The little pocket mouse (Perognathus longimembris) is a species of rodent in the family Heteromyidae. It is found in Baja California and Sonora in Mexico and in Arizona, California, Idaho, Nevada, Oregon and Utah in the United States. Its natural habitat is subtropical or tropical dry lowland grassland. It is a common species and faces no particular threats and the IUCN has listed it as being of "least concern".
Five mice of this species travelled into space and orbited the Earth and Moon in an experiment on board the Apollo 17 command module in December 1972. Four of the mice survived reentry. Six other little pocket mice were sent into orbit with Skylab 3 in July 1973, though these animals died only 30 hours into the mission due to a power failure.