SpaceX CRS-1

SpaceX CRS-1, also known as SpX-1, was the third flight for Space Exploration Technologies Corporation's (SpaceX) uncrewed Dragon cargo spacecraft, the fourth overall flight for the company's two-stage Falcon 9 launch vehicle, and the first SpaceX operational mission under their Commercial Resupply Services contract with NASA. The launch occurred on 7 October 2012 at 20:34 EDT (8 October 2012 at 00:34 UTC).

History
In May 2012, it was reported that the CRS-1 Falcon 9 had been transported to Cape Canaveral. The CRS-1 Dragon later arrived on 14 August 2012. On 31 August 2012, a wet dress rehearsal was completed for the CRS-1 Falcon 9, and on 29 September a static fire test was completed; both of these tests were completed without the Dragon capsule attached to the launch vehicle stack. The mission passed its Launch Readiness Review on 5 October 2012.

The launch occurred on 8 October 2012 (UTC) and successfully placed the Dragon spacecraft into the proper orbit for arriving at the International Space Station with cargo resupply several days later. During the launch, one of the nine engines suffered a sudden loss of pressure about 80 seconds into the flight, and an immediate early shutdown of that engine occurred; debris could be seen in the telescopic video of the night launch. The remaining eight engines fired for a longer period of time and the flight control software adjusted the trajectory to insert Dragon into a near flawless orbit.

Mission timeline
Dates are listed in UTC.

Flight day 1, launch (8 October)
The mission plan, as published by NASA before the mission, called for the Falcon 9 to reach supersonic speed at one minute, 10 seconds after liftoff, and pass through the area of maximum aerodynamic pressure, "max Q"—the point when mechanical stress on the rocket peaks due to a combination of the rocket's velocity and resistance created by the Earth's atmosphere—10 seconds later. The plan called for two of the first-stage engines to shut down to reduce the rocket's acceleration at approximately 2 minutes 30 seconds into the flight, when the Falcon 9 would nominally be 90 kilometers (56 miles) high and traveling at 10 times the speed of sound. The remaining engines were planned to cut off shortly after—an event known as main-engine cutoff (MECO). Five seconds after MECO, the first and second stages separate. Seven seconds later, the second stage's single Merlin vacuum engine was projected to ignite to begin a 6-minute, 14-second burn to put Dragon into low-Earth orbit. Forty seconds after second-stage ignition, Dragon's protective nose cone, which covers Dragon's berthing mechanism, was planned to be jettisoned. At the 9-minute, 14-second mark after launch, the second-stage engine was scheduled to cut off (SECO). Thirty-five seconds later, Dragon was planned to separate from Falcon 9's second stage and reach its preliminary orbit. Dragon would, per plan, then deploy its solar arrays and open its guidance and navigation control (GNC) bay door which holds the sensors necessary for rendezvous and Dragon's grapple fixture.

Flight day 2 (9 October)
The mission plan called for the Dragon spacecraft to perform a coelliptic burn that would place it in a circular coelliptic orbit.

Flight day 3 (10 October)
As Dragon chased the International Space Station, the spacecraft established UHF communication using its COTS ultrahigh-frequency Communication unit (CUCU). Also, using the crew command panel (CCP) on board the station, the expedition crew monitored the approach. This ability for the crew to send commands to Dragon is important during the rendezvous and departure phases of the mission.

During final approach to the station, a go/no-go was performed by Mission Control Houston and the SpaceX team in Hawthorne to allow Dragon to perform another engine burn that brought it 250 meters (820 feet) from the station. At this distance, Dragon began using its close-range guidance systems, composed of LIDAR and thermal imagers. These systems confirmed that Dragon's position and velocity are accurate by comparing the LIDAR image that Dragon receives against Dragon's thermal imagers. The Dragon flight control team in Hawthorne, with assistance from the NASA flight control team at the Johnson Space Center's International Space Station Flight Control Room, commanded the spacecraft to approach the station from its hold position. After another go/no-go was performed by the Houston and Hawthorne teams, Dragon was permitted to enter the keep-out sphere (KOS), an imaginary sphere drawn 200 meters (656 feet) around the station that reduces the risk of collision. Dragon proceeded to a position 30 meters (98 feet) from the station and was automatically held. Another go/no-go was completed. Then Dragon proceeded to the 10-meter (32 feet) position—the capture point. A final go/no-go was performed, and the Mission Control Houston team notified the crew they were go for capture of Dragon.

At that point, Expedition 33 crew member Akihiko Hoshide of the Japan Aerospace Exploration Agency used the station's 17.6 m robotic arm, known as Canadarm2, reached for and grappled the Dragon spacecraft at 10:56 UTC. Hoshide, with the help of Expedition 33 Commander Sunita Williams of NASA, guided Dragon to the Earth-facing side of the station's Harmony module. Williams and Hoshide swapped places and Williams gently berthed Dragon to Harmony's Common Berthing Mechanism at 13:03 UTC.

The opening of the hatch between Dragon and the Harmony module, which was originally not scheduled to occur until 11 October, was moved up and occurred at 17:40 UTC.

Remainder of mission (11 to 28 October)
Over a period of two and a half weeks, the ISS crew unloaded Dragon's payload and reloaded it with cargo for return to Earth.

After its mission at the orbital laboratory was completed, newly arrived Expedition 33 Flight Engineer Kevin Ford used the Canadarm2 robotic arm to detach Dragon from Harmony, maneuver it out to the 15-meter (50-foot) release point, and release the vehicle. Dragon then performed a series of three burns to place it on a trajectory away from the station. Approximately six hours after Dragon departed the station, it conducted a deorbit burn, which lasted up to 10 minutes. Dragon's trunk, which contains its solar arrays, was then jettisoned. The landing was controlled by automatic firing of its Draco thrusters during reentry. In a carefully timed sequence of events, dual drogue parachutes deploy at an altitude of 13700 m to stabilize and slow the spacecraft. Full deployment of the drogues triggers the release of the three main parachutes, each 35 meters (116 feet) in diameter, at about 3000 m. While the drogues detach from the spacecraft, the main parachutes further slow the spacecraft's descent to approximately 4.8 to 5.4 m/s. Even if Dragon were to lose one of its main parachutes, the two remaining chutes would still permit a safe landing. The Dragon capsule is expected to land in the Pacific Ocean, about 450 km off the coast of southern California. SpaceX uses a 100-foot boat equipped with an A-frame and an articulating crane, a 90-foot crew boat for telemetry operations, and two 24-foot rigid-hull inflatable boats to perform recovery operations. On board are approximately a dozen SpaceX engineers and technicians as well as a four-person dive team. Once the Dragon capsule splashed down, the recovery team secured the vehicle and then placed it on deck for the journey back to shore.

SpaceX technicians will open the side hatch of the vehicle and retrieve these time-critical items. The critical cargo items will be placed on a fast-boat for the 450-Kilometer trip back to California for eventual return to NASA that will then take care of the precious science cargo and handle post-flight analysis of the samples. The rest of the cargo will be unloaded once the Dragon capsule reaches SpaceX's test facility in McGregor, Texas.

Primary payload
When launched the CRS-1 Dragon was filled with about 1995 lb of cargo, 882 lb without packaging. Included is 260 lb of crew supplies, 390 lb of critical materials to support the 166 experiments on board the station and 66 new experiments, as well as 232 lb of hardware for the station as well as other miscellaneous items.

The Dragon will return 1995 lb of cargo, 1673 lb without packaging. Included is 163 lb of crew supplies, 866 lb of scientific experiments and experiment hardware, 518 lb of space station hardware, 68 lb of spacesuit equipment and 55 lb of miscellaneous items.

Secondary payload
For some months prior to the launch, a 150 kg prototype second-generation Orbcomm satellite was planned to be launched as a secondary payload from Falcon 9's second stage.

Although the secondary payload made it to the Dragon insertion orbit, an engine anomaly on one of the nine engines on the Falcon 9 first stage during the ascent resulted in automatic engine shutdown and a longer first-stage burn on the remaining eight engines to complete orbital insertion while subsequently increasing use of propellant over the nominal mission.

The primary payload contractor, NASA, requires a greater-than-99% estimated probability that the stage of any secondary payload on a similar orbital inclination to the International Space Station will reach their orbital altitude goal above the station. Due to the engine failure, the Falcon 9 used more propellant than intended, reducing the success probability estimate to approximately 95%. Because of this, the second stage did not attempt a second burn, and Orbcomm-G2 was left in an unusable orbit and burned up in Earth's atmosphere within 4 days after the launch.

Both SpaceX and Orbcomm were aware, prior to the mission, of the high risk that the secondary payload satellite could remain at the lower altitude of the Dragon insertion orbit, and that was a risk that Orbcomm agreed to take given the dramatically lower cost of launch for a secondary payload.

Falcon 9 engine anomaly
During the ascent, an engine anomaly occurred with one of the nine engines on the Falcon 9 first stage. SpaceX has emphasized for several years that the Falcon 9 first stage is designed for "engine out" capability, with the capability to shut down one or more malfunctioning engines and still make a successful ascent. In the event, the SpaceX CRS-1's first stage shut down engine no. 1, and as a result continued the first-stage burn on the remaining eight engines longer than usual at a somewhat reduced thrust to insert the Dragon spacecraft into the proper orbit. SpaceX referred to the event as a "Rapid unscheduled disassembly" which, although unintended, was the first inflight demonstration of Falcon 9's "engine out" design, and "provides a clear demonstration of the engine out capability."

In response to the anomaly, NASA and SpaceX jointly formed the CRS-1 Post-Flight Investigation Board. Preliminary information from the post-flight review board indicates that the Engine no. 1 fuel dome, above the nozzle, ruptured but did not explode. The burning fuel that exited before the engine was shut down caused the fairing rupture, as seen in the flight video recordings. Subsequent investigations revealed in a Congressional hearing pinpointed the issue as an result of an undetected material flaw in the engine chamber jacket, likely introduced during engine production. During flight, the data suggests this material flaw ultimately developed into a breach in the main combustion chamber. This breach released a jet of hot gas and fuel in the direction of the main fuel line causing a secondary leak and ultimately a rapid drop in engine pressure. As a result, the flight computer commanded shutdown of engine 1 and Falcon 9 continued on its path to ensure Dragon’s entry into orbit for subsequent rendezvous and berthing with the ISS.