tn additiol1, the a~tronallts' vision was tested both bt>fore and
after the flights and tIle test results I~ere compared with preflight
measurements. lbere were no significant differences in the level
of thei r acui ty J us 5hOll'l1in the following tabulation of test j'esul ts:
Astronau1: Preflight + Postflight
n.s. O.D. o.s. 0.0.
Cooper F,lT 20/15 20/Ei 20/1S 20/15
Near 20/1:; 20/15 20/20 20/20
Conrad Far 20/15 20/1 5 20/12.5 20/12.5
Near 20/15 20/15 20/1S 20/15
H0111lUIl \'ar 20!lS 20/15 20/15 20/15
\l,'ar 20/15 20/15 20/1S 20/15
1.0\ e 1:I F:ll' 20/1:; 20/15 20/1r, 20/lS
Near 20/15 20/1 S 20/15 20/15
Ii is clear that the IlIcn selected to part.icipate in the space program
of the U.S. have 0xcellent cycs.ight and that ;'l~ level of performance
is sustained over long and tiring f1ight~.
~t the same time, a hindrance to top obscr ing pcrfo~~ance was that
the astronaut~ were n~ver thnroughly dark~adapted for any length of
time. Gcod dal"k-:hlaptatioll is achieved ~o':~c ~O minutes after the eyes
are initially subjcc"ed to darl:ncss. fI' enl orbit periaL! was ~)[)
ll1inl.ltes durin!: \',hkh tlH' a~trOl1auts were III full sunt i~ht for 4S lll1n-
lltl'5 ;tnd in darKn,,~1' for ".S minutes. The :istronuutc:; therefore \~ere
flllJ~' u3rk_HdapteJ fM' only 1;; 11Iil\lltes out of every ~)O ndnute orhit
(asswnill!1 no cabin 1 il1hts).
~'!~~~~\j~-()~~
The first Anwricl1n to go j rHo orhi t, astronaut .John Glenn. (~1A-G)
rl.·portl'd observing 1111 :lfHlulal' rinl
H0111Hlil \'ar 20/l5 20/15 20/1S 20/15
\'.'11 r 20/15 20/15 20/1S 20/15
I.U\C t:I F"l' 20 II~; 20/1 S 20/1'i 20/15
Near 21) /1 S ZO!1:; 2(J /15 20/15
11 is clellt that tile lilen sC'll'l.'tcd to parti d pa te i II the space program
of the U.S. have ('xcel1cnt eycs.ight and that: :'1: level of performance
i~ sUHtBined over long and ririnR fli~lts.
~t the same time, a hindrance to top obscr ing pcrfo~Rancc wa~ that
the as tror1aut~ \'I('1'e !1('vcr thnrough ly clark -adapted for any 1 ellgtl1 of
time. Gcod d:wk-8uaptation is achieved ~o,::e :SO minutes after the eyes
are initially subjcc'-eu to darkness. 1\' I.'nl (;rhit perioo war, ~)[)
11)illl.ltes durin!: Ivhkh t)!(, a~trollauts \\IPTe' III full sun! ight for 4S ndn-
\ltt'S and in darknC'~~ for ,'.S minlltes. The Hstronilut<; therefore Ivere
flllJ~' u[ll'LadaptC'd fM' only IS III.illutes out of cvcry ~)() l1IinutIC orhit
(as~umi!1~ 110 cabin lights).
~'.Il.£...NJ..s.I:.!._~\j~y~~
The first Amcrlcull to go into orhit, llf,tl'OIlUUt .lohn Glenl1. (~1A-(»)
l'l'l'0rtd observing Illl ,'ntHlla:r ril1~ flr,)lmJ the hart zon during sotell ite
2H9