By Bill D’Zio

Credit: NASA

According to a press release by NASA, the Cygnus cargo spacecraft, the SS Roger Chaffee, will depart the orbiting laboratory Tuesday, Aug. 6.  With more than three months in space, the spacecraft, built by Northrop Grumman Innovation Systems (formerly Orbital ATK), will be departing the International Space Station with live coverage on NASA Television and the agency’s website commencing at noon EDT, with release scheduled for 12:15 p.m.  Expedition 60 Flight Engineers Nick Hague and Christina Koch of NASA will use the station’s Canadarm2 robotic arm to release Cygnus.   After ground controllers remotely unbolt the craft from the Earth-facing port of the Unity module and maneuver it into release position.

The Cygnus spacecraft delivered several tons of supplies and scientific experiments to the International Space Station, and has been docked since then. With the primary mission complete, several important secondary mission will kickoff. Over the following days, Cygnus will maneuver to a safe distance away from station. If all goes according to plan, Cygnus will begin deploying a series of CubeSats.

NASA’s Seeker Robotic External CubeSat Inspection Vehicle will be deployed, and operations will begin to demonstrate its ability to maneuver around Cygnus and take high-resolution inspection photos. Seeker and companion Kenobi onboard Cygnus are an attempt to reduce the cost of in space inspection through highly automated extravehicular inspection of crewed and uncrewed spacecraft.  Designed and built inhouse at NASA Johnson Space Center (JSC), was funded as an International Space Station (ISS) “X-by” Project and within a budget of $1.8 million.  Seeker is an evolution on past free-flying inspector development efforts such as the Autonomous Extravehicular Activity Robotic Camera Sprint (AERCam Sprint) and Mini AERCam.

For Seeker to successfully demonstrate in space automated inspection, it will maneuver within 50m of the target vehicle (Cygnus).  Once completed, seeker will dispose itself.  Seeker has integrated some commercial off-the-shelf (COTS) and space-rated COTS items.  Notably, The Seeker Guidance, Navigation, and Control (GNC) system is composed entirely COTS items.

In-space inspection has been done since the first visual inspection of the Gemini VI and VII spacecraft after their rendezvous in 1965. As spacecraft complexity, mission complexity, increased risk due to space debris and mission duration increases, the need for inspection has grown.  Inspection techniques and technologies have also advanced with systems like the ISS robotic inspections.  This system requires many hours of planning and analysis prior to execution and the MSS has a large mass of 4,600 kg.  Seeker is intended to overcome these limitations and reduce overall cost and mass.

 Seeker will transmit those images to its Kenobi receiver inside Cygnus for storage and transmission to the ground at a later date.

Northrop Grumman launched its Cygnus cargo spacecraft bound for the International Space Station at 4:46 p.m. EDT Wednesday, April 17. The Antares rocket carrying Cygnus CRS-11 Liftoff was from Virginia Space’s Mid-Atlantic Regional Spaceport Pad-0A at NASA’s Wallops Flight Facility on the state’s Eastern Shore. This is the final Cygnus mission under the initial Commercial Resupply Services (CRS)-1 contract with NASA. Northrop Grumman will continue to service the ISS with a CRS-2 contract begins with a cargo launch in the fall 2019.

Cygnus Honors Apollo 1 Hero

This Cygnus space craft, the SS Roger Chaffee, was named after the late Roger Bruce Chaffee(February 15, 1935 – January 27, 1967). Chaffee was an Eagle Scout, American naval officer and aviator, Purdue Alumni, and Astronaut. Chaffee was selected to be an astronaut as part of NASA the 3rd group of Astronauts. He served as capsule communicator (CAPCOM) for the Gemini 3 and Gemini 4 missions and received his first spaceflight assignment in 1966 In 1967, Chaffee, along with fellow astronauts Virgil “Gus” Grissom and Ed White succumbed to fire during a pre-launch test for Apollo 1. Chaffee was a distinguished individual, and was posthumously awarded the Congressional Space Medal of Honor and a second Air Medal.

Typically, after delivering cargo, deploying cubsats and taking out ISS trash, Cygnus maneuvers to re-enter Earth’s atmosphere, concluding the mission.  This time, things are a little different.  As Cygnus matures as a spacecraft, so does it’s ability for expanded capabilities.

Prior Cygnus spacecraft used traditional liquid propellent thrusters for attitude control.  This time, a package of four control moment gyroscopes is installed aboard the Cygnus spacecraft.    A control moment gyroscope or commonly referred as a  “CMG” is a device that uses momentum for attitude control and commonly used in spacecraft attitude control systems.  They have been used as far back as Skylab in the 1970s.

Short missions in space don’t typically warrant the expense, complexity and mass of CMGs as compared to using thrusters.  As the duration of the mission extends, CMGs benefits start to outweigh thrusters.  “We’ll use the control moment gyros to control the spacecraft attitude, as opposed to fuel,” said Frank DeMauro, vice president and general manager of Northrop Grumman’s space systems division.

The upgraded Cygnus spacecraft will use four spinning gyroscopes and the physics of conservation of momentum to manage the spacecraft’s pointing, or attitude.  The result greatly increase the useful life of the spacecraft.  By using gyroscopes  rather than chemical propellent, Cygnus spacecraft’s consumption of liquid propellants will go down and therefore be able to stay in orbit longer since less propellent is needed., which feed thrusters normally used to change the supply ship’s orientation.  The upgrade will allow the Cygnus spacecraft to remain in orbit for up to a year. Prior Cygnus missions have previously lasted no more than three or four months.

Cygnus is planned to remain in orbit until later this year which will also allow  Northrop Grumman to demonstrate the ability to fly two Cygnus spacecraft simultaneously and support payloads on the cargo craft for extended durations.  This may open up additional commercial opportunities for Northrop Grumman beyond ISS.

More details of Cygnus’ mission and Expedition 60 crew activities are available at:

http://www.nasa.gov/station