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Originally posted by saskwatch
looks like just a couple seagulls at the end of the video there, no need to panic folks
Originally posted by nineix
Here's a nice technical read all about Reaction Control Thrusters (RCTs), ice particles and other fun stuff that's really fascinating.
Thrusters, Light Flashes, and Ice Particles
Space Shuttle Thrusters, Light Flashes, and Ice Particles
Some Insights from an Expert
“In a discussion with a NASA aerospace engineer familiar with the space shuttle reaction control system, I learned that the thrusters never generate any light while operating… Quite to the contrary of what might be construed from Oberg's assertion, there is no ‘flash’ in the sense that the propellant itself generates little if any light at all during a burn.”
“I recently had the opportunity to discuss various aspects of the space shuttle's RCS propellant supply system with a NASA aerospace engineer who was involved in the design, testing, and performance evaluation of the RCS from the nearly the beginning of the shuttle program. Unlike Oberg, this engineer observed tests of thruster firings close up on a routine basis.”
“Oberg had a long career as a flight officer in the Mission Control Center at Johnson Space Center, and frequently appears as an expert on spaceflight for TV news and on the lecture circuit. But it turns out his description is wrong or at least misleading on several important points… while Oberg may well be an expert on many aspects of space flight, he evidently has no particular expertise or experience with the RCS propulsion system.”
“But the dribble volume is large enough that the snow generated can be seen as a white plume in reflected sunlight. It is totally invisible without some external source of illumination.”
“I have been puzzled for a long time about why the rocket combustion gases were so easy to see when they are supposed to be nearly invisible. The puzzle is apparently solved: these photos show jets of microscopic snow at the end of the firing cycle in reflected sunlight. In Figure 3, plumes from two primary RCS rockets on the left can clearly be seen. ”
“But the L5D thruster firing supposedly responsible for the flash was 1.2 seconds in duration, so the pre- and post-burn flashes should have been 1.2 seconds apart, not 0.4 seconds. Worse for the thruster theory, the exhaust exits the nozzle at a speed of 3500 meters per second. If it is assumed that the exhaust plume hit the objects just as the thruster shut down, the objects would have to be over 4 kilometers away from the shuttle, since that is the distance the exhaust plume would travel in 1.2 seconds before impinging on the objects.”
“In a previous article  I noted that the time display in the Mission Control Room, which appeared briefly in the STS-102 video, indicated that the light flash occurred at least 5 seconds before the closest thruster firing, which occurred at 12:30:39 GMT. Since it is impossible for the thruster firing to be the cause of an event that preceded it in time, it could not have been the cause of the light flash – assuming the mission control time display was accurate.”
“Based on Oberg's statements, it had seemed to me that in both the STS-48 and STS-102 videos the high-speed "projectiles" seemingly pursuing slower-moving objects might be explained as ice chunks expelled from the nozzle during the rocket burn. But as the presence of such ice in the thruster would indicate a possibly serious problem with the shuttle propulsion system, this explanation no longer seems feasible. ”
“The information I've received from an expert in the shuttle's RCS propulsion system provides a compelling refutation of Oberg's argument that thruster firings were the cause of the objects' behavior in both cases.”
Originally posted by Arken
"We still have the terrestrial spacecraft under surveillance...."...