The CRS-5 mission lifted off today in a pre-dawn launch at 4:47 am EST from Space Launch Complex 40 at Cape Canaveral Air Force Station, Florida. As the unmanned spacecraft rose into orbit to resupply the International Space Station, the first stage of its Falcon 9 booster made an historic attempt at a powered landing on a drone barge positioned in the Atlantic Ocean, which did not come off successfully.

CRS-5 launched under scattered clouds as the Falcon 9 generated 1.3 million lb of thrust. One minute and ten seconds into the flight, the spacecraft went through its area of maximum aerodynamic pressure, called max Q, and the first stage engines cut out at two minutes and 37 seconds. Traveling at an altitude of 50 miles (80 km) and ten times the speed of sound, the first stage separated from the second, which propelled the Dragon into orbit with a seven-minute burn.

Normally, this would have been the end for the Falcon 9 booster as it crashed back into the Earth's atmosphere, but as part of SpaceX's program to develop a completely reusable spaceflight system, today's launch was followed by an experimental power landing of the rocket on an "autonomous spaceport drone ship," which is a custom-built platform measuring 300 x 100 ft (91 x 30 m) with wings extending the width to 170 ft (52 m), and uses computerized thrusters to keep stationary.

After separating from the second stage, the Falcon 9 first stage executed a series of engine burns, beginning with a "boostback" burn to set it on course for the landing site. This was followed by a supersonic retro propulsion burn to help slow it, then a final burn to slow it to 2 m/s (6.5 ft/s) as the landing legs deployed for an attempted soft touchdown on the barge.

According to a tweet from Elon Musk, the rocket made it to the drone spaceport, but "landed hard." Musk went on to say that it was "Close, but no cigar this time." However, he also said that this boded well for future missions.

SpaceX says the landing had only a 50 percent chance of success and direct real-time communications were not available during the landing, which was carried out autonomously by the Falcon 9's computers. Details will be available as videos and data are gathered from telemetry and the chase plane stationed to monitor the landing.

Meanwhile the Dragon spacecraft will carry out 44 hours of maneuvers as it matches orbits with the ISS. CRS-5 is carrying 5,200 lb (2,360 kg) of supplies for the station as well as critical materials for 256 experiments. This includes the Cloud-Aerosol Transport System (CATS), which uses a laser to study the effects of aerosol particles on the Earth's atmosphere, and an Imax camera.

This was the seventh flight of the SpaceX Dragon to the ISS and its fifth commercial flight under NASA's Commercial Resupply Services contract. The first launch scheduled in December was abandoned due to an unsatisfactory static test of the Merlin engine used to power the Falcon 9, and the second attempt on January 6 was scrubbed due to two thrust vector actuators on the second stage drifting, which triggered an automatic abort.

After docking with the ISS, the Dragon spacecraft will remain berthed for four and a half weeks, when it will return to Earth with experimental materials hardware, crew supplies, and rubbish for a splashdown off Long Beach, California.

Source: SpaceX

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