In 2001, NASA sent the science behind toothpaste and salad dressing into space; the research later helped produce three P&G patents

Your toothpaste and salad dressing have more in common than you might think, and NASA has spent more than two decades studying why. Ever since 2001, NASA has been sending its experiments to the International Space Station to investigate the properties of colloids, a wide range of mixtures including everything from shampoo to vinaigrette, because gravity makes them difficult to study properly. According to NASA Science, Procter & Gamble received three patents based on the ISS experiments. The partnership between NASA and P&G is unusual but scientifically useful.

What is a colloid, and why does gravity ruin the experiment

Colloids are mixtures in which small particles are suspended in another substance without dissolving. Examples of colloids include paint, milk, lotions, and salad dressing. Toothpaste is one of them too. On Earth, gravity can cause particles to settle, oil to separate from water, and products to spoil sooner. That is why salad dressing often needs to be shaken before use. Scientists needed a way to study colloids without gravity affecting the results. The microgravity aboard the space station was ideal for their needs. According to a NASA summary of two decades of research on the space station, the absence of gravity enables researchers to analyze particle settling and separation.


The 2001 experiment that opened the door

According to NASA, in 2001, NASA's colloid physics work got a boost when the Physics of Colloids in Space experiment flew to the station aboard Space Shuttle flight STS-100. The experiment operated for thirteen months within the Destiny laboratory aboard the station, collecting information about such colloidal suspensions as paints, milk, cosmetics, and salad dressings, the same physics that govern how toothpaste stays consistent on a store shelf. Although P&G was not involved, the experiment showed that space could be used to study the same physics that affect consumer products on Earth.

Testing on the ground before going to orbit

Sending an experiment to the International Space Station involves far more than packing it up and launching it. To prepare for microgravity, Procter & Gamble tested the experiment in parabolic aircraft, the so-called "vomit comets." NASA scientist Dr. William Meyer, who worked on the experiment with P&G representatives, said stabilizing dispersed ingredients was one of the key technical problems, and NASA was happy to help solve it.

How P&G turned that groundwork into real patents

More than a decade after that 2001 experiment, P&G scientist Dr. Matthew Lynch found himself interacting with the same NASA scientists who would go on to form NASA's Division of Space Life and Physical Sciences Research and Applications. That connection gave the two organizations their first real chance to collaborate directly; P&G wanted to understand why its mostly colloidal products separated over time, while NASA could study them in microgravity aboard the space station.

"We wanted to take gravity out of the equation," Lynch told NASA Science. Under the Space Act Agreement, P&G funded the research, while NASA provided scientists, hardware and station time. As part of preparing for this new collaboration, Procter & Gamble tested its experiment hardware in parabolic aircraft, the so-called "vomit comets," working with NASA scientist Dr. William Meyer, who said stabilizing dispersed ingredients was one of the key technical problems. P&G conducted its first experiment in the Advanced Colloids Experiment series, which was sent to the station in 2013. In 2019, NASA said the collaboration had taken about ten years in total, spanning early ground-based preparation through six rounds of station experiments that ran from 2013 onward. The researchers used the station's confocal microscope to create three-dimensional images of colloids in microgravity, similar to a CT scan of suspended particles. Detailed observations and repeated tests under different temperatures, particle sizes, and stirring rates produced data that could not be gathered on Earth. The project led to three patents being approved in 2019.

Why this matters the next time you squeeze the tube

None of this suggests that toothpaste was invented in orbit. But it does suggest that research begun with a 2001 shuttle mission helped advance the physics behind the stability of many consumer goods. As the NASA Gallery for Advanced Colloids Experimentation notes, the findings help P&G design products that do not separate, something shoppers rarely notice on the shelf. The ISS is more than a place for astronauts to live and perform spacewalks. Some of its most tangible achievements come from practical research, such as how to keep mixtures from separating.