Re: Newbie with questions

[P3D John W Roberts <roberts@xxxxxxxxxxxxxxxxx>]

>Date: Tue, 11 Mar 1997 13:14:48 -0600
>From: P3D Jim Crowell  <crowell@xxxxxxxxxxxxxxx>
>Subject: Re: Newbie with questions

>At 10:24 AM -0800 3/11/97, P3D John W Roberts wrote:
>>
>>Not so fast! You could have the rocket eject two 2D cameras, which hang
>>down from their own parachutes (thus pointing straight down), take circular
>>photos, and are timed to photograph a certain time after going to zero-G
>>(for instance). You could put a spring in to push the cameras apart, or
>>just rely on turbulence of the air to get the proper separation on some
>>of the launches.
>>

>Ooo, I like it!  You could have them attached by a cable & spin it like a
>bolo to keep them at the proper separation...fast shutter speeds are no
>problem, at these distances depth of field is totally unnecessary so you
>can open the aperture _way_ up...   :-)

Actually, come to think of it, yes you could. That would be a much more
complicated solution than the one I proposed, but it would also be more
capable. You could put aerodynamic surfaces on the two cameras so that
they would tend to pull the line taut and set the assembly in a stable
horizontal spin. This would precisely control the separation - also, by
adding another degree(?) of control, you could take horizontal pictures
if you wanted to. With a little bit of electronics and a photodetector,
you might even get horizontal photos in a chosen direction.

Back before the Russians started landing spacecraft with cameras on Venus,
there was a proposal in the US to develop a single-wing device shaped like
a maple leaf (they called the shape a "samara"), to fall through Venus'
atmosphere, taking pictures as it went. The device would not have any moving
parts - a lens and a line imager (rotated by the motion of the probe) would
scan the scene below, and a radio link would relay the information to a 
receiver in Venus orbit (I think). I thought it was a clever idea, but
processing the imagery would be fairly tricky. [If you'd like to see how
it would work, silver maple seeds work very well, and red maple are sometimes
pretty good - I don't think sugar maple seeds usually spin very well. With
an ideal seed you get very rapid spinning, and very slow downward motion.]

John R


------------------------------