Huygens shortlived?

Is it true that Huygens ceased transmission less than 2 hours after
touchdown? Whilst it was a magnificent achievement to travel so far and
land perfectly, it seems a great shame that the probe was so short
lived. I'm suprised the designers didnt make it rugged enough and
powered enough to survive several days.

dexx wrote:
I'm suprised the designers didnt make it rugged enough and
powered enough to survive several days.

As I understand, the issue was that Huygen's relay satellite, Cassini,
was only going to be in a position to listen to Huygens for a few
hours. There was no point in giving Huygens a longer life.
Mike Miller, Materials Engineer

dexx writes:

Is it true that Huygens ceased transmission less than 2 hours after
touchdown? Whilst it was a magnificent achievement to travel so far and
land perfectly, it seems a great shame that the probe was so short
lived. I'm suprised the designers didnt make it rugged enough and
powered enough to survive several days.

But there was nobody to talk to. Cassini couldn't stay in
communications range for several days.

In sci.space.tech dexx wrote:
Is it true that Huygens ceased transmission less than 2 hours after
touchdown? Whilst it was a magnificent achievement to travel so far and
land perfectly, it seems a great shame that the probe was so short
lived. I'm suprised the designers didnt make it rugged enough and
powered enough to survive several days.

Why?
It had a low resolution camera, and all the data from that had already been
recieved.
It would have needed a bigger transmitter, bigger battery, ...

All that would have been gained would be atmospheric pressure and
identical pictures.

dexx wrote:
Is it true that Huygens ceased transmission less than 2 hours after
touchdown? Whilst it was a magnificent achievement to travel so far and
land perfectly, it seems a great shame that the probe was so short
lived. I'm suprised the designers didnt make it rugged enough and
powered enough to survive several days.

one design limitation factor was the length of time that Cassini would
be "over the horizon" wrt the lander. Huygens doesn't have powerful
enough transmitters to relay the datastream directly to Earth, so having
longer batt life wouldn't do anything but waste money and resources if
it couldn't see its mothership and thus transmit data.

Building enough transmitter power to send to Earth directly would very
likely have major scalability issues, which in turn would have a direct
impact on other mission profiles (maybe they could have had a powerful
transmitter but little or no instrumentation to feed it data, f'rinstance).

Mission planning for any tpye of space vehicle is a series of tradeoffs
between various things: time, money, propellant, payload, *type* of
payload, mission duration, mission capability, etc. etc.

Bottom line: for any launcher and any vehicle and any mission profile,
there's only so much you can include. Add more of thing X and you have
to take away from things Y, Z and A'.

--
Terrell Miller


"Every gardener knows nature's random cruelty"
-Paul Simon George Harrison

Huygens was European, and the Europeans on that project bowed to anti-nuclear
groups and did not include a radio-thermal nuclear generator. The result is a
short-lived probe similar to the Soviet Venus landers. It took 8 years to get
the probe there, and when we did, we got pictures of rocks on the surface that
we can't examine more closely since the power source of the probe only had 10
minutes of life left in it.

Was there no also an issue of cassini going over the horizon, and
therefore not being able to receive more.

With only passive sensors (ie no diggers) is there much difference
between 2 hours and 10 days?

Though yes - I think RTG power would probbaly have been better, though
would not have saved on weight. I it charged its batteries before
leaving Cassini with power from Cassini's RTG.

"Tkalbfus1" wrote in message
...
Huygens was European, and the Europeans on that project bowed to
anti-nuclear
groups and did not include a radio-thermal nuclear generator. The result
is a
short-lived probe similar to the Soviet Venus landers. It took 8 years to
get
the probe there, and when we did, we got pictures of rocks on the surface
that
we can't examine more closely since the power source of the probe only had
10
minutes of life left in it.


How much of Cassini are you willing to sacrifice so that it can carry a
larger, heavier Huygens probe?

dexx wrote:
Is it true that Huygens ceased transmission less than 2 hours after
touchdown? Whilst it was a magnificent achievement to travel so far and
land perfectly, it seems a great shame that the probe was so short
lived. I'm suprised the designers didnt make it rugged enough and
powered enough to survive several days.

I suspect you're going to be snowed under by responses to this, but...

Huygens was specifically designed as an *atmospheric* probe. It was supposed
to descend through the atmosphere, take readings, hit the surface and die.
Anything beyond that was gravy. They were hoping for ~30 minutes of surface
data; they reckon it was actually transmitting for about five hours.

The second point is that Huygens couldn't contact Earth directly. It had to
relay all its data through Cassini, and Cassini was due to drop below
Titan's horizon (that was the two hour figure). I believe --- can anyone
confirm this? --- that Cassini had to repoint its main antenna at Huygens
to pick up anything at all, which meant that it wasn't pointed at Earth,
which meant that it was completely out of touch, and since Cassini is a
hell of a lot more valuable than Huygens that's probably not a good idea.

The third point is that since noone knew anything about Titan's environment,
there was no way of designing a complex, long-duration lander that could
survive. The designers opted for a limited lifetime probe because that way
they could be sure of getting *some* data. The next probe will get more.

That said, I sympathise --- Huygens has returned just enough information to
let us know that Titan's really interesting without actually telling us
much about it. I wish Huygens had landed within sight of the coast! And I
do wish that it had been politically feasible to power Huygens with an RTG
instead of batteries; that would have been a simple way to increase the
lifetime without increasing the complexity (and reducing the reliability).

When's the next Titan mission due? Not for years and years and years, isn't
it?

--
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"dexx" wrote in news:1105885111.638247.89710
@z14g2000cwz.googlegroups.com:

Is it true that Huygens ceased transmission less than 2 hours after
touchdown? Whilst it was a magnificent achievement to travel so far and
land perfectly, it seems a great shame that the probe was so short
lived. I'm suprised the designers didnt make it rugged enough and
powered enough to survive several days.

Powered with what? Chemical batteries were the only
practical method, and payload margins were extremely
tight.

--Damon