Astronaut Scientific Debriefings, 1962-1963

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DRAFT OF NOTE ON THE SCIENTIFIC OBSERVATIONS
Toward the end of the flight, between 16 hr and 47 min (UT) and 17 hr
and 03 min (UT), 24 May 1962, Lt. Cdr. Carpenter made a series of observati ons
on a l uminous band visible around the horizon.
The most decis i ve observat i on
was made wi th an air glow f i lter supplied by Mr. Iawrence Dunkelman of Goddard
Space Flight Center.
The f i lter transmits a narrow band of wavelengths,
approx i.mately 11 Angstroms wi de at the half power poi nt and centered at t he
wa,ve length of the strongest radiation of the ni ght a i rglow, namely 5577 Angstroms
The f i lter cut out all other Ught, but passed the light of the , luminous band,
which i s thus identi f i ed as the 5577 l ayer .
Lt. Cdr. Carpenter noted that the layer was very bri ght.
He f ound
t hat Phecda:Ursae Majori s, magn itude 2.5 was lost to si ght at the brighte st
part of the layer.
Assuming that the image of Phecda occupi es about 1 SY.Uare
-8
o_,)J­
mi nute of' arc on the retina, or 8.18 x 10 steradi ans,
O.ssuming that a star of
6
2
magnitude o.8 yields 10-
lux (1umensJm ) we f i nd that the brightness of t he
l ayer i s about 3 lumen1m2 )(steradian) or 3 x 10-4 sti lbs.
Thi s i s e~ui va lent
~t
(S"-~)
t o about 4 x 104 erg;,m2 )(sterad:i.anh_, taking the least mechani cal e y_ui valent
of light as 1. 6-1 x 10-3 watts per lumen f or 556o A as per the AIP handbook.
It
is about 50 t imes as bright as a white surface i lluminated by moonlight.
The angular hei ght of the layer was found i n 5 di fferent ways :
1.
By direct esti mate - 8° to 10°.
2.
By noti ng that it is approximately twice the height of
t he twilight layer.
Lt. Cdr. Carpenter estimated the hei ght of the twi light
l ayer a,s 5 sun diameters , whi ch means 2-1/2 degrees, hence the hei ght of the
5577 layer would be 5°.
3.
By observation of the star Phecda (ju Ma) as it passed
t he middle of the luminous band.