The rise of the reusable rocket is ushering in a new era of spaceflight. In the past, rockets were typically single-use and discarded after carrying their payload into space. Rockets consisted of multiple stages, and as they gained altitude and speed, they would cast off these stages one by one. The rocket parts either fell back to Earth or went into orbit; either way, they were typically not recovered or reused. However, the rocket itself is the most expensive component of a space launch. Reusable rockets could potentially cut the cost of spaceflight by a hundredfold, making spaceflight more economically feasible and commercially viable.
Reusable rockets could potentially cut the cost of spaceflight by a hundred-fold.
The Space Shuttle was in fact partially reusable, but the cost of refurbishment made it no more cost-effective than expendable rockets. After launch, its boosters parachuted into the ocean and were retrieved for refurbishment, which was a very involved and expensive process because salt water corroded the material. The company SpaceX, founded by entrepreneur Elon Musk, is currently developing and testing cost-effective reusable rocket technology, with an eye towards the company’s ultimate mission of making life multi-planetary. SpaceX designs rockets with a built-in extra fuel margin to provide the rockets with enough power to deliver a payload into space and safely land the first stage back on Earth.
On December 21, 2015, SpaceX made history by successfully re-landing the first stage of its two-stage Falcon 9 rocket. The rocket sent 11 communications satellites into orbit before returning and landing at Landing Zone 1 in Cape Canaveral, marking the first successful orbital rocket landing in history. On April 8, 2016, SpaceX launched a Falcon 9 rocket that delivered cargo to the International Space Station. The first stage of the rocket returned to Earth and successfully landed on an autonomous drone ship off the coast of Florida, achieving another important milestone. In total, SpaceX has successfully re-landed eight Falcon 9 rockets, three on land and five at sea.
The Falcon 9 rocket employs... a restartable ignition system, grid fins, and deployable landing gear.
A number of new technologies enable the successful landing of rockets back on Earth. The Falcon 9 rocket employs many cutting edge technologies including a restartable ignition system, grid fins, and deployable landing gear . When the rocket is launched, it is placed on a trajectory heading out of Earth’s atmosphere and into orbit. To land the first stage of the rocket back on Earth, it must be placed on a return trajectory heading back to the landing site. The restartable ignition system provides the rocket with the power to decelerate and perform this turnaround maneuver before landing. The Falcon 9 rocket also employs grid fins during atmospheric reentry to enable precision landing. Grid fins are attached to the side of the rocket and consist of intersecting planar surfaces that form cube shaped cells. At hypersonic speeds, the orientation of the fins can be adjusted to control the rocket’s lift vector, which allows for precise steering of the rocket as it descends through Earth’s atmosphere. Landing gear is mounted on the bottom of the rocket and consists of four carbon fiber and aluminum deployable landing legs that allow the rocket to land in a stable, upright position. In addition to these other cutting edge technologies, the rocket also has an autonomous vehicle control system and a suite of navigation sensors that help guide and control the landing.
So far, SpaceX has an impressive record of successful launches and re-landings of their Falcon 9 rockets. What’s next? Although SpaceX has successfully landed many rockets, they have not yet reused any of the re-landed rocket boosters. However, at the end of March 2017, SpaceX plans to launch the SES 10 communications satellite to space aboard a reused Falcon 9 booster. This launch will provide valuable information about the performance of the reused rocket, and if all goes smoothly, will mark a major step towards making space more accessible for commercial clients and push the boundaries of space exploration and discovery.