Update, January 6 at 5:54 a.m. PT: The planned launch for Tuesday, January 6, has been scuttled. "A thrust vector control actuator for the Falcon 9's second stage failed to perform as expected, resulting in a launch abort," reports NASA. The space agency says that the next available opportunity to launch would be on Friday and that SpaceX is examining the possibility of executing the mission then.
SpaceX, Elon Musk's private space-exploration company, will attempt Tuesday to move one step closer to its goal of building the "world's first reusable rocket." After it pushes a capsule containing supplies up into space for rendezvous with the International Space Station (ISS), the first stage of a Falcon 9 rocket will return to Earth and attempt to land itself on a platform floating in the ocean. If the Falcon 9 achieves this feat, it will be the first rocket ever to have done so.
The rocket is scheduled to lift off on Tuesday at 3:20 a.m. PT from Cape Canaveral Air Force Station in Florida. Viewers can watch the event on SpaceX's website or NASA TV. After the main rocket gets its payload -- a Dragon capsule full of supplies -- safely on its way to the ISS, it will attempt to display incredibly precise navigation by touching down on an "autonomous spaceport drone ship" bobbing in the Atlantic Ocean. The free-floating platform measures 300 by 100 feet, with wings that extend its width to 170 feet, according to SpaceX.
"While that may sound huge at first, to a Falcon 9 first stage coming from space, it seems very small," says the space company in a statement about the mission. "The leg-span of the Falcon 9 first stage is about 70 feet and while the ship is equipped with powerful thrusters to help it stay in place, it is not actually anchored, so finding the bull's-eye becomes particularly tricky." So tricky in fact, that the company has likened it to "trying to balance a rubber broomstick on your hand in the middle of a wind storm."
SpaceX puts the odds of success at 50 percent and is viewing the mission as the first in a series that should eventually lead to a fully reusable rocket.
To help the rocket navigate, SpaceX has equipped it with four fins arranged in an X-wing pattern. The fins are tucked in during launch and deploy on reentry. "Each fin moves independently for roll, pitch and yaw, and combined with the engine gimballing, will allow for precision landing -- first on the autonomous spaceport drone ship, and eventually on land," says SpaceX. You can watch the fins in action here:
The Falcon 9 has -- as you might have guessed -- nine different engines aboard that not only help it reach thrust speeds of up to 1.5 million pounds on launch but that also will fire to slow the rocket's descent on reentry. The rockets fire in a series of three bursts, each burst successively slowing the rocket's descent more and more, till it is finally traveling at a speed of about 4.5 miles per hour just before it lands.
With two test flights last year, SpaceX has already shown that Falcon 9s are capable of slowing themselves down and deploying their landing gear. In both those tests, however, the rocket tipped into the ocean after it touched down, causing damage that made it unsuitable for reuse. Reusability is a cornerstone of Musk's SpaceX program, which aims to dramatically cut the cost of space travel and make it more accessible to the masses. This will be the fifth of 12 resupply missions for SpaceX rockets to the ISS as part of a $1.6 billion contract with NASA.