Japanese probe approaches weird-looking asteroid

a reply to: JimOberg

Looks like a really worn, eight-sided die, with the numbers missing.

"Weird", indeed!

a reply to: JimOberg

Looks like dice,who said god doesn't play dice with the universe?

Reminded me of phobos


-dex

Nice to see groups other than Nasa conducting missions..

originally posted by: dragonridr
a reply to: JimOberg

Looks like dice,who said god doesn't play dice with the universe?

Einstein says no, Hawking says yes.

What's a poor astrophysicist to believe?

originally posted by: Blue Shift

originally posted by: Devino
a reply to: JimOberg

Ryugu has a diameter of about 900 metres, consistent with predictions. Ryugu has a pronounced equatorial bulge (a feature seen in many asteroids) as well as crater-like features up to 200 metres across.

I find it odd that many small moons and asteroids have such relatively large craters. It would seem logical that an impact of that size would break the asteroid apart.

Maybe they're not so much an "impact," as a "bump," with both objects flying off each other without massive damage to either.

The crater suggests an impact. Perhaps this object, Ryugu, is a loosely packed aggregate similar to a pile of gravel and dirt in which a slow impact might make this crater yet it is not the only small body with a rather large crater on its surface. It seems that just about all images of small moons, asteroids and comet nuclei have large craters. They shouldn't be there yet I have come to expect to see them in close up images.

You remind me of my childhood. I poked everything with a stick first...

originally posted by: Devino
a reply to: JimOberg

Ryugu has a diameter of about 900 metres, consistent with predictions. Ryugu has a pronounced equatorial bulge (a feature seen in many asteroids) as well as crater-like features up to 200 metres across.

I find it odd that many small moons and asteroids have such relatively large craters. It would seem logical that an impact of that size would break the asteroid apart.

The most extreme example is probably Saturn's famous "Death Star" moon, Mimas. It's hard to imagine how it could have sustained such a large impact without totally shattering.

originally posted by: prevenge

originally posted by: Devino
a reply to: JimOberg

Ryugu has a diameter of about 900 metres, consistent with predictions. Ryugu has a pronounced equatorial bulge (a feature seen in many asteroids) as well as crater-like features up to 200 metres across.

I find it odd that many small moons and asteroids have such relatively large craters. It would seem logical that an impact of that size would break the asteroid apart.

How do you know that's not what happened, and this one is the chunk that broke off?

I would think it very unlikely yet it could be. However this is not a rare feature on small bodies floating around in our solar system, it is rather quite common.

How many close up images of objects like these are there of craters on their surface, relatively large craters on small bodies? The Moons Mimas and Phobos come to mind.
DexterRiley has posted a nice image of Phobos;

If you look closely there are rilles, with crater chains inside, that go all the way around to the other end of the Moon that appear to terminate at two opposing poles. They kind of resemble magnetic field lines.

What was thought to be known about crater impacts does not fit with what has been observed. So perhaps small bodies can sustain high energy impacts and stay mostly intact or perhaps there is another mechanism that creates these craters that does not require high energy impact. Either way the answer seems to be that we do not know.

originally posted by: AndyFromMichigan

originally posted by: Devino
a reply to: JimOberg

Ryugu has a diameter of about 900 metres, consistent with predictions. Ryugu has a pronounced equatorial bulge (a feature seen in many asteroids) as well as crater-like features up to 200 metres across.

I find it odd that many small moons and asteroids have such relatively large craters. It would seem logical that an impact of that size would break the asteroid apart.

The most extreme example is probably Saturn's famous "Death Star" moon, Mimas. It's hard to imagine how it could have sustained such a large impact without totally shattering.

That is just what I was thinking, as you can see in my post below yours. Mars' moon Phobos is also a very interesting example. Not only does it have a relatively huge crater, perhaps too large for such a small body, but it is also full of crater chains. I wish I had more time to post images. Crater chains are hard to explain using impact theory, extremely unlikely scenario, especially when these chains follow rills that then seem to behave like magnetic field lines.

originally posted by: Devino
The crater suggests an impact.

I'm no craterologist.

I second the request for an explanation as to why the image is 2004-era vodafone 0.6 megapixel camera quality, when the Japanese lead the world in camera-optics-electronic-gizmos...

Why have they provided such a crappy photo? Indeed, why have they even bothered to send a probe into space if my Sony Xperia smartphone's camera apparatus is better equipped for the task (proportionately speaking, in terms of scaled-up fit-for-purpose standards), being as it is the best on the terra-firma smartphone market?

Strikes me as suspicious.

Best smartphone cameras --- Worst space probe cameras = ???

Something doesn't add up. Like when the viewing public was provided with footage 'filmed-off-a-screen-at-mission-control' of the Moon landing. Deliberately degraded imagery...

originally posted by: Devino
a reply to: JimOberg

Ryugu has a diameter of about 900 metres, consistent with predictions. Ryugu has a pronounced equatorial bulge (a feature seen in many asteroids) as well as crater-like features up to 200 metres across.

I find it odd that many small moons and asteroids have such relatively large craters. It would seem logical that an impact of that size would break the asteroid apart.

The impact causes temperature to rise so much that the materials of both objects vaporize. At 6000C, even tungsten carbide will melt and vaporize.

a reply to: FlyInTheOintment

The mission is not to take pictures. The mission is to return samples. Space and weight are a premium on any spacecraft and the mission determines the instrumentation. The actual function of the optical camera is navigation, not tourism. But the pictures will improve when the telescopic unit is for mapping the asteroid in preparation for the landings.

global.jaxa.jp...

originally posted by: Blue Shift

originally posted by: Devino
The crater suggests an impact.

I'm no craterologist.

No? Me neither. It doesn't stop me from trying to understand though.

From what I have read we currently we have two known mechanisms for the creation of craters, volcanoes and impacts (not to mention collapsed lava tubes, Cenotes and sink holes). When dealing with small astronomical bodies such as these we can rule out volcanoes, and the rest for the most part, leaving impacts as the only accepted cause. There seems to be be a problem with this.

Phobos is a perfect example of this problem and one I have tried to find an answer to. Assuming that this small, 7 mile radius (17 mile long), moon could withstand such a huge impact that made the Stickney crater, 5.6 mile radius, what caused the rilles and crater chains that seem to emanate from this crater and terminate on the other side?

Here is a nice image of these chains on Phobos;
Compliments of Wikipedia

And this one in 2D from Sky and Telescope Which attribute the rilles and crater chains to fracturing from tidal forces;
A better image can be found here.

And this from a paper at Science Direct that suggests they are due to secondary impacts and rolling debris in a low gravity environment.
The similarity to magnetic filed lines in these images seems to suggest an electromagnetic origin. I suppose it could be from fracturing due to tidal forces from Mars or secondary impacts in a very low G environment (0.0057 m/s²) but I remain skeptical.

a reply to: Phage
Also considering that this is a picture of an object that is 900 meters wide at a distance of over 155 miles I would say well done from such a small craft. I am eagerly awaiting an analysis of samples returned from this rock.

Nice find

originally posted by: Phage
a reply to: FlyInTheOintment

The mission is not to take pictures. The mission is to return samples. Space and weight are a premium on any spacecraft and the mission determines the instrumentation. The actual function of the optical camera is navigation, not tourism. But the pictures will improve when the telescopic unit is for mapping the asteroid in preparation for the landings.

global.jaxa.jp...

The Real mission is not to show the Borg walking around on the surface!

a reply to: Devino
Since there are striations which overlay the crater, it's not likely they are related. At least some of the grooves had have to have occurred after the impact.

One of the most highly regarded theories (which you reject?) has to do with tidal stresses. Phobos, in a death spiral toward Mars, is beginning to approach its Roche limit. Just because someone thinks something looks like something else doesn't mean it is. No magnetism involved. No electric universe. Just gravity.

She canna take eny more c'pn. She's breakin up!

agupubs.onlinelibrary.wiley.com...


Oh, and apart from how unlikely you may think it is, models show that an impact origin for the crater is entirely possible.

The reason for its shape has a lot to do with the fact that it's too small for its gravity to form it into a sphere. It also has an equatorial bulge, caused by material slipping due to centrifugal forces from it's spinning.

Phil Plait has a good write-up on this asteroid and the images: www.syfy.com...

The cool thing about the images is that you can use cross-eye method to see them in stereo:



The asteroid rotates backwards, so that big impact crater might have had a big impact (pun intended) after all.