SpaceX supply ship begins journey to space station
BY STEPHEN CLARK
Posted: April 18, 2014
SpaceX's commercial Dragon supply ship thundered into orbit Friday to begin a two-day pursuit of the International Space Station, setting up the delivery of 2.4 tons of fresh supplies and experimental cargo to the 450-ton research complex Sunday.
The launcher picked up speed, breaking the sound barrier about 70 seconds after liftoff and rocketing through the stratosphere before releasing its nine-engine first stage less than 3 minutes into the flight.
The first stage fell away, leaving the upper stage's single Merlin 1D engine to accelerate the rocket and Dragon payload into orbit as the vehicle flew northeast from Cape Canaveral, paralleling the U.S. East Coast to reach the space station's exact orbital inclination.
The 12-foot-diameter first stage was programmed to ignite its engines two times during its fall back into the Atlantic Ocean, slowing its velocity before deploying four landing legs made of carbon fiber and aluminum honeycomb.
Monday's launch was the first Falcon 9 rocket to fly with landing legs.
Elon Musk, SpaceX's CEO and chief designer, posted an update Friday night on Twitter saying the first stage made a good landing despite high waves in the recovery zone a few hundred miles northeast of Cape Canaveral.
"Data upload from tracking plane shows landing in Atlantic was good! Several boats enroute through heavy seas," Musk tweeted, adding a few minutes later that the first stage's flight computers continued transmitting for 8 seconds after reaching the water, an indication the rocket must have splashed down with minimal damage.
SpaceX says the experimental first stage recovery is a stepping stone toward reusing the Falcon 9 rocket, which Musk says is critical for reducing the cost of space transportation.
If the stage landed intact, it would mark the first time SpaceX has retrieved part of a Falcon rocket after launch.
"I'm feeling pretty excited," Musk told reporters in a telephone call from SpaceX headquarters in Hawthorne, Calif. "This is a happy day. Most important of all is that we did a good job for NASA ... Everything else is secondary to that."
The mission is SpaceX's third resupply run to the space station, coming after successful flights in October 2012 and March 2013 to kick off the execution of a $1.6 billion logistics contract with NASA. Signed in December 2008, the deal covers 12 missions for the delivery of a cumulative 44,000 pounds of cargo to the space station.
After reaching orbit Friday, the Dragon spaceship deployed from the Falcon 9's second stage about 10 minutes after liftoff, receding from the view of an on-board "rocketcam" backdropped by the muted blue colors of the ocean splashed against the stark blackness of space.
The spacecraft automatically unfurled two power-generating solar arrays with a wingspan of 54 feet.
SpaceX engineers initially ran into a problem with the Dragon spacecraft's propulsion system, causing the capsule to miss an appointed engine burn to set up for its two-day chase of the space station.
But Musk said the glitch, traced to an isolation valve, was bypassed by the use of a backup valve and the cargo mission was on track to reach the space station early Sunday.
Late Friday, the Dragon spacecraft opened its navigation bay door, exposing the ship's laser and thermal guidance sensors to be used in the final phase of its approach to the space station.
Controllers plan a series of orbit-raising burns over the next day-and-a-half, leading to the arrival of Dragon in the vicinity of the complex in the predawn hours Sunday, U.S. time.
Grapple is scheduled for 7:14 a.m. EDT (1114 GMT) to wrap up a 40-hour rendezvous that began with the Falcon 9 rocket's launch Friday.
The Dragon spacecraft launched Friday sports several upgrades over previous SpaceX cargo vehicles, nearly quadrupling the ship's capacity for powered cargo. The modifications include additional freezers for biological samples and redesigned cargo racks to accommodate additional payloads, according to SpaceX.
The mission is also taking up research experiments in the Dragon's unpressurized trunk for the first time. The passengers include a NASA optical communications terminal to demonstrate high data-rate links between the space station and the ground, along with a high-definition camera suite to collect videos of Earth.
The payload packages will be mounted outside the space station by the lab's Canadian-built robotics system.
Astronauts will manually remove items stowed inside the Dragon spacecraft's internal section, including 1,576 pounds of science and research gear, 1,049 pounds of crew provisions, 449 pounds of vehicle hardware, and 271 pounds of spacewalk tools.
The Dragon will arrive with a fresh spacesuit for the space station's six-person crew, a space age garden to demonstrate vegetable growth in microgravity, and legs for Robonaut 2, a humanoid robot launched on a 2011 space shuttle mission.
The space station will repack the Dragon spacecraft's pressurized module with experiment samples and other hardware destined to return to Earth. Dragon's departure and splashdown in the Pacific Ocean is scheduled for May 18.
Follow Stephen Clark on Twitter: @StephenClark1.