Cassini-Huygens Reaches Phoebe

Anonymous Explorer writes "The Cassini-Huygens probe is set to fly by the largest outer Saturn moon of Phoebe today. Cassini will be roughly 2000 km from the surface of Phoebe at 1:56 Pacific time Friday, June 11. Thats pretty darn close. The newest images of Phoebe are already thousands of times better than the previous ones taken by the Voyager 2 mission in 1981. Phoebe is interesting in that it maintains a retrograde orbit around Saturn. This has lead to the hypothesis that it is an ancient asteroid that has been captured by the gravitational pull from Saturn. Phoebe may provide some important insights into the composition of early building blocks of our planets. Phoebe was discovered in 1898 by American astronomer William Pickering. As always, discussion about this mission can be found at #cassini on irc.freenode.net."

Comments

More about Phoebe

[JaF893]

Here are some links about phoebe and the Cassini-Huygens:
Phoebe
Cassini-Huygens

Re:Two objects on the picture

[youknowmewell]

That is actually Phoebe on both sides. The right one is a picture of Phoebe 13 hours after the left one. it takes Phoebe only 9 and a half hours to make a full spin on it's axis (It has 9 and a half hour days). Those are two different hemispheres.

A little more on Retrograde

[Pi_0's don't shower]

For those of you who want a bit of information, check out this link on retrograde motion, which does an excellent job of explaining what retrograde is. For those who are curious but too lazy to click, some of the interesting info is given below:

# Venus rotates slowly in the retrograde direction.

# The moons Ananke, Carme, Pasiphaë and Sinope all orbit Jupiter in a retrograde direction, and are thought to be fragments of a single body that Jupiter captured long ago. Many other minor moons of Jupiter orbit retrograde.

# The moon Phoebe orbits Saturn in a retrograde direction, and is thought to be a captured asteroid.

# The moon Triton orbits Neptune in a retrograde direction, and is thought to be a captured Kuiper belt object.

# The planet Uranus has an axial tilt which is very near to 90, and can be considered to be rotating in a retrograde direction depending on one's interpretation.

Use Celestia to preview the image quality

[Rei]

I'm really excited about the new photos... I hope they release full res mosaics and don't delay... pre-processed surface texture and heightmap data would be nice, too.

If you want to get an idea of just how high res pictures they're going to get, do the following:

1) Download the program "Celestia". Build and run it.
2) While it is building, pull up the last picture that Cassini took of Phoebe.
3) When Celestia comes up, full screen it.
4) Go into the configuration and tell it to include full details. Exit the configuration menu.
5) Press enter, and type in "Phoebe". Press enter.
6) Press 'g' to go to Phoebe (note: Phoebe is currently false-texture in Celestia, since we don't know much about it)
7) Middle click and hold down, and drag the mouse until you're at a distance of 658,000 kilometers.
8) Press ctrl-'+' to zoom, until the resolution of Phoebe that you're seing on the screen is about the same as that in the NASA picture (note: resolution, not size. The nasa picture is enlarged).
9) Without changing the zoom, hold middle click againa nd drag the mouse until the distance is 2,000 kilometers.
10) Hold down shift, and use the arrow keys to look around. That's the sort of resolution images that they should be able to get.

Impressive, isn't it? I can't wait! :)

Anticipation

[amightywind]

The newest images of Phoebe are already thousands of times better than the previous ones taken by the Voyager 2 mission in 1981.

No, but it is hoped they will be. At best, the newest released images are 10x better than Voyager. Expect the high res images later today. You are getting ahead of yourself.

Re:Everything is a moon

[bhima]

It has a retrograde orbit

Captured asteroid?

[barakn]

This has lead to the hypothesis that it is an ancient asteroid that has been captured by the gravitational pull from Saturn

Phoebe is actually believed to be a captured Kuiper Belt object (KBO). This means its composition might be very icy/organic, making it more like a non-active comet than an asteroid.