Commercial Resupply Services

CRS-2 contracts were awarded in January 2016 to Orbital ATK’s continued use of Cygnus, Sierra Nevada Corporation’s new Dream Chaser, and SpaceX’s new Dragon 2, for cargo transport flights beginning in 2019 and expected to last through 2024.

[8] The Antares and Falcon 9 launch vehicles and Cygnus and Dragon cargo spacecraft were developed using Space Act Agreements under NASA's Commercial Orbital Transportation Services (COTS) program.

[9] The first flight contracted by NASA, COTS Demo Flight 1, took place on 8 December 2010, demonstrating a Dragon capsule's ability to remain in orbit, receive and respond to ground commands, and communicate with NASA's Tracking and Data Relay Satellite System.

[12][13] Orbital Sciences first launched the Antares rocket from the Mid-Atlantic Regional Spaceport on 21 April 2013 with a test payload.

[15][16][17][18] Transport flights began under Commercial Resupply Services phase 1 (CRS-1) in 2012: Following the failure, the Antares 230 system was upgraded with newly built RD-181 first-stage engines to provide greater payload performance and increased reliability.

[37] The contracts were expected to include a variety of requirements:[37] CRS-1 contractors Orbital Sciences[note 1] and SpaceX each submitted CRS-2 proposals, joined by Sierra Nevada, Boeing, and Lockheed Martin.

[43][37] Sierra Nevada Corporation's Dream Chaser, the SpaceX Dragon 2, and Orbital ATK[note 1] Cygnus were selected, each for a minimum of six launches.

[45][46] When NASA issued the Commercial Resupply Services phase 2 (CRS-2) request for proposal (RFP) in September 2014, it received interest from five companies: Lockheed Martin, Boeing, Orbital ATK, Sierra Nevada, and SpaceX.

NASA officials explained that selecting three companies rather than two for CRS-2 increases cargo capabilities and ensures more redundancy in the event of a contractor failure or schedule delay.

[47] Inside-cargo is typically transported to and from the space station in "the form factor of single Cargo Transfer Bag Equivalent (CTBE) [which is the] unit for size of bag used to transport cargo from visiting vehicles,[48] such as SpaceX Dragon, Northrop Grumman Cygnus, or JAXA H-II Transfer Vehicle (HTV).