Photo/IllutrationAn artist’s rendition of Hayabusa 2 landing near the artificial crater on Ryugu and collecting underground sand and stones (Provided by the Japan Aerospace Exploration Agency)

  • Photo/Illustraion

The Hayabusa 2 space probe on July 10 started its descent on a delicate mission to collect the world’s first underground samples from an asteroid, the Japan Aerospace Exploration Agency (JAXA) said.

The probe is slowly approaching the asteroid Ryugu and is expected to land shortly after 10 a.m. on July 11, if everything goes smoothly.

Once on the surface, Hayabusa 2 will fire a bullet into the surface near an artificial crater and collect the flying sand and stones, according to JAXA’s plan.

After several seconds, it will leave the asteroid.

“Finally, the time has come,” JAXA project manager Yuichi Tsuda told his team members. “(The landing mission) is a very important milestone, but let’s do it in a calm manner, like we have always done.

“Let’s allow Hayabusa 2 to touch Ryugu tomorrow one more time.”

This mission has been fraught with potential problems, but so far, Hayabusa 2 has performed remarkably well since it traveled to the asteroid, about 340 million kilometers from Earth.

It first touched down on Ryugu in February, fired a bullet into the asteroid, and collected surface samples from the impact.

In April, the space probe dropped an explosive box that propelled a copper sphere into Ryugu, creating the crater.

Around 11 a.m. on July 10, Hayabusa 2 started descending from its home position at an altitude of 20 kilometers toward the artificial crater.

The expected landing site is apparently covered with a 1-centimeter-thick layer of underground sand spread by the impact of the copper sphere. The probe is expected to collect that sand after it rises from the bullet’s impact.

When the probe reaches an altitude of 500 meters, likely on the morning of July 11, JAXA will decide if the conditions are right to continue with the landing.

If the plan is given the green light, Hayabusa 2 will make its own judgments based on information from its altimeter and images from its cameras.

The project team, however, has concerns. The flying sand caused by the bullet fired in February created poor visibility, and the probe’s cameras could not capture clear images of the situation on the asteroid.

If the space probe loses sight of the landing spot or other problems occur, the landing mission could be called off.

In that case, JAXA will discuss whether another attempt should be made on July 22 or later.