F. LOUANGE

The Panel recommends that, given a new alleged UFO photograph, the decision to invest effort into its investigation should be taken only if both of the following conditions are fulfilled:

1. the original documentation (negative, slide, videotape) is available, and
2. there is at least one other independent source of information - either witness testimony or some other physical record.

If, after visual examination, the displayed object has not been identified (planet, balloon, cloud, etc.), investigation should be performed in two steps:

Step 1 consists of establishing or rejecting the authenticity of the photograph (or other record), taking into account evidence for unintentional false operation of equipment and various spurious phenomena that may affect the recording equipment. However, this concept of authenticity is at best relative, since in this area of investigation only negative conclusions may be considered as final, so that authenticity can never be demonstrated absolutely.

Step 2, if warranted, consists of extracting as much information as possible from the photograph or other record, so as to obtain as much information as possible about the object of interest (size, shape, distance, albedo, emitted energy, spectrum, etc.).

When the original film is available and analysis seems justified, all technical data concerning the site, viewing conditions, camera, film, processing, etc., must be collected. If the camera is available (in an ideal case still loaded with the original film), it must be used to perform the following calibrations:

1. Photos of density patterns for relative photometry;
2. Photos of sources calibrated in intensity, in various positions in the frame (for absolute photometry);
3. Photos of spatial frequency patterns, to determine the modulation transfer function (MTF); and
4. Photos taken at the same site as the original, eventually with models to simulate the object.

The film should be processed under rigorously controlled conditions (if it has not already been processed commercially). If the camera is available but empty, the same operations should be conducted with a film of the same type as the original.

The investigator should visit the original site and make measurements concerning the three-dimensional geometry of the observed landscape or this information should be extracted from detailed maps. If the photograph has been acquired at nighttime, an astronomical map of the sky at the time of acquisition will be necessary. The investigator should determine the meteorological conditions from the official offices or air bases in the neighborhood with particular attention to the horizontal visibility. The investigator should also take into account all quantified or quantifiable elements of the witness testimony including the estimated shape, angular size, velocity, color, etc.

For analysis of the photograph, it is essential to work from the original negative. This should be carefully washed and examined under a microscope to look for possible tell-tale artifacts and scratches, and to check the regularity of the grain structure so as to detect multiple exposures. The negative should be analyzed by conventional photographic instruments (enlarger, projector, etc.), and the information on the negative should be digitized by a microdensitometer.

Once digitized, the image may be analyzed by computer analysis, using the classical tools of contrast enhancement, noise suppression, contour detection, restoration, etc., and more specialized techniques such as maximum-entropy analysis that may be used to remove the effects of target motion and/or camera motion. Such analysis will assist in the detection of a possible hoax. For instance, a suspension thread may be brought into evidence through standard differential operations. Also, one may estimate the distance (hence the size) of the object through MTF computations, based on an analysis of atmospheric diffusion and contour blurring. If there are black areas on the object, it is possible to obtain estimates of the distance by comparing the luminance of such regions with other identified black parts of the scenery. If the object is nearer than the minimum depth of field, one should be able to detect geometrical distortions in the image. If the operator had a slight movement while taking the picture, analysis of the corresponding blur on the object and on other elements of the landscape may allow the calculation of a possible range for the distance of the object.

In the case of a color photograph, one should carry out the above procedures in three steps using three appropriate color filters for scanning.

If an event is recorded on a cine camera, each frame may be analyzed as above. However, it is now possible to obtain additional information by combining and comparing the sequence of images.

V. R. ESHLEMAN

A recurrent theme in certain UFO reports is the concept of an apparition that flies in formation with an aircraft-borne observer. Without making a judgment on any such reports, we could recommend that UFO investigators familiarize themselves with natural phenomena that display this "flying-in-formation" characteristic. Greenler (1980) is a useful resource, from which the attached list was made. The precise mechanisms for the origin of most of these phenomena have been determined and are explained in Greenler, but quite a few have still not been deciphered satisfactorily. Even an experienced observer might be surprised in seeing a particularly rare example. I have studied certain related phenomena in my research involving electromagnetic probing of planetary atmospheres, but was quite astonished a few years ago when I saw a particular example of the following list. A bright white light flew for minutes in perfect formation between my aircraft and the ground, with the air below and above apparently being transparently clear.

Formation flying phenomena:

Arcs: Kern, Lowitz, Wegener anthelic, Hastings anthelic, Tricken anthelic, Parry, alternate Parry, suncave Parry, sunvex Parry, upper tangent, lower tangent, supralateral, infralateral, circumzenithal, circumhorizontal, anthelic, subanthelic, contact.

Halos: Hevel, 8 degree, 18 degree, 22 degree, 46 degree, circumscribed.

Bows: fog, cloud, dew, supernumerary.

Rainbows: primary and secondary; direct and reflected; raindrop and ice crystal; white, red, and red-to-blue.

Pillars: sun, moon, city-light, anthelic.

Rings or Circles: Bishop, Bottlinger, parhelic, subparhelic, coronal.

Dogs: sun, moon, elongated, subsun.

One should also consider: Nighttime: moon, Venus, Jupiter, bright stars, etc., gegenschein, zodiacal light, comet, in-cabin light reflected by window.

Other forms: glory (specter of the Brocken), subsun, wet and dry heiligenschein, seven suns, lenticular and other distant small clouds, several different kinds of mirages.

V. R. ESHLEMAN

It is possible that some of the radar cases presented to the panel have a natural explanation. It seems likely that some possible natural explanations could be investigated without cooperation or assistance from the controlling military authorities except for a time record of unidentified traces that occur during designated test periods.

Some of the observations suggest that time-variable atmospheric ducting may on occasion result in echoes being obtained from distant ground locations as a result of refraction. Some of accounts described (a) groups or swarms of echoes that persist for some time in the same general location; (b) apparent trajectories of echo sources that exhibit sudden changes in the vertical and/or horizontal positions; and in particular (c) the tendency of apparent echo sources to concentrate over mountain tops. These are all characteristics to be expected of ducting conditions due to weather. These effects can come and go over long periods of time and they can also lead to scintillation or other changes over short time periods. (See, for instance, Hall & Barklay 1989.)

An atmosphere is said to be "superrefractive" when a horizontal light or radio ray curves downward with a radius of curvature that is less than the distance to the center of the planet. The atmosphere of the planet Venus is at all times globally superrefractive below an altitude of about 30 kilometers. In principle, echoes could be obtained from every area of the spherical surface of Venus from a radar system located at any position on the surface. If the air of Venus were perfectly clear, an observer would see all areas of the surface, all areas repeating in range to indefinite distances. In the four giant planets also, the large gradients of refractivity (or density) in their atmospheres produce superrefractive conditions.

The Earth's atmosphere is normally not superrefractive. However, common weather effects (in particular thermal inversions, where the air temperature increases with altitude, and/or the water-vapor content decreases with altitude) can and do produce regions of superrefraction that are localized geographically and in height. As a result, atmospheric ducts (channels that trap and conduct radar waves) can form that carry the signals far beyond the normal horizon. Such ducts can bend rays down to a distant surface area or, more easily, to a distant mountain top. Backscattering of the radar energy from the ground or from discrete objects on the ground then results in echoes that appear to the radar to be due to a target that is far away and (if the angle of elevation of the returning energy is measured) high in the atmosphere. A similar transient ducting of sound can produce the experience of hearing the whistle of only one particular train out of the many that originate at difference times from a busy track in the next valley.

As is well known, atmospheric ducting is the explanation for certain optical mirages, and in particular the arctic illusion called "fata morgana" where distant ocean or surface ice, which is essentially flat, appears to the viewer in the form of vertical columns and spires, or "castles in the air."

People often assume that mirages occur only rarely. This may be true of optical mirages, but conditions for radar mirages are more common, due to the role played by water vapor which strongly affects the atmospheric refractivity in relation to radio waves. Since clouds are closely associated with high levels of water vapor, optical mirages due to water vapor are often rendered undetectable by the accompanying opaque cloud. On the other hand, radar propagation is essentially unaffected by the water droplets of the cloud so that changes in water vapor content with altitude are very effective in producing atmospheric ducting and radar mirages.

With regard to "impossible" flight paths that may appear to be indicated by some of the echoes obtained by military radars, it is important to note that the records presented to the panel are based on measured time delays and measured elevation and azimuth angles-of-arrival of the reflected energy from the echoing object. As presented, certain target positions were plotted as height versus time. But height is computed from two parameters: (1) the measured time delay, which is a very good indication of range; and (2) the measured vertical angle of arrival, which may not be a valid representation of the vertical direction to the target. In particular, when ducting occurs, reflections from distant and distinct surface targets (buildings, bridges, trucks, etc.) may be received at elevation angles of several degrees, so that a ground target at a range of 100 kilometers, for example, would appear to represent an object at a height of several kilometers. Atmospheric turbulence would distort the duct and could cause sudden changes in angle of perhaps a few tenths of a degree, which would be interpreted as a sudden change in altitude of the order of half a kilometer. The horizontal angle of arrival would also be affected by turbulence, adding to the chaotic character of the apparent flight path.

V. R. ESHLEMAN

One of the optical displays reported by E. Strand may be of special significance as a tentative bridge across the wide gulf that exists between the UFO and scientific communities.

Two women reported an unusual, colored, intermittent light display that slowly moved over two hours of observation made from a remote cabin in Norway in the post-midnight hours of August 3, 1991. The sky was clear until the end of the observation period, when a few clouds moved in. The key point about this display is that while there was no local thunderstorm activity, there was an electrical storm in the direction of the display, but the storm was 120 kilometers away. For decades, it has been conventional scientific wisdom that all of the visible electrical activity of such storms is within and below the clouds, that in this case would have been below the observers' horizon.

Recent developments in the observations and theory of electrical activity in the high atmosphere (mesosphere and low ionosphere) demonstrate that this conventional wisdom is in error (see, for instance, Pasko et al., 1996; Sentman & Wescott, 1995). Some of the reports of observations in the Hessdalen area could be related to phenomena that occur above storms, up to an altitude of nearly 100 kilometers, well above the observers' horizon. This electrical activity goes by the names of "blue jets," " red sprites," and "short-lived elves." There have in fact been sporadic reports of these phenomena decades ago, but these reports were dismissed by the "experts." Now these events have been captured on film and video.

V. R. ESHLEMAN

My perception is that the SETI (Search for Extraterrestrial Intelligence) and UFO studies of a decade ago shared positions beyond the pale of "respectable" science. They no doubt still do in the view of many scientists. However there have been several fundamental advances during the past few years that indirectly provide some increase in plausibility for both areas, and the SETI community seems to be responding with renewed vigor. It may be useful for our panel to consider some UFO-SETI comparisons, and the different cultures of their respective participants. These are my personal and incomplete thoughts on this subject.

There have been recent advances concerning the question of the possible existence and state of extraterrestrial life (ETL). Knowledge that there is such life would increase the presumptive probability of extraterrestrial intelligent life (ETIL). SETI investigators search for the latter mainly by examining the radio spectrum for telltale electromagnetic signals that may be purposely sent or inadvertently leaked from a technological society. UFO investigators may invoke visitation by ETIL as a fallback or default explanation of an apparition or event which they believe cannot be explained any other way. There are huge gaps in our knowledge that must be filled in before we can pretend to understand either of these subjects.

With regard to the first question, the existence and possible abode of ETL, three major recent developments are of particular note:

1. It is only in the last few years that we have finally obtained direct evidence of the existence a planetary-sized body orbiting a star other than our Sun. We now have evidence for several (of order of 10), and more are being discovered as the Doppler observational technique is being improved. There are billions of stars in our galaxy alone, and these results suggest that stars may quite generally be accompanied by planets. One may expect that conditions on these planets would vary over a wide range, at least as wide as the range covered by the planets of our solar system. (See, for instance, Cosmovici et al., 1997.)
2. Life that is fundamentally different from nearly all near-surface life on Earth has been found deep in terrestrial rock and in the deep ocean, where it exists under conditions long assumed to be so hostile as to be sterile. It would appear that near-surface and subterranean life forms are essentially independent and that either could exist without the other. It is also possible that life started several different times on Earth after epochs of total extinction caused by asteroidal and cometary impacts. These new findings suggest that life might have started independently at two levels on Earth, or that life can adapt to extraordinarily different environments. The development of life, under conditions that are thought to be favorable and under conditions that we previously thought to be unfavorable, may be the rule rather than the exception for the innumerable planets that probably exist in our galaxy. (See, for instance, Cosmovici et al., 1997.)
3. A meteorite found in Antarctica and known to have come from Mars (from isotopic "fingerprinting" of its elements) has several detailed internal characteristics (structural, chemical, and elemental) that may, it is claimed, be attributed to effects of ancient microscopic life indigenous to Mars. (McKay et al.,1996). This interpretation is controversial and research on this and other meteorites is continuing.

These subjects are currently being investigated widely and were featured among the many areas discussed at an international meeting in July 1996 held in Capri, Italy, on the subject of Astronomical and Biochemical Origins and the Search for Life in the Universe (Cosmovici et al.,1997). About 200 astronomers, biologists, chemists, physicists, and other scientists from 27 countries met for this Fifth International Conference on Bioastronomy and Colloquium No. 161 of the International Astronomical Union. This meeting was supported by international and national scientific organizations including the International Astronomical Union, the International Scientific Radio Union, the National Aeronautical and Space Administration, the European Space Agency, the Consiglio Nazionale delle Richerche, and other Italian organizations; clearly, this was a mainstream scientific meeting. The SETI community was very visibly represented in all aspects of the conference, but the problem posed by UFO reports was never mentioned.

However, the UFO and SETI communities share defining attributes including a surfeit of putative evidence that remains unidentified, and the lack of a single example that can be unequivocally verified, repeated, understood, or captured. That is, both are subject areas of investigation that totally lack identified objects. Then why is one moving into the mainstream of acceptable science while the other is not?

It may not be generally realized that the several different groups of SETI observers have received and tabulated an appreciable number of URS, or unidentified radio signals, in the course of listening to billions of radio channels for hundreds of thousands of hours, looking in tens of thousands of directions. They measure signals that are noise and signals that range up to many times stronger than can be explained in terms of natural noise. They identify nearly all of the strong signals as coming from radio and TV stations, from military radars and various kinds of communications systems, from satellites and deep space probes launched by various national and international organizations, and from many kinds of equipment that leak electromagnetic energy over broad spectral bands. After very thoughtful and vigorous winnowing, there has been a residual number of strong signals received by every group that are, and will no doubt remain, unidentified. But these are not described and released to the media as something unusual or mysterious. This is because they could not be verified by other observers or by repeat observations at the same frequency and in the same direction in the sky. Improved techniques and protocols are being developed to markedly reduce the frequency of URS (even to the point where there may be concern that a real ETI signal could be discarded). Nevertheless, it is to be expected that continuing URS will persist in the SETI endeavor, and will remain unidentified and undiscussed.

The SETI participants include a large fraction of scientifically trained radio astronomers, and they employ complex and expensive equipment that includes the largest antennas and most sensitive electronic and digital systems in the world. The UFO community is much broader and diverse, and cannot bring to bear the instrumental firepower that is routine in SETI research. In fact, no equipment is involved in most UFO case studies. The nature of UFO phenomena is such that it would be unreasonable to demand repeat observations of the same kind of incident and independent confirmation of events by different observers.