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SpaceX COTS Demo Flight 2
SpaceX COTS Demo Flight 2
SpaceX COTS Demo Flight 2
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SpaceX COTS Demo Flight 2
Dragon 1 C102 approaching ISS on 25 May 2012
Names
  • COTS 2
  • Dragon C2+
Mission typeISS resupply
OperatorSpaceX
COSPAR ID2012-027A Edit this at Wikidata
SATCAT no.38348Edit this on Wikidata
Mission duration9 days, 7 hours, 57 minutes
Spacecraft properties
SpacecraftDragon 1 C102
Spacecraft typeDragon 1
ManufacturerSpaceX
Start of mission
Launch date22 May 2012, 07:44:38 (2012-05-22UTC07:44:38Z) UTC[1]
RocketFalcon 9 v1.0 (B0005)
Launch siteCape Canaveral, SLC‑40
End of mission
DisposalRecovered
Landing date31 May 2012, 15:42 (2012-05-31UTC15:43Z) UTC
Landing site26°55′12″N 120°42′00″W / 26.92000°N 120.70000°W / 26.92000; -120.70000[2]
Orbital parameters
Reference systemGeocentric
RegimeLow Earth
Inclination51.6°
Berthing at ISS
Berthing portHarmony nadir
Berthing date25 May 2012, 16:02 UTC
Unberthing date31 May 2012, 08:07 UTC
RMS release31 May 2012, 09:49 UTC
Time berthed5 days 16 hours 5 minutes[3]

SpaceX COTS Demo Flight 2 (COTS 2), also known as Dragon C2+, was the second test-flight for SpaceX's uncrewed Cargo Dragon spacecraft. It launched in May 2012 on the third flight of the company's two-stage Falcon 9 launch vehicle. The flight was performed under a funded agreement from NASA as the second Dragon demonstration mission in the Commercial Orbital Transportation Services (COTS) program. The purpose of the COTS program is to develop and demonstrate commercial sources for cargo re-supply of the International Space Station (ISS). The Dragon C2+ spacecraft was the first American vehicle to visit the ISS since the end of the Space Shuttle program. It was also the first commercial spacecraft to rendezvous and berth with another spacecraft.[4]

Initially, the objectives of the C2+ mission were to have been accomplished by two separate missions; Dragon C2 would have carried out a fly-by of the ISS, practiced rendezvous maneuvers and communications with the station, before returning to Earth. A second mission, Dragon C3, would have been the first mission to berth with the station. In July 2011, NASA gave tentative approval to combine the objectives of the two missions. In December 2011, NASA formally approved the merger of the COTS 2 and 3 missions into the Dragon C2+ flight. There were several launch delays, the last one occurring on 19 May 2012, due to a launch abort during the last second before liftoff.

Dragon C2+ successfully launched from Cape Canaveral on 22 May 2012. During the mission's first three days all of the COTS 2 objectives were successfully completed. The mission's COTS 3 phase began on 25 May when Dragon rendezvoused again with the ISS and then was successfully captured using the Canadarm2. It was berthed to the station later that day, using the robotic arm. Dragon stayed for almost six days during which the astronauts unloaded cargo, and then reloaded Dragon with Earth-bound cargo. On 31 May, Dragon unberthed from the ISS, its capsule landed in the Pacific Ocean off the California coast and was recovered. All the objectives of the mission were successfully completed, and the Falcon 9-Dragon system became certified to start regular cargo delivery missions to the ISS under the Commercial Resupply Services program.

History

[edit]
Dragon C102 capsule being lowered onto its trunk at LC-40 on 16 November 2011 during pre-launch processing.

NASA and SpaceX signed a contract for COTS cargo resupply services on 18 August 2006.[5][6] The agreement called for three test-flights, under the COTS phase 1 demonstration program.[7] The first COTS mission, COTS Demo Flight 1, was completed successfully on 8 December 2010, when the Dragon capsule was successfully recovered from orbit, making it the first commercially built and operated spacecraft to ever do so.[8] Due to the mission's success, SpaceX asked NASA to combine the COTS 2 ISS flyby flight, which would have seen a Dragon spacecraft approach the station but stay about 10 km away from it, and the COTS 3 flight that would berth with the ISS.[7] At a 15 July 2011 meeting, NASA tentatively approved combining the two COTS missions to accelerate the program into the operational supply mission phase in 2012.[9] On 9 December, NASA officially approved the merger of the COTS 2 and 3 missions into the renamed Dragon C2+ flight.[10][11]

The Falcon 9 launch vehicle arrived at SpaceX's Cape Canaveral, Florida facilities at Launch Complex 40 (LC-40) in July 2011.[12] The mission's Dragon spacecraft arrived at the launch site on 23 October 2011.[13] On 1 March 2012, a fueled countdown test called a Wet Dress Rehearsal (WDR), was successfully completed for the COTS 2 mission.[14] On 16 April its Flight Readiness Review (FRR) was completed by NASA and stated that a 30 April launch was feasible.[14][15] Following the review SpaceX announced a launch delay due to continued flight software testing issues, and the next major mission milestone was the successful Falcon 9 static-fire engine test on 30 April.[16] NASA approved Dragon's flight software on 11 May, solving an issue that had previously been responsible for several launch date postponements.[17] On 17 May, the mission passed its final launch review and the Falcon 9/Dragon were erected on the launch pad in preparation for the launch.[18] The first launch attempt, on 19 May, was aborted at T-00:00:00.5 due to a pressure issue in one of the Falcon 9's engines.[19] The launch window was nearly instantaneous, for fuel-efficiency reasons, leaving little margin for error due to fuel consumption restrictions caused by the extra manoeuvres required to certify the Dragon spaceship before attempting to berth with the ISS.[20] Dragon's launch window could have been longer, but the extra fuel required to catch the ISS would have likely surpassed safety margins, due to the pre-berthing tests.[21][22]

Original plan

[edit]

Under the original Dragon testing plan, the C2 and C3 missions would have been flown instead of C2+. C2 would have rendezvoused with the ISS, however it would not have performed the capture and berthing part of the mission. The third test-flight was intended to be Dragon's first mission to berth with the ISS. Following a 15 July 2011 meeting between SpaceX and NASA officials, the COTS 3 mission objectives were tentatively combined with the proposed COTS 2 demonstration flight, due to the Falcon 9's two previously successful launches, and the Space Shuttle fleet recently being retired.[23]

On 9 December 2011, NASA formally approved the two missions' merger, and set the initial launch date for 7 February 2012.[24] Several delays occurred between December and May 2012, mostly due to SpaceX needing to further test hardware and software.[11] The Dragon C2+ mission successfully launched on 22 May, from Cape Canaveral Launch Complex 40 (SLC‑40).[25] It successfully completed all COTS 2 mission objectives, then berthed with the ISS, and completed all COTS 3 mission objectives, before successfully splashing down in the Pacific Ocean, off the California coast on 31 May.[26] Since all COTS objectives were met during the Dragon C2+ flight in May 2012, the need for COTS Demo Flight 3 was eliminated.[27]

Mission timeline

[edit]

Flight day 1, launch (22 May)

[edit]
The COTS 2 Falcon 9 successfully launches with the Dragon spacecraft on 22 May 2012.

Launch occurred at 03:44 EDT (07:44 UTC) on 22 May 2012.[28] This was the first time a Falcon 9 was launched at night.[29] After lift-off, main engine shut-off occurred at approximately the 180-second mark, and the first stage began to be separated. Following stage separation, the second stage ignited.[21] The Dragon's nose cone was then jettisoned.[21] And at about nine minutes into the flight, the second-stage engine shut-off occurred and separated from the Dragon spacecraft.[21] The Dragon spacecraft successfully deployed its solar arrays at about 13 minutes into the flight.[21][30]

The initial COTS 2 tests began during this flight segment, when Dragon performed a test of its Absolute GPS (AGPS) system, using global positioning system satellites to determine its location.[20] Next, Dragon opened its bay door which housed its grapple fixture and relative navigation sensors, a thermal imager and the LIDAR based DragonEye.[31] After a checkout of these sensors was completed, Dragon demonstrated its ability to abort during an approach, first with a continuous firing of its Draco engines and then with a pulsed firing.[31] A free drift demonstration then began, allowing the spacecraft to float freely without using its thrusters which would normally correct its orbital path.[20][31]

Flight day 2 (23 May)

[edit]

On flight day two, Dragon began a series of thruster burns, called "height adjustment" burn (HA-1), and "co-elliptical" burn (CE-1).[20][31][a] The CE-1 burn changed Dragon's orbit characteristics by placing it into a circular orbit around the Earth.[20][31] The HA-1 burn raised Dragon's altitude to within a few kilometres below the ISS, in preparation for the next day's rendezvous demonstration.[33]

Flight day 3 (24 May)

[edit]
Dragon spacecraft seen from the ISS during the fly-under on day three, 24 May 2012.

On flight day three, Dragon performed height adjustment burn 2 (HA-2) at 07:58 UTC, to get within about 10 km (6.2 mi) of the ISS, the "communication zone."[34][35] At 08:43 UTC co-elliptical burn 2 (CE-2) raised its orbit to nearly the same plane as the ISS, and brought it to within 2,500 m (8,200 ft) below the station.[35][36] During this "fly-under," Dragon established communications with the station using its COTS Ultra-high frequency Communication Unit (CUCU).[35] Dragon performed a test of its Relative GPS (RGPS) system, which used the relative positions of the spacecraft to the space station to determine its location.[37][38] Also, using the Crew Command Panel (CCP) on board the Cupola module, the Expedition 31 crew briefly interacted with Dragon, monitoring the fly-under and just before 11:00 UTC sending a command to Dragon to turn on its strobe light.[38] At about 11:25 UTC the Dragon made its closest approach to the ISS.[38] Once the fly-under was completed, Dragon fired its thrusters to begin a loop out in front, above and then behind the station in a racetrack oval pattern at a distance between 7 and 10 km (4.3 and 6.2 mi).[35] The Dragon performed a final burn for the day, at 11:57 UTC, that moved it away from the ISS, and set the spacecraft up for a re-rendezvous with the station the next day.[38] After Dragon cleared the station's vicinity, NASA approved the berthing to occur on day 4, meaning all the original COTS 2 mission requirements were met.[39][40]

Flight day 4 (25 May)

[edit]
The Dragon spacecraft being berthed to the International Space Station on day four, 25 May 2012.

On flight day four, Dragon performed HA-3 and CE-3 thruster burns to bring it 2.5 km (1.6 mi) below the station once again.[41] NASA's Mission Control Houston team then gave SpaceX the go ahead to perform another set of burns that brought Dragon to within 1,400 m (4,600 ft) of the station.[41] Another decision was made at Mission Control Houston, and then Dragon moved to 250 m (820 ft) from the station.[42] At this point, the COTS 3 demonstration objectives began.[41] Dragon's DragonEye system demonstrated and confirmed that its position and velocity were accurate by comparing its LIDAR image to its thermal imagers.[41] A series of checkout maneuvers commenced. The SpaceX flight control team in Hawthorne, California, commanded the spacecraft to approach the station from its hold position.[41] It moved from 250 to 220 m (820 to 720 ft) below the station.[41] The crew, using the command panel, then instructed Dragon to retreat, and the spacecraft moved back down to the hold point.[41] This test ensured that Dragon's range to the ISS was accurate, and that the flight control team saw the spacecraft's acceleration and braking perform as expected.[41] It was in a holding pattern at 250 m (820 ft), and once again the Dragon flight team commanded it to approach the station.[41] At the 220 m (720 ft) position, the crew commanded the vehicle to hold.[41]

Another decision was made in Houston, and Dragon was permitted to enter the Keep-Out Sphere (KOS), a virtual area 200 m (660 ft) around the station intended to prevent collision with the orbiting complex.[43] Two additional and non-planned holds occurred: one at 150 m (490 ft) to further verify LIDAR; and finally one by SpaceX at 70 m (230 ft) to re-configure the LIDARs.[44] Stray reflections from the JAXA JEM module's External Facility (EF) caused interference with the LIDAR;[42] SpaceX decided to narrow the LIDAR's field-of-view to eliminate the reflections.[44]

Dragon proceeded to a position 30 m (98 ft) from the station and automatically came to a stop for a hold.[44] Another decision was made, and then Dragon proceeded to the capture point position at 9 m (30 ft).[44] A final decision was made, and the Mission Control Houston team notified the crew they were go to capture Dragon.[44] At that point, from the Cupola module, Expedition 31 crew member Don Pettit used the station's Mobile Servicing System (Canadarm2) to reach out and grapple the Dragon spacecraft at 13:56 UTC over Western Australia.[45] Upon capture, Pettit jokingly told ISS CAPCOM Megan McArthur, "Looks like we got us a Dragon by the tail. We're thinking this sim went really well, we're ready to turn it around and do it for real."[43] Pettit, with the help of fellow crewmember André Kuipers, guided and then berthed Dragon to the Harmony module's Earth-facing Common Berthing Mechanism at 16:02 UTC.[46]

Flight day 5 and remainder of mission (26 to 31 May)

[edit]
Don Pettit opening Dragon's hatch on 26 May.

On flight day five, after evaluating air quality inside Dragon, the crew opened the hatch between Dragon and the station at 05:53 EDT (09:53 UTC).[47] Pettit and Russian cosmonaut and station commander Oleg Kononenko were the first crew members to enter the Dragon.[48] They wore protective goggles and breathing masks as they performed further tests to make sure the atmosphere inside the capsule was safe, which it was, though Pettit noted that "the inside smells like a brand new car."[49]

Dragon spent approximately six days berthed to the space station, allowing astronauts time to unload its cargo.[50] They then reloaded it with Earth-bound cargo.[51] On 27 May, while being controlled by Mission Control Houston, Dextre was used to survey Dragon's trunk.[52]

Recovery of the COTS 2 Dragon on 31 May.

On its final day at the station, 31 May, the crew unberthed Dragon from Harmony using the Canadarm2 at 05:49 EDT (09:49 UTC).[3] The arm moved Dragon about 10 m (33 ft) away from the station and released it.[3] Dragon then performed a series of engine burns that placed it on a trajectory to take it away from the vicinity of the station.[53] Mission Control Houston then confirmed that Dragon was on a safe path away from the complex.[53] SpaceX instructed Dragon to close its bay door and approximately four hours after Dragon left the station, it began to conduct its nine-minute-long deorbit burn.[37] The Dragon capsule jettisoned its trunk and began to re-enter the Earth's atmosphere.[53] Its heatshield protected it during most of the re-entry and when low enough in altitude its two drogue parachutes were deployed, followed by its three main parachutes.[54] The Dragon capsule splashed down into the Pacific Ocean about 900 km (560 mi) from the Baja Peninsula at approximately 11:42 EDT (15:42 UTC) and was recovered by a small fleet of recovery vessels from the contractor hired by SpaceX, American Marine.[55][56][57]

Capsule journey post-mission

[edit]

On 5 June, the Dragon capsule arrived at the Port of Los Angeles and was transported by truck to McGregor, Texas.[58] There its toxic maneuvering propellent was removed and on 13 June its cargo was transferred into NASA's possession.[59] The cargo was then transported to the Johnson Space Center in Houston for further processing.[59] On 18 July 2012, the COTS 2 Dragon was temporarily displayed to an invited audience inside a tent, in front of the Historical Society of Washington, D.C. building.[60] On 7 September 2012, Steve Jurvetson, a member on the board of directors at SpaceX, reported that the C2+ capsule was undergoing post-flight analysis back in McGregor.[61] Later in 2012 the Dragon capsule was expected to be transported back to Hawthorne, California.[59] During the post-flight press conference, the CEO and CTO of SpaceX Elon Musk stated that there are no definitive plans for the capsule but that he would like to see it taken on a tour around the United States.[62] The capsule was displayed at the 2013 Electronic Entertainment Expo in Los Angeles, California from 11 to 13 June.[63][64] The historic Dragon C2+ capsule was ultimately placed on permanent display hanging from the ceiling at SpaceX headquarters.

On 23 August 2012, NASA announced that SpaceX and their Falcon 9-Dragon system was certified to begin their cargo delivery contract.[65] The $1.6 billion contract calls for at least 12 resupply missions.[66] The first of those flights was launched on 7 October 2012.

Payload

[edit]
The interior of the Dragon spacecraft on 26 May, showing some of the delivered cargo.

The pressurized section carried 525 kg (1,157 lb) of cargo to the ISS, which included food, water, clothing, cargo bags, computer hardware, the NanoRacks Module 9 (student experiments and scientific gear) and other miscellaneous cargo.[67][68] No unpressurized cargo was delivered on this mission.[69]

An unannounced addition to the cargo manifest, made public after the launch, was a small canister, affixed to the second stage's top, containing the 1-gram ash remains of over 300 people including Project Mercury Astronaut Gordon Cooper, and James Doohan, the actor who played Scotty on the television show Star Trek in the 1960s.[70] The remains were flown semi-secretly by Celestis, a company that has flown burial canisters in the past on SpaceX's Falcon 1 launch vehicle.[71] The second stage and the burial canister remained in the initial orbit Dragon C2+ was inserted to,[72] and burned up in the Earth's atmosphere a month later.[73]

Some of the returned cargo is seen in McGregor, Texas on 13 June 2012.

On its return to Earth, Dragon brought back 665 kg (1,466 lb) worth of pressurized cargo back to Earth; the cargo included experiment samples, experiment hardware, ISS' systems hardware and Extravehicular Mobility Unit hardware.[67][74] One of the experiments returned by Dragon was the Shear History Extensional Rheology Experiment (SHERE) administered by NASA's Glenn Research Center.[75] SHERE investigated rotational stress effects on polymer fluids.[75] Items from SHERE included a toolbox, fluid modules, stowage trays, cables and a keyboard, and science data recordings.[75] Another experiment returning with Dragon was the Multi-user Droplet Combustion Apparatus (MDCA), and the Combustion Integrated Rack-Fluids and Combustion Facility (CIR).[75] The return flight was planned to carry 660 kg (1,460 lb)

Another experiment returning at the end of this mission was the Material Science Research Rack (MSRR), which investigated microgravity experiments on aluminum-alloy rods.[75] Returning from MSRR were cartridges from thermal and vacuum investigations done on metal rods in the SETA-2 and the MSL-CETSOL and MICAST studies.[75]

Originally, SpaceX also intended to launch two secondary payload satellites from the Dragon sometime in the first 72 hours after launch;[76] however, on 28 December 2011, SpaceX and Orbcomm announced a revised schedule that dropped the satellite deployment from the Dragon C2+ flight plan.[77]

Delays

[edit]

COTS Demo Flight 2 was to take place as early as 2010, but was delayed by internal SpaceX issues; and then in 2011 by NASA issues.[78] As planned on the manifests, COTS 2 was to fly in June 2011.[10] It was delayed to late 2011, and then followed by further delay by the failure of the Russian Progress 44 cargo resupply vessel in August; this incident could have forced the ISS to be temporarily abandoned in mid-November.[79] Another delay was caused due to the berthing procedure which requires two ISS personnel to be trained and available for the procedure; in early December 2011 only one person was trained to berth the Dragon.[80] The launch date moved as follows: 6 June 2011, 8 October 30 November and 19 December;[81] and 7 January 2012, 30 April, and 7 May.[81]

With a busy launch schedule at Cape Canaveral, and with other missions to the ISS, NASA and SpaceX did not announce a new date until mid-March for a 30 April launch.[82][83] More testing was required by SpaceX for the computer code that controlled berthing, causing another delay to be announced on 23 April, delaying the launch to 7 May at 09:38 EDT (13:38 UTC).[84][85] A further delay was announced by NASA, pushing the launch to sometime in May.[84] On 4 May, the new targeted launch date was set for 19 May at 04:55 EDT/08:55 UTC. The launch proceeded nominally but was automatically aborted at T−00:00:00.5 when pressure in engine number 5 rose to unacceptable limits.[86] After making repairs, the launch date was set for 22 May at 03:44 EDT (07:44 UTC), with a secondary backup date of 23 May at 03:22 EDT (07:22 UTC) if a longer delay became necessary.[21]

Launch attempts

[edit]
Attempt Planned Result Turnaround Reason Decision point Weather go (%) Notes
1 19 May 2012, 8:55:26 am Abort — Technical 19 May 2012, 8:55 am ​(T−0:00:00.5) 80% Launch was automatically aborted with higher than acceptable pressure detected in engine 5.[87] This was due to a faulty check valve, which was then replaced later that day.[87]
2 22 May 2012, 7:44:38 am Success 2 days 22 hours 49 minutes 90% Nominal launch, inserted Dragon into preliminary orbit, nine minutes and 48 seconds after launch.[1]
[edit]
  • COTS 2 Dragon capsule in SpaceX hangar at LC-40 on 23 October 2011.
    COTS 2 Dragon capsule in SpaceX hangar at LC-40 on 23 October 2011.
  • SpaceX technicians stow cargo in the COTS 2 Dragon at LC-40 on 4 April 2012.
    SpaceX technicians stow cargo in the COTS 2 Dragon at LC-40 on 4 April 2012.
  • Astronauts Donald Pettit (foreground) and André Kuipers practice grappling Dragon in a simulation aboard the ISS on 11 April 2012.
    Astronauts Donald Pettit (foreground) and André Kuipers practice grappling Dragon in a simulation aboard the ISS on 11 April 2012.
  • Dragon with trunk pontoons installed on 26 April 2012.
    Dragon with trunk pontoons installed on 26 April 2012.
  • The Falcon 9/Dragon vertical at launch pad on 18 May 2012 in preparation for the launch.
    The Falcon 9/Dragon vertical at launch pad on 18 May 2012 in preparation for the launch.
  • At launch pad around 05:00 EST on 19 May 2012 (five minutes after automated abort). Strongback is being reapplied.
    At launch pad around 05:00 EST on 19 May 2012 (five minutes after automated abort). Strongback is being reapplied.
  • Falcon 9, Flight 3, launch on 22 May 2012 (video).
  • Dragon C2+, flight day four, berthing with the ISS on 25 May 2012.
  • Dextre inspecting Dragon's trunk on 27 May 2012
    Dextre inspecting Dragon's trunk on 27 May 2012
  • Expedition 31 posing inside of Dragon on 29 May 2012.
    Expedition 31 posing inside of Dragon on 29 May 2012.
  • The recovered Dragon C2+ capsule in McGregor, Texas on 13 June 2012.
    The recovered Dragon C2+ capsule in McGregor, Texas on 13 June 2012.
  • Artist's rendering of Dragon berthed to the ISS
    Artist's rendering of Dragon berthed to the ISS

See also

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Notes

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References

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Bibliography

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

SpaceX COTS Demo Flight 2

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SpaceX COTS Demo Flight 2, also designated as Dragon C2+, was the second demonstration mission in NASA's (COTS) program, conducted by to validate the capabilities of its spacecraft for orbital cargo delivery to the (ISS). Launched uncrewed on May 22, 2012, from Air Force Station's Space Launch Complex 40 aboard a rocket, the mission achieved a historic first by successfully rendezvousing with, berthing to, and departing from the ISS, while delivering approximately 460 kg (1,014 lb) of supplies and returning 620 kg (1,367 lb) of cargo, including scientific samples. The spacecraft splashed down successfully in the Pacific Ocean off the coast of on May 31, 2012, completing all primary objectives despite a minor issue with the sensor during approach, which was resolved by software adjustments. This flight represented a pivotal milestone in commercial spaceflight, as it was the first time a privately developed docked with the ISS and returned cargo to , restoring U.S. capabilities lost after the program's retirement in 2011. Under the COTS initiative, funded by a $396 million agreement, demonstrated key technologies including autonomous navigation, proximity operations, and reentry systems, paving the way for operational Commercial Resupply Services (CRS) missions. Administrator hailed the berthing on May 25, 2012, as a moment that "firmly locked into place the future direction of America’s space program," emphasizing the partnership's role in fostering and reliability in beyond . The mission's success, with fewer anomalies than comparable government programs, validated Dragon's design for pressurized cargo transport and return, enabling subsequent CRS flights starting in October 2012.

Background

COTS Program Overview

The (COTS) program, initiated by in 2005, was designed to foster the development of U.S. commercial capabilities for delivering cargo to the (ISS) after the program's retirement in 2011, thereby ensuring a sustainable and cost-effective supply chain for low-Earth orbit operations. By partnering with private companies, sought to stimulate innovation in space transportation while reducing reliance on government-funded systems, ultimately enabling routine commercial resupply missions to support ongoing ISS research and habitation. SpaceX was selected as one of two primary COTS partners in August 2006, receiving up to $396 million in funding through a to develop and demonstrate its transportation system. The company's initial milestone, COTS Demo Flight 1, launched on December 8, 2010, aboard a rocket and completed a successful orbital test flight lasting 3 hours and 19 minutes, achieving two orbits before recovery off the coast, marking the first U.S. commercial spacecraft to reach orbit and return safely, though it did not approach the ISS. Building on this success, COTS Demo Flight 2 integrated the objectives of the planned COTS 2 and COTS 3 missions to streamline development and accelerate certification for operational flights. The mission relied on the launch vehicle, a two-stage rocket capable of delivering up to 10,450 kg to low-Earth orbit, paired with the uncrewed Dragon capsule, which featured a pressurized module with a capacity of up to 3,310 kg (7,300 lb) of supplies and automated rendezvous systems for ISS proximity operations. The ISS served as the core destination, providing the necessary orbital infrastructure to test berthing and transfer in a representative environment.

Original Mission Objectives

The original mission objectives for SpaceX's (COTS) Demo Flight 2 built upon the success of Demo Flight 1 in December 2010, which demonstrated basic launch, orbit, and recovery capabilities of the spacecraft. The primary goals centered on achieving autonomous rendezvous with the (ISS), berthing to the node using the Canadarm2 robotic arm, demonstrating cargo transfer between Dragon and the ISS, and ensuring a safe return to Earth via . These objectives were designed to validate the integrated systems for operational resupply missions, including precise navigation, proximity operations, and pressurized cargo handling. To support these primary aims, secondary goals included testing Dragon's navigation sensors, notably the DragonEye LIDAR system for relative ranging during approach, as well as deploying and verifying the functionality of the spacecraft's solar arrays in orbit. Additional tests focused on reentry performance, confirming the heat shield's integrity under atmospheric conditions and the deployment of parachutes for a controlled . These elements were critical for demonstrating Dragon's readiness for crewed and cargo operations beyond initial demos. NASA approved the combination of COTS Demo Flights 2 and 3 into a single mission on December 9, 2011, to accelerate certification for operational ISS resupply flights, allowing the inclusion of ISS berthing and cargo transfer in one launch. The mission was planned for a approximately 9-day duration, with launch from Space Launch Complex 40 (SLC-40) at Air Force Station, , and splashdown in the about 450 kilometers west of .

Mission Preparation

Development Delays

The development of SpaceX's COTS Demo Flight 2 encountered significant early delays in 2010 and 2011, stemming from internal challenges at SpaceX related to Falcon 9 rocket testing and certification. The maiden Falcon 9 launch in June 2010 was postponed due to delays in certifying the vehicle's flight termination system, which were compounded by limited Air Force range safety resources following a GPS satellite mission. These issues diverted engineering resources and slowed progress on Dragon spacecraft hardware for subsequent demonstrations, extending the gap between the first COTS flight in December 2010 and the planned second flight from an initial target of February 2011 to October 2011. NASA's ongoing reviews for Dragon's integration with the International Space Station, including assessments of rendezvous and safety protocols, further contributed to these setbacks by requiring iterative design adjustments. In 2011, additional complications arose from the failure of the Russian Progress M-11M resupply mission in August, which created scheduling conflicts for operations and prioritized alternative cargo deliveries over commercial demonstrations. This incident, which left the ISS short on supplies, led to adjust the overall manifest, potentially slipping the COTS Demo Flight 2 from late 2011 to early 2012 to accommodate crew rotations and recovery efforts. The impending retirement of in July 2011 also heightened pressure on the COTS timeline, as it underscored the need for reliable commercial resupply but indirectly exacerbated integration scheduling with ISS activities. Certification hurdles emerged following the success of COTS Demo Flight 1 in 2010, which demonstrated orbital operations but not berthing; additional requirements were imposed for Dragon's autonomous berthing system to ensure safe proximity operations with the ISS. These included upgrades to , installation of range finders and GPS receivers for precise , and extensive ground testing such as thermal vacuum simulations and closed-loop sensor validations to verify the system's reliability. had to redesign elements of the second Dragon vehicle specifically for these berthing capabilities, adding months to the development schedule. The cumulative effect of these factors resulted in major timeline shifts, with the original goal for full COTS demonstrations evolving into a May 2012 launch for Demo Flight 2 after approved the combination of Demo Flights 2 and 3 objectives into a single mission, known as C2+, in December 2011. This merger, initially proposed by in early 2011 and tentatively agreed upon by in July, allowed the berthing demonstration—originally planned for Demo 3—to be incorporated into C2+ while streamlining certification and reducing overall program costs.

Pre-Launch Activities

The Dragon C102 spacecraft, the second flight unit of SpaceX's Cargo Dragon, underwent initial processing at the company's headquarters in Hawthorne, California, where it was outfitted with propulsion systems, avionics, and environmental controls prior to shipment to Cape Canaveral Air Force Station in Florida. Upon arrival, technicians at Space Launch Complex 40 (SLC-40) integrated the Dragon capsule with the Falcon 9 rocket's second stage, a process that included mating the spacecraft to the launch vehicle adapter and conducting functional tests of interfaces such as power, data, and separation mechanisms. Payload loading followed, with approximately 460 kg (1,014 lbs) of pressurized cargo—consisting of crew provisions like food, water, and clothing, along with science experiments such as the NanoRacks-CubeLabs Module-9—secured inside the capsule's cargo bay to ensure stability during ascent. Ground operations at SLC-40, repurposed from Titan launches to support up to 12 missions annually, involved coordination between engineers and the U.S. Air Force's 45th Space Wing for certifications and FAA launch licensing. 's Mission Control provided oversight for integration milestones, while the ISS program team ensured compatibility with station operations, including joint reviews of docking protocols. approvals confirmed compliance with flight termination systems and debris mitigation plans, enabling the stacked vehicle to be raised vertically on the launch mount for final closeouts. Although the mission was uncrewed, astronauts from ISS Expedition 31, including flight engineers Don Pettit and , received specialized training at to operate the station's Space Station Remote Manipulator System (SSRMS) for Dragon's capture and berthing, using the Crew Command Panel to issue proximity commands during rendezvous. In the lead-up to the May 2012 launch window, multiple readiness polls were conducted across , , and range control teams, verifying vehicle health, weather conditions, and orbital parameters with no significant anomalies reported. These polls, held daily during the assessment period, incorporated meteorological data from the 45th Weather Squadron to confirm favorable launch constraints, such as upper-level winds and risks.

Launch and Flight Operations

Launch Sequence

The attempted launch on May 19, 2012, was aborted approximately 0.5 seconds before liftoff due to a high pressure reading in engine 5 of the first stage. resolved the issue through a software update that adjusted the pressure limits, allowing preparations to continue for the next window. Following pre-launch activities that verified the vehicle's readiness, the rocket—powered by nine Merlin 1A engines on the first stage—lifted off successfully from Space Launch Complex 40 (SLC-40) at Air Force Station, , on May 22, 2012, at 07:44 UTC. The ascent proceeded nominally, with Max-Q reached at T+1:24, main engine cutoff () at T+3:00, and stage separation at T+3:05, followed immediately by ignition of the second stage's Merlin Vacuum engine at T+3:12. The second stage burned until cutoff (SECO) at T+9:14, inserting the into an initial with an apogee of 340 km, perigee of 310 km, and inclination of 51.6 degrees. Dragon separated from the second stage at T+9:49 and began its autonomous operations. The spacecraft's solar arrays deployed successfully at T+11:53, providing power for the subsequent orbital phase.

Rendezvous and Berthing

Following the successful launch on May 22, 2012, which placed the Dragon spacecraft into its initial orbit, the mission proceeded to rendezvous with the International Space Station (ISS) over the subsequent three days. On May 24, Dragon executed a fly-under maneuver approximately 2.5 kilometers below the ISS to validate its relative navigation sensors and communication systems with the station's communications unit for proximity operations (CUCU). The following day, May 25, 2012, Dragon initiated its final approach along the R-bar (radial) trajectory, achieving capture by the ISS's Space Station Remote Manipulator System (SSRMS, or Canadarm2) at 13:56 UTC and completing berthing at 16:02 UTC to the nadir port of the Harmony module. The rendezvous relied on autonomous navigation technologies to ensure precise relative positioning with the ISS. Dragon utilized absolute GPS for its global positioning and relative GPS for station-relative navigation, supplemented by the DragonEye sensor system, which integrated LIDAR for range and velocity measurements with thermal imagers for visual confirmation during close proximity. Safety protocols included designated hold points at 250 meters, 220 meters, 30 meters, and 10 meters from the ISS, where Dragon paused for system checks and go/no-go approvals from mission control; entry into the 200-meter keep-out sphere required explicit authorization to mitigate collision risks. These maneuvers demonstrated Dragon's ability to maintain station-keeping and execute collision avoidance burns if necessary. During the approach, the LIDAR encountered unanticipated reflections from the ISS structure, prompting additional holds at 150 meters to verify the sensor and at 70 meters to reconfigure it; the issue was resolved by a software adjustment that reduced the LIDAR's field of view, allowing the autonomous approach to continue successfully. During berthing, Expedition 31 crew members monitored Dragon's approach through station cameras while operating the SSRMS from inside the ISS. The grappled Dragon's active at the 10-meter hold point, initiating soft capture followed by repositioning to the nadir port for hard mate, where structural connections and umbilicals were secured to integrate the spacecraft with the station. Although the approach was fully autonomous as planned, ground control teams at NASA's and SpaceX's mission operations retained manual override capabilities for contingencies, such as an abort trajectory to retreat Dragon if anomalies arose during proximity operations. Hatch opening occurred the next day, May 26, 2012, confirming a leak-free seal.

Orbital Operations

Following the berthing of the Dragon spacecraft to the International Space Station on May 25, 2012, the ISS crew opened the hatch to the pressurized cargo module, providing full access for operations. Dragon remained docked for six days, from May 25 to May 31, 2012, allowing the crew to conduct cargo handling and verification activities. During this period, approximately 460 kg of non-critical supplies—including food, clothing, water, and student experiments—were transferred from Dragon to the station for use by the Expedition 31 crew. In turn, about 620 kg of return cargo, comprising scientific samples, experiment hardware, and station equipment, was loaded into the spacecraft. The docked phase also enabled the activation of microgravity science demonstrations by the ISS crew, including the Aquarius payload with 15 student-led experiments under the Student Spaceflight Experiments Program (SSEP). These investigations examined the effects of microgravity on physical, chemical, and biological systems, such as plant growth and crystal formation, providing educational insights and preliminary data for further research. Mission teams verified Dragon's integrated systems during orbital operations, confirming the functionality of its environmental control and subsystem, solar array power generation, and thruster propulsion for station-keeping and attitude control. These checks demonstrated the spacecraft's readiness for prolonged ISS integration in future missions.

Return and Recovery

Deorbit and Reentry

The Dragon capsule undocked from the on May 31, 2012, at 09:49 UTC, after completing cargo transfer operations. Expedition 31 flight engineers used the station's to maneuver the spacecraft to a release point approximately 10 meters away, initiating a safe departure. Following unberthing, the capsule performed three separation burns using its thrusters at 09:50 UTC, 09:52 UTC, and 09:55 UTC, gradually increasing distance from the ISS while conducting a fly-around maneuver to allow of the spacecraft's protection systems and docking mechanisms. Approximately four hours after undocking, at 14:51 UTC and an altitude of about 400 kilometers, the Dragon executed its deorbit burn. The Draco thrusters fired for 9 minutes and 50 seconds, reducing the spacecraft's velocity by roughly 223 (100 meters per second) to set a targeting in the , approximately 560 miles west of . This maneuver lowered the perigee sufficiently for atmospheric reentry, demonstrating the precision of the propulsion system essential for future cargo return missions. Reentry commenced at 15:25 UTC when the capsule crossed the entry interface at around 400,000 feet over the Pacific south of , traveling at approximately 17,000 miles per hour. Peak heating occurred at about Mach 10, with surface temperatures reaching up to 3,000 degrees , during which the PICA-X underwent controlled to dissipate thermal loads. Onboard sensors monitored performance, temperature profiles, and structural integrity throughout the descent, providing critical data to validate the ablative material's effectiveness under orbital reentry conditions. The spacecraft maintained attitude control via Draco thrusters during the plasma blackout phase, ensuring a stable orientation. As the capsule descended, drogue parachutes deployed at 15:35 UTC and an altitude of 45,000 feet to stabilize and decelerate the vehicle from supersonic speeds. Full deployment of the drogues triggered release of the three main parachutes at 15:37 UTC and approximately 10,000 feet, reducing descent velocity to 16-18 feet per second. The mission concluded after a total duration of 9 days, 7 hours, and 57 minutes, marking the successful return of the Dragon from its demonstration flight.

Splashdown and Retrieval

The capsule from the COTS Demo Flight 2 achieved a safe reentry and splashed down in the on May 31, 2012, at 15:42 UTC, approximately 560 miles (900 km) west of , , at coordinates 27° N, 120° W. Recovery operations commenced immediately after splashdown, with a SpaceX-led team utilizing a fleet consisting of a 185-foot (56 m) equipped with a crane, an 80-foot (24 m) crew boat, and two 25-foot (7.6 m) fast response boats, supported by engineers and a four-person dive team. The team attached recovery lines to the capsule's parachutes shortly after it stabilized on the water surface, securing it for towing without incident. The flotilla then proceeded to the , completing the initial retrieval within hours of splashdown. Upon arrival at the port, the capsule was offloaded and transported by truck to SpaceX's test site in , for comprehensive post-flight analysis, including data download from onboard systems and detailed inspection of structural integrity. Engineers particularly focused on evaluating the PICA-X heat shield's performance, assessing char levels and to determine its viability for future reuse, a key milestone in demonstrating the Dragon's partial reusability. The capsule, designated C102, was retired after this single flight and later placed on display at the .

Payload and Science

Upward Cargo Manifest

The upward cargo manifest for SpaceX COTS Demo Flight 2 delivered a total of 520 kilograms to the , including packaging materials, to support ongoing operations and research during Expeditions 31 and 32. This cargo was stowed within the spacecraft's pressurized volume using standardized racks and cargo bags designed for compatibility with the ISS's logistics systems. Crew supplies formed the largest portion, totaling 306 kilograms and comprising essential provisions such as 13 bags of standard rations (approximately 117 meals), five bags of low-sodium rations (about 45 meals), , pantry items including batteries, waste collection devices, and official flight kits. These items ensured sustenance and basic needs for the station's inhabitants without including high-value or time-sensitive materials. Scientific experiments and utilization payloads accounted for 21 kilograms, primarily the NanoRacks-CubeLabs Module-9, which housed student-led investigations into topics like microbial growth and in microgravity, along with ice bricks for cooling and transferring experiment samples. Computers and supplies weighed 10 kilograms, including a , batteries, and cables. Additional cargo bags, totaling 123 kilograms, were carried for use in future resupply missions.

Returned Materials

The Dragon spacecraft returned approximately 620 kilograms (1,367 pounds) of cargo from the (ISS), including packaging for a total of 660 kilograms (1,455 pounds), marking the first commercial demonstration of significant downmass capability. This return payload encompassed a diverse array of items essential for ongoing ISS research and operations, transported safely through reentry and splashdown in the . Among the returned materials were utilization payloads totaling 93 kilograms (205 pounds), which included scientific samples from the Research Rack (MSRR). These featured sample cartridge assemblies containing protein crystals grown in microgravity, valued for their potential applications in pharmaceutical development due to improved structural quality compared to Earth-based analogs. Other utilization items comprised hardware from experiments such as the Plant Signaling investigation and the Shear History Extensional Experiment (SHERE), though without biological samples in those cases, emphasizing the mission's role in facilitating time-sensitive scientific returns. Crew preference items accounted for 143 kilograms (315 pounds), consisting of personal effects and used supplies from Expedition 31 crew members, such as clothing, hygiene products, and official flight kits, enabling the rotation of personal items critical for long-duration habitation. Hardware returns formed the largest category at 345 kilograms (760 pounds) of systems components, including multifiltration beds, fluids control equipment, and iodine-compatible water containers for ground-based , alongside 39 kilograms (86 pounds) of spacewalk hardware like (EMU) components and gloves. Data storage drives containing experiment results were also repatriated within these systems, supporting post-mission data processing and hardware diagnostics. This return validated Dragon's reentry and recovery systems, including its PICA-X thermal protection, as the first private spacecraft to bring back substantial cargo from the ISS post-Space Shuttle era, thereby restoring NASA's ability to retrieve irreplaceable research samples and equipment previously limited by one-way cargo vehicles. The mission's success underscored the viability of commercial providers for bidirectional ISS logistics, enhancing scientific productivity by enabling the return of biological and materials samples for detailed Earth-based study.

Outcomes and Legacy

Mission Success Metrics

The SpaceX COTS Demo Flight 2, also known as Dragon C2+, achieved 100% success in meeting its predefined mission objectives, demonstrating the full capabilities of the Cargo Dragon spacecraft for autonomous operations to the (ISS). These objectives encompassed safe launch on the rocket, orbital insertion, autonomous rendezvous and proximity operations, soft capture and berthing with the ISS, cargo transfer verification, unberthing, deorbit, reentry, and splashdown recovery, all conducted without any safety violations or interruptions to ISS operations. The mission validated the spacecraft's ability to perform these tasks independently, relying on onboard sensors and Draco thrusters for navigation, while ground teams monitored but did not intervene in real-time flight control. A minor sensor issue during approach was resolved by software adjustments, demonstrating system redundancy. No significant anomalies occurred during the flight, with all systems operating nominally throughout the approximately 9-day duration from to May 31, 2012. Minor performance variations in thruster output were observed during rendezvous but were automatically compensated by redundant systems, ensuring no impact on trajectory or berthing. Post-flight analysis of the PICA-X confirmed expected and wear patterns consistent with design simulations, with no structural compromises detected upon recovery. The absence of safety issues underscored the reliability of the integrated and systems under NASA's (COTS) framework. NASA's post-mission evaluation, detailed in the agency's FY 2012 Performance Report and subsequent Office of Inspector General assessment, affirmed that SpaceX had met or exceeded all technical milestones outlined in the COTS Space Act Agreement. This review, conducted in mid-2012, certified the Dragon spacecraft's readiness for operational cargo resupply missions under the Commercial Resupply Services (CRS) contract, paving the way for the inaugural CRS-1 flight later that year. The evaluation highlighted the mission's role in restoring U.S. commercial access to the ISS following the Space Shuttle program's retirement. Key performance metrics included berthing precision achieved within the required tolerances for soft capture by the ISS's , with final alignment errors minimized through autonomous corrections. Reentry dynamics remained under design limits, with peak g-forces below 4g to protect the returned , and all environmental control systems functioning as planned. These outcomes established critical benchmarks for in future uncrewed and crewed missions.

Influence on Future Programs

The success of COTS Demo Flight 2 directly led to NASA's certification of for operational cargo resupply missions under the Commercial Resupply Services (CRS) contract, enabling the launch of CRS-1 on October 7, 2012, using a capsule (C103) of the same design as the one (C102) that flew the demonstration. This mission validated key technologies, including the PICA-X reusable heat shield, which withstood reentry temperatures exceeding 3,000 degrees Fahrenheit and demonstrated durability for multiple uses, and the autonomous docking system, which achieved precise rendezvous and berthing with the without human intervention. These advancements formed the foundational legacy for the Crew Dragon spacecraft, influencing its development under NASA's , where the first crewed flight (Demo-2) occurred on May 30, 2020, restoring U.S. capabilities to the ISS. The mission paved the way for NASA's commercial cargo strategy, facilitating over 30 CRS missions by SpaceX through 2025 and enabling crew rotations via Commercial Crew missions, which significantly reduced U.S. dependence on Russian Soyuz spacecraft for ISS access starting in 2020. As of 2025, Dragon cargo and crew variants continue to provide reliable ISS resupply and transport services, with the 33rd CRS mission launched in August incorporating enhanced propulsion for station reboosting; mission data from COTS Demo Flight 2, including navigation and thermal protection insights, has informed Starship's cargo variant designs for future deep-space logistics.

References

  1. https://www.nasa.gov/wp-content/uploads/2015/06/649910main_cots2_presskit_051412.pdf?emrc=55fba3
  2. https://www.nasa.gov/news-release/spacex-launches-nasa-demonstration-mission-to-space-station/
  3. https://www.nasa.gov/news-release/nasa-administrator-calls-station-following-spacex-historic-feat/
  4. https://oig.nasa.gov/docs/IG-13-016.pdf
  5. https://www.nasa.gov/news-release/nasa-hails-success-of-commercial-space-program-private-space-station-resupply-underway-plans-readied-for-astronauts/
  6. https://www.nasa.gov/commercial-resupply-services-overview/
  7. https://appel.nasa.gov/knowledge-resource/commercial-orbital-transportation-services-cots-critical-knowledge/
  8. https://www.nasa.gov/news-release/nasa-announces-launch-date-and-milestones-for-spacex-flight/
  9. https://www.nasa.gov/wp-content/uploads/2015/06/649910main_cots2_presskit_051412.pdf
  10. https://www.nasa.gov/wp-content/uploads/2015/06/641018main_pk_objectives.pdf
  11. https://www.nasa.gov/image-article/spacex-nasa-prepare-launch/
  12. https://www.space.com/15766-spacex-space-capsule-launch-abort.html
  13. https://www.nbcnews.com/id/wbna47485195
  14. https://www.planetary.org/articles/dragon-makes-history-berths
  15. https://www.planetary.org/articles/spacex-cots-2-mission-preview
  16. https://www.nasa.gov/wp-content/uploads/2016/08/sp-2014-617.pdf
  17. https://www.nasa.gov/news-release/spacex-dragon-transports-student-experiments-to-space-station/
  18. https://spaceflightnow.com/falcon9/003/cots2status.html
  19. https://spaceref.com/status-report/spacex-dragon-mission-summary/
  20. https://www.nasa.gov/image-article/dragon-splashes-down/
  21. https://cosmoquest.org/x/2022/05/this-week-in-rocket-history-spacex-cots-2/
  22. https://spacexnow.com/capsules
  23. https://www.nasa.gov/wp-content/uploads/2015/06/640968main_spacex_manifest_042012.pdf
  24. https://www.nasa.gov/wp-content/uploads/2023/10/fy-2012-management-performance.pdf
  25. https://www.nasa.gov/news-release/first-contracted-spacex-resupply-mission-launches-with-nasa-cargo-to-space-station/
  26. https://sma.nasa.gov/LaunchVehicle/assets/nasa-spaceflight-now-article.pdf
  27. https://www.nasa.gov/wp-content/uploads/2015/06/694074main_spacexcrs-1presskit.pdf
  28. https://www.spacex.com/updates
  29. https://www.nasa.gov/news-release/nasa-sets-coverage-for-spacex-33rd-station-resupply-launch-arrival/
  30. https://www.nasa.gov/blogs/spacestation/2025/09/03/nasa-spacex-complete-dragon-space-station-reboost/
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