NASA has been producing compelling and fascinating space photography for quite some time. If you’re not familiar with what they’ve been shooting, do yourself a favor and check out the NASA image gallery.
One of the more interesting places that NASA has been receiving images from is the International Space Station. Since installing a cupola (a small windowed dome) in February 2010, astronauts aboard the station have been experimenting with various photographic techniques.
One of the more interesting ones has been long exposures to create star trails. On Earth, the process is simple, point the camera at the sky and let the Earth rotate while leaving the shutter open.
On ISS, it’s slightly different, the station orbits the planet once every 90 minutes (or 16 times in a 24 hour period), traveling at speeds that top 17,000 mph.
Astronaut Don Pettit, Flight Engineer for Expedition 31 which ventured into space in May of 2012, took a number of photos during his time on the station.
Some where daily life images, but Pettit also tried his hand at creating long exposure images. He described his techniques thusly, “My star trail images are made by taking a time exposure of about 10 to 15 minutes. However, with modern digital cameras, 30 seconds is about the longest exposure possible, due to electronic detector noise effectively snowing out the image. To achieve the longer exposures I do what many amateur astronomers do. I take multiple 30-second exposures, then ‘stack’ them using imaging software, thus producing the longer exposure.”
For more of Pettit’s images check out NASA’s Flickr gallery.