SpaceX flyby of space station an historic first

The SpaceX Dragon capsule successfully made its first burn to approach the space station at 3:58 a.m Thursday. It was the final test before the SpaceX capsule docks at the ISS.

By Clara Moskowitz,?Space.com / May 24, 2012

This computer generated image shows the SpaceX Dragon spacecraft with solar panels deployed. The world's first private supply ship flew tantalizingly close to the International Space Station on Thursday, May 24, 2012 in a critical test in advance of the actual docking scheduled for Friday, May 25, 2012.

AP Photo/SpaceX

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A private spaceship on its first trip to the International Space Station made a flyby of the orbiting laboratory early Thursday (May 24), zipping just below the outpost in an unprecedented space first.

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The unmanned vehicle, called?Dragon, is built by Space Exploration Technologies Corp. (SpaceX), and is the first commercial spacecraft ever launched toward the space station. During the rendezvous, the spacecraft approached within 1.6 miles (2.5 km) of the outpost. Dragon launched to orbit??from Cape Canaveral, Fla.,?early Tuesday (May 22) atop a SpaceX Falcon 9 rocket and is due to arrive at the station on Friday (May 25).

Today was a?final testing day for the capsule?before it can be cleared to attempt its first docking. The capsule performed a near flyby of the space station just as designed, without any mishap.

IN PICTURES: SpaceX Falcon 9 rocket

"Today is a really great day," NASA flight director Holly Ridings said during a briefing after the flyby. "It's been very, very successful up to this point."

Crewmembers inside the orbiting lab have been monitoring the vehicle's activities.

"We all look forward to it," space station Expedition 31 flight engineer Andre Kuipers of the European Space Agency said this morning. "We will dedicate today to Dragon." [SpaceX's Historic Dragon Flight to Space Station]

The capsule successfully made its first burn to approach the space station at 3:58 a.m. EDT (0758 GMT), and followed with another engine firing at 4:43 a.m. EDT (0843 GMT) that took Dragon to a position 1.6 miles (2.5 km) below and 25 miles (40 km) behind the?International Space Station, officially beginning its flyby. At around 7:25 a.m. EDT (1125 GMT), Dragon made its closest approach, passing through the imaginary line called the R-bar connecting the station and Earth.

From this spot, cameras on the outpost searched for sightings of the approaching capsule.

"Dragon may or may not be visible," NASA commentator Josh Byerly said. "Dragon should be a small dot on the horizon."

Shortly before 7 a.m. EDT (1100 GMT), station astronauts sent instructions to Dragon to turn on a strobe light as a test to make sure the craft can respond to commands sent by the astronauts. Though the light was invisible to the crew, the spacecraft's systems indicated that the command was received and responded to.

"It's too far out and brightly illuminated to see the strobe light," Kuipers said.

The space station is a $100 billion orbiting research lab built by a coalition of five international space agencies, including NASA, the Russian Federal Space Agency, the European Space Agency, the Japanese Aerospace Exploration Agency, and the Canadian Space Agency.

During Thursday's flyby, Dragon tested its navigation and communications instruments, including a system called Relative GPS that uses the distance between the station and the capsule to determine Dragon's position in space. The vehicle will also tried out its "COTS Ultra-high frequency Communication Unit" to send signals to the space station.

As Dragon approached the station, the spacecraft was visible as a small bright dot in the distance.

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