I'm going to start a new topic for this (mostly because the erroneous apostrophe in the title of the topic I've been using annoys me!).

Splash, Thud, or Whimper? Cassini's Huygens Probe Rendezvous with Titan

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Everything I need to know I learned through Googling.

Why will it be so long between separation and entry?

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"All your bias are belong to us." Ara Pacis
"A witty saying proves nothing." Voltaire

Since Huygens has no propulsion system, Cassini must be on the same track as Huygens at the time of release, i.e., a collision course with Titan. The long lead time gives Cassini enough room to change its course so as not to collide with Titan.

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Everything I need to know I learned through Googling.

Is a 2.5 hour battery the best that could be done? Was this an engineering contraint, budgetary or was that the best battery when the thing was originally designed/built?

CJSF

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Two years ago moved from my town
I was looking up past the city lights
But the city lights got in my way

See the constellation ride across the sky
No cigar, no lady on his arm
Just a guy made of dots and lines

-from "See The Constellation"
by They Might Be Giants

Don't know if this was posted here before, but here is a webpage with some test images taken by the camera. Just to give an idea what to expect.


Harald

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"Flying in space is risky business, but just staying on this planet is risky business too." - John Young, astronaut

Cassini will go below the horizon after this time, so it wouldn't pay to have a battery that lasts longer.

Harald

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"Flying in space is risky business, but just staying on this planet is risky business too." - John Young, astronaut

This one I do not understand. I can run my trawlin motor for a days on one battery, and Cassina completes another orbit in a month, why not shut Huygens down for a month and and fire it up again?????

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jwj

It's ok not to know. We should try harder to find out.

How would you do that? If Huygens is shut down all the way, then there's no way of waking it up again. If you want to allow for waking it up again, then it has to either have some sort of timer running or have some portion of the communications system remain on and listening. Even then you've got to assume it's going to survive the landing and then be able to hold out for a month. It doesn't seem like a possibility worth planning for.

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Everything I need to know I learned through Googling.

My guess would be, apart from size and weight issues, that without heating the battery, once it drops below a critical temperature it wouldn't be able to emerge from hibernation

Solar Views: Titan

That's a real low temperature to kep a battery at for a month. To keep the battery warm would take power which would drain the battery so it would be self defeating.

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By asking questions we sometimes get the wrong answers, from wrong answers we learn to ask the right questions.

The signal timing problem was another issue. I found this article absolutely fascinating:

http://www.spectrum.ieee.org/WEBONLY...1004titan.html

The Cassini receiver for the Huygens probe couldn't fully account for doppler shift. The article covers how the problem was found and a workaround devised. From the article:

and ...
The effect is that the flight takes longer and the landing is later than originally planed. If they hadn't done the testing and had gone with the original plan, though, we likely woudn't have gotten any useful data from the probe. Still, I hope there aren't any other real issues yet to be found ...

And just how long will your motor last at -300F?

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Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson

From looking through the PDF on the Huygens misison from the NASA/ESA site, here's a head's-up. To verify the exact departure trajectory, the orbiter will take a 5x5 imaging mosaic to show the probe at about 1400 UT on Christmas Day. After 11 hours or so it may look like just another faint star, but it should be encouraging enough to just see the thing. The timeline shows a 2.5-day window allotted for probe imaging, in fact.

On a slightly whining note:

Does anyone else find the Cassini mission homepage incredibly disappointing, especially as compared to the MER effort?

I mean, one of the top items STILL remains the story of the high school ballet dancer who participated in the planning. That stuff is fine for the cruise segment of the mission. But Cassini is in orbit and Huygens is being released. Can't we see more than the occasional wallpaper and human-interest story?

Who do I complain to about this?

(Done venting now.)

It might help: http://saturn.jpl.nasa.gov/news/contact-us.cfm

On the MER mission page, I used a similar outreach address to ask a technical question that got answered.

The bottom of http://saturn.jpl.nasa.gov/home/index.cfm lists editor and writer credits if you want to go into JPL and do some persuading.

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Thanks, 69,

I was being kinda' facetious -- I don't really intend to complain. It just seems like the web coverage on Cassini has been a big letdown in comparison to what has been done with MER.

Thankfully S & O have been keeping me entertained longer than I had counted on.

Live pictures! Just kidding. Artwork:

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Just for scale, a picture of Huygens with people.



It's 2.7 meters, about the same diameter as a MER spacecraft.

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I have been harping about the lack of detail in the orbital science work, doppler measurements, the list goes on and on. The ESA site is slightly better, but they are holding the science data close to the vest

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jwj

It's ok not to know. We should try harder to find out.