Astronaut Scientific Debriefings, 1962-1963

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It thus appears that there i s a strong i llusion whi ch exaggerates
angles near the horizon, and whi ch was evi dently also present i n MA-6, si nce
Lt . Col. Glenn also reports 7° to 8° as the height of the luminous band.
The
i llusion is perhaps comparable to the well-known illusion which makes the moon
seem larger near the hori zon.
Carpenter also noti ced and photographed the Glenn ef fect.
He reports
white objects resembling snowflakes, seen at sunri.se on all three orbits. '
However, he also saw these objects 7 minutes after the f i rst sunrise and agai n
43 minutes after sunrise; and zll, llm, 23m, 26ffl, 3(1!! and 45m after the second
sunri se. It i s thus quite clear that they are not related to sunri se, except
perhaps i n the sense of being most easily visible then.
Carpenter managed to photograph a few of these particles.
Some of them
were very considerably brighter than the moon, which was then very near the f i rst
quarter. At this t ime, the moon i s about -10; the particles may have been be­
t ween -12,5 magni tude (10 x bri ghter than the moon) and -15 magni tude (100 x
bri ghter than the moon).
The second i s -considered more l ikely, in vi ew of the
appearance of the full moon (-12,5) as shown on MA-6 photographs.
At -15 , the
particle brightness i s consistent with centimeter size snowflakes.
The
particles were verbally described by Carpenter as between l mm and 1 cm i n size ,
and having a strong visual resemblance to snowflakes.
Shortly before reentry, just at sunri se, Carpenter performed the de­
ci si ve experiment of hitting the capsule walls with hi s hand.
The blows promptly
resulted i n the liberation of large numbers of particles. It i s thus clear that
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at least those parti cles observed in the MA-6 flight emanated from the capsule .
The possibility that the particles might be dye marker or shark re­
pe l lant , both of which are green and both of which are exposed to the vacuum,
was considered by Mr. Frank M. Crichton, NASA capsule inspector.
Crichton had
test s made which demonstrated that nei ther material tended to escape f rom the