A little while ago the SpaceX Dragon spacecraft ended its CRS-12 (Cargo Resupply Service 12) mission for NASA splashing down smoothly in the Pacific Ocean a little more than 420 kilometers (about 326 miles) off the coast of California. The Dragon left the International Space Station a few hours before.
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 August 16, 2017.
The Dragon spacecraft brought back to Earth about 1,700 kg (about 3,800 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. Some mice from the Rodent Research-9 study have been brought back to Earth alive. Some experiments were devised by non-profit organizations working with NASA in scientific and educational programs.
SpaceX is the only American company that has a spacecraft that can bring 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.
The next resupply mission for the Dragon cargo spacecraft could begin as early as December 2017, although the launch dates are always approximate. For the moment they have to verify that the samples and experiments have returned to Earth undamaged. According to plans, the Dragon that accomplished the CRS-12 mission was the last totally new and in the next missions partially used spacecraft will be used.