At 03:59 UTC on October 1, SpaceX’s CRS-23 Dragon successfully completed its one-month mission to the ISS, becoming the first Cargo Dragon to splashdown in the Atlantic Ocean.

Previously, Cargo Dragons have splashed down in the Pacific or the Gulf of Mexico. Because CRS-23 landed in the Atlantic, it only took a few hours to return samples back to Kennedy by helicopter after landing. The recovery ship that collected the Cargo Dragon has a primary mission of astronaut recovery, with a helipad for use in the event of a medical emergency. In this case, the samples were fast-tracked back to land so they could be analyzed before their return to gravity had an opportunity to affect them. Processing samples both before and after launch at the same lab (at Kennedy Space Center) helps with consistency in the measurements.

Among the experiment samples returned to Earth was an experiment that used surface tension in a liquid between two rings to form a container, much like a soap bubble. The container was then spun to study the formation of proteins called amyloids associated with diseases like Parkinson’s and diabetes to help in the development of treatments.

CRS-23 also brought back samples from experiments trying to improve astronauts’ health in space, including two muscle cell slides: one treated with a muscle loss inhibitor and the other with a muscle growth agent. The two biomaterials in the experiment may also be helpful for elderly people on Earth, who are prone to lose muscle mass over time.

The final experiment which returned on CRS-23 investigated liver enzymes to figure out why some drugs aren’t metabolized by astronauts in space as well as when they are on Earth. The experiment was specifically looking at how gene expression, the process of interpreting DNA, changes in microgravity to understand why drugs are less effective in space.

Mice were dosed with the common painkiller acetaminophen, the active ingredient of Tylenol. RNA from the mice was extracted and mixed with chemicals to make testing in space easier. Onboard the ISS, astronauts performed a method called Polymerase Chain Reaction (PCR) to make a lot of copies of that small sample. PCR is the same process used in the slower but more accurate COVID-19 test. Because of a dye that bonded to some of the mouse DNA, there is a visible difference in how much acetaminophen was metabolized. This makes it possible to determine how much of an effect microgravity had on gene expression related to drug metabolization.

More Information

NASA press release

Ring Sheared Drop (NASA)

Genes in Space-8 (NASA)