{"id":38360,"date":"2018-07-16T01:05:27","date_gmt":"2018-07-15T17:05:27","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/cygnus-departs-iss-following-reboost-test\/"},"modified":"2018-07-16T01:05:27","modified_gmt":"2018-07-15T17:05:27","slug":"cygnus-departs-iss-following-reboost-test","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/cygnus-departs-iss-following-reboost-test\/","title":{"rendered":"Cygnus departs ISS following reboost test"},"content":{"rendered":"

The Northrop Grumman OA-9E Cygnus spacecraft has departed the ISS at the concluding phase of her mission. The departure comes five days after a unique test objective. The cargo resupply vehicle provided a reboost to the Station with a short 50 second burn of its main engine on the aft of the vehicle, raising the Station\u2019s altitude by 295 feet. This test will pave the way for future, longer burns, removing some of the orbital stationkeeping strain from the Russian assets.<\/p>\n

Cygnus concluded her stay at the ISS on Sunday, released from the grip of the Space Station Remote Manipulator System (SSRMS).<\/p>\n

Two tons of trash had been loaded into the since-emptied vehicle, following its delivery of 3,350 kilograms (7,385 lb) of cargo to the International Space Station.<\/p>\n

This included 800 kilograms (1,764 lb) of propellant. The cargo included 1,191 kilograms (2,626 lb) of hardware for the US and international segments of the outpost and 13 kilograms (29 lb) for the Russian segment.  The payload also included 132 kilograms (291 lb) of hardware to support spacewalks, 100 kilograms (220 lb) of computer equipment and 811 kilograms (1,788 lb) of supplies and provisions for the crew.<\/p>\n

The vehicle was then refilled with trash, set to burn up along with the vehicle during its destructive re-entry. That will occur on July 30, following the deployment of six cubesats.<\/p>\n

However, the vehicle still had one final role to conduct on the ISS, a first-ever reboost of the Station by a commercial vehicle.<\/p>\n

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Cygnus Reboost firing \u2013 as envisioned by Nathan Koga for NSF\/L2<\/p>\n

This was the first time since the retirement of the Space Shuttle fleet in July 2011, a US spacecraft had performed a reboost of the ISS.<\/p>\n

Although the Station is high above the heavens, there is still a very thin amount of air in the 220 mile orbit of the ISS, enough to provide a tiny amount of atmospheric drag that results \u2013 over time \u2013 in the Station losing some altitude while increasing velocity.<\/p>\n

Reboosts of the Station\u2019s altitude are required to counter the natural decay of the ISS\u2019 orbit as it races around the planet.<\/p>\n

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Reboost events were commonplace during the Shuttle era, conducted via firings of the Reaction Control System (RCS) thrusters on the docked orbiters, providing a thank you present to the Station that was protecting and \u2013 in later years \u2013 feeding the orbiter during her stay.<\/p>\n

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Shuttle docked to the ISS timelapse<\/p>\n

With reboosts required every couple of months, the Russian visiting vehicles would also chip in with the occasional push, a practice that has continued to this day, in tandem with Europe\u2019s since-retired ATV craft.<\/p>\n

The Station also has a set of thrusters on the Zvezda module can be employed. However, they are mainly reserved for when a Visiting Vehicle can\u2019t conduct the task, as the requirement of protecting the Station\u2019s propellant stores is paramount.<\/p>\n

Future Visiting Vehicles, such as the Commercial Crew vehicles, are also being evaluated for potential reboost capabilities and now a Commercial Resupply Services (CRS) vehicle has shown it is capable of helping take up some of the load.<\/p>\n

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Dragon 2, Starliner and CRS2 Dream Chaser all at the ISS \u2013 via Nathan Koga for NSF L2<\/p>\n

\u201cWe actually started engaging NASA on this topic probably the fall of last year,\u201d noted Frank DeMauro, Vice President and General Manager of the Advanced Programs Division for Northrop Grumman Innovation Systems.<\/p>\n

The reboost was small and negligible, classed officially as a Detailed Test Objective in which Cygnus fires its main engine for just a few seconds to demonstrate its capability to perform more robust ISS orbit raising maneuvers in the future.<\/p>\n

\u201cWe have a large engine on the back of the spacecraft that puts out a lot more thrust [than the 32 maneuvering thrusters on Cygnus], and this is the engine we use for orbit raising burns,\u201d noted Mr. DeMauro.<\/p>\n

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The S.S. J.R. Thompson at its 10 m capture point \u2013 as the Station arm reaches out to grapple Cygnus. (Credit: Nathan Koga for NSF\/L2)<\/p>\n

\u201cSo we started talking with NASA at the program office about the possibility of Cygnus providing some form of orbit raising capability using that engine.  And one of the things we decided to do earlier this year is to put this Detailed Test Objective in place and at least work through the process of seeing if we could get that approved by NASA and of course specifically the safety review panel.\u201d<\/p>\n<\/p>\n

See Also<\/h4>\n