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Expeditions Diaries Expedition 31: Letters to Earth Beating Stray Light
Beating Stray Light
Source: NASA Blogs
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Missions
Posted:   12/10/12

Summary: Astronaut Don Pettit continues his diary from Expedition 31 on the International Space Station. In this installment he talks about dealing with reflected light in space photography and capturing images in the far infrared.

Beating Stray Light
Posted on Jun 22, 2012 04:35:50 PM


Don Pettit in the ISS Cupola. Credit: Don Pettit
Stray light—those nasty reflections off our Space Station windows—can ruin the aesthetics of nighttime imagery and viewing. Reflected light from our numerous control panels and computer screens is hardly noticeable until you closely inspect your pictures, typically after returning to Earth when there is no possibility for a retake. The reflections are aggravated by the design of our windows: four layers of glass resulting in eight parallel mirrored surfaces. For photographers, they can create a haunting tunnel of colored blotches that project off to infinity, like being in a house of mirrors.

To eliminate these reflections requires attention to many small details. Any source of low-level light has to be masked. Even when this is done, light coming from the adjacent Node 3 and Node 1 modules is enough to ruin a nighttime sequence of images. Then there’s the toilet, close to our windowed Cupola, which, when occupied, spills sufficient rays to spoil an image. I have found that it is possible to train your crew to use it in the dark.

As a final measure, I spread a cloth baffle across the base of the Cupola with an opening sufficient only for my head. Like a flattened projection of a turtleneck sweater, this final barrier effectively excludes errant rays. Equipped this way, as soon as your eyes become adjusted for night, both your view and your images will be spectacular.

Warm Regards
Posted on Jun 22, 2012 04:39:04 PM


If Matisse and Van Gogh worked together to make a portrait of the Expedition 31 crew, this is what it might look like: Left to right in the first image are Joe Acaba, Gennady Padalka, Oleg Kononenko, Sergey Revin, and André Kuipers (I was running the camera).

Don Pettit's reflection in the Cupola window on the ISS in the far infrared. Credit: Don Pettit


The thermal camera I used operates in the far infrared, with wavelengths around 10 microns, which is close to body temperature. I was using it to image the window heater in the Cupola, and played around with it a bit before putting it away. Note that regular glass is not transparent in thermal infared, so glasses look like mirrors (and so do our windows).
Expedition 31 crew in the far infrared. Left to right in the first image are Joe Acaba, Gennady Padalka, Oleg Kononenko, Sergey Revin, and André Kuipers. Credit: Don Pettit



While onboard the ISS, the members of the Expedition 31 crew performed numerous experiments to study how Earth life adapts to the space environment. These included planting various types of plants and monitoring their growth in microgravity. The data from these experiments will be useful in understanding how life from Earth might be influenced by long-duration missions beyond our planet.

 


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