With last Friday’s successful launch of CRS-13, SpaceX marked its fiftieth orbital launch. The milestone comes less than twelve years after the company’s first, unsuccessful, mission lifted off in March 2006, in which time SpaceX has gone from another hopeful startup to one of the biggest players in the global launch industry.
Space Exploration Technologies Corporation was founded by Elon Musk in May 2002 with the goals of reducing the cost of access to space, improving reliability and eventually helping to place humans on Mars. Musk had previously founded software company Zip2 and online payment service PayPal. Musk had been involved in a project to send plant life to Mars. However, he was forced to abandon this when he was unable to find an affordable launch solution.
SpaceX initially envisioned a fleet of three differently-sized rockets: the smallest and simplest was the Falcon 1, with larger Falcon 5 and Falcon 9 vehicles being introduced later to accommodate heavier payloads. To keep costs down, most major components of the rockets would be built by SpaceX themselves. Falcon was named after the Millennium Falcon ship in the Star Wars films, with the numbers 1, 5 and 9 denoting the number of first-stage engines on each version of the rocket.
Falcon 1 was a two-stage rocket which measured 21.3 meters (70 feet) in length and 1.7 meters (5.5 feet) in diameter. Capable of placing a 670-kilogram (1,480 lb) payload into low Earth orbit, the rocket used RP-1 kerosene propellant and liquid oxygen oxidizer. Its first stage was powered by a single Merlin engine, while the upper stage used the smaller, pressure-fed, Kestrel. Both engines were built in-house by SpaceX. Being smaller and less complex than their other proposed rockets, SpaceX built Falcon 1 first in order to minimise their financial risk if the project was unsuccessful.
Two Falcon 1 launch pads were built. The first, Space Launch Complex 3W at California’s Vandenberg Air Force Base, was constructed on the site of a former Thor-Agena and Atlas launch complex that was last used in 1995 for the final Atlas-E/F launch. The second was situated on Omelek Island, part of Kwajalein Atoll in the Marshall Islands. In the middle of the Pacific Ocean, close to the equator, Omelek would allow Falcon to launch to almost any orbital inclination.
Falcon’s first flight was set from Vandenberg, with the Naval Research Laboratory’s experimental TacSat-1 payload. Concerns over the rocket’s flight path – which would see it overfly the Titan IV launch pad at Space Launch Complex 4E – meant that the Air Force would not approve the launch until Titan had made its last launch – which occurred in October 2005. Instead, the US Air Force Academy’s FalconSAT-2 spacecraft was chosen for the first launch, which would take place from Omelek. TacSat-1 was never launched, and SLC-3W never saw a Falcon 1 launch. Ironically, when SpaceX began launches from Vandenberg with the Falcon 9 rocket, it was from the former Titan launch complex.
With FalconSAT-2 aboard, Falcon 1 was ready for launch at the end of November 2005, with the first attempt on 27 November local time (26 November in UTC) scrubbed due a ground support equipment fault that allowed oxidiser to leak from tanks at the launch pad – leaving SpaceX unable to top off the rocket’s tanks following a weather delay in the countdown. During the next attempt, in December the rocket’s first stage tank buckled as fuel was drained during an extended weather delay – a valve had failed to open which allowed a vacuum to form within the tank.
Falcon 1’s third attempt to launch was made on 25 March 2006, with the rocket finally lifting off at 10:39 local time (22:39 UTC on 24 March). The launch quickly failed, with the first stage engine losing thrust thirty-four seconds after liftoff and the rocket falling into the Pacific.
The failure was traced to a corroded nut in the first stage fuel pump inlet, which allowed fuel to leak out and catch fire around the tail of the rocket. FalconSAT-2 survived the launch, it was thrown clear on impact and fell through the roof of a storage building on Omelek, landing next to its own shipping container.
After the failure was investigated and design and process changes implemented to avoid a repeat, Falcon 1 flew again in March 2007. Carrying a demonstration payload and two experimental packages for NASA, Falcon flew for longer than it had on its maiden flight and reached space for the first time, but again failed to achieve orbit. As the first stage separated, it clipped the second stage engine. This recontact pushed the second stage off course, requiring a maneuver to re-attain is planned trajectory. The rapid change or orientation caused oxidizer in the second stage to begin sloshing around in its tank, generating an inertia which slowly overcame the rocket’s attitude control system.
The third Falcon 1 launch took place in August 2008, with the Operationally Responsive Space Office’s Trailblazer satellite, two NASA CubeSats and a Celestis space burial payload aboard. The launch introduced several changes to the rocket, including a regeneratively-cooled Merlin-1C engine in place of the ablatively-cooled Merlin-1A on the first stage, and an improved second stage. The launch failed during stage separation – SpaceX had not accounted for residual thrust in the regeneratively-cooled engine, which caused the two stages to collide after the first was jettisoned.
SpaceX immediately identified the cause of the failure and modified Falcon’s flight profile to incorporate a short pause between first stage engine cutoff and separation, allowing the residual thrust to die down. Less than two months after the Trailblazer failure, Falcon 1 became the first privately-developed liquid-fuelled rocket to reach orbit when it successfully orbited a demonstration payload named RatSat.
Falcon 1’s fifth and final launch successfully deployed Malaysia’s RazakSAT imaging satellite in July 2009.
The Falcon 1 was to have been replaced by a stretched version, the Falcon 1e, however this never flew. Instead, SpaceX opted to concentrate on larger rockets, carrying small satellites as secondary payloads rather than giving them dedicated launches. Another rocket that never made it to the launch pad was the Falcon 5, an intermediate version between Falcon 1 and Falcon 9 with five Merlin engines on the first stage, but otherwise similar in configuration to the original Falcon 9 design.
NASA awarded SpaceX a contract in 2006 under its Commercial Orbital Transportation Systems (COTS) project. NASA had called for unmanned spacecraft capable of delivering cargo to the International Space Station, maintaining the United States’ ability to deliver supplies and equipment to the outpost following the Space Shuttle’s retirement.
SpaceX proposed Dragon, a recoverable spacecraft it had already been developing privately, which was selected alongside RocketPlane Kistler’s K-1 vehicle. The second contract was re-awarded to Orbital Sciences Corporation (now Orbital ATK) after Kistler failed to keep up with project milestones. At the end of 2008, NASA awarded twelve Commercial Resupply Services (CRS) missions to SpaceX and eight to Orbital, providing operational missions to be completed by the vehicles developed under COTS.
Alongside Dragon, SpaceX brought the Falcon 9 rocket into production. A two-stage rocket that would be used to boost Dragon into orbit, Falcon 9 used nine Merlin engines on its first stage, with a tenth – vacuum-optimised – Merlin Vacuum (MVac) engine powering the second stage. In its initial configuration, which has retrospectively become known as the Falcon 9 v1.0, the nine first stage engines were arranged in a square grid pattern. Although SpaceX initially intended to launch Falcon 9 from Omelek, these plans never came to fruition. Instead, SpaceX leased Space Launch Complex 40 at the Cape Canaveral Air Force Station, demolishing the former Titan IV launch complex which had stood dormant since Titan’s 2005 retirement and rebuilding it for Falcon.
SpaceX has since built additional Falcon 9 launch complexes at Vandenberg Air Force Base’s Space Launch Complex 4E – to support polar-orbit missions – and Launch Complex 39A at the Kennedy Space Center, to the north of SLC-40. SpaceX has also begun construction of a privately-owned facility at Boca Chica in Texas, which is expected to support commercial missions.
Falcon 9 lifted off from Space Launch Complex 40 on 4 June 2010 to begin its maiden flight. Carrying the Dragon Spacecraft Qualification Unit (DSQU), a vehicle designed to mimic the aerodynamic properties and mass of a functional Dragon spacecraft, Falcon successfully achieved orbit. Six months later Falcon 9’s second flight lofted the first Dragon spacecraft on its first COTS demonstration mission. Dragon completed two orbits of the Earth before deorbiting itself for a successful recovery off the coast of California. In addition to Dragon, Falcon 9 deployed several CubeSats for the US government.
With Dragon’s first demonstration completed successfully, SpaceX and NASA agreed to combine the objectives of the two remaining demonstration missions, which were to have consisted of a longer-duration free-flight mission with a rendezvous, but no docking, at the space station, and an initial cargo delivery to the station. The combined mission, Dragon C2+, lifted off on 22 May 2012. Dragon arrived at the International Space Station on 25 May and was berthed to the nadir port of the Harmony module for almost six days. The mission concluded with Dragon’s successful recovery on 31 May.
The success of the C2+ mission cleared the way for SpaceX to begin flying its Commercial Resupply Services missions. The first, CRS-1, lifted off in October 2012. Falcon 9 suffered an engine failure during first stage flight. However, the eight remaining engines continued to burn, and the rocket was still able to achieve orbit. Dragon completed a successful mission, although an Orbcomm communications satellite that was also being carried aboard the rocket could not be placed into its correct orbit and reentered a few days later. SpaceX had designed Falcon 9 with an engine-out capability, allowing it to survive and adapt to the loss of a first-stage engine. The fifth and final launch to use the Falcon 9 v1.0 vehicle was Dragon’s CRS-2 mission, in March 2013.
In September 2013, SpaceX launched the first flight of an upgraded Falcon 9 v1.1 vehicle. Both stages of the rocket were stretched, with upgraded Merlin-1D engines introduced and the first-stage engine arrangement changed from the square grid to an octagonal pattern, or OctaWeb. On its maiden flight, the Falcon 9 v1.1 deployed Canada’s CASSIOPE satellite and five smaller spacecraft. It was the first Falcon 9 mission to use a payload fairing – as all previous flights had been made with an unencapsulated Dragon – and the rocket’s first launch from Vandenberg Air Force Base on the west coast.
Using the enhanced performance of the Falcon 9 v1.1, SpaceX made its first geostationary launch in December 2013, successfully deploying the SES-8 communications satellite. One month later, Falcon made a second geostationary launch when it boosted Thaicom 6 into orbit.
Falcon 9’s first launch of a major US Government payload – aside from Dragon missions – came in early 2015 with the Deep Space Climate Observatory, or DSCOVR. A long-delayed space weather research satellite developed in partnership between the National Oceanic and Atmospheric Administration (NOAA), NASA and the US Air Force, DSCOVR was deployed into a very highly elliptical orbit, placing it on course for the L1 lagrangian point between the Earth and the Sun. Later the same year Falcon made its first dual-payload geostationary launch, with two commercial communications satellites: ABS-3A and Eutelsat 115 West B. For this launch, both satellites were built around Boeing’s BSS-702SP bus, a low-mass all-electric platform designed to be launched in pairs.
The upgrades introduced with the Falcon 9 v1.1 allowed SpaceX to chase an objective it had held since Falcon’s inception: reusability. In order to reduce launch costs, SpaceX intended to recover the first stages – and ultimately other components – of its rockets, so that they could fly again on future missions. Falcon 1 vehicles – and early Falcon 9s – carried parachutes that were intended to deploy after stage separation to guide the first stages to a controlled splashdown in the ocean. SpaceX was never able to recover a stage by this method, and ultimately abandoned it in favor of a powered, vertical, landing.