Viking lander SSA

I'm modeling a Viking lander at the moment, but it is not clear to me how
the Surface Sampler Assembly boom changes from it's flattended (wound up)
state into it's free (extended) state. I know it has got something to do
with heat.

It's not really important for my model, but I was just intriqued by the way
they can control the arms reach. Seems like a pretty nifty way of doing
this.

Thanks,

Olaf

On Fri, 5 Aug 2005 11:59:22 +0200, "Olaf van der Zalm"
wrote:

I'm modeling a Viking lander at the moment, but it is not clear to me how
the Surface Sampler Assembly boom changes from it's flattended (wound up)
state into it's free (extended) state. I know it has got something to do
with heat.

....Nope. What it was, Olaf, was a flattened tube that was unrolled and
shoved through a cylendar housing. This forced the tube to pop open
and become rigid. Rather ingenious as it kept the weight down and
provided a path for the samples to enter the sample test chambers with
a minimum amount of mechanics.

OM

--

"No ******* ever won a war by dying for | http://www.io.com/~o_m
his country. He won it by making the other | Sergeant-At-Arms
poor dumb ******* die for his country." | Human O-Ring Society

- General George S. Patton, Jr

...Nope. What it was, Olaf, was a flattened tube that was unrolled and
shoved through a cylendar housing. This forced the tube to pop open
and become rigid. Rather ingenious as it kept the weight down and
provided a path for the samples to enter the sample test chambers with
a minimum amount of mechanics.

Ok thanks for the info. The Nasa Reference Publication 1027 (Viking '75
Design and Test Summary, Volume 1 - Lander Design, Figure 106) shows a
heat-treated boom, therefore I assumed the main mechanism for the boom to
bemoe rigid had something to do with thermal expantion.

Olaf

On Fri, 5 Aug 2005 20:25:21 +0200, "Olaf van der Zalm"
wrote:

Ok thanks for the info. The Nasa Reference Publication 1027 (Viking '75
Design and Test Summary, Volume 1 - Lander Design, Figure 106) shows a
heat-treated boom, therefore I assumed the main mechanism for the boom to
bemoe rigid had something to do with thermal expantion.

....The heater was to keep the tube material from getting too frozen to
be malleable, much in the same way that heaters are used on parachutes
to keep them from freezing together in space before use.

OM

--

"No ******* ever won a war by dying for | http://www.io.com/~o_m
his country. He won it by making the other | Sergeant-At-Arms
poor dumb ******* die for his country." | Human O-Ring Society

- General George S. Patton, Jr

OM wrote:

...Nope. What it was, Olaf, was a flattened tube that was unrolled and
shoved through a cylendar housing. This forced the tube to pop open
and become rigid. Rather ingenious as it kept the weight down and
provided a path for the samples to enter the sample test chambers with
a minimum amount of mechanics.



You can sort of suspect where that came from, can't you?
Someone was looking at a metal tape measure, and suddenly a light
blinked on.
I didn't realise it used the inside of the tube to convey the samples.

Pat

On Fri, 05 Aug 2005 14:51:41 -0500, Pat Flannery
wrote:

You can sort of suspect where that came from, can't you?
Someone was looking at a metal tape measure, and suddenly a light
blinked on.

....Bing-****ing-O, Patrick!

I didn't realise it used the inside of the tube to convey the samples.

....Yep. Here's how it worked: the tube was extended into the soil at
an angle, and there was a conical "blade" edge at the head of sampler.
The soil bunched up in the head, then the sampler arm was tilted
upwards about 45 deg above horizontal. Then a "clapper" mechanism
would essentially vibrate the soil down the arm and into the sample
collection and distribution system to be separated and used by the
life and soil properties detection devices. It was really a brilliant
design, and a big leap above the "scissor" sample arm used on Surveyor
as it was a hell of a lot sturdier.

OM

--

"No ******* ever won a war by dying for | http://www.io.com/~o_m
his country. He won it by making the other | Sergeant-At-Arms
poor dumb ******* die for his country." | Human O-Ring Society

- General George S. Patton, Jr