Huygens' Titan Descent

In article .com,
"Impact9" wrote:

JPL is reporting it made the landing and transmitted for 1.5 hours
after impact.

I am a bit puzzled why they only made the probe last the few short
hours after it detached from cassini. They could of built a better
battery when Voyager I is like 28 year and still going. I know it is
like -300F and mechanical things won't operate long in that harsh
environment. Assuming the probe could survive the environment it would
of been nice to be able to tap it for everything possible.


The issue is how long the orbiter is in range to relay data from Huygens
to Earth. It's only a few hours, so a longer-life battery for Huygens
would have been pointless.

"richard schumacher" wrote in message news:no-spam-

I am a bit puzzled why they only made the probe last the few short
hours after it detached from cassini. They could of built a better
battery when Voyager I is like 28 year and still going. I know it is
like -300F and mechanical things won't operate long in that harsh
environment. Assuming the probe could survive the environment it would
of been nice to be able to tap it for everything possible.


The issue is how long the orbiter is in range to relay data from Huygens
to Earth. It's only a few hours, so a longer-life battery for Huygens
would have been pointless.

If that were the "only" reason then I would disagree. Cassini will be
passing by Titan again in a few weeks. I would think they could have held
data and then blasted it at the satellite each time it passed.

However, as I understand it that is not really why they kept the life to
only a few hours. I think it had more to do with just getting it down
safely, the weight of the probe on Cassini, cost, and probably just the
general expectation that conditions were not favorable to the life of the
unit being long.

Glenn

In article ,
Glenn Mulno wrote:
However, as I understand it that is not really why they kept the life to
only a few hours. I think it had more to do with just getting it down
safely, the weight of the probe on Cassini, cost, and probably just the
general expectation that conditions were not favorable to the life of the
unit being long.

A long surface life would have required, at the very least, an RTG, which
would have run up the cost, mass, and various other complications quite a
bit. Moreover, Huygens was planned and sold as primarily an *atmosphere*
mission -- even the camera (which is a US contribution, incidentally) was
optimized as much for cloud imaging and sunlight measurements as for
surface pictures.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

it still is one HUGE success. Monumental, really. Just too bad the major news
networks didnt even mention it or show a photo tonight.
This sorry state of socially irresponsible affairs in the USA must end soon.



Henry Spencer wrote:

In article ,
Glenn Mulno wrote:
However, as I understand it that is not really why they kept the life to
only a few hours. I think it had more to do with just getting it down
safely, the weight of the probe on Cassini, cost, and probably just the
general expectation that conditions were not favorable to the life of the
unit being long.

A long surface life would have required, at the very least, an RTG, which
would have run up the cost, mass, and various other complications quite a
bit. Moreover, Huygens was planned and sold as primarily an *atmosphere*
mission -- even the camera (which is a US contribution, incidentally) was
optimized as much for cloud imaging and sunlight measurements as for
surface pictures.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

In article ,
muldar wrote:
it still is one HUGE success. Monumental, really. Just too bad the major news
networks didnt even mention it or show a photo tonight.
This sorry state of socially irresponsible affairs in the USA must end soon.


That's what you get for getting your news from TV :-)

NPR and BBC radio haev given it decent coverage so far, and it would
supise me if they don't have more on NPR's Sunday AM hour.
--

a d y k e s @ p a n i x . c o m

Don't blame me. I voted for Gore.

"muldar" skrev i en meddelelse
...

it still is one HUGE success. Monumental, really. Just too bad the major
news networks didnt even mention it or show a photo tonight.
This sorry state of socially irresponsible affairs in the USA must end
soon.

You think this sorry state of affairs is confined to the USA? Since I
don't have cable or sat dish, I can take only the two TV channels that are
carried on airwave here in Denmark. One is the old national TV channel that
was the monopoly station in the old days. On this channel there was heavy
coverage on the new opera house that was inaugurated in Copenhagen on the
same day as the Huygens landing, both in the regular news and as a special,
hours-long program. There was nothing about the Huygens landing. The other
channel did have something, but not much. And also heavy coverage of the
new opera house.
Thank heavens for the Web. :-) (I'll check it later when there isn't so
much run on the relevant sites.)

Jon Lennart Beck.

In article ,
"Glenn Mulno" wrote:

"richard schumacher" wrote in message news:no-spam-

I am a bit puzzled why they only made the probe last the few short
hours after it detached from cassini. They could of built a better
battery when Voyager I is like 28 year and still going. I know it is
like -300F and mechanical things won't operate long in that harsh
environment. Assuming the probe could survive the environment it would
of been nice to be able to tap it for everything possible.


The issue is how long the orbiter is in range to relay data from Huygens
to Earth. It's only a few hours, so a longer-life battery for Huygens
would have been pointless.

If that were the "only" reason then I would disagree. Cassini will be
passing by Titan again in a few weeks. I would think they could have held
data and then blasted it at the satellite each time it passed.

However, as I understand it that is not really why they kept the life to
only a few hours. I think it had more to do with just getting it down
safely, the weight of the probe on Cassini, cost, and probably just the
general expectation that conditions were not favorable to the life of the
unit being long.

A lifetime of weeks would have required nuclear heaters at least, and
perhaps a nuclear thermal electric source as well. That means more
mass, probably more then anyone wanted to pay to send.

A lifetime of weeks would have required nuclear heaters at least, and
perhaps a nuclear thermal electric source as well. That means more
mass, probably more then anyone wanted to pay to send.

not to forget that try landing heavier probe somewhere quite unknown
would probably lead to assured failure

it s good to get back something !

I have another question. The one photo I have seen from the surface
(unprocessed?) seems to have plenty of light. I found this surprising and
am assuming this was considered in the planning stage and the photo system
is extra sensitive. (?) Any comments on the data size of the images.

--
Detective Tom Polhaus: " Heavy. What
is it?"
Sam Spade: "The, uh, stuff that dreams
are made of."
"Glenn Mulno" wrote in message
...
"richard schumacher" wrote in message news:no-spam-

I am a bit puzzled why they only made the probe last the few short
hours after it detached from cassini. They could of built a better
battery when Voyager I is like 28 year and still going. I know it is
like -300F and mechanical things won't operate long in that harsh
environment. Assuming the probe could survive the environment it would
of been nice to be able to tap it for everything possible.


The issue is how long the orbiter is in range to relay data from Huygens
to Earth. It's only a few hours, so a longer-life battery for Huygens
would have been pointless.

If that were the "only" reason then I would disagree. Cassini will be
passing by Titan again in a few weeks. I would think they could have held
data and then blasted it at the satellite each time it passed.

However, as I understand it that is not really why they kept the life to
only a few hours. I think it had more to do with just getting it down
safely, the weight of the probe on Cassini, cost, and probably just the
general expectation that conditions were not favorable to the life of the
unit being long.

Glenn

On Fri, 14 Jan 2005 23:45:48 -0500
"furtig" wrote:

I have another question. The one photo I have seen from the surface
(unprocessed?) seems to have plenty of light. I found this surprising
and am assuming this was considered in the planning stage and the
photo system is extra sensitive.

Basically, yes. You can take a long exposure in a dark room with fast film and get good results. You just have to wait for the right number of photons.

(?) Any comments on the data size of
the images.

I think it was about 35k per image. Very heavily compressed. Considering the environment it was collected in I think the images are fastastic.

It's a shame that the Galileo/Jupiter entry probe didn't have a simlar scaled down imaging capability.
--
Michael Smith
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