STS-75 Shuttle 'Tether Experiment'

By James Oberg,
jamesoberg@aol.om

Whispers
(a UFO releated discussion board)
5-10-00

The STS-75 tether videos are remarkable scenes and convey a powerful impression of large, distant circular unknowns. The video is visually striking.

What possible prosaic explanations are there?

While any serious analysis of what these scenes really show should require knowledge of the operating characteristics of the camera and of the illumination environment of these scenes, none of these steps appear to have been taken in previously published versions. There's still misinformation about whether the camera was a CCD or vidicon (it was a vidicon, with an image intensifier circuit). There's still confusion over the timing of the scenes of the "swarm" (it's advertised as having occurred immediately after the tether break, but actually it occurred three days later) and the illumination (the tether image is said to be self-luminous, but it's actually sunlit near sunset).

But even without technical analysis of these features, the video itself contains internal features which can help assess what is actually "seen" on it. Also, there are video scenes NOT broadcast, but known to be in the possession of producers of these shows, that also can cast a truer light on the events.

Two features stand out for appraisal: the thickness of the tether image, and the notched circles which cross the field-of-view (FOV). In both cases, we can assess the question of whether these are REAL objects or are camera artifacts, based solely on the scenes broadcast.

The tether thickness must be an illusion, because the tether itself is less than a centimeter in diameter. Yet on the scenes of the free-flying tether, its full 20-kilometer length is matched by a scaled width, in angular terms (or in pixels), on the order of hundreds of meters. At the tether range (140-180 km), a pixel is only about 100-meters across, so an image several hundred meters in size has "spilled over" several pixels (five or so) beyond the actual pixels illuminated directly by the bright reflecting tether.

This effect is evident when the camera zooms in on the tether. Although the length increases by a factor of two, the width remains the same. On other scenes, not shown in these broadcasts, the tether length varies even more, by a factor of ten. The tether image width does not vary at all. This is clear indication that the "width" is a false artifact of the camera optics.

The true visual nature of the tether can be determined from observations made around the world at the time of the break, Feb-March 1996. See the "see-sat" archives for messages from that time period. I personally also witnessed the tether, sunlit and NOT self-illuminated (one sequence in front of my eyes involved it actually climbing out of Earth's shadow and becoming pink, then white along its length).

Other videos from shuttle transmissions -- bright cities, lightning bursts, even stars -- show another ordinary feature of the camera system. It "dims out" the center of bright images. This creates "do-nut stars" and bright rims around ground lights on the dark side of Earth. On water dumps, brighter ice particles also exhibit the "hollow center" optical effect. It does the same with the shuttle image, creating a dim centerline on the bright pseudo-image. This is self-evidently a feature of the camera optics, not a visual feature of the observed objects. In one scene I recall watching, a dot moved across a bright city at night, and the dot disappeared as it transitted the dark core of the city lights -- not burrowing UNDER the city, obviously, but its own light being lost in the glare of the city itself.

The prosaic explanation of the impression of moving "behind" a phantom "fat tether" is that the dots -- of whatever nature -- crossed the FOV until they merged with the tether image. That image was ALREADY so bright the local pixels had defaulted to "overbright protect" dimming. The addition of the brightness of the dots made no difference, the center of the visual field was still dimmed out. The crossing dot APPEARED to vanish, presumably (but incorrectly) due to physical occultation. Some observers even describe the illusion of a shadow being cast by the tether image on the disks -- a physical impossibility given the tether's actual physical thickness.

Now, the notched circles -- these are very unusual images, not common on other shuttle videos. But a careful analysis of the many cases of notched circles crossing the STS-75 screen shows a tell-tale pattern: the position of the notch clocked around the rim is a direct function of the position of the circle on the FOV. As a circle moves, at different points on the FOV, the notch is in different positions. But as the circle moves across the screen, it repeats the notch position of circles that had previously been at the new position it reaches.

Map this out, and you can see this consistent pattern. So, if the notch position is a function of the position on the FOV, we are talking about a camera-related factor here, an artifact of the optical system, and not a "REAL" image of some object.

Other video scenes , known to be in the possession of some researchers but not included in the released productions, show these notched circles independent of the tether. One sequence shows a pattern of notched circles crossing the FOV, then a camera refocus activity that results in -- a star field.

The hypothesis that the notched circles are out-of-focus point sources -- either star fields when the camera is focused close, or nearby debris when the camera is focused to infinity -- is further supported by the f-stop state of the camera system. Typically, these famous shuttle scenes of moving dots occur only under very specific and rare lighting conditions. A B&W CCTV is viewing the dark earth (usually monitoring for lightning bursts), set to infinity with f-stop fully open. I am advised by camera experts that this reduces the depth of field and leads to nearby small objects being out of focus at ranges of several meters, even as great as 5-8 meters.

Since the STS-75 flight records show that the famous "swarm/tether" scene was made three days after the tether break (and not immediately afterwards, as many viewers were led to misconstrue), then it is possible that the shuttle crew had returned to normal shuttle operations. And indeed they had. A check (by me) of shuttle crew activities show that the "swarm/tether" scene was proceded a few hours earlier by a routine water dump, a process that is known to create clouds of debris particles, many of which linger around the shuttle for several hours before drifting off.

Understanding the phenomenon which created these STS-75 scenes thus requires an appreciation of what was really going on, and when, on this flight, as well as a knowledge of similar scenes which arguably had similar causes. It requires technical knowledge of the hardware, its operating characteristics and limitations, and the illumination situation of the scenes. It would be helped by explanatory narratives from the actual eyewitnesses, the astronauts aboard the shuttle and the flight controllers in Mission Control in Houston.

Sadly, that information is not present in the produced/released videos which have been seen to date. Consequently, viewers can be expected to jump to erroneous conclusions regarding the nature of these videos, based on the pre-selected data shown them versus the data withheld from them.

Other issues remain with the interpretation of the scene as showing genuine kilometers-wide circles in space near the shuttle. Such hypothesized objects would be on the same angular size and brightness of a full moon as viewed from Earth's surface. It is not a matter of a handful of amateur astronomers viewing and not seeing such immensely impressive apparitions -- these are images which would have been visible in the daytime sky to anybody on Earth, on the ground or on ships or in aircraft, along the track of the shuttle (they would also have been visible in satellite imagery, including weather satellite views). Not a single report of fast-moving moon-like circles in the sky has been found from anywhere on Earth during this period when the videos were showing the images that have been thus interpreted. The mandatory deduction from this is that such objects never existed.