SpaceX-3 launches science cargo to International Space Station

The manifest for the uncrewed Dragon includes almost 5,000 pounds of material including a spacewalking suit for astronauts plus related hardware and supplies for more than 150 science investigations to be conducted by the space station crews.

"SpaceX is delivering important research experiments and cargo to the space station," said William Gerstenmaier, NASA associate administrator for human exploration and operations. "The diversity and number of new experiments is phenomenal. The investigations aboard Dragon will help us improve our understanding of how humans adapt to living in space for long periods of time and help us develop technologies that will enable deep space exploration."

The Dragon spacecraft, making the company's third operational cargo mission to the station, separated from its Falcon 9 second stage as planned and deployed its twin solar arrays on time.

"Looks like everything's good on Dragon," SpaceX founder and CEO Elon Musk said during a news conference following the launch. "I'm feeling pretty excited, this is a happy day," Musk said.

The launch took place on a day that started with heavy clouds and occasional rain at the launch site at Cape Canaveral Air Force Station in Florida. The launch preparation teams from SpaceX and payload teams for NASA had to work inside tight schedules to safely set up for launch between the bouts of poor weather.

"They did a lot of good work," Gerstenmaier said.

The weather was on the front of everyone's mind throughout the morning, but cleared up enough about two and half hours before the 3:25 p.m. launch time to allow a liftoff.

"Weather was our primary concern," said Hans Koenigsmann, vice president of Mission Assurance for SpaceX. "It's a really good day."

Musk also reported early signs of success in SpaceX's test to have the first stage of the Falcon 9 reignite its engines and slow the stage to a soft landing on the ocean's surface a few minutes after liftoff. All data is not in yet, he said, but the slowdown seemed to go well. He does not expect to be able to pick the first stage out of the water, however, because the ocean waves were substantial having been roiled up by days of rough weather. He said the flight encourages him to continue its pursuit of recovering a first stage intact.

"I think we have a decent chance of bringing a stage back this year, which would be wonderful," Musk said.

"It looked great, it looked like it was doing what it was supposed to do," Koenigsmann said.

The science-related equipment includes the VEGGIE system that is designed to grow leafy vegetables in orbit. A system called OPALS will test whether lasers can be used to carry data from space to Earth. The T-cell Activation in Aging unit will seek the cause of the depression of the human immune system in astronauts in microgravity.

The Dragon also carries four commercially available high-definition video cameras that will be mounted to the outside of the station to see how they handle the conditions of space. Although they will be inside temperature-controlled enclosures the cameras will experience the radiation of orbit. Online viewers will be able to watch the footage from the cameras.

The supply ship also carries a pair of legs for Robonaut 2, the humanoid robot that has been going through testing inside the space station since 2011.

The robot is designed to perform repetitive tasks and free up astronauts' time for science experiments and other research. Its head and torso now are supported on a moveable post in the station's pressurized module. The legs and their special fittings would allow the robot to move around inside the station. Later additions to the robot would allow it to also work on the outside of the station as an assistant to spacewalkers.

The Dragon will remain docked to the station about a month before it is released and guides itself back through the atmosphere to a parachute landing off the coast of California. It will return more than 3,000 pounds of completed experiments from the station along with other equipment and unneeded materials.