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NASA UNCLASSIFIED

Apollo 17 Crew Debriefing for Science (MSC-07632)

Date January 8, 1973
Location Manned Spacecraft Center, Houston, Texas
Type Science debriefing report
Pages 3

Science debriefing containing UV/X-ray/gamma-ray astronomy results, including observations of unexpected X-ray backgrounds and Lyman-alpha hydrogen radiation data.

Apollo 17UV astronomyX-ray backgroundLyman-alphascience results
Analysis

Apollo 17's science debriefing yielded a surprise: unexpected X-ray background radiation blanketing the entire sky, one of the major results of X-ray astronomy from the Apollo program. The crew also detected possible extragalactic radiation whose spectrum didn't fit standard galactic dust reflection theory, interstellar hydrogen streaming through the solar system, and confirmed that the Coma cluster's gravitational binding agent wasn't ionized hydrogen (deepening the mystery of what holds it together). The extracted pages focus on astronomical observations rather than anomalous sightings, but the unexplained radiation findings are notable in context.

Key Findings
  • Unexpected X-ray background observed over the entire sky, a major result of X-ray astronomy from Apollo
  • Possible extragalactic radiation detected with spectrum characteristics that don't fit standard galactic dust reflection theory
  • Coma cluster composition remains a mystery — ionized hydrogen was ruled out as the gravitational binding agent
  • Interstellar hydrogen detected streaming through the solar system, with Gary Thomas (University of Colorado) analyzing the data
  • Enormous amount of UV/spectrum data obtained for long-term computer analysis
Page Extractions 3 pages

Page 1

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statushas_content
doc_typereport
classificationnone visible
page_descriptionTitle page of NASA Apollo 17 Crew Debriefing for Science document prepared January 8, 1973.
dates1973-01-08 | date document prepared
organizations
  • National Aeronautics and Space Administration (NASA) | government_agency
  • Science Requirements Branch | NASA division
  • Planetary and Earth Sciences Division | NASA division
  • Manned Spacecraft Center | NASA facility
locationsHouston, Texas | location of Manned Spacecraft Center
references
  • MSC-07632 | document identifier
  • MSC-07132 | mission reference number
  • OPR: MSC | office of primary responsibility
  • LOC: 080-44F | location code
  • NSL | signatory
quotes
  • "APOLLO 17 CREW DEBRIEFING FOR SCIENCE" | document title
  • "JANUARY 8, 1973" | date
  • "PREPARED BY SCIENCE REQUIREMENTS BRANCH PLANETARY AND EARTH SCIENCES DIVISION" | preparation information
  • "MANNED SPACECRAFT CENTER HOUSTON, TEXAS" | location

Page 2

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statushas_content
doc_typereport
classificationnone visible
page_descriptionTechnical debriefing discussion regarding astronomical observations including X-ray background and cosmic phenomena.
page_number119
people
  • Henry | mission specialist | Apollo 17 | speaker
  • Dr. Trombka | scientist | [agency unknown] | mentioned for gamma-ray background discussion
observations
  • Discussion of Coma cluster held together gravitationally
  • Possibility of ionized hydrogen holding cluster together
  • Search for Lyman-alpha radiation from ionized hydrogen
  • Red-shifted radiation from ionized hydrogen not observed
  • Lower limit set on ionized hydrogen possibility
  • Coma cluster composition remains mystery
  • X-ray astronomy background observed over sky (unexpected)
  • Gamma-ray background observed (referenced as Dr. Trombka's discussion)
  • X-ray background above expected dark count
  • Abnormally high dark current did not interfere with experiment
  • High galactic latitude observations made both north and south
  • Spectrum observed appears like spectrum of hot stars
assessments
  • Holds real mystery as to what is holding Coma cluster together | Henry
  • Fourth point (galactic observations) may turn out most interesting | Henry
references
  • Milky Way | observation reference
  • UV from stars | observation context
  • North Galactic Pole | observation location
  • South Galactic Pole | observation location
  • X-ray astronomy results | research area
  • Gamma-ray background | research discussion
  • Dr. Trombka's gamma-ray background observations | reference
quotes
  • "gravitationally holding it together. We though it might be in the form of ionized hydrogen." | Henry
  • "We looked for lyman-alpha radiation, red shifted from the ionized hydrogen, and we didn't see any." | Henry
  • "We set a lower limit, which certainly excludes the possibility that the Coma cluster is held together by this ionized hydrogen." | Henry
  • "I think that may leave a real mystery as to what is holding the thing together." | Henry
  • "The fourth point may turn out to be the most interesting thing of all." | Henry
  • "When you look in the Milky Way, you see a lot of UV coming from the stars, but the question is, what do you see when you look up to the North Galactic Pole or down to the South Galactic Pole." | Henry
  • "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" | Henry
  • "part of this is the gamma-ray background that Dr. Trombka talked about." | Henry
  • "In the UV, nobody knows, but you never know until you look." | Henry
  • "You do have to deal with this background of stars that we know is there." | Henry
  • "So we did look at a large number of different points at high galactic latitudes, both north and south." | Henry
  • "The spectrum that we see is above this dark count." | Henry
  • "In other words, this abnormally high dark current did not, in fact, interfere with that experiment." | Henry
  • "The spectrum that we see looks like the spectrum of the hot" | Henry (cut off)

Page 3

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statushas_content
doc_typereport
classificationnone visible
page_descriptionContinuation of technical debriefing discussing astronomical observations including spectrum analysis and Earth observations from space.
page_number120
people
  • Henry | mission specialist | Apollo 17 | speaker
  • Gary Thomas | scientist | University of Colorado | researcher on hydrogen radiation
  • Charles Barthum (or similar name, possibly illegible) | scientist | [agency/affiliation unclear] | researcher
  • [Unidentified crew member] | astronaut | Apollo mission | observer of Earth spectrum
observations
  • Hot stars within field of view for spectrum analysis
  • Light from hot stars in galactic plane going out of plane and reflecting off interstellar dust
  • Certain spectrum characteristics that don't fit standard star theory
  • Possible extragalactic radiation detected
  • Lyman-alpha hydrogen radiation observations from OGO-5 satellite
  • Enormous amount of data obtained on Apollo mission
  • Hydrogen inside solar system
  • Sunlight reflecting off hydrogen
  • Hydrogen from interstellar space streaming through solar system
  • Spectrum of Earth observed from outside
  • Multiple people have observed Earth's spectrum from space
assessments
  • Most conservative interpretation is light from hot stars in galactic plane | Henry
  • Spectrum characteristics suggest possibility of extragalactic radiation | Henry
  • Detailed computer study needed but will take long time | Henry
  • Gary Thomas believes hydrogen is from interstellar space streaming through solar system | Henry's report
  • Hydrogen data will clarify and straighten out the picture considerably | Henry
  • Detailed analyses of interstellar hydrogen awaited with great anticipation | Henry's statement
references
  • OGO-5 satellite | observation platform
  • University of Colorado | research institution
  • Solar system hydrogen | observation subject
  • Interstellar space | source of hydrogen
  • Extragalactic radiation | theoretical possibility
quotes
  • "star; however, we know that there were no hot stars within our field of view." | Henry
  • "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." | Henry
  • "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." | Henry
  • "I'm looking forward very much to the detailed computer study of this, but it's going to take a long time." | Henry
  • "Fifth point: Lyman-alpha hydrogen radiation is a completely separate problem, and Gary Thomas at the University of Colorado and Charles Barthum [?] observed this from OGO-5." | Henry
  • "We obtained just an enormous amount of data on the Apollo that's going to straighten out this picture and clarify it considerably." | Henry
  • "This is hydrogen that is inside our solar system." | Henry
  • "It's sunlight reflecting off this." | Henry
  • "The hydrogen, Gary Thomas thinks, is hydrogen from interstellar space streaming through the solar system, and he is looking forward with great anticipation to getting detailed analyses of that." | Henry
  • "One more thing: the spectrum of the Earth. I keep saying 'we,' but these were the guys that were there." | Henry
  • "We looked at the Earth from outside." | Henry
  • "A lot of people have observed" | Henry (cut off)
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