The Japanese spacecraft Hayabusa2, which was launched in 2014, has just closed in on its target asteroid, the Ryugu, at a distance of about 25 miles.
To date, the Japanese spacecraft has traveled about 1.9 billion miles to get this close to the Ryugu asteroid. Its ultimate goal is to collect samples of the asteroid that contains some water and natural material, then bring these samples home to Earth in late 2020.
If successful, samples from Ryugu will give scientists a deeper understanding of what the actual condition was like when the solar system was formed some billion years ago.
Ryugu 'Firefly Stone' Asteroid
The Ryugu asteroid was discovered in 1999. Its name was derived from an undersea dragon palace, which is a popular element in the Japanese folktale.
Early this month, the first photos taken of the asteroid at a distance of about 1,600 miles showed it has a somewhat circular shape.
On June 24, however, the spacecraft was able to take photos, which revealed the actual shape of the asteroid. It is square-like and similar to the shape of a fluorite or the firefly gemstone, which is popular in Japanese culture. The asteroid's craters, as well as geographical features, also become visible.
Ryugu's shape becomes more visually interesting. As the spacecraft goes nearer and nearer to it, the asteroid is also becoming scientifically challenging for the Japanese team. Hence, the asteroid is bringing the team both good and bad news.
"First of all, the rotation axis of the asteroid is perpendicular to the orbit. This fact increases the degrees of freedom for landing and the rover decent operations," said Yuichi Tsuda, the project manager for the spacecraft.
"On the other hand, there is a peak in the vicinity of the equator and a number of large craters, which makes the selection of the landing points both interesting and difficult. This means we expect the direction of the gravitational force on the wide areas of the asteroid surface to not point directly down," he further explained.
The Ryugu asteroid is also rotating in a manner that surprises the Japanese team. Makoto Yoshikawa, another manager for the mission, noted that Ryugu performs a spin longer than similar asteroids. The Ryugu is spinning about 7.5 hours as compared to other Type C asteroids that spin around 3 hours.
In the meantime, the Japanese team said a more detailed investigation of Ryugu's properties is needed for them to design their future operational plans.
Hayabusa2 is expected to reach within 3.1 miles of Ryugu's surface by July. The spacecraft will then measure the asteroid's gravity field. By September or October, the spacecraft is expected to achieve its first "touchdown operation" on the asteroid. It plans to deploy several small rovers sometime around these months.
The spacecraft will then be "sleeping" between November and December as the sun will mostly block the communications from Ryugu to Earth and vice versa. As soon as it "wakes up," the spacecraft will then proceed with deploying more tiny rovers including a copper projectile that will create a crater on the asteroid from where samples will be collected.
Hopefully, by 2019, Hayabusa2 will make its way back to Earth just to be in time to eject a capsule containing the samples to Earth by 2020.