ISS & SS Memories

The last Space Shuttle flight took place in July 2011 (Atlantis, STS-135), and in going through the archives from ten years ago, I found this write-up about the International Space Station and the Space Shuttle seen together in the sky.

International Space Station & Space Shuttle – Docked

This past Sunday evening brought my family to Governor Dodge State Park north of Dodgeville for a stroll in the dark—and what we thought would be a “routine” flyover of the International Space Station.  Boy, were we surprised!  Even though conditions were quite hazy, the ISS made its appearance as predicted, but as it reached its culmination of 62° at 10:27 p.m. (6/17/07 CDT) we witnessed something none of us had ever seen before: a gradual brightening of the ISS to between -6 and -9 magnitude, followed by a gradual dimming back to the normal slightly negative magnitude of a favorable flyover.  We had observed a “sun glint” off of the large station’s many reflective surfaces.  What a treat!

Footnote #1: The ISS had a definite orangish tint to us, which may have been real in spite of the hazy conditions.

Footnote #2: No-line bifocals (progressive lenses) work well during the day, but try looking at a bright moving object at night (or stars in general) to see just how bad the optics are!  For night viewing, I recommend a pair of glasses (if you need them) for distance viewing only, with glass lenses (not plastic!) and 0.5 diopter greater correction than you normally use.  I have such a pair, but forgot to bring them with me that night.

International Space Station & Space Shuttle – Undocked

This past Tuesday, the Space Shuttle Atlantis (STS-117) undocked from the International Space Station, and, as luck would have it, there were two opportunities that evening to view the pair—separated by only 46 miles—cross the sky in a beautiful pas de deux.  The first and best event, which culminated at 9:33 p.m. (6/19/07 CDT), was still impressive in spite of bright twilight because the spacecraft were so bright.  The brighter and oranger ISS was leading Space Shuttle Atlantis by about 3° when first sighted low in the NW, which expanded to about 6° at culmination since both spacecraft were closer to Wisconsin and the axis between the two least foreshortened, shrinking again to 3° when both spacecraft disappeared into the shadow of the Earth low in the ESE.  The changing orientation of the axis connecting the two spacecraft as they crossed the sky was interesting to observe.

A curious phenomenon that my wife, daughter, and I all noticed was that the positions of the two spacecraft with respect to each other seemed to “wiggle” a bit at times as they crossed the sky.  What a strange optical illusion, because obviously both spacecraft were moving smoothly relative to Earth and relative to each other!

I also observed the second pass that evening, which reached a maximum altitude of only 14° in the WSW sky before the pair entered the shadow of the Earth at 11:07 p.m. CDT.  Both spacecraft were about two magnitudes fainter than before, and this time Atlantis seemed brighter and oranger than the ISS!

As any double star observer knows, though, the perceived color of an object is strongly dependent upon its brightness!

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