SpaceX's Dragon spacecraft arrives at space station

The unmanned Dragon capsule owned by private U.S. firm SpaceX arrived at the International Space Station (ISS) on Monday morning for its fifth commercial resupply mission to the orbiting laboratory, U.S. space agency NASA said.

The spacecraft was successfully captured by a robotic arm operated by U.S. astronaut Barry Wilmore inside the ISS at 5:54 a.m. EDT (1054 GMT), 18 minutes ahead of schedule, as the two flew over the Mediterranean Sea, NASA said.

Dragon, which was launched aboard a Falcon 9 rocket on Saturday, carried about 2.5 tons of supplies and payloads, including materials to support 256 scientific experiments in space.

The scientific payloads included an instrument that will evaluate the clouds and tiny particles in the Earth's atmosphere to potentially decipher important clues for climate change and aid in weather forecasting on the Earth.

The spacecraft is also loaded with several biological experiments that will take advantage of the microgravity environment unavailable on the Earth to advance medical knowledge.

One of the projects will study fruit flies' immune systems as a model for the human immune system, to explore how spaceflight can make organisms more susceptible to disease, especially since microbes can become more virulent in space.

Another project will grow proteins inside a 10-centimeter cube in weightlessness to research a suspected cause of Alzheimer's and similar brain ailments in people.

Dragon will remain connected to the ISS for more than four weeks before departing for a parachute-assisted splashdown off the coast of California.

This is the fifth operational cargo delivery mission for SpaceX to the ISS. The company's 1.6-billion-U.S.-dollar contract with NASA requires at least a dozen cargo delivery flights in all.

Besides SpaceX, NASA has also signed a deal with another private company called Orbital Sciences Corp. to supply cargo to the ISS.

Orbital's first two flights went smoothly, but the third failed when the company's Antares rocket exploded seconds after liftoff in late October. Endi