Encore - Brightness of the Space Shuttle
April 04, 2015
Take a look back at some of the EPODs our viewers found particularly eye-catching. Today, and every Saturday, EPOD invites you to rediscover favorites from the past. Saturday posts feature an EPOD that was chosen by viewers like you in our monthly Viewers’ Choice polls. Join us as we look back at these intriguing and captivating images.
On the evening of Wednesday, September 9, 2009, from my backyard just south of Peterborough, Ontario, I set up my camera to capture and record the second transit of the evening of the Space Shuttle Discovery (Space Transportation System - STS-128) and the International Space Station (ISS). They had recently undocked for Discovery’s return to Earth later the next day. Both spacecraft travel from west to east which is left to right on the above image. The STS-128 is preceding the ISS by about one hour and ten minutes. According to the tables from the Heavens Above website the STS-128 was expected to have a magnitude of 0.7 and the ISS a magnitude of about -1.3.
As shown above, both spacecraft are passing through the Big Dipper (right center). The bright star at left center is Arcturus. Note that the shuttle looks more like an iridium flare and has a maximum magnitude of close to -2.5 or approximately 12 times greater than was forecast! As I stood there watching "naked eye," I noticed what looked like a faint haze glow around the shuttle and could also detect a faint comma-like tail below it. It looked more like a comet than the STS-128. However, the sky was clear of any cloud or haze; only light pollution on the northwestern horizon, from Peterborough, marred the clarity of the sky. None of these naked eye details show on the one-minute time exposure.
Of course, the next morning when I checked the SpaceWeather website it all became clear to me. I had been fortunate enough to have witnessed and recorded a “space dump”. The STS-128, in preparation for its return to Earth, was doing a scheduled emptying of its excess waste and liquids (pure and otherwise). I was thankful to know that I was not just seeing things the night before and that there was a logical explanation for what I had observed. The increased brightness of the shuttle over the ISS was really quite astounding. I would have never believed that a water dump could affect the reflectivity of a spacecraft that's so much smaller and inherently less reflective than the ISS.
Photo details: Nikon 400D camera; with Sigma 10 to 20 mm lens; set at 10 mm; f/4.0; 800 ISO and 60 seconds; image taken at 9:42 p.m.