[Space] condensation on lenses

Jonathan Foote jtfoote at ieee.org
Wed Jun 9 20:42:04 UTC 2010

There are chemical handwarmers that use an exothermic reaction
(mixture enthalpy of NaOH) that require no air. Not sure how cool it
is to loft a flexipack of highly corrosive stuff, but there's also
CaCl2 formulations.

There are also these reusable phase-change ones that I first saw in China:
I think that's supersaturated sodium acetate trihydrate which is pretty benign.
This  might have the benefit of starting the heat-generating
crystallization spontaneously when it gets cold enough.
Worth a try?

On Wed, Jun 9, 2010 at 10:08 AM, Blake Barrett <Blake at blakebarrett.net> wrote:
> Bryan,
>    The thought of using a hand warmer has arisen before, but all the ones we
> have come across are either electric (and thus requires batteries) or are
> chemical based that require oxygen to create their heat. After that we
> stopped looking into it, but if you can think of a way to make that work
> that'd be great.
> Blake
> On Wed, Jun 9, 2010 at 9:59 AM, Bryan Klofas <bklofas at gmail.com> wrote:
>> Hey Everybody--
>> I noticed in the pics from the last launch that significant condensation
>> formed on the sideways-facing camera on the way down. This makes sense,
>> as the camera is very cold up at altitude, and very quickly it's down in
>> the relative warmth of ground temp. And while on the ground, you can see
>> the lens clearing up.
>> In past balloon launches, to keep the camera warm throughout the flight
>> I've either used strip heaters (kapton-type), or the heat from the
>> mini-ITX that was flown. However, both of these solutions require a lot
>> of energy, and I don't really want to add more batteries to the payload.
>> One idea might be to have a small window on the outside of the balloon,
>> and use a pocket heater to heat the window. Or just put the pocket
>> heater near the extended lens? I wonder how the camera would feel with a
>> pocket heater on it?
>> I think we would probably need to try this with a downward-facing
>> camera, because maybe the heater will only keep condensation from
>> forming on half of the window, and we could easily see that with the
>> blurryness of the ground images (and any associated gradients).
>> Any thoughts?
>> --
>> Bryan Klofas, KF6ZEO
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> --
> Blake
> blake at blakebarrett.net
> 1 559 455 7855
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