A little while ago the SpaceX Dragon spacecraft ended its CRS-19 (Cargo Resupply Service 19) mission for NASA splashing down smoothly in the Pacific Ocean almost 500 kilometers (about 300 miles) off the coast of California. The Dragon left the International Space Station a few hours earlier.

Shortly after landing, SpaceX boats went to retrieve the Dragon to transport it to the coast. The cargo brought back to Earth will be delivered to NASA soon, probably tomorrow. The Dragon spacecraft reached the International Space Station on December 8, 2019.

The Dragon spacecraft brought back to Earth more than 1,600 kg (about 3,600 lbs) of mixed cargo between the pressurized and the non-pressurized section that include various scientific experiments and biological samples. Part of the samples are contained in the freezers because they need to be kept at low temperatures.

SpaceX is the only American company that has a spacecraft capable of bringing intact cargo back to Earth so the Dragon missions are really important for NASA. Samples produced during many of the experiments conducted on the International Space Station may require in-depth analyzes possible only in specialized laboratories on Earth.

Medical research, other biological research and experiments of other types are conducted on the Station. When they need to bring something back to Earth a little cargo can be transported together with the astronauts on the Soyuz spacecraft but their total volume requires a cargo spacecraft that can bring them back to Earth.

Typically there are groups of mice that are brought back to Earth after spending a period in space, as if they were little astronauts. In this case, these are the mice from the Rodent Research-19 (RR-19) experiment to evaluate the influence of myostatin, a protein that restricts muscle development in animals.

In this case, other animals have also been brought back to Earth: they’re rotifers, small creatures that live in freshwater and have a high resistance to radiation. The Rotifer-B1 investigation aims to assess that resistance in a microgravity environment.

Originally, the Dragon spacecraft was due to return to Earth on Sunday but the weather forecast indicated high seas in the splashdown area. As a result, NASA and SpaceX decided for a 2-day postponement of its departure to have a better weather.

The next resupply mission for the Dragon cargo spacecraft could begin as early as March 2020, although launch dates are always approximate. That will be the last mission part of the first contract with NASA, and it will be followed by at least 6 missions part of the second contract, which will be carried out with the new version of the Dragon cargo spacecraft. For the moment they have to verify that samples and experiments returned to Earth are undamaged.