December 1, 2000:
On another newsgroup there was a discussion of my explanation of the STS-48 zig-zag dots, and a rebuttal of my explanation offered by Mike Bara (jambara@citilink.com (Michael Bara)) at
http://www.lunaranomalies.com/rebuttal.htm

I posted the following response:

It’s fair to ask why I’m making these arguments here, and my answer is experimentation with what sorts of logical reasoning is effective in discussing these topics with UFO buffs. I might add the phrase “what sorts, if any”, but I’ll save my taunts for other exchanges. Here is how I see the prosaic explanations of the striking STS-48 video, and I am truly interested in responses to the lines of argument.

Bara: [[The shadow argument is completely destroyed by the fact that another bright object crosses the screen from right to left, passing nearly the same point at which the "target object" first appears, and remains visible. This is a proof that no such "shuttle shadow" exists. ]]
-------- JimO:
No, this is just proof that space has three dimensions, and suggests that the shadow region lies close to the shuttle, while farther away along the same line-of-sight is in sunlight. In fact, this situation can be confirmed by using the shuttle’s actual orientation in space (neither Bara nor any other UFO writer ever did this).
Relative to the velocity vector, the shuttle is oriented belly forward, left wing down, nose dipped slightly forward. At sunrise, the sun is left of the velocity vector (this is the so-called “Beta angle”, which changes throughout a flight).
The result is that the line-of-sight from the shuttle to the sun, at sunrise (a minute before the famous event), is out the nose and about 30 degrees depressed. Consequently, the space above the left wing (which is the direction the TV camera is viewing) is shadowed close to the wing, but sunlit farther out.
And the most famous dot does appear in that direction, just as a particle drifting away from the shuttle would appear as it moved out over the left wing.
In general I find it significant that these notorious “UFO videos” (STS-48, STS-75, STS-80, etc) occur just after sunrise, as a camera is still looking back towards the dark Earth and the newly-sunlit particles are starkly visible against a dark background. The darkness makes the auto-iris and gain control on the vidicon TV cameras go to maximum, which enhances the effect.
That’s especially notable for moving objects, which leave streaks on the camera optics -- even stars do this, when the camera pans rapidly.
There are many features of space shuttle hardware, space operations, and orbital mechanics which would cast light on these controversies, but which are ignored in the descriptions commonly found in the UFO press and on www sites. I speculate it’s because the promoters of these theories realize that the more ignorant and misinformed are their intended victims, the more vulnerable they are to deceptive explanations such as “UFOs”.

Bara: [[Oberg argues that Hoagland's statement that the object should brighten as is "rises into the sunlight" is false because no brightening takes place after the object is in full sunlight. He does not address the significant and indisputable dimming of the target object just after it crosses the airglow boundary. According to Oberg's own reasoning, this should not occur. The target object starts below the airglow boundary, increases in brightness as it crosses the boundary, and then dims noticeably and continues dimming. It should resume its previous level of luminosity and stay constant until it is out of frame, according to Oberg's (small object, close to the shuttle) model. ]]

------ JimO:
By no means. The dimming of the ‘main dot’ is no problem at all for the nearby debris theory. It’s just getting farther away from the camera, starting at perhaps 20 feet and moving out to 30 or 40 feet. The brightness graph in Kasher’s report shows exactly the kind of gradual dimming one would expect of something getting farther away.

Bara: [[It has been established (Kasher) that 2 vernier rockets (L5D and R5D) did fire during the noted "flashes" (there are 2). However, he also showed that neither could have caused the movement of the target object due to trajectory (noted above) location and velocity of the verniers. Kasher has also shown that the target object begins to accelerate some 1.2 seconds after the firing of the L5D, making the minimum distance to an "ice particle" nearly 2 miles. At this distance, an ice particle would have to be enormous to be visible, and the blast would not account for the observed acceleration due to dissipation. Further, he shows from NASA telemetry that all the verniers fired at least twice during the duration of the tape (including L5D and R5D) and no similar flashes were visible.]]

---- JimO:
Not exactly. The RCS jet firing occurred at precisely the time of the flares and of the interval when some of the dots changed direction (the timing is based on time codes read directly off the videotape, and I don‘t know how Kasher determined there was a time difference between these events). Debris out over the wing would be well within the flow field from plume bounce-back from structural elements of the shuttle’s aft end, and their change of motion is all in the direction AWAY from this zone. Also, telemetry does NOT show any other firings of the L5D vernier thruster during the period the camera was viewing the same region, so Bara’s statement is not accurate.
See again http://www.igs.net/~hwt/zigzag.html for explanations of the shuttle’s pointing during this event.
====
JimO adds:

*I worked at NASA’s Johnson Space Center from 1975 to 1997, in various Mission Control Center specializations, including propulsion and rendezvous. In fact, I was on a different shift on STS-48, running a tracking radar test on a deployed payload. But I’ve watched hundreds and hundreds of hours of downlink TV on the big screen. I got a good impression of what was ‘ordinary’ in terms of the shuttle cameras and the space environment.
“Secret” clearances were standard until the early 1990’s, mostly just to protect physical access. For DoD payloads, it covered mission design and payload characteristics, nothing higher than ‘Secret’. And even that’s all gone now, the control hardware’s been torn out.
Nobody tells me or advises me in any way what to say or not say, I’m a lifelong UFO nut who wanted to apply his professional expertise to ‘classic’ cases within my area of specialization. And that’s what I’ve been doing. Nobody’s agenda but my own: find out, and tell about. I’ve upset people at all ends of ideology, politics, and every other ‘=ism’ on the planet.
What are we seeing in the video? It looks to me like small nearby sunlit shuttle-generated debris, usually ice (off the water dump nozzles or any of 100 valves in the thrusters, or even the flash evaporator, and sometimes from the post-MECO SSME feed line purge), sometimes junk from inside the payload bay, or fragments of insulation blankets, or strips of tile gap filler that are manually inserted during pre-flight processing -- there are many sources of such debris.
The small stuff is around a lot, but usually doesn’t even show up in the full sunlight TV scenes, the camera’s iris is auto-stopped way down against background glare and brightness. But when viewing the dark Earth, the CCTVs -- especially the old-model B&W cameras with higher low-light sensitivity -- open way up, and set auto gain control really high, so dim dots show up. This is most spectacular just after sunrise, when the background Earth is still dark but the shuttle is flying through space bathed in sunlight that’s invisible until some object enters it.

*A compelling pattern, in my view, is that the most famous ‘UFO videos’ all occur during these brief intervals just after sunrise when the camera remains viewing the dark Earth, but the shuttle has risen into sunlight. Within a few minutes, the field-of-view encompasses a sunlit surface, and the camera sensitivity drops drastically. But STS-48, STS-63, STS-75, STS-80, all the ‘famous’ UFO sequences, ALL happen to occur in these unique illumination conditions. This fact is withheld from you by the promoters of these stories, and understandably so -- you might see a different interpretation than the one they’re trying to sell.
Two correlations support the prosaic explanation for this sequence. First, sunrise occurs, and some dots ‘appear’. Eighty seconds later, a flare appears, exactly during the 1.2 second firing of a pair of attitude-control thrusters. Several dots change motion during -- and, I must stress - ONLY during, this interval. And nothing changes direction at any other time in the sequence. That strikes me as pretty hard to explain as only ‘random coincidence’.
The course changes of the dots are all AWAY from the flare, and are consistent with having their initial linear motions pushed by an expanding effluent cloud from the thruster. The particular thruster, L5D, is an aft-left pod down-pointing jet, but all the down-pointing jets are notorious for plume impingement on shuttle structure (wing elevon, body flap, even one of the main engines) that creates substantial ’bounce-back’ that reduces thruster efficiency (compared to other jets in other directions) by a large fraction.
In 1982-1983, in preparation for shuttle maneuvering near close-in payloads, I drew up the reference charts used in Mission Control about exactly this effect. So it’s not at all strange to me to see these dots move away from the plume front.
Even after a shuttle moves into sunlight, dots sometimes still ‘appear’ as the debris moves out of the shuttle’s shadow (don’t forget, the camera view is ‘down sun’ towards the dark Earth). There’s a spectacular sequence of a water dump on STS-75 where a wide stream of dots ‘appears’ in mid-field, and there are so many ice particles you can actually make out the three-D shape of the shuttle shadow. But don’t expect to see that kind of explanatory video on any UFO show or conference.

*Streaks are caused by any fast-moving objects, even stars when the camera pans fast. I interpret the streaks to be two pieces of debris closer to the thruster that are more highly accelerated by its firing.
There are lots of videos that show dots changing course during a thruster firing. It’s just that the promoter-programs aren’t going to show you them, so you don’t get confused from their intended spin.
Here’s another ‘inconvenient fact’ that’s always omitted from the pro-UFO descriptions.
The event occurred just after the crew had awakened, and were preparing breakfast and taking their turns in the ‘head’. This hardly strikes me as the timing for a pre-arranged demonstration.

*I’m struck by the fact that none of the pro-UFO researchers seem to have bothered to ask the primary witnesses, the flight crew and the mission control operators. Instead they make a posteriori arguments why people shouldn’t pay attention to what they might say. I interpret this to mean the UFO promoters know the testimony will be contrary to the images they intend to present.

*NASA’s official response to a congresswoman’s inquiry, on behalf of Don Ratsch, was a November 1991 letter signed by Joe Loftus, Bill Pitts, and astronaut Karl Henize: “The objects seen are Orbiter-generated debris, illuminated by the sun. . . .The flicker of light is the result of the firing of the attitude thrusters on the Orbiter, and the abrupt motions of the particles result from the impact of gas jets from the thrusters.”

*STS-48 co-pilot Ken Reightler: “We saw lots of this on STS-48 because we had a dump nozzle that was leaking.” The same nozzle leaked on the shuttle’s next mission and “created the same shower of ice particles -- but this time apparently no one misinterpreted them as UFOs.”