wwp@yahoogroups.com:
Caption Help
gerardoant 2007-Apr-03 01:10:00
Hola todos.
I found a nice place to take my pano for this challenger theme that
Don, Landis et all pic for us. But this time it is a very technical
stuff that I would like to explain in easy words to everyone. As
usual: could some one of you help me with my poor English and correct
my caption? (final caption will have some links to pictures for easy
understanding)
Please answer directly to me to keep wwp list clean.
Thanks in advance, Gerardo
Here is the pano if you like to see:
http://www.merida360.com/wwp/atmosfera/atmosfera.html
Vacuum Chamber
Atmosphere is the general name for a layer of gases that
surround a celestial body of sufficient mass. The gases are
attracted by the gravity of the body, and are retained for a
longer duration if gravity is high and the atmosphere's
temperature is low. But? it is possible take it out for a
while??... not exactly but we have something near: here you are
inside a vacuum chamber which essentially take out all gases it has
inside. The inside pressure could be less than 100.000.000 times the
outside pressure (1/100.000.000).
This chamber is use to restore back the aluminium coating from the
main mirrors at the National Observatory in Venezuela. Due the dust,
humidity and oxidation the mirrors reflectivity is lost and almost
once every two years the aluminium coating is removed and applied a
new one.
The chamber has two meters diameter and several vacuum pumps
spent around two hours to take out all the inside air. Three tungsten
bars are used to burn out an small amount of pure aluminium and due
the small pressure inside the chamber the aluminium is deposited over
the glass in a very tiny and regular layer. During the process the
round plate is spinning to help get a more homogeneous reflective
layer.
The round plate and the triangle plate at the ceiling are use also
as electrodes. A big current is applied over them creating a
magnetic field that attract small particles from down to upside
electrode cleaning the glasses. This process, call efluvium, is
easily watch from the outside windows as a very nice blue light path.
After several hours of work the "new" mirrors are take out from
the chamber and put back again inside the telescopes.
This picture reflect the status few seconds before burn the
aluminium, there are nine small mirrors ready to get a new
reflective layer. Can you see all them? (answer is here in
this picture)