Shortly after he began filming, he was startled to hear a gunshot, and seeing the President raise his arms, he first thought that the President was morbidly play-acting being shot [2, p. Zapruder kept filming while another shot rang out, this one fatally wounding the President in the head. The film was initially withheld from the public given the disturbing graphic violent content , but it was utilized as evidence by the U.
The bipartisan Warren Commission or WC for short was necessitated after the primary and only suspect in the crime, a local man named Lee Oswald, was himself murdered two days later by a local vigilante named Jack Ruby.
The Commission considered the question of a conspiracy, but ultimately found no compelling evidence of one [3, p. Three additional independent U. The stir it created is not surprising, given the sequence of events depicted in it, namely the graphic violence, especially the depiction of a fatal wound to the head caused by a high-powered military rifle bullet, something that ordinary citizens would not have had an inkling about in that era.
Responding to such claims, the illustrious Nobel-prize winning physicist Luis W. Alvarez would shortly thereafter publish his own analysis of the Zapruder Film [10]. Alvarez examined a number of different questions being posed at the time, including the number of shots based on jiggle analysis , the shutter speed of the camera, and the President's reaction to the fatal shot. In the current paper, the physics surrounding the shot that struck President Kennedy in the head near-instantly killing him will be examined in considerably more detail.
The effect produced by such high-energy projectiles [14] , [15] upon collision with a human head is catastrophic as has been characterized through ballistics experiments [12] , [16]. In examining this, three separate dynamical phenomena will be considered in Section 2 that explain behaviors observed in the Zapruder Film, namely 1 the initial effect of the forces directly imparted to the target head by the projectile discussed in Section 2.
Kennedy assassination crime scene in Dealey Plaza, Dallas, Texas. The map is oriented with true north pointing toward the top of the page; non-permanent geographic features e.
In the Zapruder Film President Kennedy is seen to react to three separate gunshots, the first missing him and the limo [6] , [16] , [4] , [17] , the next two hitting him with increasing accuracy. Further discussion of the first two shots is beyond the scope of this paper other than to note that all three gunshots had associated 1—2 frame anomalous movements, and a outward impulse is observed on the jacket lapel of Texas Governor John Connally who had accompanied President and Mrs.
Kennedy in the motorcade and was collaterally wounded in chest at the same time the President begins showing signs of being injured [12] , [6] , [7] , but no other discernable impulses are otherwise seen on either of the two men prior to the third shot. Figure 2 shows the two Zapruder Film frames that captured the fatal shot, namely Z the moment just before impact and Z the moment just following impact.
In Z the catastrophic effect of the energy deposit from a supersonic projectile passing through a human head is clearly evident. However, while it is not immediately noticeable at this scale and not detectable while viewed in motion at normal speed , a careful comparison between the two frames also reveals that President Kennedy's head snaps forward from Z to Z [9, pp.
There is nothing new in this observation—early researchers with access to the still frames first noticed this in the mid-to-late s. Notable among these is author Josiah Thompson, who estimated the position of the President's head relative to two fixed objects on the rear of the limousine, the results of which are plotted in his book Six Seconds in Dallas [9, p. It is also crucial to note that this anomalous forward impulse at Z is only observed on Kennedy's head—it is not observed on any of the other limo occupants with reference to dotted lines c , d and f , nor is it even observed on Kennedy's own torso line b , wherein lies his body's center-of-mass CM.
This implies that an isolated real force acted directly and solely upon the President's head just prior to Z; the only plausible source for this instantaneous, isolated forcing mechanism is manifestly and unequivocally the projectile impact.
Therefore, what follows in Sections 2. Un-enhanced high-resolution digital copies of Zapruder Film Frames and Z and Z showing the high-powered rifle gunshot that fatally wounded President Kennedy. Frame has been horizontally adjusted to correct for tracking error between the two frames. The annotated red line segments demarcate features relevant to the kinematical discussion in the text: dashed line O is flush with the back of Kennedy's head in Z; lines a and e are stable limo features viz.
Kennedy's hat and hair; line d is Governor and Mrs. Connally; and line f is the Secret Service agents. The interaction of a firearm projectile passing through a human body target constitutes an inelastic collision , that is, one where the kinetic energy KE of the two-body bullet-target system is not conserved e.
This concept will be returned to in Section 2. Because such collisions are neither elastic nor perfectly inelastic, the physical description of the interaction can be more complicated. Nevertheless, assuming in the case under consideration that the projectile collision occurred near the center of the target thus not imparting torque , it is possible to consider the interaction in terms of a linear impulse, J x , which in one dimension for the CM frame is given as [e.
Equation 1 applies to the bullet passage through an entire head, but this may be broken down into three separate impulses brought on by 1 the skull entrance, 2 passage through the skull cavity i. For simplicity, any resistance presented by the hair and scalp is assumed to be of second order and thus negligible [e. Equation 1 is therefore rewritten as. From Eq. Attention is first given to the terms involving passage through bone, namely the first and last terms on the right side of Eq.
Sturdivan and Bexon [20] derived a model describing the probability of penetration of human skulls by high-speed projectiles viz. As explained by Sturdivan [20] , [16] , when a high-speed projectile impacts the head and penetrates the skull, it first perforates a hole in the outer table of approximately the same diameter of its own presented area. However, as the bullet breaks through into the inner, less-dense trabecular layer, the area expands roughly in a cone shape until it finally breaks out a wider hole through the inner table.
It is this cratering process that assists forensic pathologists in establishing skull entrance or exit wounds [25] , [22] , thus facilitating the determination of the direction of the bullet's passage relative to the body and the direction of origin of the shot. Building upon the skull-cratering model described above [20] , the impulse force is modeled in the current paper by assuming a perfectly inelastic collision [26, pp.
The interaction of the two bodies during collision according to Newton's Second and Third Laws is given by. Solution of ordinary differential equations ODEs 3 and 4 is easily obtained by first recasting them as. Combining Eqs. Finally, substituting Eq. Equations 11 and 8 form the basis for calculating the first and third terms of Eq.
In this case, the collision would then be a perfectly inelastic collision, and the total incoming momentum of the projectile p 1 would be completely transferred to the skull and head. Using dimensional analysis, Sturdivan [33] derived a drag law for the passage of a spherical projectile through tissue as a combination of an inertial term and a viscous friction term.
The tissue-strength term in Eq. Similarly, for Eq. However, it is known in practice that a high-speed projectile will undergo deformation from collisions with bone [36] , [37] , [16] , [14] , [38] , as well as during subsequent passage through soft tissue [16] , [38].
This was certainly the case for the Kennedy assassination, as evidenced by the badly deformed bullet fragments recovered from the limousine and autopsy, and will be addressed further in Section 2.
For the bullet velocity at impact, v 1 , the retardation of the projectile through the intervening atmosphere must be taken into account. However, to corroborate the measured value, and to facilitate application of the model to an arbitrary source sniper location and projectile, the theoretical modeling study in this paper is extended here to include calculations accounting for the projectile passage through the ambient atmosphere of the crime scene.
The bullet impact velocity at the target location may be estimated theoretically by accounting for aerodynamic drag. The one-dimensional aerodynamic drag force is given by [e. The equation of motion for the projectile may thus be written as. Values for the crime scene parameters may be found in the literature [16, p. Although the influence of departures of the ambient atmospheric temperature, humidity and wind from a mean state are small [41] , the projectile's KE is proportional to the square of its speed.
T v is calculated as [42, p. Hourly meteorological surface observations at Dallas Love Field from the U. From these values and Eq. Windspeed and direction were included in Table 1 because they factor into the aerodynamic drag calculations 19 and 21 by altering the bullet velocity relative to the fluid.
It can be seen that winds were out of the west, which was obliquely against the direction of the bullet trajectory, 5 thus increasing the relative speed and drag. Substituting into Eq. The known parameters from the assassination crime scene may now be applied to the equations derived above.
Throughout this paper centimeter-gram-second CGS units are used unless otherwise noted. Table 2 summarizes the values used for the parameters along with their sources for performing impulse force calculations. For the skull passage Eqs. Values for these parameters may be found in Table 2. The presented areas of the projectile may be estimated from its diameters at skull entrance and exit. Because the Carcano bullet is extremely stable during normal flight through air, the entrance diameter d 0 is simply the cross-sectional diameter of an unfired bullet, which is known to be 0.
Although the bullet was broken into at least three fragments [38] , it is assumed that the autopsy measurements nevertheless provide an objective best-estimate of the effective presented area of the projectile on exit [Sturdivan, L. To allow for uncertainties [48, pp. Finally, the stress-strain curve reported by Keaveny et al.
Soft tissue force calculations may be performed based upon Eqs. The total path of the projectile through the brain tissue is taken to be 11 cm, which corresponds to the U. As mentioned previously, the equations for velocity retardation assume a constant presented area A , and the force equations are dependent upon both A and v. Given that most of the bullet deformation occurs initially before rapidly diminishing with decreasing velocity [16, p.
Then given A L and v L , the drag force through the layers F d A L , v L may be calculated using either 15 or 16 ; Figure 3 shows the results for the range of assumed projectile effective exit diameters d e. Here it is seen that both models yield very comparable results for the case under consideration, both in terms of magnitude and in variation, thereby providing confidence in their application in this work.
Finite-difference layer drag force computations for deforming half-parabolic growth spherical projectile passage through visco-elastic soft tissue i. The different colored lines correspond to different effective exit wound diameters, d e , spanning the range described in the Autopsy Report.
The integrated drag-force impulse is calculated via the finite-difference approximation as. Equation 24 forms the basis for calculating the second term of Eq. Note again that the tissue drag force equations were derived assuming spheres [33] , [34] , so a spherical projectile is also implicitly assumed here.
This approximation conveniently eliminates the need to specify the 2-axis orientation of the bullet during passage e. It is recognized that the projectile is assumed to deform and fragment after the initial collision with the skull which breaches the copper jacket [12] , [38] to the extent that tumbling may be ignored [14] , and a primary effect of tumbling is simply to increase the presented area of the projectile [49] which is already accounted for in the finite-difference model Eq.
Although the visco-elastic soft tissue presents less resistance than rigid bone, the increased presented area caused by the initial bullet-bone collision and subsequent deformation over a much greater path length yields this greater integrated impulse.
Figure 4 b shows the reduction of the bullet speed during passage, which translates to the power-of-two loss of KE to the surrounding environment Figure 4 c. Here it is seen that the KE transfer from the projectile to the soft tissue brain is maximized before the midpoint, which arises primarily from the increased presented area [16, p. This large deposit of energy is propagated away from the projectile path via a separated flow field and pressure wave known as temporary cavitation [36] , [37] , [34] , [16] , [49] , [14] , [15] discussed more in Section 2.
Modeled effects of collision of a deforming, high-speed spherical projectile i. However, to the author's knowledge, there simply does not exist a precise measurement of the target mass, namely that of President Kennedy's head although it may be noted that Kennedy's hat size is reported to have been 7 3 8 , 6 which is an average size for an adult male.
Thus, in this work a best estimate for Kennedy's head mass is obtained from a tabulation of published anthropometric datasets compiled by Yoganandan et al. Zero relative motion was assumed before impact, so to obtain an estimate of the total movement of the head from the previous observed position viz. From the projectile velocity calculations Figure 4 b , the total time for the bullet passage through the head i.
The uncertainty estimates correspond to the uncertainty in the estimated target mass. The last row shows values derived from momentum conservation for a total inelastic collision of the projectile with the target i.
Note that nearly identical results were obtained using the Sturdivan model [33] for the soft-tissue calculations, albeit slightly larger and thus in slightly better agreement, but are not shown in the interest of brevity.
Included for reference in Table 3 are calculations assuming a perfectly inelastic collision of the projectile with the target i. Note it may also be deduced that the bullet was well airborne at Z and the moment of impact probably occurred just after the shutter closed. In fact, the bullet may very well have been just outside or within the camera's field-of-view FOV at Z The explosion observed in the Zapruder Film and its dynamical effects are explored in more detail below in Section 2.
The calculations may have slightly underestimated the observed head snap given that they were based upon a linear impulse imparted to the back-center of the head [16, p.
Additionally, given the downward trajectory of the projectile and initial inclination of the target , the earth's gravity which was implicitly neglected would have imposed a small additional acceleration to the impulse.
Another consideration is that the growth of the projectile presented area, A , may have been larger than that estimated using the effective exit diameter—this is quite possible given that the projectile had fragmented fragments were found in skull cavity during the autopsy and it would have created secondary missiles [14] from the initial skull collision.
Other factors include the assumptions employed in the soft tissue drag formulas, whereby parameters such as the drag coefficient C d were assumed constant, but more likely varied as the projectile's speed slowed e. Finally, while uncertainties in parameters were accounted for as much as possible, this could not be done for a handful of them, especially bio-mechanical parameters e. But all said, the computed magnitudes are found to be physically consistent with less than the limiting case of a perfect inelastic collision i.
The calculated changes in momentum as defined by Eq. Additionally, the small deficits in the target momentum gains are consistent with the consideration that the impulse calculations may have slightly underestimated the observed head snap.
Conservation of momentum for bullet and target interaction cf. Clearly there is a backward movement, but the movement is delayed and slower than the forward impulse discussed above.
The impact occurred just following the shutter closure of Z; this means that the bullet what was left of it was long gone by the time of the shutter opening at Z [50] , [16]. Frames Z—Z have been adjusted to remove jiggle caused by camera tracking errors of the cameraman. Solid particles i. Note that the bullet was already long gone by the time the shutter opened at Z [50, p. Alvarez [10] considered this problem based upon simple idealized energy and momentum conservation arguments, along with simple experiments involving tape-wrapped melons as proxies for live human heads; subsequent experiments have repeated Alvarez's results using more realistic proxies [11] , [12] , [13].
In this paper, the backward movement is reexamined theoretically in more detail. Like the current author, Prof. Alvarez estimated that the recoil would be about twice the initial velocity brought about by the collision. Although the phenomenon of a high-energy projectile passing through a heterogenous body e. Indeed, it is often the case that scientific descriptions of nature are counter-intuitive and can run contrary to common sense [e.
However, the development of high-speed cameras has gone a long way toward facilitating observation and physical understanding of gunshot wound ballistics. In the case of a Newtonian fluid, the stresses imposed by such perturbations under high Reynolds number conditions i.
In the case of soft tissue as opposed to a purely Newtonian fluid such as water , an analogous phenomenon is manifested in what is called temporary cavitation [36] , [37] , [34] , [16] , [49] , [14] , [15] , namely the temporary development of a near-vacuum in the wake of the bullet that is rapidly closed via the pressure gradient and elasticity in the tissue [14] , [49] , [15] , [18] , resulting in restoring forces that can lead to additional violent undulations before the material fully returns to equilibrium [14] , [15].
Tragically this is observed in the Zapruder Film. Here the large wound inflicted on the President's head was not a bullet exit wound, but rather the region of maximum temporary cavitation associated with KE transfer [49] , [16].
This KE deposit propagated radially outward in the form of an expanding pressure wave [14] , [15] resulting in a rupture and explosion of the skull. Restoring force undulations are also gruesomely apparent in the Zapruder Film as brain tissue pulsing and dripping out of the wound in frames Z—Z not shown here , and Mr.
Thus, in this paper a different method is sought. Rather than attempting to demonstrate or prove the general hypothetical question of whether or not high-speed projectile impacts on head cavities can lead to recoil effects which Prof. Alvarez and others have demonstrated in the affirmative , one only needs to consider the physics of this particular special case. The objective here is simply to explain the observed behavior in the Zapruder Film, treating it as a case study. In Z—Z Figure 5 an expulsion of mass i.
Separate direction and slope trajectories were developed for two bulletsthe one that caused the President's back and neck wounds, and the one that caused his fatal head wound. The margins of error were indicated as circles within which the shots originated. The southeast corner window of the depository was inside each of the circles. Bronson, that some independent researchers believe shows a figure or figures in the sixth floor depository window several minutes before the shooting.
The film came to the attention of the committee toward the end of its investigation. Some members of the committee's photographic evidence panel did conduct a preliminary review without enhancement of the film. While motion was detected in the window, it was considered more likely to be a random photographic artifact than human movement.
Nevertheless, the limited review was not sufficient to determine definitively if the film contained evidence of motion made by human figures. Top of Page b Witness testimony While the committee relied primarily on scientific analysis of physical evidence as to the origin of the shots, it also considered the testimony of witnesses. The procedure used to analyze their statements was as follows: First, all available prior statements were read by the committee and studied for consistency.
The objective was to identify inconsistencies either between the words of one witness and another or between the various words of a witness whose story had changed. Second, an attempt was made to locate the witnesses and to show them the statements they made in the course of the original investigation. Each witness was asked to read his statements and to indicate whether they were complete and accurate. If statements were inaccurate, or if a witness was aware of information that was not include, he was asked to make corrections or provide additional information.
In addition, where relevant questions had not been asked, the committee asked them. Any information provided by a witness in years after the assassination--must be viewed in light of the passage of time that causes memories to fade and honest accounts to become distorted.
Certainly, it cannot be considered with the same reliability as information provided in Page 50 To the extent that they are based on witness testimony, the conclusions of the committee were vitally affected by the quality of the original investigation. The inconsistencies in the statements--the questions not asked, the witnesses not interviewed--all created problems that defied resolution 15 years after the events in Dallas.
Nevertheless, the committee considered all of the witness statements and determined to what extent they corroborated or independently substantiated, or contradicted, the conclusions indicated by the scientific evidence. An example of such witness testimony is that relating to the discovery of the rifle and shell casings in the Texas School Book Depository.
Because detailed versions of witness testimony taken in the original investigation are a matter of public record, only brief resumes are included here. When he squeezed through the opening, he saw a rifle between two rows of boxes.
The time was p. It was determined in both investigations that the bullet found on a stretcher at Parkland Hospital had been fired from the rifle found in the depository, as were two fragments recovered from the Presidential limousine. It is highly likely that the bullet found on the stretcher was the one that passed through Governor Connally's wrist, leaving tiny particles behind, and the frag- 8 The committee firearms panel determined that the evidence stored in the National Archives ballistically matched the bullets fired by the FBI in tests from the Mannlicher-Carcano found by Boone.
Since the rifle had been test fired numerous times since , its barrel had been altered by wear, and bullets the panel fired from the rifle did not match either the FBI test cartridges or those found on the sixth floor of depository or that found on the stretcher. Page 51 ments retrieved from the limousine came from the same bullet as the fragments taken from President Kennedy's brain. The suspicion has been based to some extent on allegations that police officers who first discovered the rifle identified it as a 7.
Both a study of proportions and a comparison of identifying marks indicated that only one rifle was involved. The committee also weighed the firsthand testimony of witnesses but with caution, because of the problem of the passage of time.
Besides the statements of law officers on the scene immediately after the assassination, it considered the accounts of bystanders in Dealey Plaza, bearing in mind that these were recollections of fleeting mo- Page 52 ments when emotions were running high.
The committee noted, however, that a number of the Dealey Plaza witnesses said they saw either a rifle or a man with a rifle in the vicinity of the sixth floor southeast corner window of the book depository. Top of Page 3.
Since the Commission further concluded that Oswald was the assassin of the President, his background is relevant. His mother remarried, and, from until , the family lived in a number of cities in Texas and Louisiana. This marriage ended in divorce when Oswald was nine. In , Oswald and his mother moved to New York City. His school record was marked by chronic truancy, and a psychiatric examination suggested that he was emotionally disturbed.
Oswald and his mother returned to New Orleans in After finishing the ninth grade, the year-old Oswald dropped out of school. The following year, he joined the U. Marine Corps. Asserting the ill-health and distressing financial situation of his mother, Oswald obtained a release from the Marines in Following his discharge, he spent 3 days with his mother in Fort Worth, Tex. From there, he traveled to the Soviet Union where he tried to become a Soviet citizen.
Having become disillusioned with Soviet life, he returned to the United States with his wife and baby daughter the following year. The Oswalds arrived in Fort Worth, Tex. Oswald moved to Dallas in October where he found a job with a graphic arts company. Marina followed in November, but their marriage was plagued by intermittent feuding.
In March , according to the Warren Commission, Oswald purchased a Mannlicher-Carcano rifle and telescopic sight from a Chicago mail order house. He also ordered a. Walker, a retired Army general who had been relieved from his post in West Germany for distributing rightwing literature to his troops.
Walker was not harmed. In April , Oswald went to New Orleans. In May, she joined Oswald in New Orleans. On July 19, Oswald was dismissed from his job for inefficiency. In August, he distributed pro-Castro leaflets and also made two radio broadcasts on behalf of the Castro regime.
Oswald went to Mexico City in the latter part of September. He visited the Russian Embassy and Consulate and the Cuban Consulate there, but he failed to get permission to travel to either country. He returned to Dallas on October 3, He visited Marina in Irving on several occasions but continued to try to find a place to live in Dallas. He began work at the Texas School Book Depository 2 days later.
On October 20, Marina gave birth to their second daughter. Oswald next visited Marina and his children in Irving on the evening of November He returned to Dallas the following morning. Tippit was shot and killed. At approximately 2 p.
He was subsequently charged in the murder of Tippit and named as a suspect in the Kennedy assassination. On November 24, , while he was being escorted through the basement of Dallas police headquarters in preparation for being transferred to the Dallas County Sheriff's office, Oswald was fatally wounded by a single shot fired from a pistol by Jack Ruby, a Dallas nightclub operator.
As noted, the Warren Commission had traced the chain of possession of the alleged assassination rifle and determined that the name on the money order and purchase form used to buy the rifle was "A. Hidell" which it determined to be an alias used by Oswald. Photographs of Oswald holding a rifle were also recovered from among his personal possessions, and the Commission concluded that the rifle in the photograph was the one found on the sixth floor of the book depository.
This determination, coupled with Warren Commission evidence of Oswald's ownership of the rifle, if accepted, proved conclusively that Oswald was the owner of the murder weapon.
Page 54 Nevertheless, doubt has been cast on the evidence that Oswald owned the rifle in question. Critics of the Warren Commission have asserted that the chain of possession is meaningless, because more than one Mannlicher-Carcano was issued with the serial number C The committee posed these questions: Could the handwriting on the money order used to purchase the rifle and the application for the post office box be established with confidence as that of Lee Harvey Oswald? Top of Page 1 Handwriting analysis.
Among the documents provided to the panel was the money order sent to Klein's Sporting Goods Co. Although Oswald was fingerprinted when he was arrested in Dallas on November 22, , he refused to sign the card. Top of Page 2 The backyard photographs. The originals had, however, been destroyed, and microfilm copies that existed were not suitable for conclusive tests. While in the custody of the Dallas police from November 22 to November 24, , Oswald claimed that he did not own a rifle and that the photographs were composites, with his head superimposed over someone else's body.
This was done by studying the photographs and the single available original negative for unique identifying characteristics that would have been imparted by that camera. Once this was successfully done, the objects imaged in the photographs, as well as their shadows, were analyzed photogrammetrically. Finally, the materials were visually scrutinized, using magnification, stereoscopic analysis and digital image processing.
In contrast, some of the critics who claimed the photographs were faked relied on poor quality copies for their analyses.
After subjecting these original photographic materials and the camera alleged to have taken the pictures to sophisticated analytical techniques, the photographic evidence panel concluded that it could find no evidence of fakery. The panel found a unique identifying mark present on the weapon in the Archives that correlated with a mark visible on the rifle in the Oswald backyard photographs, as well as on the alleged assassination rifle as it appeared in photographs taken after the assassination in A great deal of what the Commission sought to show about Oswald rested on her testimony, yet she gave incomplete and inconsistent statements at various times to the Secret Service, FBI and the Commission.
Marina's role in what happened in Dallas rested primarily on the results of scientific analysis. The committee found no evidence that would indicate that Marina had foreknowledge of the assassination or that she helped her husband in any way in his efforts to assassinate the President.
In its investigation of conspiracy, the committee's undertaking was not furthered by Marina's testimony, since she professed to know little of Oswald's associates in New Orleans or Dallas.
Page 56 In addition, the relative lengths of component parts of the alleged assassination rifle at the National Archives were compared to component parts of the rifle that appeared in various photographs, including the backyard photographs.
During the course of the committee's investigation, George de Mohrenschildt, who had been a friend of Oswald, committed suicide. The committee, pursuant to a subpena, obtained de Mohrenschildt's personal papers, which included another copy of the Oswald backyard photograph. This copy, unlike any of those previously recovered, had an inscription on the back: "To my dear friend George, from Lee.
If Oswald did sign the photograph, his claim that he did not own the rifle and that the photograph was a fake could be discounted.
He picked up one of the fragments using rubber-tipped forceps and, with the care of a jeweler setting a stone, placed it into a housing beneath the lens of a 3D surface scanning microscope. These artifacts are usually held at the National Archives. They were transported to NIST so that Renegar and the rest of the NIST ballistics team could scan them and produce digital replicas that are true down to the microscopic details.
The mission of the National Archives is to provide the public with access to artifacts such as these, and it receives many requests for access to them. This project will allow the Archives to release the 3D replicas to the public while the originals remain safely preserved in their temperature and humidity-controlled vault. In addition to the two fragments from the bullet that fatally wounded the president, the digital collection includes another bullet that struck both the president and Texas Gov.
John Connally. Edwin Walker that was thought to involve the same firearm. In the lab, the NIST ballistics team used a technique called focus variation microscopy to image the artifacts. As the lens moved across the object, it built a 3D surface map of the microscopic landscape beneath it, like a satellite mapping a mountain range.
Renegar and NIST physical scientist Mike Stocker spent countless hours rotating the metal fragments beneath the lens of the microscope to image every facet, then stitching the image segments together where they overlapped.
If you held one of the original fragments in the palm of your hand, you would see that the metal is warped and twisted into a complex shape. But magnified on the computer screen, it is a world unto itself: a highly complex and undulating terrain that bends, dips and doubles back.
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