A SpaceX capsule rocketed to the International Space Station on Monday, carrying tons of science research, plus ice cream.

Experiments make up most of the 2.9 metric tons of cargo, which should reach the orbiting station on Wednesday. That includes 20 mice that will return alive inside the SpaceX Dragon capsule in about a month.

The Dragon also is doubling as an ice cream truck this time.

There was extra freezer space, so NASA packed little cups of vanilla, chocolate and birthday cake ice cream, as well as ice cream candy bars. Those treats should be especially welcomed by US astronaut Peggy Whitson, in orbit since November. She's due back at the beginning of September. Newly arrived US astronaut Randolph Bresnik turns 50 next month.

The mice are part of a study of visual problems suffered in space by some male astronauts. Scientists will study the pressure in the animals' eyes, as well as the movement of fluid in their brains. Thirty days for mice in space is comparable to three years for humans, said Florida State University researcher Michael Delp, the dean of the College of Human Sciences, who heads the project.

The Dragon also holds an instrument to measure cosmic rays hitting the space station. The Army has an imaging microsatellite on board for release this fall in a technology demo; the military wants to see how small satellites, about the size of a dorm refrigerator, with low-cost, off-the-shelf cameras and telescopes, might support critical ground operations.

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