Data from the Hayabusa2 probe showed changes in speed and direction, indicating it had touched down on the asteroid and was blasting back to its orbiting position, according to the Japan Aerospace Exploration Agency (JAXA).
About 50 members of the operation team and some 20 other people who were monitoring the developments Friday morning at JAXA’s control room, in Sagamihara, Kanagawa Prefecture, erupted in joy when signals arrived confirming Hayabusa2 had landed and fired a projectile, pumping their fists, clapping and hugging.
“We have completed our mission,” JAXA Research Director Takashi Kubota told reporters.
“Today, the hand of humankind has reached a new starlet,” said Hayabusa2 Project Manager Yuichi Tsuda, an associate professor at JAXA’s Institute of Space and Astronautical Science, at a news conference. “The touchdown was in the best conditions, and as desired.”
The asteroid is thought to contain relatively large amounts of organic matter and water from some 4.6 billion years ago, when the solar system was born.
After landing, the probe was set to return to its orbit around Ryugu, with further touchdowns planned for later in the year.
Hayabusa2 will eventually fire an “impactor” to blast out material from underneath Ryugu’s surface, allowing the collection of “fresh” materials unexposed to millennia of wind and radiation.
Scientists hope those samples may provide answers to some fundamental questions about life and the universe, including whether elements from space helped give rise to life on Earth.
Communication with Hayabusa2 is impossible at times because its antennas are not always pointed toward Earth.
The mission has not been completely plain sailing, and the probe’s landing was originally scheduled for last year.
That was pushed back after surveys found the asteroid’s surface was more rugged than initially thought, forcing JAXA to take more time to find a suitable landing site.
The Hayabusa2 mission, with a price tag of around ¥30 billion ($270 million), was launched in December 2014 and is scheduled to return to Earth with its samples in 2020.
Photos of Ryugu — which means “dragon palace” in Japanese and refers to a castle at the bottom of the ocean in an ancient Japanese tale — show an asteroid shaped a bit like a spinning top, with a rough surface.
Hayabusa2 observes the surface of the asteroid with its camera and sensing equipment but has also dispatched two tiny Minerva-II rover robots, as well as the French-German robot Mascot, to help surface observation.
Scientists are already receiving data from those probes deployed on the surface of the asteroid.
The 10 kilogram (22-lb.) observation robot Mascot is loaded with sensors and can take images at multiple wavelengths, investigate minerals with a microscope, gauge surface temperatures and measure magnetic fields.
At about the size of a large fridge, Hayabusa2 is equipped with solar panels and is the successor to JAXA’s first asteroid explorer, Hayabusa — which is Japanese for falcon.
That probe returned from a smaller, potato-shaped asteroid in 2010 with dust samples, despite various setbacks during its epic seven-year odyssey, and was hailed as a scientific triumph.