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Spacecraft Hayabusa2 Returns Photos of Asteroid Prior To Contact (syfy.com)
New submitter FranklinWebber writes: Spacecraft Hayabusa2 is approaching its target, asteroid Ryugu, after a three-and-a-half year trip. The Japan Aerospace Exporation Agency (JAXA) has released photos of the asteroid taken from a distance of several hundred kilometers and showing a diamond-shaped object.
Like its predecessor spacecraft a decade ago, Hayabusa2 is designed to collect samples from an asteroid and return them to earth. JAXA explains: "A C-type asteroid, which is a target of Hayabusa2, is a more primordial body than Itokawa [the target of Hayabusa and an S-type], and is considered to contain more organic or hydrated minerals.... we expect to clarify the origin of life by analyzing [samples from Ryugu]."
The Bad Astronomy blog has more discussion of the mission: "The spacecraft will deploy an impactor that will slam a 2.5 kilo piece of copper into the surface at 2 km/sec. This will dig down into the asteroid, revealing material underneath, which can then be analyzed to understand Ryugu's interior."
Like its predecessor spacecraft a decade ago, Hayabusa2 is designed to collect samples from an asteroid and return them to earth. JAXA explains: "A C-type asteroid, which is a target of Hayabusa2, is a more primordial body than Itokawa [the target of Hayabusa and an S-type], and is considered to contain more organic or hydrated minerals.... we expect to clarify the origin of life by analyzing [samples from Ryugu]."
The Bad Astronomy blog has more discussion of the mission: "The spacecraft will deploy an impactor that will slam a 2.5 kilo piece of copper into the surface at 2 km/sec. This will dig down into the asteroid, revealing material underneath, which can then be analyzed to understand Ryugu's interior."
Here is a recent YouTube video from space enthusiast and Kerbal guru Scott Manley. It attempts to explain the differences in capturing images of distant objects using spacecraft compared to, say, taking pictures with a smartphone. The most important aspect to keep in mind that is these images are taken from really far away, and so the objects being resolved are really tiny (i.e., subtend a tiny angle in the field of view).
Let's throw some math at this. The target asteroid is roughly 0.9 km across, and was imaged from 320 to 240 km away. Even at the closest of four images, the asteroid was only 0.2 degrees (13 arcmin) across - less than half the apparent size of the full moon from here on Earth. Now, if Hayabusa2 was not going to get much closer, the designers of the spacecraft could have spec'ed a camera system with a narrower field of view, i.e., a greater magnification, so that it could resolve the asteroid better from that distance. But this spacecraft is going to get very, very close to the asteroid (probably land on it), and a camera with a narrow field of view would be a hindrance to good science when the spacecraft gets close up. Put differently: you wouldn't want to use a telescope to take a portrait of your friend.
The designers had to make tradeoffs. The main camera has a field of view of about 6 degrees. On the bright side, things only get better from here as the spacecraft gets closer. It will spend the majority of its mission just 20 km away.
Hayabusa2's diameter is roughly 800m and these photos were taken around the 300km mark. That's like taking a photo of a human being from 7km away, but in space...after the mechanical stress of a rocket launch, 3 years of high temperature extremes and radiation, in ridiculously low light levels and on hardware that has to be as close to 100% reliable as you can make it. Hats off to the team, that's pretty damn impressive in my book.
There's also the fact that it was taken using the "navigation camera", not the "pretty-photo-taking camera".
This camera has just enough resolution to make sure it's going in the right direction.
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