NASA-UAP-D5, Apollo 17 Crew Debriefing for Science, 1973

CL FLU AER

MSC-07632
H NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

© APOLLO 17
‘CREW DEBRIEFING

FOR SCIENCE

JANUARY 8, 1973

PREPARED BY

SCIENCE REQUIREMENTS BRANCH
PLANETARY AND EARTH SCIENCES DIVISION

INDEXING DATA
DATE soOPRs T PGM SUBJECT SIGNATOR a

‘Merete pineal Neate eaten
\aeeilatamne inet: salam tes eacaaernenamarenenerereefaiites enone

MANNED SPACECRAFT CENTER.
HOUSTON,TEXAS

COE 4% 1228

HENRY
(CONT'D)

119

gravitationally holding it together. We though it might be
in the form of ionized hydrogen. We looked for Lyman-alpha
radiation, red shifted from the ionized hydrogen, and we
didn't see any. We set a lower limit, which certainly ex-
cludes the possibility that the Coma cluster is held together
by this ionized hydrogen. I think that may leave a real

mystery as to what is holding the thing together.

The Socentil point may turn out to be the most interesting
thing of all. 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. One of the most exciting
results of X-ray astronomy was the fact that an X-ray back-—
ground 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
— and south. The spectrum that we see is above this
dark count. In other —"e 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

120

HENRY star; however, we know that there were no hot stars within

(CONT'D)
our field of view. Therefore, the most conservative inter-
pretation, 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.

Fifth point: Lyman-alpha hydrogen radiation is a completely
separate problem, and Gary Thomas at the University of
Colorado and Charles Barthum [7] observed this from OGO-5.
We obtained just an enormous enount of data on the Apollo
that's going to straighten out this picture and clarify it
considerably. This is hydrogen that is inside our solar
system. It's sunlight reflecting off this. The hydrogen,
Gary. Thomas thinks, is hydrogen from interstellar space
streaming through the solar system, and he is looking for-
ward with great anticipation to getting detailed analyses

of that.

One more thing: the spectrum of the Earth. I keep saying
"we," but these were the guys tha…