Where Falcon 1 is designed to launch small payloads into low-earth orbit, the Falcon 9 is designed to carry heavier payloads and travel further above the Earth, such as into geostationary orbit. The two rockets share many similar attributes, including that they are both two-stage rockets, use liquid oxygen and rocket grade kerosene (RP-1) as fuel, utilize the same structural design, and use the same avionics and launch systems. They both also use the same SpaceX-designed Merlin engines--but while the Falcon 1 uses a single Merlin engine, the Falcon 9 has nine Merlin engines. Also a potential future version of the Falcon 9 will be a three-stage rocket with nine Merlin engines on both its Stage 0 and Stage 1 boosters.
The test of the Falcon 9's first stage was conducted on Saturday, November 22, at the company's McGregor Test Facility in Texas. The test lasted for 178 seconds, "simulating the climb of the giant rocket from the surface of the Earth towards orbit."
"At full power, the rocket generated 855,000 pounds of force at sea level. In vacuum, the thrust increases to approximately one million pounds or four times the maximum thrust of a 747 aircraft. The test consumed over half a million pounds of propellant. All nine engines fired for 160 seconds, then two engines were shut down to limit the acceleration and the remaining seven engines continued firing for 18 more seconds, as would occur in a typical climb to orbit."
Being able to shut down some of the engines while the rest of the engines remained functional was a critical part of the test. The engines are designed with some level of redundancy, so that the rocket can still theoretically achieve orbit even if some of the engines fail. SpaceX claims that the Falcon 9 will be the first launch vehicle since NASA's Saturn V and Saturn 1 rockets to be able to lose an engine and "still be able to complete its mission without loss of crew or spacecraft." In 1968, the Apollo 6 mission suffered several issues with the second stage of it Saturn V rocket during liftoff, which caused two of the five second stage engines to shut down; the remaining three engines fired for longer to compensate, as did the third stage engine when it came online. While Apollo 6 was not able to achieve all of its original mission objectives, the redundancy built-into the Saturn V's engines allowed the Apollo 6 Service Module to reach orbit and accomplish at least some of the mission. Without the redundancy built-in to the engine system, Apollo 6 might not have been able to reach orbit (this was an unmanned mission, so human lives not were at risk).
"The full mission-length test firing clears the highest hurdle for the Falcon 9 first stage before launch...In the next few months, we will have the first Falcon 9 flight vehicle on its launch pad at Cape Canaveral, preparing for lift-off in 2009." -- Elon Musk, CEO and CTO of SpaceX
SpaceX is scheduled to conduct three Falcon 9 launches for NASA, with the third and final launch designated to berth with the International Space Station (ISS).