Hayabusa 2 Probe To Fire A Bullet Into An Asteroid Today — Watch It Live

Artist illustration showing Hayabusa 2 gathering a sample of material released from Ryugu’s surface. The craft will fire a bullet into the surface. Blast material will float upward in the low-gravity of the asteroid and travel into the horn, the “proboscis” sticking out from the probe, and then collected in a canister. It all goes down this afternoon. Akihiro Ikeshita / JAXA

The Japanese Hayabusa-2 spacecraft will touch down on and grab a sample of asteroid Ryugu today. You can watch it live here starting at 3:45 p.m. Central Time this afternoon (Feb. 21). The whole sequence, from touchdown and sample retrieval to ascending back into orbit, will take about 2½ hours. For updates in case plans change, check the Hayabusa Twitter site.


Hayabusa 2 touchdown — live streaming starts 3:45 p.m. CST today Feb. 21; 6:45 a.m. Tokyo time (JST) Feb. 22

This will be the second time Japan has attempted to sample an asteroid. On Nov. 19, 2005, during the first Hayabusa mission, the spacecraft attempted its first touchdown on asteroid Itokawa. After contact, the probe was supposed to fire a small projectile at the surface; dust and bits of rock kicked up by the impact would be collected in a canister for the flight home. But on the way down a sensor detected an obstacle. The probe reacted by placing itself in “safe mode” which prevented the firing device from working. Fortunately, it did touch down for about 30 minutes, disturbing the surface enough for a bit of dust to waft upward into a collection canister. The minute particles finally made back to Earth for analysis in June 2010. If you’re a qualified scientist you can request a study sample from NASA here.

Views of the two hemispheres of Ryugu seen from just 12 miles (19 km) away. JAXA

Assuming all goes well, Hayabusa 2 will take a pinch of Ryugu this afternoon from a chosen site marked with a reflective target that was dispatched to the surface earlier. As I write, scientists at the Japan Aerospace Exploration Agency (JAXA) are painstakingly guiding Hayabusa to the surface.

In this view, the sun is at the spacecraft’s back and shines directly at Ryugu, so no shadows are visible. But it’s perfect lighting to see the reflective target marker that will help guide the probe to the rocky surface today to gather its first sample. The “thumb” sticking out at the bottom is a giant boulder. JAXA

Once it lands on Ryugu  — a tiny body just 3,000 feet (914 meters) across and located 170 million miles (274 million km) from Earth — a device will shoot a bullet made of the metal tantalum into the gravelly surface at 985 feet per second (300 m/s). Scientists had hoped for a dustier surface, but it turned out to be so rocky they had to perform new tests firing into gravel in the lab to make sure particles would be released and travel into the canister. It worked! It helps that the gravity of the asteroid is so slight that even modest fragments will blast off from the impact.

Hayabusa will fire a tantalum bullet at the asteroid to break up and move rock fragments into its collector horn. Tantalum is a hard, dense, corrosion-resistant metal with a high melting point. It’s also a rare element not likely to be found on the asteroid that scientists can easily distinguish from asteroid rock should the bullet break into bits on impact. A bullet made of iron or another more common material might be mistaken for asteroid material. JAXA

Once the sample has been retrieved and sealed in the canister, the probe will back off from Ryugu and return to orbit. At least two more sampling attempts from other parts of the asteroid will be made before Hayabusa 2 departs in December this year and returns to Earth in December 2020.

This short movie shows Hayabusa 2 and its sampler horn during a rehearsal for touchdown. JAXA

UPDATE 6:30 p.m. CST: The landing and sample retrieval was a success!

1 Response

  1. Edward M Boll

    A beautiful Moon last night. First clear night in a long time. The Moon was too bright to get a view of Wirtanen. Still hoping to get a view of it yet this month.

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