Hayabusa 2 at Asteroid Ryugu

[bison]

The asteroid probe of the Japanese Aerospace Exploration Agency (JAXA), known as Hayabusa 2, is expected to begin its official approach phase to asteroid Ryugu on Tuesday, June 5th. It will then be about 2500 kilometers from the asteroid. Its ion engines will cut off and the probe will coast the rest of the way. A new, though low resolution, image of the asteroid is expected at that time, 

The asteroid  Ryugu is small, in the neighborhood of 900 meters in diameter. Its light curve suggest that it rotates in about 7.6 hours. The light curve was almost steady, suggesting that the asteroid is nearly spherical in shape. That's interesting because objects as small as this do not have sufficient gravity to pull themselves into neat spheres. 

Please find a link to an article, with further details, below:

http://www.planetary.org/blogs/emily-lakdawalla/2018/0525-keep-up-with-hayabusa2.html

 

[bison]

JAXA had a press conference today. They reported that the Hayabusa 2 probe is working properly, and will continue to approach Ryugu, preparatory to eventual landing on the asteroid. Further information about the mission, and its findings so far, will be released over the next few days.

A low resolution image of Ryugu was released. While already close to the asteroid, by interplanetary standards, about 2600 kilometers, the image shows limited detail. From what can be gathered, the asteroid may be less a sphere than a hemisphere. The upper part in this image looks flattened. Very much better images will be gotten, as Hayabusa 2 continues to approach its objective.

Please find a link to the image of asteroid Ryugu, below:

https://pbs.twimg.com/media/DfFHwPIXkAAGeXo.jpg 

Edited June 7, 2018 by bison
corrected link address

[bison]

The Hayabusa 2 probe is now reportedly only about 1500 kilometers away from Ryugu. Maneuvering thrusters have been used to apply fine corrections to the probe's trajectory, as it draws nearer the asteroid.

Navigation is being done by camera, by repeatedly noting the positions of Ryugu, and certain stars. A new image of the asteroid has been released. It is still low in resolution, but offers considerable improvement over the previous one.

The asteroid is obviously quite compact in shape, rather than elongated. Again, it appears rounded, but rather flat on one side; something like a dome, turned sideways.  A report from JAXA, with images, is linked, below:

http://www.hayabusa2.jaxa.jp/topics/20180611b_e/   

Edited June 11, 2018 by bison
added descriptive details

[bison]

Hayabusa 2 is now just 750 kilometers from Ryugu. It is moving toward the asteroid at about 1.7 meters per second, equivalent to a brisk walking pace.

They surveyed the area around the asteroid with one of the cameras, looking for moons, or orbiting debris that might need to be avoided. None were found.

A new image of the asteroid has been released; it gives nearly three times the resolution of the previous one, and is linked below. It has been confirmed by Hayabusa that the asteroid rotates in about 7.6 hours, a value previously assigned by observations from Earth.

https://imgur.com/Y86PZsp

Edited June 14, 2018 by bison
removed superfluous word, added information

[L.A.T.1961]

Images are starting to get interesting.  

[bison]

Here is a motion study of asteroid Ryugu, made up of separate images. The images have been processed to smooth the pixel edges, and to bring out faint surface details. One can see surface features come and go as the asteroid rotates. Ryugu gives the impression of having an equatorial bulge, which is common in loosely consolidated 'rubble pile' asteroids.

http://www.hayabusa2.jaxa.jp/topics/20180616je/index.html 

Edited June 16, 2018 by bison
omitted superfluous word

[Minimalists]

Interesting stuff fellas....

Edited June 16, 2018 by Alien Origins

[bison]

A clearer motion sequence of asteroid Ryugu rotating, has been presented. Its shape appears to be like two slightly irregular, shallow cones, attached at their bases. The poles of rotation are at the points of the cones. A number of darkish surface features are seen to flash by, as the asteroid rotates, some resembling craters.  Ryugu is seen to rotate to the right, which confirms the suspected retrograde rotation. 

 A video of the new motion sequence is linked below:

http://www.unmannedspaceflight.com/index.php?act=attach&type=post&id=43059 

Edited June 18, 2018 by bison
corrected misspelling, removed defective link address, added correct address

[The Caspian Hare]

https://spaceflightnow.com/2018/06/20/asteroid-ryugu-revealed-by-approaching-japanese-spacecraft/

In the final days of a three-and-a-half year pursuit, Japan’s Hayabusa 2 sample return spacecraft is beaming back clearer images of asteroid Ryugu, an unexplored object that scientists say resembles a spinning top or dumpling nearly 180 million miles from Earth.

The approaching Hayabusa 2 spacecraft is revealing Ryugu for the first time, sharpening views of an asteroid scientists hope to sample later this year. The nearly 3,000-foot (900-meter) wide asteroid has never been visited by a space mission before now.

Launched aboard a Japanese H-2A rocket on Dec. 3, 2014, Hayabusa 2 is Japan’s second space mission dedicated to bringing samples from an asteroid back to Earth. The mission’s predecessor, named Hayabusa, returned microscopic specimens from asteroid Itokawa in 2010 after a series of malfunctions prevented it from capturing the planned amount of material.

[bison]

Two of the new images of Ryugu, taken on the the 20th, make it possible to derive a three dimensional picture of the asteroid. It takes some effort to see this, but the effect is quite good.  Large copies of these two images are linked below. Look straight at the two images. Relax your eyes and let the two images merge into one, in the space  between them. This central image portrays surface features of the asteroid in high relief.

http://www.unmannedspaceflight.com/index.php?act=attach&type=post&id=43085 

Edited June 21, 2018 by bison
corrected link address

[bison]

I'm particularly interested in the especially bright feature, at the very top of the images. In the left one, it looks like an arc, in the right, it appears as a wedge shape, shifted slightly to the left. I thought of the rim of a crater, illuminated by very-low angle sunlight, but the shape of the arc, at  the implied angle, looks too round, where it should appear elliptical.  

[bison]

Here is a new motion sequence of Ryugu rotating , based on the latest images. The very bright area at the top appears to rotate behind an obscuring dark promontory. One can still see the top edge of the bright area, behind the obstruction.

Judging by how sunlight is returned by other features on the surface, this bright area must be unusually reflective. Are we looking at a salt deposit, like that found on Ceres, in the Occator crater? Given the facts that Ryugu is very much smaller than Ceres, and unlikely to be geologically active, and that the bright area here appears nearly vertical, this might not be so likely. 

https://imgur.com/91PDNxF   

[Merc14]

11 minutes ago, bison said:

Here is a new motion sequence of Ryugu rotating , based on the latest images. The very bright area at the top appears to rotate behind an obscuring dark promontory. One can still see the top edge of the bright area, behind the obstruction.

Judging by how sunlight is returned by other features on the surface, this bright area must be unusually reflective. Are we looking at a salt deposit, like that found on Ceres, in the Occator crater? Given the facts that Ryugu is very much smaller than Ceres, and unlikely to be geologically active, and that the bright area here appears nearly vertical, this might not be so likely. 

https://imgur.com/91PDNxF   

A lot more detail in those images. 

[bison]

Hayabusa 2 came within about 40 kilometers of the asteroid Ryugu yesterday. The best image obtained has a resolution of 256 by 256 pixels. Objects the size of houses are now visible on the surface. Dr. Yuichi Tsuda, project manager, compares the ascertained shape of the asteroid to a fluorite crystal, which is to say, it appears somewhat octahedral. He calls the form of Ryugu 'scientifically surprising'.

The text of the June 25th press briefing, which includes the image, is linked below:

http://www.hayabusa2.jaxa.jp/topics/20180625je/index_e.html

Edited June 25, 2018 by bison
added qualifier, added information

[Merc14]

2 hours ago, bison said:

Hayabusa 2 came within about 40 kilometers of the asteroid Ryugu yesterday. The best image obtained has a resolution of 256 by 256 pixels. Objects the size of houses are now visible on the surface. Dr. Yuichi Tsuda, project manager, compares the ascertained shape of the asteroid to a fluorite crystal, which is to say, it appears somewhat octahedral. He calls the form of Ryugu 'scientifically surprising'.

The text of the June 25th press briefing, which includes the image, is linked below:

http://www.hayabusa2.jaxa.jp/topics/20180625je/index_e.html

Things are getting very interesting now. 

[bison]

Hayabusa 2 is now in a parking orbit of Ryugu, at a distance of 20 kilometers. It will remain in this orbit for some time, before descending  again. 

 A new image, with substantially better resolution than the last has been released. The very light-colored object at the top appears to have a fairly regular series of sawtooth peaks. It still appears distinct from the rest of the surface.

There are few craters visible, and these are indistinct, as if old and obscured with debris.  Please find a link, below, to the new image:

http://www.unmannedspaceflight.com/index.php?act=attach&type=post&id=43124

Edited June 27, 2018 by bison
added information