The impactor is believed to have exploded 40 minutes later, and shot a metal object into Ryugu's surface at a speed of two kilometers per second to make a crater.
In announcing the findings, JAXA said they could help explain the origin of Earth's water. The small explosive device called a Small Carry-on Impactor (SCI) is a conical container weighing 14 kilograms (30.8 pounds).
It was created to come out of a cone-shaped piece of equipment.
Once the dust has settled, JAXA plans to send the spacecraft back to the crater to collect samples of material that have been unexposed to the sun or space rays. One bad move and pieces of the asteroid could have damaged the spacecraft.
Japan's Hayabusa2 spacecraft slammed a copper cannonball into the 3,000-foot-wide (900 meters) asteroid Ryugu last night (April 4), in an effort to blast out a crater that the probe can study in detail over the coming weeks and months.
A Japanese probe began descending towards an asteroid on Thursday on a mission to blast a crater into its surface and collect material that could shed light on the solar system's evolution. Hayabusa 2 deployed the SCI and then moved to a safe location on the other side of the asteroid before JAXA launched the SCI at the surface.
'So far, Hayabusa2 has done everything as planned, and we are delighted, ' said mission leader Makoto Yoshikawa. "But we still have more missions to achieve and it's too early for us to celebrate".
Hayabusa2 successfully touched down on a tiny flat surface on the boulder-rich asteroid in February, when the spacecraft also collected some surface dust and small debris.
Hayabusa-2 should depart from Asteroid Ryugu in December this year, and it should touchdown on Earth in late-2020. It was attached to the Hayabusa-2 and packed with plastic explosive.
If the mission proves successful, the probe will return to the crater to collect rock samples from deep within the asteroid, which have been protected from the harsh environment of space.
Because the impact of the copper mass could send up floating debris from Ryugu that could smack into the space probe, Hayabusa 2 will ascend to an altitude of about 20 km over a two-week period.
After that task is complete, all that's left for Hayabusa2 to do is head back to Earth, carrying with it precious souvenirs of the space rock it will have spent a year and a half studying.
An onboard explosive charge was scheduled to detonate last night at 10:36 p.m. EDT (0236 GMT and 11:36 a.m. Japan time this morning), sending the plate hurtling toward Ryugu's boulder-strewn surface at about 4,500 miles per hour (7,240 km/h).