In microgravity, familiar things behave in weird ways. Flames form spheres, human bones lose density, and calluses on the feet disappear. Various liquids also act strangely.
It’s no surprise a team of forensic researchers wanted to know how a changed gravitational environment would affect blood spatter: how blood interacts with surfaces, what patterns it makes, and how microgravity might reshape the future of forensic work.
First experiments by cosmic forensic experts
These questions marked the start of the first study of blood behavior in free fall and helped launch a new field dubbed “astrocriminology.”
Led by Professor Graham Williams of the University of Hull (UK), the team flew on a parabolic research aircraft. The modified Boeing 727 from Zero Gravity creates short periods of microgravity through its up-and-down trajectory.
During a roughly 20-second free fall, researchers released drops of a blood substitute onto sheets of paper and then analyzed the resulting stains using standard terrestrial protocols. Participants say the idea sounds simple, but the team faced real challenges creating a safe, controlled setup inside an aircraft that was essentially falling for those 20 seconds. The entire rig had to be securely fastened to the cabin, and the experiments were carried out inside a repurposed pediatric incubator.
For the tests, scientists used a blood analog made of 40 percent glycerin and 60 percent food dye, writes IFLScience. This mixture matches human blood in density and viscosity and leaves stains similar to real blood.
Ultimately, researchers discovered how microgravity affects blood behavior. On Earth, blood typically follows a parabolic arc under gravity until it hits a surface. In simulated space conditions, blood traveled in straighter lines until it reached the surface — a clear demonstration of inertia.
The second key observation was that blood spread over a smaller area on the surface, ScienceAlert reported.
“In the absence of gravity, surface tension and the adhesion of blood droplets increase,” said Professor Graham Williams. “That means blood in space tends to stick to surfaces more… Blood droplets spread more slowly and therefore take shapes and sizes different from those on Earth.”
At the start of the experiment, scientists expected that removing gravity would reduce uncertainty in their calculations. But surface tension dominated so strongly that the researchers found even greater variability in their estimates.
What is this for?
As Dr. Zak Kowalski of Staffordshire University, a study co-author and experienced criminologist, put it, “Studying the structure of bloodstains can provide valuable reconstructive information about a crime or accident.” These early steps in astrocriminology matter for forensic work in space — though hopefully they’ll never have to be used in a real crime. So far, there hasn’t been a criminal offense in space.
Kowalski says forensic medicine is more than solving crimes; it’s also crucial for reconstructing or analyzing technical malfunctions on board spacecraft such as the International Space Station or a shuttle.
The results of the study were published in the journal Forensic Science International: Reports.
