Documents / Report
This is the final report of the Scientific Study of Unidentified Flying Objects, conducted by the University of Colorado under Air Force contract F44620-67-C-0035, with Edward U. Condon as scientific director and Daniel S. Gillmor as editor. It was submitted to the National Academy of Sciences on 15 November 1968 for review. The report includes field studies, photographic and radar analyses, case studies, historical chapters and appendices such as the Robertson Panel report and the Twining letter.
wavelength of till' radio waVl'S which it u~:cs.
In the period since 1945 the technology has had an enormous devel-
opment so that nowadays there are elaborate networks of land and ship-
based radar systems. as well as radar systems carried by most airplanes,
which have become vitally necossary to the safe operation of civil and
military aircraft. In a.dition to the use of radar in connection with
navigation, it has hecome a valuable tool in meteorological work in
that distant rain storms can be detected by radar. Also the trails of
ionizeJ air left by meteorites can be detected and studied by radar,
providing for the first time the means for observing meteorites in the
daytime.
There are many popular misconceptions about radar. It is important
at the outset to realize that the returned radar ~ignal does not give a
:I 5h[1rpl~' focu~~ed imagp or picture of the obstac:lc that has been
detected. What one gets when it is displayed on a cathode-ray screen
is simpl~' a diffuse blob of light indicating that something is there,
In the direction the antenna is pointed (with some exceptions) and at
the distance indicated by the time delay between transmission and
reception of the hack-scattered pulse. Of course; a large airplane
gives a more intense signal than a flock of small birds at the same
ra~ge. and skilled operators learn to make valid inferences about the
nature of the object detected from other things that they know about
thl' g"neral situation tog'-'tr.cr with the Tngnitudc of the returned
signal.
It i:; imlJortant ;11 sec to re...:;ogni ze til,lt the propagat i on of the out-
I~OJn~ and the back-scat1:l'rl,d jluIses is ,JrJinnri 1y assumcJ to be recti-
1inear and at the no 1'111'1 1 speed of light, But. the' actllal propagation
is affecte·c! hy telllperature and humidity Jiffcrenc8 in the air path
along which tht' radio pulse travels, This can give risl~ to anomalous
propagation that l:; analogous to hut in ;:letail not iJentical with the
effect~ which ~ive risp to mirage~ in the propagation of light through
St'ch an atmosphere. Usually the raJar set t1lwrator docs not know
56
w:lvelcngth Dr till' J';tdill wave'S which it u~·cs.
In thc period since 1945 the technology has had an enormous devel-
opment so that nowadays there are elaborate networks of land and ship-
based radar sy~tems, as well 8S radar systems carried by most airplanes,
which have become vitally necossary to the safe operation of civil and
military aircraft. In a .. ditlon to the use of radar in connection with
navigation, it has hecome a valuable tool in meteorological work in
that distant rain storms can ce detected by raJaI'. Also the trails of
ionizetl air left by meteorites can he detected and studied by radar,
providing for the first time the means for ob~erving meteorites in the
daytime.
Th':1"(' are many pO]1\:1ar misconceptions ab~)ut radar. It is important
at the outset to realize that the returned radar ~ignal does not give a
:1 sharpl!' focu!':!"ed imagp or picture of the obsta<:le that has been
detected. What one gets when it is displayed on a cathode-ray screen
is simply a diffuse blob of light indicating that som;:'l:hing is there,
In the direction the antenna is pointed (with some exceptions) and at
the distance indicated by the time delay between transmission and
reception of the hack-~;cattered pulse. Of course, a large airplane
gives a more intense signal than a flock of small bjrds at the same
rarge, and skilled operators learn to make valiJ inferences about the
nature of the object detected from other things that they know about
the general situation toger~2r with th~ D1 lgnitude of the returned
signal.
It i~; inlJlortant ;11s" to recognize tlwt the pr()pa~ati(Jn of the out-
1~()JI1~ and the bClck-scaUl'r(,d pulses is ,Hdilwri 1:, assumeu to he recti-
1 irw<ll' and at tht' normal sJlt'cu of I ighL. But till' actllal pTPpagation
1:; affcctc·d hr tl'mpt'l'ature <lnd humidity diffclcnca in the air path
along which tht' r'ilJi0 pulse travel!;. This can give r.:sc to anomalous
prnpagatioll that l:; analogous to hut in ::1ctail not identical with the
effect, which ~ive ris€' to miragC',; in the pr'Jpagation of light through
:5\':::h an atmosphere. Usually the radar sct o)X'f'ator docs not know
56 Report, from the classic collection. The PDF is mirrored here; the original link is under it. 1497 pages are in the text index: search them above, or from the library's search.