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WASHINGTON — Northrop Grumman’s satellite servicing spacecraft successfully docked with an Intelsat communications satellite Feb. 25 in a bid to keep the nearly 19-year-old satellite in service an additional five years, Northrop Grumman and Intelsat executives said Feb. 26.
Northrop Grumman’s Mission Extension Vehicle-1, which launched in October, underwent months of in-orbit testing before finally docking with Intelsat-901 in a so-called graveyard orbit 300 kilometers above the geostationary arc where most large communications satellites operate. The docking occurred Feb. 25 at 2:15 a.m. Eastern.
MEV-1 and Intelsat-901 will undergo additional checkouts as a combined stack before Northrop Grumman moves them into the geostationary arc so Intelsat-901 can resume service in late March. MEV-1 will remain attached to Intelsat-901 and use its own thrusters to keep the satellite properly oriented in orbit.
“This is the first time in history a docking has ever been performed with a satellite that was not pre-designed with docking in mind, and the first time two commercial satellites have ever docked,” said Joe Anderson, vice president of operations and business development at SpaceLogistics, Northrop Grumman’s subsidiary focused on satellite servicing, on a Feb. 26 call with reporters.
MEV-1 launched on an International Launch Services Proton rocket in early October and used onboard electric propulsion to raise its orbit to that of Intelsat-901’s by Feb. 1, Anderson said. The 2,300-kilogram servicer then completed a series of calibrations and tests of cameras and rendezvous systems while approaching Intelsat-901, pausing 80 meters from the satellite Feb. 24, Anderson said.
The next day Northrop Grumman moved MEV-1 next to Intelsat-901 and docked with the satellite using a capture mechanism that went “through the throat” of Intelsat-901’s apogee engine, Anderson said.
Northrop Grumman is currently building a second MEV for Intelsat that is on track to launch later this year, according to Tom Wilson, SpaceLogistics president and vice president of Northrop Grumman Space Systems. Arianespace is slated to launch MEV-2 on an Ariane 5 rocket.
A Intelsat executive told reporters Feb. 26 that the MEV-1 docking operation went so well that the team plans to dock MEV-2 with its host satellite in geostationary orbit rather than take it temporarily out of service in order to conduct the rendezvous in a higher orbit.
“This is a good pathway to the next docking for MEV-2, which we intend to do with customers on the satellite,” said Jean-Luc Froeliger, Intelsat’s vice president of satellite operations and engineering. “We’re very confident that we will have minimum perturbations of our services on our next docking.”
Intelsat has not publicly identified the host satellite for the MEV-2 mission.
In designing the MEV servicing spacecraft, Northrop Grumman combined its GEOStar communications satellite bus with elements of the Cygnus cargo tug the company uses to deliver supplies to International Space Station, Anderson said.
Northrop Grumman had previously expected to launch MEV-1 in 2018. Wilson said the additional year of preparation allowed Northrop Grumman to incorporate additional safety measures, such as the inclusion of patented technology to avoid electrostatic discharges on orbit.
Intelsat is Northrop Grumman’s first and so far only customer for MEV satellite life extension missions. Now that MEV-1 has demonstrated its ability to dock, Northrop Grumman is hopeful it can attract new customers.
“For years we heard customers say, ‘if you were there now we would use your service.’ Now we are here,” Wilson said.
MEVs are designed for 15 years of service, meaning Northrop Grumman can eventually use MEV-1 and the future MEV-2 to service spacecraft beyond its Intelsat contracts.
Wilson said that while nothing precludes Northrop Grumman from building additional MEVs beyond the first two, the company is focused on another system that uses a so-called Mission Robotic Vehicle mothership to attach smaller Mission Extension Pods to satellites. Northrop Grumman has three prospective customers interested in using the next-generation pod system, Wilson said.
Intelsat CEO Stephen Spengler said Intelsat-901 will enter service at the 332.5 degrees east orbital slot, where it will cover North and South America, Africa and Europe using C-band transponders and steerable Ku-band beams. The satellite will replace Intelsat-907, a 17-year-old satellite now four years past its design life.
Intelsat-901 and Intelsat-907 are nearly identical satellites, Spengler said. The MEVs allow Intelsat to defer spending on new replacement satellites by keeping old but still useful satellites in service, he said.
Intelsat-901 had only a few months of remaining fuel before it would have needed to retire for good in a graveyard orbit, Froeliger said.