SpaceX sent a capsule of 40 mice. Eight of them, they are calling “mighty mice”, according to the AP.

They are mice that have been genetically enhanced to have twice the muscle mass of regular mice.

It’s so scientists can study the effects space has on the body and how astronauts can stay fit on long space trips.

The SpaceX capsule has more than just mice for science.

Barley grains from Budweiser, a robot named Cimon and holiday care packages were also launched into space.

The barley is for an experiment on how weightlessness affects germination.

Cimon is a robot sensitive to astronauts’ emotions, his purpose is to help the astronauts for the next three years.

Five astronauts are currently living in the space station. Three from the U.S., two Russians and one Italian.