S.S. Roger Chaffee at the Space Station
|Mission type||ISS resupply|
|Spacecraft||S.S. Roger Chaffee|
|Spacecraft type||Enhanced Cygnus|
Thales Alenia Space
|Start of mission|
|Launch date||17 April 2019, 20:46:07 UTC|
|Launch site||MARS LP-0A|
|Berthing at ISS|
|Berthing port||Harmony nadir or Unity nadir|
|RMS capture||19 April 2019 09:28 UTC|
|Berthing date||19 April 2019 11:31 UTC|
|Unberthing date||23 July 2019 (planned)|
|RMS release||23 July 2019 (planned)|
|Mass||3,436 kg (7,575 lb)|
|Pressurised||3,162 kg (6,971 lb)|
|Unpressurised||239 kg (527 lb)|
Cygnus NG-11, previously known as CRS OA-11, is the twelfth flight of the Northrop Grumman robotic resupply spacecraft Cygnus and its eleventh flight to the International Space Station under the Commercial Resupply Services contract with NASA. The mission launched on 17 April 2019 at 4:46 PM EDT (20:46 UTC). This is the last mission from the extended CRS contract; followup missions are part of the CRS2 contract. NG-11 was also the first mission to utilize the Antares twenty four hour prior load where critical hardware could be loaded into Cygnus just twenty four hours prior to launch.
Orbital ATK and NASA jointly developed a new space transportation system to provide commercial cargo resupply services to the International Space Station (ISS). Under the Commercial Orbital Transportation System (COTS) program, then Orbital Sciences designed and built Antares, a medium-class launch vehicle; Cygnus, an advanced maneuvering spacecraft, and a Pressurized Cargo Module which is provided by Orbital's industrial partner Thales Alenia Space. Northrop Grumman purchased Orbital in June 2018; its ATK division was renamed Northrop Grumman Innovation Systems. Coincidentally Nepalese satellite NepaliSat-1 and a Sri Lankan satellite Raavana 1 were launched as part of Cygnus NG-11 to the space.
The COTS demonstration mission was successfully conducted in September 2013, and Orbital commenced operational ISS cargo missions under the Commercial Resupply Service (CRS) program with two missions in 2014. Regrettably, the third operational mission, Orb CRS-3, resulted was not successful due to spectacular Antares failure during launch. The company decided to discontinue the Antares 100 series and accelerate the introduction of a new propulsion. The Antares system will be upgraded with newly built RD-181 first-stage engines to provide greater payload performance and increased reliability.
In the meantime, the company had contracted with United Launch Alliance for an Atlas V launch of CRS OA-4 in late 2015 from Cape Canaveral, FL, with a second Atlas V Cygnus launch in 2016. The company had planned Cygnus missions for the first (CRS OA-5), second (CRS OA-6) and fourth quarters (CRS OA-7) of 2016. Two of which flew on the new Antares 230 and one on the aforementioned second Atlas V. These three missions enabled Orbital ATK to cover their initial CRS contracted payload obligation. This particular mission, known as NG-11, is part of an extension program that will enable NASA to cover the ISS resupply needs until the Commercial Resupply Services 2 contract enters in effect, and thus the E indicates that it actually is an extension above the originally contracted payload transport.
Production and integration of Cygnus spacecraft is performed in Dulles, Virginia. The Cygnus service module is mated with the pressurized cargo module at the launch site, and mission operations are conducted from control centers in Dulles and Houston.
Production and integration of Cygnus spacecraft is performed in Dulles, Virginia. The Cygnus service module is mated with the pressurized cargo module at the launch site, and mission operations are conducted from control centers in Dulles and Houston. This will be the eighth flight of the Enhanced-sized Cygnus PCM.
The spacecraft for the NG-11 is named the S.S. Roger Chaffee after Roger Chaffee who lost his life during training for the Apollo 1 mission.  On 17 April 2019 at 4:46:07 PM EST, Antares launched the NG-11 mission to the International Space Station from Wallops Island, Virginia.
Total weight of cargo: 3,166 kg (6,980 lb).
- Crew supplies
- Science investigations
- Spacewalk equipment
- Vehicle hardware
- Computer resources
- Three CubeSats for NASA's ELaNa-26 mission Virginia CubeSat Constellation (Aeternitas, Ceres, Libertas)
- Seeker Demo a NASA free flying CubeSat for vehicle inspection
- SatRevolution's CubeSat - Światowid
- KRAKsat - CubeSat created by Polish students from AGH University of Science and Technology and Jagiellonian University  in cooperation with SatRevolution
- AeroCube 10A/10B by Aerospace Corporation 
- BIRDS 3
- IOD-1 GEMS
- NSLSat 1
- SpooQy 1
- ThinSat 1A..1L
- SASSI2 3U Cubesat by University of Illinois and Purdue University School of Aeronautics and Astronautics
- "Worldwide launch schedule". spaceflightnow.com. Retrieved 12 February 2015.
- "International Space Station Flight Schedule". Students for the Exploration and Development of Space. 15 May 2013.
- Clark, Stephen (12 April 2019). "Launch schedule". Spaceflight Now. Retrieved 17 April 2019.
- Gebhardt, Chris (1 June 2018). "Orbital ATK looks ahead to CRS2 Cygnus flights, Antares on the commercial market". NASASpaceFlight.com. Retrieved 2 June 2018.
- "Cygnus Fact Sheet" (PDF). Orbital ATK. 24 March 2015. Archived from the original (PDF) on 26 September 2015. Retrieved 14 August 2015.
- Erwin, Sandra (5 June 2018). "Acquisition of Orbital ATK approved, company renamed Northrop Grumman Innovation Systems". SpaceNews. Retrieved 23 July 2018.
- "Nepal's first ever satellite launched into space". kathmandupost.ekantipur.com. Retrieved 18 April 2019.
- Sputnik. "Nepal, Sri Lanka Launch Their First Nano-Satellites Using US Rocket". sputniknews.com. Retrieved 19 April 2019.
- Gebhardt, Chris (14 August 2015). "Orbital ATK make progress toward Return To Flight of Antares rocket". NASASpaceflight.com. Retrieved 17 April 2019.
- Leone, Dan (17 August 2015). "NASA Orders Two More ISS Cargo Missions From Orbital ATK". SpaceNews.com. Retrieved 17 August 2015.
- Leone, Dan (20 August 2015). "NASA Considering More Cargo Orders from Orbital ATK, SpaceX". SpaceNews.com. Retrieved 17 April 2019.
- Northrop Grumman. "S.S. Roger Chaffee" (PDF). northropgrumman.com. Retrieved 17 April 2019.
- Martz, Michael (17 April 2019). "Rocket launches from Wallops Island with student-inspired satellites from Richmond-area schools". Richmond Times-Dispatch. Retrieved 19 April 2019.
- "International Space Station Payload Opportunities on Cygnus" (PDF). Northrop Grumman. 2018. FS009_13_1.
- "Upcoming ElaNa CubeSat Launches". NASA. Archived from the original on 13 March 2019. Retrieved 12 March 2019.
- KRAKsat project website
- Krebs, Gunter. "AeroCube 10A, 10B". Gunter's Space Page.