NASA has sent samples of human sperm to the International Space Station to study how fertilization could happen in space.

The mission, called Micro-11, rocketed frozen human sperm and bull sperm for a comparison to the space station early this month. The aim? NASA wants to know: Do sperm squirm the same in space?

Lack of gravity affects human sperm motility and fertility. During fertilization for mammals, the activated sperm swims to fuse with an egg, and it faces a vastly different environment depending on gravity.

Earlier studies for other types of sperm have pinpointed a number of issues in space.

Experiments with sperm from sea urchins and bulls have suggested that activating movement happens more quickly in microgravity, while the steps leading up to fusion happen more slowly or not at all, NASA explained. Delays or problems at this stage could prevent fertilization from happening in space.

Astronauts on the space station will thaw the samples and add a chemical mixtures to activate the sperm. Theyll then record how well the sperm move in space. Samples will be sent back to a lab at the University of Kansas for further study.

The experiment is being managed by NASAs Ames Research Center in Californias Silicon Valley. The sperm was launched into space April 2 as part of SpaceXs fourteenth cargo resupply mission to the space station.