NG-23 Cygnus Back on Track, Arrives at ISS Tomorrow

NASA and Northrop Grumman announced this evening that the NG-23 Cygnus cargo spacecraft is back on track enroute to the International Space Station.  NG-23 was supposed to arrive there this morning, but experienced a propulsion anomaly yesterday. The problem has been resolved and it will get there just one day late. [Update, September 18: NG23 successfully berthed to the ISS this morning.]

NG-23 launched on a Falcon 9 rocket from Cape Canaveral Space Force Station at 6:11 pm ET on Sunday. Everything appeared to be going well until late yesterday afternoon when NASA and Northrop Grumman announced a delay in its arrival at the ISS because its “main engine stopped earlier than planned during two burns designed to raise the orbit of the spacecraft for rendezvous with the space station.” No further information was released.

Earlier today NASA’s list of upcoming events included NG-23’s arrival tomorrow, which was confirmed in a press release about 9:40 pm ET tonight.

NASA coverage begins at 5:45 am ET. Cygnus berths rather than docks. It will be captured by the robotic Canadarm2 at 7:18 am ET with NASA astronaut Jonny Kim at the controls and then installed onto a port. Coverage of installation begins at 8:25 am ET.

This is the first Cygnus XL, an upgraded version of the spacecraft that can carry 33 percent more cargo than its predecessor. Although it’s designated NG-23, it’s actually the 22nd Cygnus to fly to space, not the 23rd. NG-22 was damaged during shipping from its manufacturer, Thales Alenia Space, in Italy to the launch site in Florida so they skipped that one for now.

NASA said the propulsion issue yesterday was due to a conservative software setting.

“Data shared by the spacecraft confirmed that Cygnus XL operated as intended during two planned maneuvers when an early warning system initiated a shutdown command and ended the main engine burn because of a conservative safeguard in the software settings.”

NG-23 is delivering 11,000 pounds of scientific equipment and cargo for the ISS crew. The plan is for it to remain at the ISS until next March, although it will have to be temporarily removed from its port when Russia’s Soyuz MS-28 arrives in November to maintain proper separation between the two during Soyuz’s docking sequence. Soyuz MS-28 is scheduled for launch on November 27 with Russian cosmonauts Sergey Kud-Sverchkov and Sergey Mikayev and NASA astronaut Christopher Williams.