Department of War PURSUE File
NASA-UAP-D5, Apollo 17 Crew Debriefing for Science, 1973
1973
Editorial summary
During the Apollo 17 mission in January 1973, ultraviolet experiment co-investigator Dick Henry reported observations from lunar orbit that produced unexpected scientific results, according to the crew debriefing for science conducted on January 8, 1973. The experiment detected ultraviolet radiation across multiple observation points at high galactic latitudes, both north and south of the galactic plane. The spectrum observed appeared consistent with radiation from hot stars, yet Henry noted that no hot stars were present within the instrument's field of view.
Henry presented the most conservative interpretation of these findings: the detected ultraviolet light originated from hot stars within the galactic plane, traveling outward and reflecting off interstellar dust. However, he acknowledged that certain spectral characteristics did not align with this dust-reflection theory. He identified an alternative possibility, that the radiation detected was extragalactic in origin, though he emphasized that a complete explanation would require detailed computer analysis, which he expected to be a lengthy process. The observations were made in an environment where an abnormally high dark current reading might have interfered with the ultraviolet detector, but Henry confirmed the spectrum remained detectable above this background noise.
The debriefing document reflects the Apollo 17 crew's systematic approach to addressing unexpected observations during their lunar mission. Henry's account demonstrates the standard scientific method applied to space-based observations: comparing detected spectra against known sources, identifying discrepancies with existing theories, and proposing alternative explanations pending further analysis. His remarks indicate the ultraviolet experiment produced data that would require significant computational study to fully understand, a common outcome of early space science missions that collected more information than could be immediately analyzed.
This document is now part of the public record as cleared for release by the Department of War in the PURSUE Release 01 on May 8, 2026.
Editorial summary written by govweird from the declassified document text. The official government description follows below.
Government description
Apollo 17 was the ninth crewed U.S. mission to the Moon, and the sixth to land Astronauts on the lunar surface. This document is an excerpt from the Apollo 17 Crew Debriefing for Science on January 8, 1973, in which Dick Henry, co-investigator on the ultraviolet experiment on Apollo 17, discusses seeing results that were unexpected. • Pages 119-120. “One of the most exciting results of X-ray astronomy was the fact that an X-ray background was observed over the sky that nobody had expected, and part of this is the gamma-ray background that Dr. Trombka talked about. In the UV, nobody knows, but you never know until you look. You do have to deal with this background of stars that we know is there. So, we did look at a large number of different points at high galactic latitudes, both north and south. The spectrum that we see is above this dark count. In other words, this abnormally high dark current did not, in fact, interfere with that experiment. The spectrum that we see looks like the spectrum of the hot star; however, we know that there were no hot stars within our field of view. Therefore, the most conservative interpretation, I think, is that what we're seeing is light from hot stars in the galactic plane going up out of the plane and reflecting off interstellar dust. There are certain characteristics of the spectrum, though, that don't fit that theory, and it's at least possible that this is extragalactic radiation. I'm looking forward very much to the detailed computer study of this, but it's going to take a long time.”
Caption issued by the U.S. Department of War on war.gov/ufo. Verbatim, unedited.
Originating agency
National Aeronautics and Space Administration
Record type
Incident date
1973
Incident location
Unspecified
Release tranche
Release 01 (May 8, 2026)
Distribution
Cleared for public release