NASA's Artemis program is planned to return astronauts to the moon and establish a permanent laboratory in orbit by the end of this decade.
Meanwhile, private companies are taking important steps to bring paying customers further into space. As humanity's footprint expands beyond Earth's known terrain to the moon and possibly beyond, an intriguing new field is emerging on the final front: astroforensics.
This discipline, still in its infancy, is driven by the inevitability of human nature. The space provides a unique and harsh environment for forensic investigations. Environments involving changing gravity, cosmic rays, extreme temperatures, and the need for oxygen-providing climate systems are a few examples of the unearthly variables that future explorers will face.
Unlike Earth, where gravity, a constant force, shapes many aspects of our reality, the significant reduction of gravity in space introduces new challenges in understanding how evidence behaves. This shift is crucial for forensic sciences such as the analysis of bloodstain patterns, which rely heavily on gravitational effects to determine the conditions under which bloodstains form.
The thought of gravity in space immediately conjures up images of astronauts hanging eerily in the void of space or floating gymnastics on the International Space Station (ISS).
However, true zero gravity exists far away from celestial bodies. When it is close to a body such as a moon or a planet, gravity will be present, even when it is in orbit around a planet such as Earth.
Therefore, most environments in space have low or microgravity rather than zero gravity. Given that gravity is ubiquitous and largely constant, we pay very little attention to it, and usually automatically include it in calculations as a constant without thinking about it.
Altered gravity
But for a forensic science discipline like bloodstain pattern analysis, gravity plays a crucial role in how liquid blood in the air interacts with a surface and creates stain patterns. Bloodstain pattern analysis is the use of fluid dynamics, physics and mathematics to understand the flight and origin of blood and interpret how it is deposited on a surface in criminal investigations.
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In a recently published study, we and our colleagues sought to understand the basics of how the changed gravity environment in space will impact future forensic science disciplines.
For this study, published in Forensic Science International: Reports, we used a parabolic flight research aircraft that induces short periods of microgravity due to its up-and-down flight path. This type of flight is colloquially called the 'vomit comet'.
During this period of free-falling microgravity, a number of blood drops were projected onto a piece of paper, and the resulting bloodstain was then analyzed using routine Earth-bound protocols. Although the concept sounds simple, creating a safe and controllable area where experiments could be conducted in an aircraft that essentially fell to Earth for twenty seconds was a challenge.
Therefore, the experimental environment had to be attached to the cabin of the research aircraft, and all bloodstain formation and documentation had to be made easily controllable. Experiments were conducted in a repurposed pediatric incubation chamber, also known as a glove box. This chamber is used in space medicine research to study bleeding control.
A synthetic analogue of blood was used instead of real blood due to concerns about biological hazards in the aircraft cabin. This analogous substitute mimicked the physical properties of blood's viscosity and surface tension. To start the experiment, the analog blood was loaded into a syringe, and once microgravity in free fall was induced, the syringe was manually pressed to project the blood over a distance of 20 cm onto a sheet of white paper.
While this bears little resemblance to real criminal scenarios, it is the interaction between the blood and the surface that is of interest to the forensic examiner - rather than the actual projection mechanism. The bloodstained papers were then photographed and analyzed according to normal procedures.
We discovered that microgravity does indeed change the behavior of the blood droplets and the stains they create. On Earth, blood tends to fall parabolically, with gravity pulling on it until it hits a surface. But in this case, the blood continued to flow in a straight line until it hit the surface.
This straight-line flight path is a fluid example of inertia in action. However, with a distance of only 20 cm, this had minimal effect on the subsequent pattern.
This difference would become more apparent over greater distances, but the operational limitation of the parabolic research aircraft means it would be difficult to reproduce effectively. The second important observation was the dispersive action of the blood on hitting the surface.
In Earth's typical gravitational environment, liquid blood droplets will undergo a series of stages in the staining process. This entails the collapse of the droplet, the formation of a small wave and the spreading into a final spot shape.
However, when gravity is eliminated from this action, the spreading action is inhibited by the predominant force of surface tension and cohesion, resulting in a spot shape and size smaller than that of its terrestrial counterpart.
We are at the dawn of a new era of research, exploring the impact of the alien environment on the behavior of forensic evidence. Yet the impact of this research is not only limited to the forensic sciences, but also to the more traditional physical sciences, such as fluid dynamics in spacecraft design and analyzing errors in forensic space technology after a spacecraft malfunction.
Expanding research in this new forensic discipline will require larger microgravity environments and the authors would be eager to operate the Galaxy's first extraterrestrial forensic science laboratory.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
