov-Gerasimenko, and NASA’s Dawn mission which is currently heading for Ceres after orbiting Vesta for a year. 

A video shows how the MASCOT lander will hit the asteroid and explore its surface. Credit: DLR