Japan’s Hayabusa2 probe has just made history — again. The spacecraft gathered samples from the surface of the asteroid Ryugu earlier this year, and it bombed the asteroid a few months later. Now, the probe has taken another trip to the surface to scoop up pristine material that used to be buried below the surface.
Japan Aerospace Exploration Agency (JAXA) launched Hayabusa2 in 2014, taking four years just to meet up with Ryugu in its orbit some 185 million miles (300 million kilometers) from Earth. It started by dropping off some barrel-shaped robots to get the lay of the land, and then it descended to pick up its first sample in February 2019.
Hayabusa2 carried several tantalum slugs, which it fired at the surface after each landing. The impact launched particles upward and into the probe’s collection compartment — that first landing collected material from the top layer of the asteroid. The most recent collection is crucial because it may have included material from deeper inside Ryugu.
In April, Hayabusa2 launched the 5.5-pound (2.5kilogramsm) Small Carry-on Impactor (SCI). The SCI used a shaped HMX explosive charge to launch the impactor at Ryugu at more than 2 kilometers per second. The result was a small, artificial crater. Regolith on the surface of Ryugu has been bombarded by solar radiation for eons, but just below the surface is pristine material that is virtually unchanged since the birth of the solar system. That’s what Hayabusa2 was after this time.
[PPTD] These images were taken before and after touchdown by the small monitor camera (CAM-H). The first is 4 seconds before touchdown, the second is at touchdown itself and the third is 4 seconds after touchdown. In the third image, you can see the amount of rocks that rise. pic.twitter.com/ssZU5TV3x9
— HAYABUSA2@JAXA (@haya2e_jaxa) July 11, 2019
This landing required careful preparations — any problems could risk the loss of the first sample which is still inside Hayabusa2. The probe landed about 20 meters from the center of the crater, using its second tantalum slug to scoop up ejecta. Visual examination of the area showed varying color compared with other parts of the asteroid, so the team believes it does indeed have material from inside Ryugu.
Hayabusa2 will remain in orbit of Ryugu for several more months, departing in November or December. The spacecraft will arrive back at Earth in late 2020, at which point scientists will be able to examine the Ryugu samples up close. JAXA doesn’t know exactly how much of Ryugu is coming back to Earth, but it hopes to get up to 100mg of material from the asteroid. That doesn’t sound like a lot, but it will be the only perfectly preserved sample of the solar system from an object more distant than the moon.
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