This may add to the discussion a few months ago with peri****hian and others over this image:
JimO notes: This letter was sent by NASA to reply to an inquiry from Donald Ratsch about the “STS-37 blob” UFO, and Mr. Ratsch has graciously shared it with all who asked.
August 16, 1993
Letter SN5-93-42
Dear Mr. Ratsch:
Congresswoman Helen Delich Bentley has requested that NASA respond to your letter of May 3, 1993, regarding the unusual events that you observed during the airing of ‘Today in space’ on January 29, 1992.
A team of scientists in the flight Science Branch reviewed your video tape of the show ‘Today in space’. They found your description of the events to be accurate, but do not agree with your interpretation that the events represent UFOs.
The scenes in question were identified as coming from the STS-37 mission when the Orbiter was approaching the west coast of South America. The original source of the imagery was determined to be an astronaut-acquired 16 mm Arriflex motion picture film. The object in question was analyzed and was determined to be a water drop on the window. After the analysis was complete, we spoke with the STS-37 crew. The crew said that they remembered the droplet hitting the window, and added that the source of the drop was from liquid which one of the crew members was drinking.
<snip>
2. The object is a water drop on the inner pane of one of the overhead windows on the Orbiter flight deck.
3. The object grows larger because the camera position is moved.
4. The change in shape of the object may be an optical illusion, due to the water droplet surfaces magnifying and focusing the Earth’s limb and the deep space background. However, droplets attached to a surface, through surface tension, can change shape as a function of air flow in the crew cabin and/or accelerations of the Orbiter.
5. The object appears to move because the camera was moved by the astronauts.
6. The object does not cast a shadow on the Earth. The dark region below the object is a piece of dirt on the window. In the higher resolution film (enclosed), many similar objects can be seen as well. The apparent motion of the droplet and the dirt on the window are highly synchronized, due to the motion of the camera. Note, there are three panes in the window and it isn’t known on which window surface the dirt is residing.
7. The video was collected on STS-37 using an Arriflex 16 mm motion picture camera (magazine number 140). The source used on ‘Today in Space’ was a film-to-video conversion, which was sampled each sixth frame. STS-37 was launched on April 5, 1991, and landed on April 11, 1991. The exact time and date of the photography are unknown.
Sincerely,
David E. Pitts
Chief, Flight Science Branch
NASA
Lyndon B. Johnson Space Center
Houston, TX 77058
Enclosure – Detailed summary
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Methodology
From the screening of the film, the analysts performed an experiment to determine if the anomalous object was inside the flight deck or outside the window. Fortunately multiple pieces of debris were noted on the Orbiter windows which were tracked during the time period of interest. If the object were inside the Orbiter, then any camera motion would make the anomalous object appear to move a greater image distance than an object on the window. If the anomalous object were outside of the Orbiter, then the object on the window would appear to move a greater distance.
Two independent pieces of debris on the window, two points on the limb of the Earth and the anomalous object were tracked. Tracking consisted of taking the spatial position of these points for each frame over the time period of interest (approximately 100 frames). The digitizing was performed on high quality film to video conversion of the film so that the brightness values could be obtained to ensure that the exact same point was taken frame by frame.


