• _tT ri s r ma coi· s qi_ _3 ·_ PAGE S NO _ Of• _ti_ COPIES SERIES 8 __ 21 July 19U5 · · m r Fy Authority of the District Engin•e TO ·Major Gen Groves The test was performed t-wo days ahead of th tentative scliedule b ecm se everything of importance to t he test was ready 1 2 • A study of 'the weathe r indicat ed that a Vlq'i_e ty of wind directions at slow speeds going in general N W and N E could be expected with different directi ons and speeds at different levels for 1-6 and 17 July 945 These slow winds would ·be advantageous in localizing the outfall of ac tive material from th e cloud to the site an nearby desert a eas They would alsQ dilute the outfall OOst effectively i n the early hours of the life of the cloud when it would help t he most The monitoring problem would be worse holllever because of the wide area covered · 3 In the two days ava le the population of the surrounding areas was located by 0-2 on larp scal e' maps for a radius of 75 to 100 miles The deserted areas correspondetl fortunately to the most probable courses of the · outfall from the cloud a a predicted by the directions of the winds at the various altitudes Troops under lajor Palmer were available if mnitoring indicated that evacuation was necessary - · 4 At zero miil lB five hours five cars with Dr J Hoffman in charge were stationed with Major Palmer and troops at the outlet road near the east-west highway-' ¥380 They were in radio conummi cation with Base Camp and Post #2 Outlying monitor cars were in San A ntonior Roswell Carrizozo md Fort Summer to cover these areas in case the speed of the cloud was greater than predicted oJ r-- 5 Dr Aebersold was in general charge of the monitoring at Base Camp and t he three shelters at · l 0 000 yards with 1 ocal telephone and radio collll Um cation There was a technician mnitor apd do tor in each shelter and at Base camp - - _- i --- 6 Dr HelllP 8Lnann in charge of all the monitoring program was at S 10 000 the center of colllllllnication· ang fina 1 decisions ·also Brig n Dr • bppenlieimer Dr Ba bridge Mr• Hubba rd etc • F r -l 7• ·Thi s officer acted ·as liasion in a secondary COJlllllln cation' center in Base Camp l t i- · Friedell was locate 1dth 0-2 at Albuquez que as another collllIUDi cailon cent er via ODP distance for cont ollil g t'M field monitorigg iii case · · Base Cjmp qommunic mr· • All ps re kqed in 1 ' d_entic l - maps 111011 1 ng px e-l1h lnary locai1 ot s of the lilo t_heir presume' course· t fe · two possibl paths of the cloud WNVf and NNE de nding upon th tj tu le -which · · it reached houses and nearby ranges · etc ••• _ aod · th · •• liminary plans submitte 1 tr Sff rm r•· • -' · ··· r 't ------ ---------- y · ·o t Jl M _ · - r Jff- lnRtfi _· fmt Y _ 1 • n1 ol J r l 1 m s1on f _ _ I I to iD 1 · •lel S iftff · ' · ldm y j £ ' - - - Eill' i o riS -N tJ D_'13 ¼ ''ll n fh _ -' • Jt 2 • -2- 4t l _ July_ 1945 f 9 The shot -was fired at 0530 on 16 July 1945 The energy developed in the test - s several times greater than tllat expected by scientific group The cloud column mass and top i eached a pbenomfnal height variously estima ted as 50 000 to 70 000 f eet It remained towering over the - northea st com r--0£ the site f or ·several hours This was surficient tin e-for the majority 0 £ the laz gesh_part i cl to fall out Various levels were seen to move 1n different directions In generar the- lower one-third di'ttteiLeast-rd the middle portion to the west d· northwest while the upper thiro moved northeast Jlacy small she ets of dust moved independently at all levels a1 d large sheets • rem ined practically in situ By zero plus 2 h ours the ma in masses were no ·longer identifiable except for the very high white mass preswnably in t he stratosphere 10 By o800 hours the monitors reported an area 9f high intenait y in a canyon 20 miles northeast of zero Since this '1'8 S bf yond the tolerance set and equally nigh intensities were expected in other areas four more monitor cars were sent into this northeast area from 3ase Camp 'nle roving monitors in t his area were each ac compani d by a trooper in a 4 wheel dr ive lnd· authorized to evacuate families if necessary · At no hOU le in this whole north and northeast area between 20 miles and 40 miles zero was a - dangerous intensity · found The highest _ intensities fortunately wbre only found in deserted regions The highest found is shO III in detail attached 11 Intensities in the -deserted canyon were high enough to caus e serious physiological effects lL The distribution over the countryside was spotty and subject to local 'linds and contour It skipped the nearby highway #380 20mi N E except for low intensities which -re equaled at twice aIJd three times the distances It is presumed that the largest outfall occurred in the N E quadrant of the site This can only be explored by horseback at a later date 12 The monitors all t ook considerable risks knowingly and many· have received exposures of considerable amunts i e 8r total This is safe within a considerable margin They should not be exposed to more radia tion within the next month · · • • · 13 The dust could be measured at low int ensities iOO np les north and northeast of the sij e oa the L th day Attached 1 2 There is s till a tremendous · quantity of radi oactive dust floating in the •air• 14 Neither t he Base Camp or the _shelters were- contaminat ed very lllllCh 15 Partiall - evicera teq dead wild jack rabbits were found inore than 800 ya nis from zero presullllbly killsd by' t t e pl l5t _ A house 3 miles away had focrs tQfn lc v and llllf f ered ot ller extensive _c -age - _ - Jarm • o6 • • • - • • - r ·- - - -- ' - • _ 16 Details in cating blast heat and othe - ef f' ects rked--out until the area around the crater J'cipol a _down' ' · It is this of ficer's opinion however that lethal or severe casualiti s would occur in expos ed personnel up to two miles f r om a variety or combinat i on of caus es ie blast heat ultraviof et and mis sles • ·· · • - • -3- 21 July 1945 f The light intensity was sufficient at nine ml lee to have caused temporary blindness and this would be longer lasting at shorter distances Several observers at 20 mil el were bothered by a '1arge bl l nd spot for 15 m inute11 after the 11hot· The light ·together with the heat and ultrav 1 ol t radiation would • probably cause severe daDBge to the unprotected eyes at 5 miles damage · ___J uff l cient to put personnel out of acti m'l everal days if' not - permane ltJ- ill - of7 l le personne J -obeyed the safety- precautions turing the test eo that-n such injury resulted 17 A great deal of experience was obtained on the requirements for quick and adequate monitoring Excellent' radio colllDllJrl cations good transportation and better and m ire rugged meters are required 18 It _is this officer's opinion based on the d amap to •Jumbo• 2400 ft the extent of the g' yl zed sand a11 up to 500 ft • the extent of the cleaned off areai about 1 mil e the farm house at J miles • that this explosion was a great many times more violent than the· 100 ton test Conservative• estimates by the scientific groups put it at least equivalent to 10 000 tolUI· of T N T ' -1 9 While no house a vestigated received a dangerous amunt ie no IDre than an ac cullllll d two weeks dosage of 60r the dust outfall from the various porti ons _o f the cloud was potentially a very dangerous hazard over a band alm ist 30 miles wide extending alm st 90 miles northeast of the site 20 It is this officer's opinion that this site of a similar test of this magnitude except under It- is reco111JJendj 9d that the site be expanded or a radius of at least 150 miles without population be repeated is too SJll1lll for a repetitinn very special condftione larger one p11eferably with a be obtained if this test is to - Chi6t of Medical Section SLW fp J lµlhattan District c Jaj Gen Groves 2 R Oppenheimer 1 Col Warren • 1 - - -- J --- t J'v· a ·