Experiment arrives at the ISS to see if astronauts can keep things cool

A science experiment that arrived at the International Space Station on Friday will help engineers build heating and air conditioning units to keep astronauts alive on missions.

The physical mechanics of boiling and condensation of liquids, the process central to heating and cooling systems, work differently in space as the lack of gravity affects the movement of fluids. Researchers from Purdue University in the US have now built specialized hardware to fit into NASA's Fluids Integrated Rack to study condensation in microgravity.

"We have developed over a hundred years' worth of understanding of how heat and cooling systems work in Earth's gravity, but we haven't known how they work in weightlessness," Issam Mudawar, a professor of mechanical engineering at Purdue University, leading the experiment, said in a statement.

"We are ready to literally close the book on the whole science of flow and boiling in reduced gravity," he predicted.

The contraption was sent to the space lab in a Cygnus cargo capsule as part of Northrop Grumman's 19th commercial resupply mission to the ISS, which launched was launched by an Antares rocket from NASA's Wallops Flight Facility in Virginia on August 1 at 0031 UTC. 

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The latest module is part of the second installment of the Flow Boiling and Condensation Experiment (FBCE). The first experiment launched in 2021 was designed to study how water boiled, whilst the second experiment explores condensation reactions.

Both experiments are expected to remain onboard the ISS until 2025. Mudawar and his colleagues will gather data from the fluid experiments and compare it to data collected on Earth. The results will inform engineers on how to build effective ventilation, heating, and air conditioning devices if they can figure out what processes drive heat transfer in low gravity.

"Both boiling and condensation involve simultaneous flow of liquid and vapor in a flow channel. Liquid is much heavier than vapor and the relative motion of the two in Earth gravity is dictated by buoyancy, which is proportional to the product of density difference between the liquid and vapor and the prevailing Earth gravity," Mudawar explained to The Register.

"Absent gravity on the ISS the relative motion is no longer dictated by buoyancy, but rather by other forces such as flow inertia and surface tension, rendering behavior distinctly different from what we have learned from Earth Gravity experiments."

The team also believe their research could also help develop new technologies for energy and power systems too. Spacecraft could be refueled more safely in orbit, for example, if scientists understand and can control the flow of cryogenic propellant in space. ®