Sightings of venting from ATS 4 Centaur in 1968

From: Ted Molczan <>
Date: Tue, 11 Mar 2014 20:46:43 -0400
My search for visual sightings of re-entries has uncovered evidence of a couple of sightings of venting from the Centaur
of the ill-fated ATS 4 mission. I am passing this along for the benefit of anyone who may be interested in such
phenomena. I am also seeking comment on Sighting 2, during which the Centaur was at best poorly illuminated and quickly
entered eclipse. I am unclear as to how it could have been seen at all, let alone as bright as reported.

I will begin with a review of the sightings and the evidence linking them to ATS 4 Centaur.

Sighting 1: USNS Guantanamo Bay, Cuba

The first sighting is found among the NSA's declassified UFO documents, in this report from United States Naval Station
Guantanamo Bay, located near 19.94 N, 75.15 W:

Here is my more readable version of the body of the report:

<<< Summary

This report describes the sighting of a UFO. The possibility exists that it may be a decaying satellite as indicated in
Reference A.


1. Reference A. reported a satellite of Cosmos 234 decaying and indicated various track positions for possible
sightings. Reference B. reported a probable sighting.

2. The subject UFO was sighted at 110028Z by numerous personnel aboard ship in the GTMO area and by others aboard the
Naval base. The object was sighted to the north of NAVBASE GTMO approximately 60 degrees above the horizon, and on a
course of 130 degrees true. The object was glowing brightly and emitted what appeared to be a spiral trail of smoke or

3. Crewmen aboard the USS Barry and Lasalle managed to obtain Kodachrome photographs of the subject object. In this
respect, attachments (1) and (2) are hereby forwarded, for developing and information. >>>

The reported time of the sighting was 1968 Aug 11 at 00:28 UTC. Cosmos 234 decayed days earlier, so could not have been
what was seen. For a time, I suspected debris from the 1965-082 launch, but was not convinced of a correlation, and the
"spiral trail" was more suggestive of propellant venting than a re-entry. Before checking for possible sources, I
decided to look for other possible sightings.

Sighting 2: USNS Roosevelt Roads, Puerto Rico

I found a report in the Project Blue Book case files, of a similar, near contemporaneous sighting, by CDR. R. H. Healy,
at USNS Roosevelt Roads, in Puerto Rico, located near 18.22 N, 65.66 W - about 1,000 km to the east of Guantanamo. It
was not investigated by Blue Book, but filed for information. The six page record of the sighting begins here:

The documents reveal that Cdr. Healy initially wrote to NASA's Kennedy Space Center, 10 days after his sighting. KSC
responded with a form letter advising that UFO investigations were a USAF mission, and suggested he contact the Foreign
Technology Division (FTD) at Wright-Patterson AFB. On 1968 Oct 23, he apparently forwarded a copy of the same report he
sent to NASA, which seems to explain how it ended up in the Blue Book files. Here is my transcript:

<<< 20 Aug 1968

UFO sighting of 10 Aug 68

Dear Sir,

At approximately 2025Q on 10 Aug I saw a phenomenon in the sky I feel I should report to you. When I went out of my
house I saw a narrow, bluish-green band of light to the WNW that I at first thought was the aurora borealis - I realize
it is a northern latitude specialty. It ran from the horizon over Pico del Este Mt. to a point 60 deg above and over my
quarters at the U.S. Naval Station Roosevelt Rds P. R. I then noticed a bright, yellow-white light, with an elliptical
halo around it, slightly above the mountain and in the band of bluish-green light.

I called to my wife, as I thought maybe I was seeing my first flying saucer, and when I did so I took my eyes of the
object, and lost it. She noticed a white light which appeared to be the size of a first magnitude star moving in the
band of light.

It was then I realized that it was probably a satellite and that the band of light was more than likely reflected from
the sun which had set an hour or so earlier.

When the white light reached directly overhead it disappeared. There were no clouds. The band of light ran from 20 deg -
30 deg of arc in front, to the same distance behind, and moved through the sky with the white light, the "tail"
disappearing also at the overhead point. The white light transited the sky at about the same rate that I observed an
Echo satellite pass years ago in the Pacific.

I have had ten years flying experience, both in jets and props.

Enclosed clipping could be related.

Could you tell me if a satellite transited WNW to ESE over this area on the night in question. Also, what caused the
band of light? Is this unusual? >>>

The reported time of the sighting equates to 1968 Aug 11 at 00:25 UTC. As with the Cuban sighting, there was strong
evidence of venting, so I decided to check for recent launches that might correlate, which led me to ATS 4. I was
puzzled by the sightings having occurred well after a GTO burn would typically have been planned, until I remembered
that this had been one of the failed ATS missions. The historical record confirmed that the Centaur-ATS 4 stack had been
left stranded in LEO. The available TLEs reveal a close correlation in time and track with the sightings from Cuba and
Puerto Rico.

The launch of Atlas-Centaur 17 occurred on 1968 Aug 10 at 22:33:02 UTC. The Centaur's first burn achieved nearly the
planned LEO parking orbit: 29 deg, 220 X 769 km orbit, per the first TLE. The second Centaur firing, to enter GTO, was
planned to occur after a 61 min. coast, at the first ascending node, but the Centaur failed to re-start. The stack was
catalogued as 1968-068A / 3344, and decayed a couple of months later. The TLE history is available on Jonathan
McDowell's site:

Here is the technical report on the performance of Atlas-Centaur 17, published nearly four years after the launch:

It is unclear whether the investigators were aware of the above or any other visual sightings, but their findings and
conclusions derived from engineering analysis of telemetry seem to explain what was seen from Cuba and Puerto Rico. Here
are a few relevant excerpts:

"It is concluded, from the evaluation of the data obtained during the investigation, that
the most probable cause of the AC-17 failure was a cryogenic leak. This leak caused the
hydrogen peroxide to freeze in the boost pump supply line, thereby preventing hydrogen
peroxide flow to the boost pump catalyst beds. Consequently, the boost pumps did not
operate for Centaur main engine second start." Pg.32

On pg.33 we learn that the liquid-hydrogen tank was depleted at T + 5000 seconds.

"Flight data also recorded a disturbing torque on the vehicle during the coast period.
This disturbance began sometime during the period when no flight data were obtained,
between T + 805 and T + 1205 seconds. When data were reacquired at T + 1205 seconds,
the guidance and flight control data showed an unexplained increase in axial thrust of
about 4.5 newtons (1 lbf) and a change in the disturbing torques on the vehicle. Although
there were some variations in magnitude and direction, this disturbance remained on the
vehicle for the remainder of the coast period. An analysis was made to determine the
liquid-oxygen leak rate required to produce the disturbance seen on the vehicle. The
analysis showed the leak rate to be from 23 to 45 grams per second (0.05 to 0.10 lbm/
sec), dependent upon the exact location and direction of the leak." Pg.34

"Satisfactory telemetry coverage was obtained to T + 5500 and from T + 6000 to T +
6800 seconds, as shown in figure VI-56. ... Recurring data "dropouts" of less than
1 second duration occurred at the Kwajalein and Hawaii receiving stations during the
interval T + 4553 to T + 5130 seconds, because of varying signal strength. This
variation resulted from the changing relative position of the airborne antennas with
respect to the ground station because of the vehicle's tumbling motion." Pg.107

"At T + 4225.1 seconds the V-half-on mode was initiated and lasted for 40 seconds to
assure settled propellants for main engine second start. During this period the boost
pumps were commanded to start. Hydrogen peroxide did not reach the boost pumps and
main engine second start did not occur (see section Hydrogen Peroxide Engine and Supply
System). The vehicle continued to coast without attitude control and subsequently tumbled.
Because of the design of sequenced events, it was impossible to separate the
spacecraft." Pg.130

The sightings in question occurred between approximately T+6360 s and T+6540 s, during which telemetry was received from
the Centaur via KSC and Grand Bahama (Fig. VI-56, pg. 115), and C-band radar coverage was obtained from Patrick AFB,
Merritt Island, and Grand Bahama (Fig. VI-58, pg. 117). The investigation appears to have been thorough; I will leave it
to experts to judge whether it could have benefitted from the sightings.

The spiral effect noted at Guantanamo appears to be consistent with venting from a tumbling rocket. It is interesting to
note that venting was still evident more than 20 min. after the reported depletion of liquid hydrogen.

Visibility of the Centaur

The sighting from USNS Guantanamo, Cuba was aided by solar illumination of the Centaur for most of the pass. It entered
umbral eclipse at about 00:20:41 UTC, at azimuth 95 deg, elevation 23 deg. It is unsurprising that both Centaur and
plume were readily seen.

At USNS Roosevelt Roads, Puerto Rico, the Centaur rose in sun-light in the WNW, but soon entered eclipse, at azimuth
286, elevation 19 deg. During the illuminated period, the phase-angle was nearly 180 deg, so the vehicle was essentially
back-lit, and would not have been expected to have been visible to the unaided eye. Indeed, Cdr. Healy first noticed
only the plume, which he described as a "narrow, bluish-green band of light to the WNW that I at first thought was the
aurora borealis". He reported that it extended from, "the [western] horizon over Pico del Este Mt. to a point 60 deg
above and over my quarters at the U.S. Naval Station Roosevelt Rds."

Assuming that the elevation was not significantly over-estimated, as is the common tendency without benefit of
instruments, then for the plume to have been visible as high as 60 deg elevation, must have been because its length
extended above Earth's shadow. Picture the Centaur tumbling rapidly end over end, with the plume emanating from one end.
Healy may have been too close to the plane of the orbit to have noticed the spiral effect.

What is interesting is that Cdr. Healy "then noticed a bright, yellow-white light, with an elliptical halo around it,
slightly above the mountain and in the band of bluish-green light". Presumably, this was the Centaur surrounded by the
densest portion of the plume.

He lost sight of the object after he took his eyes off it to call his wife, but she then "noticed a white light which
appeared to be the size of a first magnitude star moving in the band of light." It is unclear whether that "star" was
within the solar-illuminated region, but as I noted earlier, it would not normally have been visible low in the west due
to the high phase angle.

Cdr. Healy understood that he was observing a satellite reflecting sunlight, and noted, "When the white light reached
directly overhead it disappeared", and with it the "tail". My experience has been that claims that something was seen
"directly overhead" tend to be overestimates. Mike McCant's Quicksat yields the following ephemeris that may aid in
understanding the circumstances:

  18.220  65.660    0.   USNS Roosevelt Roads     2000 30.0  0 F T T F T
***  1968 Aug  11  Sun morning  *** Times are AM UTC  ***  2332  922

 H  M  S Tim Al Azi C Dir  Mag Dys F  Hgt Shd  Rng  EW Phs  R A   Dec
 3344 ATS 4
 0 18 25      1 292   349 37.2   0 0  223 183 1566 0.6 158 1053  20.8
 0 18 46      3 291   342 29.5   0 0  223 163 1414 0.6 156 11 0  21.0
 0 19  7      5 291   345 26.8   0 0  224 139 1262 0.7 154 11 8  21.1
 0 19 28      7 290   346 25.2   0 0  224 110 1110 0.7 152 1118  21.2
 0 19 49      9 290   345 24.0   0 0  224  77  960 0.8 149 1130  21.2
 0 20 10     13 288   343 22.9   0 0  225  40  811 0.9 146 1145  21.0
 0 20 31     17 287   340 21.9   0 0  226  -1  665 1.2 141 12 5  20.6
 0 20 53     24 284   337 20.8   0 0  227 -47  524 1.6 134 1235  19.5
 0 21 14     34 279   334 19.6   0 0  228 -98  394 2.4 123 1322  16.9
 0 21 35     51 265   323 18.3   0 0  230-155  291 4.3 102 1442  10.6
 0 21 56     68 204 C 269 17.5   0 0  231-216  248 6.3  70 1644  -2.0
 0 22 17     51 145   216 17.6   0 0  233-283  295 5.0  38 1846 -14.2
 0 22 38     34 131   205 18.3   0 0  235-356  401 3.2  19 20 5 -20.1
 0 22 59     24 126   202 19.1   0 0  237-435  532 2.2  10 2051 -22.5
 0 23 20     18 124   201 19.8   0 1  239-520  674 1.6   8 2121 -23.7
 0 23 42     14 122   199 20.6   0 1  241-612  821 1.3  10 2141 -24.5
 0 24  3     10 121   196 21.3   0 1  244-711  970 1.1  12 2156 -25.0
 0 24 24      8 120   195 22.2   0 1  246-817 1121 0.9  14 22 8 -25.4
 0 24 45      6 120   195 23.3   0 1  249-932 1273 0.8  16 2218 -25.7
 0 25  7      4 119   196 24.9   0 1  252**** 1425 0.7  17 2227 -26.0
 0 25 28      2 119   192 28.0   0 1  255**** 1578 0.7  19 2234 -26.2

The pass culminated 68 deg degrees above azimuth 204 deg (SSW), when the Centaur was at 231 km altitude, and 216 km into
shadow. Although the plume may have extended into sunlight, it is unclear how sufficient light could have found its way
down to the Centaur, deep in shadow. Assuming that is how it happened.

Cdr. Healy's description of the tail extending 20-30 deg in front and behind the object suggests that it was indeed very
long. Considering that the report was not based on measurements, can any conclusions be drawn as to whether and how the
Centaur could have appeared as a mag 1 object well after entry into the umbra?

One possibility is that Cdr. Healy was mistaken, and it actually did disappear at about 19 deg elevation as expected,
but the plume remained visible longer because some of it remained in sunlight.

If we accept that the Centaur remained visible well past entry into the umbra, until it reached culmination or nearly
so, then by what mechanism could it have been illuminated to unaided visibility, let alone mag 1?

Ted Molczan

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Received on Tue Mar 11 2014 - 19:47:49 UTC

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