Ulysses mission milestone

Blob · #1 (**permalink**) 17-November-2006, 08:21 PM

Quote:

On 17 November, the joint ESA-NASA Ulysses mission will reach another important milestone on its epic out-of-ecliptic journey: the start of the third passage over the Sun's south pole.
Launched in 1990, the European-built spacecraft is engaged in the exploration of the heliosphere, the bubble in space blown out by the solar wind. Given the capricious nature of the Sun, this third visit will undoubtedly reveal new and unexpected features of our star's environment.
The first polar passes in 1994 (south) and 1995 (north) took place near solar minimum, whereas the second set occurred at the height of solar activity in 2000 and 2001.

Blob · #2 (**permalink**) 07-February-2007, 01:47 PM

Quote:

Sixteen years after its launch on Oct. 6, 1990, the Ulysses spacecraft has begun its third "solar polar orbit" -- a journey around the poles of the sun. The mission, a joint NASA-European Space Agency venture, studies how the sun's gaseous outer atmosphere spews into space, creating huge space storms. This violent "space weather," in turn, can affect Earth's electricity, satellite and cell phone communications.

Quote:

"On February 7th, the spacecraft reaches a maximum heliographic latitude of 80°S—almost directly above the South Pole" - Arik Posner, who is the Ulysses Program Scientist for NASA.

Launch window · #3 (**permalink**) 14-February-2007, 12:31 PM

17 years of great work !

Launch window · #4 (**permalink**) 20-February-2007, 02:08 PM

Surprises from the Sun’s South Pole
http://www.innovations-report.de/htm...cht-79156.html

ToSeek · #5 (**permalink**) 16-April-2008, 06:28 PM

Controllers working to keep Ulysses sun orbiter alive

Quote:

Scientists continue to extract bits of data trickling to Earth from the Ulysses solar probe as ground controllers employ new strategies to extend the life of the 17-year-old spacecraft, including a "long shot" plan to put the observatory in hibernation until the sun's activity reaches its next peak in 2013.

ToSeek · #6 (**permalink**) 11-July-2008, 10:29 PM

"I don't want to go in the cart"

Quote:

ESA issued a statement on July 3 titled "Ulysses hanging on valiantly." And on Wednesday, the following email was sent by Ulysses mission operations manager Nigel Angold to the Ulysses community, indicating that Ulysses' voyage could actually continue for some time.

777 geek · #7 (**permalink**) 12-July-2008, 01:31 PM

Third orbit in 16 years? Wasn't Ulysses sent into polar orbit through Jovian gravity assist. Wouldn't that give it a period of ~12 years? How can it have done two orbits already?

hhEb09'1 · #8 (**permalink**) 12-July-2008, 02:03 PM

Quote:

Originally Posted by Blob

"Ulysses has flown over the sun's poles only twice before--in 1994-95 and 2000-01. "

Quote:

Originally Posted by 777 geek

Third orbit in 16 years? Wasn't Ulysses sent into polar orbit through Jovian gravity assist. Wouldn't that give it a period of ~12 years? How can it have done two orbits already?

You're referring to Jupiter's own period of 12 years? Jupiter is out about 5.2 AU (5.2³~12², Kepler's Law). To have a period of six years around the Sun, an object would have a semi-major axis of 3.3 AU (3.3³~6²), or 6.6 AU major axis. In other words, an object could zoom from 5.2 AU away from the Sun to 1.4 AU past the Sun, and back, in six years. The orbit would be very elliptical.

777 geek · #9 (**permalink**) 12-July-2008, 02:06 PM

Quote:

Originally Posted by hhEb09'1

In other words, an object could zoom from 5.2 AU away from the Sun to 1.4 AU past the Sun, and back, in six years.

So Ulysses does that?

hhEb09'1 · #10 (**permalink**) 12-July-2008, 02:13 PM

Quote:

Originally Posted by 777 geek

So Ulysses does that?

I dunno, but I went back to Blob's link that I quoted, and there is a nice graphic of its orbit at the bottom of the page. Sure looks like it.

777 geek · #11 (**permalink**) 12-July-2008, 05:09 PM

Yes on further thought, that would entirely make sense. For the orbit of Ulysses to be circular polar, it would require circularisation at Jupiter. I'm reasonably sure the spacecraft was not capable of doing such a thing and gravity assist doesn't change the energy of the spacecraft. So it can't be in a circular polar orbit.

antoniseb · #12 (**permalink**) 12-July-2008, 07:07 PM

Quote:

Originally Posted by 777 geek

...gravity assist doesn't change the energy of the spacecraft. So it can't be in a circular polar orbit.

? In what reference frame does it not change the energy of the spacecraft?

777 geek · #13 (**permalink**) 12-July-2008, 07:46 PM

Quote:

Originally Posted by antoniseb

? In what reference frame does it not change the energy of the spacecraft?

Hmm yes. Good question. From the reference frame of Jupiter, the spacecraft would leave the sphere of influence with the same speed as it entered. But that is tautological since for that small portion of the journey, we're looking at the two body system. Energy is conserved for the portion where we are looking at it as a Jovian centered two body problem, but for the Sun centred frame, Jupiter could easily change the energy of the spacecraft also explaining how Voyager got as far as it did.

So my reasoning that made the eccentric orbit of Ulysses make sense, was itself flawed. Therefore, we can reach only one conclusion: Ulysses is fake!!

hhEb09'1 · #14 (**permalink**) 12-July-2008, 08:51 PM

Quote:

Originally Posted by 777 geek

Ulysses is fake!!

I think I see a hidden message in your post...

I'll rearrange those letters: i sss yeek is fUal !

I don't know what it means, it looks like it's spanish

777 geek · #15 (**permalink**) 12-July-2008, 09:28 PM

Watch your language!

hhEb09'1 · #16 (**permalink**) 13-July-2008, 12:12 AM

Nice talk

And nice footwork too

I'm really liking the word fUal though, it just seems to fit that frame of mind you were repping

Swift · #17 (**permalink**) 14-July-2008, 03:01 PM

Quote:

Originally Posted by ToSeek

"I don't want to go in the cart"

I feel happy, I feel happy...

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