NASA’s Artemis program is planned to send astronauts back to the Moon and establish a permanent orbital laboratory by the end of the decade.
Meanwhile, private companies are also taking important steps to transport their paying customers to space. As humanity’s footprint expands beyond the familiar regions of Earth, to the Moon, and possibly beyond, an intriguing new field is emerging from the final frontier: astrophorescence.
This discipline, still in its infancy, is guided by the inevitability of human nature. Space presents a unique and challenging environment for criminal investigations. Environments with changing gravity, cosmic radiation, extreme temperatures, and the need for oxygen-providing climate systems provide just a few examples of the extraterrestrial variables future explorers will encounter.
Unlike on Earth, where gravity, a constant force, shapes many aspects of our reality, the dramatically reduced gravity in space poses new challenges in understanding how evidence behaves. This change is crucial for forensic sciences such as bloodstain pattern analysis, 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 suspended hauntingly in the vacuum of space or gymnastics floating on the International Space Station (ISS).
However, true zero gravity exists very far from celestial bodies. When you are near an object such as the moon or a planet, there will be a gravitational effect, including when orbiting a planet such as the Earth.
Therefore, most environments in space have low or microgravity rather than zero gravity. Given that gravity is ubiquitous and largely constant, we pay little attention to it and often automatically include it as a constant in calculations without a second thought.
changing gravity
But for a forensic science discipline like bloodstain pattern analysis, gravity plays a critical 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 to interpret how it accumulates on a surface in criminal investigations.
In a recently published study, we and our colleagues sought to understand the beginning principles of how the changing gravitational environment of space will impact future forensic science disciplines.
For this study, published in the journal Forensic Science International: Reports, we used a parabolic flight research aircraft, which induces brief periods of microgravity due to its up and down flight path. Such flights are colloquially called “vomit comets”.
During this period of free-fall microgravity, a series of blood drops will be projected onto a piece of paper, and the resulting blood spot will then be analyzed using routine earth-bound protocols. Although the concept seems simple, there were challenges in creating a safe and controllable space to conduct experiments on a plane crashing to Earth for 20 seconds.
Therefore, the experimental environment had to be added to the cabin of the research aircraft, making all bloodstain formation and documentation easily controllable. Experiments were conducted in a redesigned pediatric incubation chamber, referred to as a glove box. This chamber is used to study bleeding control in space medicine research.
Due to biohazard concerns, a synthetic blood analog was used instead of real blood in the aircraft cabin. This analogous substitution mimicked the physical properties of blood viscosity and surface tension. To start the experiment, analog blood was loaded into a syringe, and after microgravity was established in free fall, the syringe was manually pressed to project the blood onto a sheet of white paper across 20 cm.
While this bears little resemblance to real crime scenarios, it is the interaction between blood and surface, rather than the actual reflection mechanism, that interests the forensic investigator. Bloodstained papers were photographed and analyzed according to normal procedures.
We found that microgravity actually changes the behavior of blood drops and the stains they form. On Earth, blood tends to fall parabolically, with gravity pulling it down until it hits a surface. However, in this case, the blood continued to move in a straight line until it hit the surface.
This straight-line flight path is a fluid example of inertia in action. However, a distance of just 20 cm had minimal impact on the subsequent model.
This difference will become more noticeable at greater distances, but the operational limitation of parabolic research aircraft means this will be difficult to recreate effectively. The second important observation was the spreading motion of the blood when it hit the surface.
In Earth’s typical gravitational environment, drops of liquid blood will go through a series of stages in the process of forming a stain. This requires the droplet to collapse, creating a small wave and spreading into the final spot shape.
However, when gravity is stripped of this influence, the spreading effect is inhibited by the dominant force of surface tension and cohesion, resulting in a spot shape and size smaller than its terrestrial twin.
We are at the beginning of a new era of research investigating the impact of the extraterrestrial environment on the behavior of forensic evidence. However, the impact of this research is not only limited to forensic science, but also to more traditional natural sciences, such as fluid dynamics in spacecraft design and analyzing errors in space forensic engineering following a spacecraft failure.
Larger zero-gravity environments will be needed to expand research in this new forensic discipline, and the authors would be more than happy to operate the galaxy’s first extraterrestrial forensic laboratory.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Zack Kowalske received funding from the Dan Rahn Research Fellowship from the International Association of Bloodstain Model Analysts.
Graham Williams does not work for, consult, own shares in, or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond his academic duties.