FOIA: Possible origins of optical data for the the 22 Sep 1979 Vela satellite event

POSSIBLE_ORIGINS_OF_EVENT_747_ AUG_1980.pdf
Possible origins of optical data for the the 22 Sep 1979 Vela satellite event
A report on the possible origins of optical data for the the 22 Sep 1979 Vela satellite event prepared for Patrick AFB.
Document date: 1980-08-01
Department: unknown
Author: Dale S. Sappenfield, David H. Sowle, Trella H. McCartor
Document type: report
pages: 85


Archivist's Notes: Fair to good quality document. Many blacked out areas. 'Top Secret' mark crossed out. Most pages marked unclassified. DOE classification review stamp. Marked copy 1. Stated report length is 87 pages.

Initial Notes

1. Many illustrations in the document are redacted;

2. Useful illustration of the subject of this document appears on page 52;

3. The satellite discussed is/was pointed at Earth and was specifically designed to detect nuclear explosions. It was one of a series of such satellites placed in orbit to monitor nuclear compliance.

Summary

On September 22, 1979, a VELA satellite received optical data possibly indicating a nuclear explosion. Two optical sensors were discussed: YC and YV. The data might also be interpreted as non-nuclear in origin and such sources are discussed later in the document.

Speculation early in the document stated that one of the two optical sensors may have been malfunctioning, as one sensor indicated a ground burst and the other indicated an air burst. Surface bursts yield lower silicon values than air bursts. It is assumed that soil and other surface debris cool the fireball thereby reducing silicon yield in a surface burst. The authors concluded that it was the YC sensor that malfunctioned.

After some discussion regarding interpretation of sensor data versus historical data, the document's authors concluded that, if the event was nuclear in origin, the source was a surface burst.

Two non-nuclear sources were considered and discussed:

1. "Superbolt" lightning ("100 times more powerful than 'typical' lightning"; more common in the maritime environment);

2. Sunlight reflected onto the sensors by nearby objects.

The authors stated that superbolt lightning was a possibility because the data fell within the parameters for that type of event, but did not appear convinced that this was the likely explanation.

Their discussion of "solar irradiance" or reflected sunlight was extensive and they concluded the following:

1. The reflecting object had an irregular, unusually reflective surface, speculating that one surface in particular may have been specifically "tailored to mimic a bomb";

2. May have been a truncated sphere one millimeter in size;

3. Probably not satellite debris based on its speed and trajectory: It appeared to approach the satellite from behind at a distance of one to ten meters and passed between the two sensors in less than half a second.

Supplemental

Internet research indicates that later astrophysical research determined this incident was one of the first detected gamma ray bursts.

[edit on 11/24/2007 by PrplHrt]

Military Report dated: August 1980. 85 pages.

Title: Possible Origins of Event 747 Optical Data (U) by Dale Sappenfield, David Sowle, Trella McCartor. Report to Air Force Technical Applications Center, Patrick AFB.

The Abstract states that the report investigates the data in terms of both nuclear and non-nuclear sources.
“While we cannot claim to have considered all possible non-nuclear sources, and we cannot absolutely rule out the non-nuclear sources that we have considered, we do not find a non-nuclear source that is a reasonable alternative to the nuclear source.”

Non-nuclear sources considered were: lightning and reflections of solar radiation by small flat plates and from irregularly shaped objects.
Reasons for rejecting these sources are given.

Pdf pg 8 and pg 17 both mention that of the two sensors on the satellite, the YV sensor data strongly suggest a surface burst.

Pdf pg 24:“At the 1980 Satellite Working Group Meeting, Whitaker and Horak presented results of an Event 747 calculation…..(blacked out)…..We consider the agreement between their results and our results quite satisfactory.
At the same meeting, Hillendah presented an analysis that indicates approximately an order of magnitude more mass for the Event 747 device. We do not agree with that result.”

Pdf pg 30-32
Discusses the inaccuracy found in the YC sensor and by pg 32 we find the quote:
“It is interesting to note that everyone we know who has looked at the Event 747 data first accepted and concentrated on the YC sensor data. However, by the time of the 1980 Satellite Working Group Meeting, not only we, but Mauth, and Marshall, were tending toward the view that the YV sensor data are more trustworthy. Furthermore, these opinions were reached independently, as far as we know, and were based on different lines of reasoning. Using the YV sensor data, we concluded that Event 747 was a surface burst.”

The report has a great quantity of graphs and equations to support their discussions for both nuclear and non-nuclear sources of light.
Much of the information/graphs etc were blanked out particularly in the first section of the report.