Cassini's Phoebe encounter

General physics and astronomy discussions not directly related to Celestia
Topic author
chris
Site Admin
Posts: 4211
Joined: 28.01.2002
With us: 22 years 9 months
Location: Seattle, Washington, USA

Cassini's Phoebe encounter

Post #1by chris » 09.06.2004, 22:52

I'm very excited about the upcoming Phoebe flyby by Cassini on Friday. The Cassini imaging team just release this set of images, taken from distances ranging from 4.1 to 2.5 million kilometers:

http://saturn.jpl.nasa.gov/cgibin/gs2.c ... type=image

Cassini will fly within 2000km of Phoebe, and details as small as 15 meters should be visible in the images. What does it mean for Celestia? For one, we'll need a texture that's about 48k x 24k to capture all the details from the Cassini images. Of course, only a small portion of the surface will be imaged at such high resolution--a Phoebe virtual texture perhaps?

It's fortunate that Phoebe is not in synchronous rotation; with a rotation period of only 9.3 hours, all of the surface should be illuminated at some point during the encounter. According to JPL, the entire surface should be mapped in color at between 0.3 and 2.1 km/pixel. The only gaps in a surface map of Phoebe will be at 'poles' invisible to Cassini . . .

--Chris

Evil Dr Ganymede
Posts: 1386
Joined: 06.06.2003
With us: 21 years 5 months

Post #2by Evil Dr Ganymede » 10.06.2004, 07:53

It's already time for this encounter?! My, how time flies. This will be exceedingly cool though :)

BTW, I notice that Cassini appears to be oriented incorrectly in Celestia - the dish should be pointing towards the Earth, shouldn't it? I don't think it's using a low gain antenna now that's oriented differently is it? Or is it?

granthutchison
Developer
Posts: 1863
Joined: 21.11.2002
With us: 21 years 11 months

Post #3by granthutchison » 10.06.2004, 10:21

Evil Dr Ganymede wrote:BTW, I notice that Cassini appears to be oriented incorrectly in Celestia - the dish should be pointing towards the Earth, shouldn't it?
Should be, but there's no way to maintain that orientation in Celestia at present.

Grant

Apollo7
Posts: 112
Joined: 03.05.2003
Age: 46
With us: 21 years 6 months
Location: Houston, TX

Post #4by Apollo7 » 10.06.2004, 15:24

As I understand it this will be Cassini's only enouncter with Phoebe will it not? Due to Phoebe retrograde, distant and inclined orbit, I should think this particular fly-by is very important science wise. Not only is it the start of the actual mission but its the first time we've ever seen this small moon from within 2 million Km.

Also this gives us something to chew on between June 11 and July 1 when Cassini reaches SOI.
"May Fortune Favor the Foolish" - James T. Kirk

Ynjevi
Posts: 132
Joined: 13.01.2003
With us: 21 years 9 months

Post #5by Ynjevi » 10.06.2004, 16:16

Evil Dr Ganymede wrote:BTW, I notice that Cassini appears to be oriented incorrectly in Celestia - the dish should be pointing towards the Earth, shouldn't it? I don't think it's using a low gain antenna now that's oriented differently is it? Or is it?


AFAIK Cassini doesn't always keep the dish pointed Earthwards.
That's why pictures of the encounter will be sent back to Earth no earlier than Saturday.

Evil Dr Ganymede
Posts: 1386
Joined: 06.06.2003
With us: 21 years 5 months

Post #6by Evil Dr Ganymede » 10.06.2004, 17:33

I was watching the encounter with Celestia, and funnily enough the bright patches on the current Phoebe map at this stage of it seem to correspond very closely with the bright patches in the image. Must be coincidence since I don't think the Phoebe map is based on anything known so far, but I thought it was kinda cool :)

ElPelado
Posts: 862
Joined: 07.04.2003
With us: 21 years 7 months
Location: Born in Argentina
Contact:

Post #7by ElPelado » 11.06.2004, 01:36

Evil Dr Ganymede wrote:BTW, I notice that Cassini appears to be oriented incorrectly in Celestia - the dish should be pointing towards the Earth, shouldn't it? I don't think it's using a low gain antenna now that's oriented differently is it? Or is it?


In the orbiter forum someone asked the same and here is what i remember from the asnwer: The dish its not only a dish, but also some kind of shelter: when cassini croses the rings, just before the SOI burn, the antenae will protect the craft from small rocks and ice...
---------X---------
EL XENTENARIO
1905-2005

My page:
http://www.urielpelado.com.ar
My Gallery:
http://www.celestiaproject.net/gallery/view_al ... y-Universe

Evil Dr Ganymede
Posts: 1386
Joined: 06.06.2003
With us: 21 years 5 months

Post #8by Evil Dr Ganymede » 11.06.2004, 01:53

Erk. I hope the "small rocks and ice" don't damage the dish then... if this turns into Galileo and we lose the HGA here again, I will in all likelihood want to kill someone.

lostfisherman
Posts: 64
Joined: 06.11.2003
With us: 21 years
Location: Notts, UK

Post #9by lostfisherman » 11.06.2004, 02:51

The Cassini encounter with Phoebe will happen pretty quickly.

More images are coming in.

http://ciclops.lpl.arizona.edu/view.php ... e39cddbf22

Are there any good 3d modellers out there? :)
Regards, Losty

Topic author
chris
Site Admin
Posts: 4211
Joined: 28.01.2002
With us: 22 years 9 months
Location: Seattle, Washington, USA

Post #10by chris » 11.06.2004, 02:54

The Cassini team just release another couple images of Phoebe, the best one taken from a distance of 658,000km:

Image

--Chris

ElPelado
Posts: 862
Joined: 07.04.2003
With us: 21 years 7 months
Location: Born in Argentina
Contact:

Post #11by ElPelado » 11.06.2004, 09:05

Evil Dr Ganymede wrote:Erk. I hope the "small rocks and ice" don't damage the dish then... if this turns into Galileo and we lose the HGA here again, I will in all likelihood want to kill someone.

Dont worry... it wont happen...
BTW: if in the dish appear some holes, it wont affect the dish...
---------X---------

EL XENTENARIO

1905-2005



My page:

http://www.urielpelado.com.ar

My Gallery:

http://www.celestiaproject.net/gallery/view_al ... y-Universe

ElPelado
Posts: 862
Joined: 07.04.2003
With us: 21 years 7 months
Location: Born in Argentina
Contact:

Post #12by ElPelado » 11.06.2004, 10:26

A which time the flyby is??
---------X---------

EL XENTENARIO

1905-2005



My page:

http://www.urielpelado.com.ar

My Gallery:

http://www.celestiaproject.net/gallery/view_al ... y-Universe

danielj
Posts: 1477
Joined: 15.08.2003
With us: 21 years 2 months

Post #13by danielj » 12.06.2004, 20:48

ElPelado wrote:A which time the flyby is??

When the dish will point to Earth again?We are in the middle of Saturday and there isn?t any Cassini near picture of Phoebe.JPL said that the pictures will be release today.Maybe only at the middle of the night?

Evil Dr Ganymede
Posts: 1386
Joined: 06.06.2003
With us: 21 years 5 months

Post #14by Evil Dr Ganymede » 12.06.2004, 23:35

+ + + Update! + + +

Here are the latest (released) pictures from Phoebe. And these aren't even the highest resolution pictures... (the best ones are about 10 times the resolution!). I'm sure they'll be releasing more over the next few days...

Image

http://photojournal.jpl.nasa.gov/catalog/PIA06066

lostfisherman
Posts: 64
Joined: 06.11.2003
With us: 21 years
Location: Notts, UK

Post #15by lostfisherman » 13.06.2004, 00:15

...And i can't wait to see them either, the Cassini mission is going to be absolutely fantastic!

Phoebe is one battered place isn't it...

Image
Regards, Losty

Starman
Posts: 78
Joined: 13.02.2004
With us: 20 years 8 months

Post #16by Starman » 13.06.2004, 07:05

Cassini's mission is to explore Saturn's moons, right? What's its primary objective, Europa?

Will this mission in any way help us to determine anything about the Europan oceans?

--Starman

Dollan
Posts: 1150
Joined: 18.12.2003
Age: 54
With us: 20 years 10 months
Location: Havre, Montana

Post #17by Dollan » 13.06.2004, 07:17

Actually, Europa orbits Jupiter. Cassini is at Saturn, which is the mission's primary target. however, as far as moons go, the one that will garner the most interest will be Titan.

Here's the mission's home page: http://saturn.jpl.nasa.gov/index.cfm

The next big goal is the orbital insertion on July 1. here's looking forward to a long and prosperous mission!

...John...
"To make an apple pie from scratch, you must first create the universe..."
--Carl Sagan

Evil Dr Ganymede
Posts: 1386
Joined: 06.06.2003
With us: 21 years 5 months

Post #18by Evil Dr Ganymede » 14.06.2004, 01:19

New pictures!!! (they're too big to post here, but they're awesomely high resolution!).

http://ciclops.lpl.arizona.edu/view.php?id=197 The Face of Phoebe

http://ciclops.lpl.arizona.edu/view.php?id=196 Phoebe's Surprise

http://ciclops.lpl.arizona.edu/view.php?id=193 Crater closeup on Phoebe

ElPelado
Posts: 862
Joined: 07.04.2003
With us: 21 years 7 months
Location: Born in Argentina
Contact:

Post #19by ElPelado » 15.06.2004, 08:14

Why is it called Phoebe's Surprise?
---------X---------

EL XENTENARIO

1905-2005



My page:

http://www.urielpelado.com.ar

My Gallery:

http://www.celestiaproject.net/gallery/view_al ... y-Universe

Avatar
selden
Developer
Posts: 10192
Joined: 04.09.2002
With us: 22 years 2 months
Location: NY, USA

Post #20by selden » 15.06.2004, 11:46

because nobody ever expected a body formed in space, with no weather, to have layers of materials of different types.
Selden


Return to “Physics and Astronomy”