SpaceX's Falcon 9 rocket completed a two-second ignition of its first stage while being held down onto its Florida launch pad on Monday, in preparation for Friday's launch to the International Space Station. This view of the test was taken by a remote video camera, which makes it difficult to see the flare of the rocket.

By Alan Boyle, Science Editor, NBC News

SpaceX said it completed a successful test of the engines on its Falcon 9 rocket on Monday, in preparation for Friday's planned cargo launch to the International Space Station.

The California-based rocket company's unmanned Dragon capsule is due to deliver about 1,200 pounds (550 kilograms) of supplies to the space station and bring back 2,300 pounds (1,050 kilograms) of cargo, including scientific samples and space station hardware.

Monday's static-fire test was aimed at checking the performance of the Falcon 9 first stage's nine engines before they're called upon to loft the second stage and the Dragon capsule toward orbit on Friday. The rocket was held down onto its launch pad at Space Launch Complex 40 at Cape Canaveral Air Force Station in Florida for the engine firing, which came at the end of a dress rehearsal for Friday's countdown.

"SpaceX engineers ran through all countdown processes as though it were launch day," the company said in a statement issued after the 1:30 p.m. ET firing. "All nine engines fired at full power for two seconds, while the Falcon 9 was held down to the pad. SpaceX will now conduct a thorough review of all data and continue preparations for Friday's targeted launch."

In a Twitter update, SpaceX's billionaire founder, Elon Musk, reported that the static-fire test looked good: "Engines generated 433 tons of thrust, parameters nominal."

SpaceX said the first opportunity for launch will come at 10:10 a.m. ET on Friday. This is the third Dragon to be sent to the space station, and the second flight under the terms of a $1.6 billion, 12-flight cargo resupply contract with NASA.

Another company, Virginia-based Orbital Sciences Corp., has a separate $1.9 billion contract to deliver supplies to the space station but has not yet begun flying its Antares rocket and Cygnus cargo capsule. On Friday, Orbital completed a successful static-fire test of Antares' engines in preparation for the rocket's first flight, which is expected to take place later this year.

NASA's contracts with SpaceX and Orbital are meant to help fill the gap left by the retirement of the space shuttle fleet in 2011. Russian, European and Japanese unmanned spacecraft are also used to send supplies to the space station, but Russia's Soyuz capsule is the only spacecraft currently cleared to transport astronauts to and from orbit. NASA is providing more than $1 billion to SpaceX, the Boeing Co. and Sierra Nevada Corp. to support the development of new crew-capable spacecraft for low Earth orbit.

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SpaceX tests rocket for space station launch