SpaceX achieves controlled landing of Falcon 9 first stage
BY STEPHEN CLARK
Posted: April 19, 2014
SpaceX says it made two key strides toward the eventual reusability of the Falcon 9 rocket this week with the controlled splashdown of the rocket's first stage in the Atlantic Ocean on Friday and the successful first flight of a booster prototype from the company's Central Texas test facility.
The first step was to prove the rocket's first stage could complete a series of unprecedented engine burns using leftover propellant after finishing its primary job of boosting a satellite into orbit.
Musk announced late Friday the first stage of a Falcon 9 rocket launched from Cape Canaveral earlier in the day had apparently reached a splashdown zone in the Atlantic Ocean intact, based on data from a tracking plane dispatched to monitor telemetry from the descending rocket booster.
Using Twitter to share the news, Musk said the aircraft received data for 8 seconds after the rocket reached the water, an indication the first stage at least survived the landing long enough to continue powering its transmitter.
The first stage was supposed to fire its engines twice after separating from the Falcon 9 rocket's second stage less than 3 minutes after liftoff Friday. The first burn was expected to slow the rocket's velocity enough to fall into a prescribed landing zone in the Atlantic Ocean a few hundred miles northeast of Cape Canaveral, and a second firing was to have allowed the rocket to gently settle into the sea.
Four carbon fiber and aluminum honeycomb mounting legs mounted around the base of the 12-foot-diameter first stage were supposed to extend shortly before the water landing. Friday's launch was the first SpaceX flight to feature landing legs, which officials said had no negative effect on the flight's ascent.
The first stage's sporty descent maneuvers occurred as the Falcon 9 rocket's upper stage continued into orbit with a Dragon supply ship heading for the International Space Station.
Boats stationed near the first stage's landing site were heading for the expected splashdown point late Friday, according to Musk, but rough seas were expected to make it difficult to locate and retrieve the rocket.
If the launcher stage can be plucked from the sea, SpaceX plans to return it to port and analyze its condition.
Regardless of whether the first stage is retrieved in one piece, Musk told reporters Friday the recovery experiment went further in demonstrating the Falcon 9's potential for reuse than any mission before.
"We were able to control the boost stage to a zero roll rate, which is previously what has destroyed the stage -- uncontrolled roll where the on-board nitrogen thrusters weren't able to control the aerodynamic torque and spun up," Musk said. "This time, with more powerful thrusters and more nitrogen propellant, we were able to null the roll rates."
The last time SpaceX tried to recover a Falcon 9 first stage, the rocket came down spinning, exceeding the control abilities of the nitrogen cold gas thrusters and starving the engines of fuel. After that launch from Vandenberg Air Force Base in California, crews salvaged only fragments of the Falcon 9's first stage.
Friday's rocket launch came the same week as SpaceX's new vertical takeoff and landing testbed, dubbed Falcon 9R Dev 1, flew for the first time at the company's rocket development site in McGregor, Texas.
This view from a hexacopter flying over SpaceX's Central Texas test site shows the Falcon 9R prototype reaching a height of more than 800 feet. Video credit: SpaceX
The next step, assuming sea crews are unable to recover the rocket from Friday's launch, is to return a first stage to a precision touchdown on land and determine what might be necessary to prepare it for another flight.
"The reuse must be both rapid and complete, like an aircraft or a car," Musk said. "If you have to disassemble and reassemble a car and change a bunch of parts in between driving it, it would make it quite expensive.
According to Hans Koenigsmann, SpaceX's vice president of mission assurance, the next Falcon 9 launch scheduled for May will also try for a water recovery.
"We don't have to just recover it," Musk said. "We have to show that it can be reflown quickly and easily, where the only thing you [have to do] is reload propellant."
Using the space shuttle as an example, Musk said it is critical to maintain the same approach to the Falcon 9's reusability in order to make it work.
"The unfortunate thing with the space shuttle was originally the design of the shuttle was, I think, fairly well-suited for good reuse, but then the requirements changed and that made it very difficult to reuse efficiently," Musk said. "As long as we're able to hold to our requirements, I think we'll be able to achieve rapid and essentially complete reuse."
The space shuttle's winged orbiter and segments of its solid rocket boosters were used many times, but the program was stymied by bloated costs and multi-month turnarounds between missions.
Musk aims to make reusability commercially viable and reduce the Falcon 9's launch costs.
None of SpaceX's competitors in the launch market are pursuing reusability with the same fervor. Launch industry executives expressed casual interest, at best, in the prospect for rocket reusability in a panel discussion last month.
"There's no question it's nirvana," said Robert Cleave, president of Lockheed Martin's launch services unit, which sells the Atlas 5 rocket on the commercial marketplace. "It's been nirvana since the '60s. We've had some reusable things. The space shuttle was reusable, but the price point wasn't the best."
Cleave said Lockheed Martin has interest in launcher reusability, but he doubted the paradigm was economically or technically viable in the near future. The Atlas 5 rocket is one of SpaceX's main rivals in the U.S. domestic launch market.
Stephane Israel, chairman and CEO of Arianespace, another SpaceX rival, also said reusability was not on the French launch services company's horizon for next few decades.
"There are some capabilities in Europe regarding reusability, so the technologies are existing, but it's a matter of fact that when you consider the roadmap of Ariane, we do not bet on reusability," Israel said. "We are looking at it, but it's not our primary bet that the business model is quite convincing. We will monitor closely what will happen."
Musk hopes SpaceX can recover a Falcon 9 booster this year and fly a used first stage for the first time in 2015.
Eventually, SpaceX plans to clad the rocket's single-engine upper stage with a heat shield with an eye toward reusing it as well. The company has not disclosed a timetable for a potential recovery of the second stage.
Follow Stephen Clark on Twitter: @StephenClark1.
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