On September 15, 1991, between 20:30 and 20:45 Greenwich Mean Time, the TV camera located at the back of Space Shuttle Discovery's cargo bay was trained on the Earth's horizon while the astronauts were occupied with other tasks. A glowing object suddenly appeared just below the horizon and "slowly" moved from right to left and slightly upward in the picture. Several other glowing objects had been visible before this, and had been moving in various directions. Then a flash of light occurred at what seemed to be the lower left of the screen; and the main object, along with the others, changed direction and accelerated away sharply, as if in response to the flash. Shortly thereafter a streak of light moved through the region vacated by the main object, and then another streak moved through the right of the screen, where two of the other objects had been. Roughly 65 seconds after the main flash, the TV camera rotated down, showing a fuzzy picture of the side of the cargo bay. It then refocused, turned toward the front of the cargo bay, and stopped broadcasting. There have been several scientific analyses supporting the anomalous nature of objects in the STS-48 video.

A New Look at the Evidence Supporting a Prosaic Explanation of the STS-48 "UFO" Video
Lan Fleming, New Frontiers in Science, Vol. 2 No. 2
It has been argued that the seemingly unusual behavior of objects observed during the STS-48 space shuttle mission can be explained as the reaction of small debris particles floating near the shuttle to the firing of the spacecraft's rockets. Two independent lines of evidence are presented here that suggest there could have been no causal link between the objects' behavior and the rocket firing.

Chronology of Anomalous Events during STS-48 Shuttle Mission
Vince Johnson, Houston UFO Network
After personally reviewing the video of events, some of which were obtained from the official NASA video archive, I can only surmise that the events are indeed anomalous and unexplained. The official NASA explanation of ice and debris seems unlikely due to the different directions and speeds the objects appear to be traveling. The following is a chronology of the anomalous events of STS-48 R

Commentary on the STS-48 Video: A Closer Look, and Second Thoughts
Thomas. E. Carey, 1993
Analysis of the video of a possible UFO taken by Shuttle astronauts during the STS-48 mission. R

Digital Video Analysis of Anomalous Space Objects - The STS-48 Video (PDF)
Mark J. Carlotto, Journal of Scientific Exploration, Vol. 9, No. 1, 1995
Scientific analysis of the STS-48 Space Shuttle video showing multiple objects moving in unusual trajectories in space. The video was captured by a camera aboard the Space Shuttle Discovery (mission STS-48) on 15 September 1991. Digital video analysis is performed to determine if the objects in question are ice particles disturbed by a thruster firing as contended by NASA or other objects moving independently of the shuttle.

Examination of Object Trajectories in the STS-48 "UFO" Video
Lan Fleming
Examination of the anomalous trajectories of the STS-48 objects. Objects in the video are shown to follow curved paths inconsistent with "ice particles" but consistent with large, self-propelled vehicles at a great distance from the space shuttle.

Losing the Signal - Proof That Time Stamps on the STS-48 Video Released by NASA Are Phony
Lan Fleming
Proof that the STS-48 video time stamps are wrong and were probably tampered with at NASA.

Proof of the Prosaic Nature of the STS-48 Zig-Zag Video (Skeptical)
James Oberg
The attached two charts provide convincing proof that the famous zig-zag dots of the STS-48 shuttle flight (September 1991) are exactly what space experts inside and outside NASA have always said they were: routine nearby small sunlit debris hit by the expanding exhaust of a shuttle steering rocket triggered randomly by the computer autopilot which was steering the spaceship.

Response to NASA's James Oberg's Analysis of STS-48 Video
Michael Bara, Lunar Anomalies Homepage
Several years ago, NASA employee James Oberg apparently wrote via E-mail an extensive rebuttal of Richard C. Hoagland's analysis of the STS-48 video. This rebuttal has made the rounds of various web sites and newsgroups, and has been used as an example of the supposedly "faulty" nature of Hoagland's research. As near as I can tell, this rebuttal has gone completely unchallenged. After a quick perusal of Oberg's letter, I felt it was drastically flawed on several points. The following is my response to Oberg's rebuttal. R

Star Wars Over Australia?
Graham Stewart, UFO Reporter, UFO Research (NSW), Sept. 1995
One of the most spectacular video footages of a UFO encounter was taken by cameras on board the Discovery space shuttle on 15 September, 1991. The video sequence was picked up live by a number of amateurs who were directly monitoring the transmissions. The material has been shown in news broadcasts and circulated amongst UFO researchers worldwide. R

Video from the STS-48 Space Shuttle Mission - Closeup Version (Quicktime format)
NASA, Space Shuttle Mission STS-48
A closeup version of the UFO video taken during the STS-48 Space Shuttle Mission, showing anomalous objects and behavior.

Video from the STS-48 Space Shuttle Mission (MPEG format)
NASA
This is the main UFO video taken during the STS-48 Space Shuttle Mission, showing anomalous objects and behavior.