Since last year, the Japanese probe, Hayabusa2, has been studying the asteroid, Ryugu, with the aim of returning its collected samples to Earth in 2020.

Hayabusa2 began by surveying the object’s surface, and subsequently landed multiple robotic probes on the asteroid’s rocky terrain. In February, Hayabusa2 fired a much smaller projectile into the asteroid’s surface during a brief touchdown, collecting samples from the cloud of debris that the operation kicked up.

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Why make a crater on the surface?

Hayabusa2 already has landed briefly on Ryugu’s surface and collected samples. But the surface materials scattered by the bullet-like projectile fired in February have been exposed to the solar system's weather. Studying them offers scientists a potential picture of Ryugu’s surface. But that debris won’t reveal much about the asteroid’s geological history, just as the topsoil in your yard won’t tell you much about what your neighborhood was like during the last ice age.

Making a crater will also offer clues to how asteroids similar to Ryugu respond to being struck by objects.

How did Hayabusa2 try to make the crater?

Hayabusa2 carried a device called the Small Carry-on Impactor. Unlike the small tantalum projectile that was fired at the asteroid in February as the spacecraft touched down on the surface, the impactor device detached from the spacecraf t . That allowed the probe to race to the other side of Ryugu and avoid damage from the anticipated explosion or the resulting debris.