Huygens landing.

Chris Schumacher wrote in message 58...
I was wondering if Huygens is actually going to land on Titan, or is simply
going to crash into it, a la the Ranger series?

The Ranger series of lunar landers did not have an atmosphere to
aerobrake into. Huygens has a heat shield, parachutes, provisions to
float in ethane lakes, and a thick atmosphere to aerobrake in.

Mike Miller, Materials Engineer

It will descent relatively slowly (Something like 5 m/s or so), and
there is hope it will actually survive impact/landing. This will
partly depend on the surface it will touch. It probably won't survive
hard rock, but anything softer than that it may.

As is the case with, for instance, the mars rovers, Cassini has a
single CCD-camera. By placing different filters in front of the
camera, it is possible to take separate pictures in red, green and
blue. Combining these images will result in an (approximate) color
picture.

Having said that, it is not always possible to do this, since Cassini
may be moving too fast relative to its target. The time it takes to
switch filters can be too great, causing the red, green and blue
images to be shifted with respect to each other.

Jeroen



Chris Schumacher wrote in message 58...
I was wondering if Huygens is actually going to land on Titan, or is simply
going to crash into it, a la the Ranger series?

And speaking of which, all of Cassini's images seem to be in monochrome.
Doesn't it have a color camera as well?


-==Kensu==-

"Chris Schumacher" wrote in message
8...

And speaking of which, all of Cassini's images seem to be in monochrome.
Doesn't it have a color camera as well?

Here's a pretty pair of color pics. And the bottom one is Cassini.

http://www.space.com/imageoftheday/i...ay_040527.html

--


Regards,
Mike Combs
----------------------------------------------------------------------
We should ask, critically and with appeal to the numbers, whether the
best site for a growing advancing industrial society is Earth, the
Moon, Mars, some other planet, or somewhere else entirely.
Surprisingly, the answer will be inescapable - the best site is
"somewhere else entirely."

Gerard O'Neill - "The High Frontier"

"Chris Schumacher" wrote in message
8...
I was wondering if Huygens is actually going to land on Titan, or is
simply
going to crash into it, a la the Ranger series?

No, it's definitely supposed to soft-land. It's not certain, however, how
the process will go. There are even supposed to be microphones to pick up
sounds, and lights to light things up near the end of the landing! But what
happens during landing, and shortly after, depends on what it lands on.
Rock, ice, a methane ocean--no one really knows.

And speaking of which, all of Cassini's images seem to be in monochrome.
Doesn't it have a color camera as well?

At least one of the cameras is in color. (There are also IR and UV
capabilities.) However, some of the objects it photographs don't have much
color to being with--Phoebe, for instance.

Chris Schumacher wrote in
8:

I was wondering if Huygens is actually going to land on Titan, or is
simply going to crash into it, a la the Ranger series?

It's got a parachute and a soft enough landing is hoped for that
data may be received all the way to the surface, and perhaps
after. No idea of what the surface may be like. It could be
a liquid, but not water!

And speaking of which, all of Cassini's images seem to be in
monochrome. Doesn't it have a color camera as well?

All images are monochrome. Color images are constructed by
taking multiple images through a variety of filters that can
be selected for specific wavelengths of interest. Most color
images may not be 'true' color, as imaging isn't entirely
about pretty pictures but chemistry instead.

--Damon, really looking forward to the Titan flyby images

"Damon Hill" wrote in message
. 134...
Chris Schumacher wrote in
8:

All images are monochrome. Color images are constructed by
taking multiple images through a variety of filters that can
be selected for specific wavelengths of interest. Most color
images may not be 'true' color, as imaging isn't entirely
about pretty pictures but chemistry instead.

Right, I just heard overnight that they get color pictures by taking
sussessive exposures using filters of different colors. But if there is
noticeable motion at the time of the exposures, then you can't get a clear
picture with that approach, so they just go with a monochrome image. (BTW
that single "color" could be white, or infrared, or UV or a number of other
possibilities.

--Damon, really looking forward to the Titan flyby images

Me too, but unfortunately, while Titan is probably going to be the most
colorful object on the whole tour, don't expect color pictures on this early
flyby--for exactly the reasons just described. A flyby is going to have too
much motion to get three successive exposures that match up.

In article ,
David Given wrote:
Assuming it makes it down in one piece, and doesn't sink, it may broadcast
back a small amount of data before Cassini passes below the horizon.
I believe they're not going to make any attempt to reacquire the signal on
a second pass; I can't find any information on what Huygen's power source
is. It's probably simple batteries that will be flat by the time Cassini
comes back into range.

Correct, it's batteries, and between battery exhaustion and an extremely
cold environment, there is no hope of Huygens surviving more than a short
while on the surface. (As I noted in my posting, it's primarily an
atmosphere probe, so lengthy survival on the surface was not a design
priority.)
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

"RWG" wrote in
:


"Damon Hill" wrote in message
. 134...


--Damon, really looking forward to the Titan flyby images

Me too, but unfortunately, while Titan is probably going to be the
most colorful object on the whole tour, don't expect color pictures on
this early flyby--for exactly the reasons just described. A flyby is
going to have too much motion to get three successive exposures that
match up.

True, and not in true color either. But close enough to look pretty,
and the little we can see at certain wavelengths is very interesting!
Are those continents? Seas? What?

Looks like multiple passes and radar imaging will be needed to
fill in the blanks, and leave us with even more unanswered questions.

--Damon

But if there is
noticeable motion at the time of the exposures, then you can't get a clear
picture with that approach, so they just go with a monochrome image.

For those cases, you have (automatic) image registration, if the various
colour views are largely overlapping. One problem here seems to be the slow
readout speed - apparently, Cassini needs about one minute to acquire one
image.

The big other advantage of this approach is reduced aliasing - on a consumer
camera, only about 40% or so of the chip are is "active", and each colour
channel has about a third of that. Unless, of course, you are using a camera
with a Foveon chip in it.

Jan

Chris Schumacher wrote:

I was wondering if Huygens is actually going to land on Titan, or is simply
going to crash into it, a la the Ranger series?

And speaking of which, all of Cassini's images seem to be in monochrome.
Doesn't it have a color camera as well?

-==Kensu==-

Huygens will, hopefully, soft land (see the Cassini home page regarding the
target region). Lets keep fingers crossed that Huygens makes it to the surface
in one piece - can't wait to see those images. As for the lack of colour
pictures, my understanding is that Cassini was simply travelling too fast
during orbit insertion - it couldn't take the necessary 3 images (of the same
target) to produce a colour picture. Wait until things settle down, I think the
next 4+ years are going to produce some amazing images and science.

Alan