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Images taken in space are breath-taking but capturing such stellar magnificence can’t be easy. The reality is that space is cold – really cold - and inhospitable, and then there is space debris, solar flares and electromagnetic radiation to contend with.
Space cameras not only capture striking pictures of the Universe, but take thermal records over the poles, stream spacewalks from the International Space Station (ISS) and image the surface of Mars to name a few of their many applications. Scientific cameras – especially those in space - demand incredible performance while also needing to withstand some very harsh environments, therefore they require special designs optimised for their specific needs.
All cameras consist of two main parts – an image sensor (IS) which converts incoming light per pixel into electrical signals, and front-end electronics (FEE) or camera electronics which controls, clocks, digitises analogue input and manages digital data streams amongst other tasks. Arduous conditions in space can affect how a camera performs – image sensors in particular are susceptible to space radiation, and camera electronics can stop functioning correctly due to severe environmental changes from the roasting-hot sunlight to the freezing-cold nights.
Charged coupled-devices – a light-sensitive integrated circuit which stores and displays the data for an image so that each pixel in the image is converted into an electrical charge the intensity of which corresponds to a colour in the colour spectrum – degrade strongly when exposed to radiation. They can however be built with high performance characteristics and are protected by a dedicated shield. They are considered the chosen technology for astronomical photography.
So, it might be surprising to learn that some of the photographic equipment found in space is actually quite commonplace on Earth. One of NASA’s numerous experiments onboard the ISS is the High-Definition Earth-Viewing (HDEV) project which live streams Earth from between 200 and 270 miles above the planet. You might expect the cameras to be high-tech and incredibly expensive but in fact, the system consists of four commercially available HD cameras housed in pressurised boxes containing dry nitrogen at atmospheric pressure to protect the electronics.
NASA say that rather than designing new cameras, it is actually more cost-effective to use off-the-shelf ones. Ground-based experiments showed these cameras could survive the simulated conditions of space – with a little protection – and HDEV is now putting that to the test. By analysing the video quality NASA engineers will be able to make informed decisions about which cameras to use on future missions.
But that’s not all – astronauts also use cameras within the confines of the ISS including a mixture of digital single lens reflex (DSLR) cameras from Kodak and Nikon along with mobile phones such as the iPhone 4 and HTC Nexus One. These cameras don’t have to deal with the harsh environment outside the station but are still subjected to zero-gravity and it seems they perform as well in space as they do on Earth.
What about those amazing images of the Universe from the Hubble Space Telescope? Taken with what are essentially advanced digital cameras: The Advanced Camera for Surveys (ACS) and the Wide-field Camera 3 (WFC3). ACS has three cameras – the wide field, high-resolution and solar blind cameras – each with their own specific function to obtain imagery in visible wavelengths while WFC3 works mostly in ultraviolet and infrared ranges. These cameras are designed to work in the severe realities of space, and so along with the telescope, are protected by a blanket consisting of layers of coated stainless steel and aluminium foil on a steel frame.
So, it seems that commercially available cameras are quite good for using in space. They might need a little extra protection, but they can capture some amazing images.
References and further reading
https://www.mps.mpg.de/phd/theses/design-and-optimization-of-a-space-camera-with-application-to-the-phi-solar-magnetograph
https://www.nasa.gov/mission_pages/station/research/experiments/917.html
https://en.wikipedia.org/wiki/List_of_cameras_on_ISS
https://www.nasa.gov/content/goddard/hubble-space-telescope-science-instruments
https://www.nasa.gov/content/hubble-space-telescope-advanced-camera-for-surveys
https://www.spacetelescope.org/about/faq/
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