SpaceX has launched its fourth commercial mission to the International Space Station (ISS). The CRS-4 Dragon spacecraft lifted off atop a Falcon 9 booster early Sunday morning from Space Launch Complex 40 at Cape Canaveral Air Force Station, Florida at 1:52 am EDT. On board is about 5,000 lb (2,268 kg) of cargo, including the first zero gravity 3D printer and a crew of "mousetronauts."

Today’s launch came after a delay from the original Saturday launch window due to poor weather conditions. The spacecraft is now carrying out a series of orbital maneuvers for its rendezvous with the ISS on Tuesday, when the station crew will catch the Dragon with a grapple and transfer it to a docking port, where it will remain until mid-October before returning to Earth with a collection of scientific samples.

On board the unmanned cargo vessel are supplies for the station and a collection of experiments, including the International Space Station-Rapid Scatterometer that uses radar pulses to study the wave speeds and wind directions on the surface of the oceans, a 3D printer designed to work in weightless conditions that may one day allow astronauts to print spare parts in orbit, and the Rodent Research Hardware and Operations Validation (Rodent Research-1), which includes a new habitat carrying a collection of normal and genetically modified rodent "mousetronauts" to study the long-term medical effects of weightlessness.

The CRS-4 launch comes on the heels of NASA’s announcement that SpaceX has been chosen along with Boeing to ferry astronauts to the space station. Though passengers will travel in the Dragon V2, today’s mission used the original cargo version of the Dragon as part of a US$1.6 billion NASA Commercial Resupply Services contract.

The video below shows the night launch of the CRS-4 mission.

Source: NASA

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