Orbital and NASA's Johnson Space Center are jointly developing a new space
transportation system in a three-year cooperative program to support the International
Space Station (ISS). The COTS program will involve full-scale development and flight
demonstration of a commercial cargo delivery system. The COTS system will consist of:
- Antares, a new medium-class launch vehicle being
developed by Orbital
- Cygnus, an advanced maneuvering spacecraft, and
- Several interchangeable modules for pressurized and unpressurized cargo.
The Spacecraft consists of a Service Module (SM), which can be used with either a Pressurized Cargo Module (PCM) or an Unpressurized Cargo Module (UCM) (now cancelled). The PCM is based on the MPLM-Logistics-Module, while the UCM is based on the Express Cargo Carrier, which were both used with the Shuttle. The PCM is manufactured by Thales-Alenia.
The enhanced Cygnus spacecraft will be capable of delivering up to 2,700 kg of pressurized cargo to the ISS. It can also carry an external CubeSat dispenser (first flown on OA-6) and can host internal modules with experiments to be conducted in free flight after the ISS mission.
The enhanced Cygnus will be used beginning with the fifth Cygnus mission. Due to the explosion of the first Antares-130 rocket, which was originally planned to launch all enhanced Cygnus missions, the first two will fly on an Atlas-5(401) launch vehicle with the reengined Antares-230 taking over in 2016. Also they are planning to fulfill the cargo contract with only four instead of five remaining missions. In March 2015, one more mission was added to the contract for launch in 2017. In August 2015, two more missions were added.
Under the CRS-2 selction in January 2015 Cygnus was selected for a minimum of six missions, which might use both Antares-230+ or Atlas-5(401) launch vehicles and may include versions for unpressurized cargo and extended length pressurized versions. In November 2020, two more missions were ordered. One more mission was ordered in January 2025.
Cygnus CRS-9 was the first to feature external deployers for CubeSats. The Cygnus CRS-12 mission was the first to feature conformal radiators and a rack to dispose of external payloads.
Cygnus CRS-16 carried the hosted PIRPL (Prototype Infra-Red Payload) experiment, a joint effort of the Space Development Agency (SDA) with the Missile Defense Agency (MDA) and being developed by Northrop Grumman, to develop a medium field of view, multispectral imager for OPIR to be able to demonstrate the feasibility and use of that for the Tracking Layer Tranche 1 payloads.
Cygnus CRS-22's Pressurized Cargo Module was damaged during shipment to the launch site. Cygnus NG-22 has been written off as an irrecoverable loss due to customer rejection. Salvaged hardware will be reused when deemed possible by customer agreement. Subject to customer approval a replacement for NG-22 (tentatively called NG 22R) would be built at NG's internal expense following the NG-22 insurance payout to complete the required flight obligation in its current CRS contract.
