The Japan Aerospace Exploration Agency (JAXA) confirmed today that its Hayabusa2 probe has successfully used the Earth's gravity to slingshot itself towards a rendezvous with an asteroid. The flyby maneuver saw the unmanned spacecraft swing by the Earth on December 3, with the closest approach of 3,090 km (1,920 mi) at 7:08 pm JST as it passed over the Pacific Ocean near the Hawaiian Islands.
Hayabusa2 was launched on December 3, 2014 from the Tanegashima Space Center on a mission to not only land on an asteroid, but to bomb it. Equipped with ion thrusters, it has spent the past year in an Earth-chasing solar orbit, so that when it caught up again with Earth, the planet's gravity shifted its trajectory by 80º and accelerated it from 1.6 km/s (3,579 mph) to 31.9 km/s (71,358 mph) relative to the Sun. This will allow the probe to rendezvous with C-type asteroid 1999 JU3 (aka Ryugu) in July 2018.
As Hayabusa2 flew by Earth it was tracked by the agency as well as NASA's Deep Space Network and ESA's deep space ground station, which confirmed that it is in good health at a current distance of 4.15 million km (2.79 million mi) from Earth. During the flyby, the probe's Optical Navigation Camera – Telescopic (ONC-T) captured images of the home planet.
When Hayabusa2 reaches its destination, it will study asteroid JU3 with a variety of instruments as well as using a sample grapple to collect materials from the surface and interior. These will be transferred to a reentry vehicle and fired back into the Earth's atmosphere when the asteroid explorer returns home after completing its 18-month stay at JU3.
In addition, Hayabusa2 also carries a small fleet of landers for surface studies. These include a pair of Minerva II rovers, which are designed to bounce slowly across the surface of the 900 m (3,000 ft) asteroid in its tiny gravity, and the MASCOT lander.
But the most spectacular experiment of the mission is the Small Carry-on Impactor (SCI), which is basically a space-going bazooka warhead. The SCI consists of a shaped explosive charge formed into a cone with a 2 kg (4.4 lb) liner made of copper. When the SCI is fired at the surface, the charge will detonate and the copper will turn into a molten slug that will blast open a crater in the asteroid, exposing buried material that has been protected from sunlight and damaging radiation for billions of years.
Source: JAXA