March 30, 2020

Two commercial satellites link up in space for first time


If you would like to see more articles like this please support our coverage of the space program by becoming a Spaceflight Now Member. If everyone who enjoys our website helps fund it, we can expand and improve our coverage further.
The Intelsat 901 satellite, backdropped by planet Earth, is seen by Northrop Grumman’s first Mission Extension Vehicle more than 22,000 miles over the Pacific Ocean. Credit: Northrop Grumman

A Northrop Grumman robotic servicing spacecraft has hooked up with an aging Intelsat communications satellite more than 22,000 miles over the Pacific Ocean, accomplishing the first link-up between two commercial satellites in space, and the first docking with a satellite that was never designed to receive a visitor.

Northrop Grumman’s first commercial Mission Extension Vehicle, or MEV 1, will take over propulsion responsibilities for Intelsat 901, which is running low on fuel after more than 18 years in service relaying data and television signals. MEV 1 is the first spacecraft of its kind, and officials say the successful link-up with Intelsat 901 is a harbinger for a new era of commercial satellite servicing.

The automated docking early Tuesday also marked the first connection of two satellites in geosynchronous orbit, a region high above the equator where spacecraft move at speeds that match the rate of Earth’s rotation. The ability of satellites to move in lock-step with the spin of Earth makes geosynchronous orbit, or GEO, a popular location for communications relay stations.

“It’s a very historic day,” said Joe Anderson, vice president of business development and operations at SpaceLogistics LLC, a wholly-owned subsidiary of Northrop Grumman, which built the MEV 1 spacecraft. “It’s the first time that satellites have docked in the GEO orbit. It’s the first time we’ve ever docked with a satellite that was not designed to be dock with, and it’s the first time two commercial satellites have ever docked.”

The MEV 1 spacecraft lifted off from Kazakhstan in October aboard a Russian Proton launcher, flying in tandem on the same rocket with a Eutelsat telecom satellite. After its release into an elliptical, or egg-shaped transfer orbit, MEV 1 activated electric thrusters to circularize its orbit more than 22,000 miles (roughly 36,000 kilometers) above Earth.

MEV 1 arrived in the vicinity of Intelsat 901 on Feb. 5, according to Anderson.

Intelsat 901 left its operating position and raised its altitude by 180 miles, or 290 kilometers, to the so-called GEO graveyard orbit, where geostationary satellites are typically decommissioned. Managers selected the GEO graveyard orbit for the first MEV docking to reduce the risk to other active satellites from space debris in the event of an accident.

“This has been a long time in the making,” Anderson said in an interview Wednesday with Spaceflight Now. “The company’s been working on developing this capability for over 10 years now. Our construction began back in 2016, and we launched here last October, made it into orbit, up to up to the GEO graveyard orbit, where we rendezvoused with this Intelsat satellite earlier this month.”

This series of images shows the MEV’s final approach to the Intelsat 901 satellite, and its attachment to Intelsat 901’s engine nozzle. Credit: Northrop Grumman

Since Feb. 5 up until Monday of this week, we were doing a number of approaches, calibrating our sensors and our algorithms, testing out our procedures,” Anderson said. “And then on Monday, we did the final approach. It was quite exciting.”

Switching from low-impulse electric thrusters to higher-power conventional liquid-fueled jets, MEV 1 approached the Intelsat 901 spacecraft and paused at pre-planned waypoints 80 meters (262 feet) and 20 meters (65 feet) from its docking target.

The robotic servicing craft was designed to extend a stinger into the nozzle of the main engine on Intelsat 901, which has not been used since the weeks after the satellite’s launch in 2001. A liquid apogee engine is mounted to the base of about 80 percent of the communications satellites in geosynchronous orbit.

A series of images released Wednesday by Northrop Grumman showed the MEV’s stinger entering the Intelsat 901 engine. Mechanical fingers reached out and grabbed the target craft to pull the two satellites together at 2:15 a.m. EST (0715 GMT) Tuesday.

“We lowered our orbit down down to about 80 meters behind the client satellite, and from there began the approach to the client,” Anderson said Wednesday. “The satellite autonomously maneuvers from one waypoint to the next is approaching the client. It takes a couple of hours to do that approach, and then we get to the final waypoint right behind the client, we get permission from the client to to do the docking and send the command, and a few minutes later we were captured and clamped together, locked together and the MEV took over control.”

Ground teams at Northrop Grumman’s satellite control center in Dulles, Virginia, and at Intelsat’s operations center in nearby Tysons Corner orchestrated the docking. But MEV 1’s on-board computer, using data gathered by a scanning LIDAR ranging sensor and infrared and visible cameras, guided the spacecraft toward Intelsat 901 autonomous, with occasional go-aheads from ground controllers.

Artist’s illustration of the Intelsat 901 satellite (left) after the docking of the Mission Extension Vehicle (right). Credit: Northrop Grumman

MEV’1 next act will be to relocate Intelsat 901 to a new operating position in geosynchronous orbit at 27.5 degrees west longitude, again using the spacecraft’s fuel-efficient xenon-fed electric thrusters. The servicer will also adjust the inclination, or tilt, of Intelsat 901’s orbit from 1.5 degrees back over the equator.

“Right now, we’re over the Pacific Ocean, and we’ll be continuing to drift westward to relocate the Intelsat satellite over to their new operating position in the Atlantic Ocean region,” Anderson said. “So they’ll be going to a new location at 27.5 degrees west longitude, and it will go into service there. The end of March, beginning of April timeframe is when we should be there. At that point, Intelsat will transfer the traffic from one of their other communications satellites to the Intelsat 901 satellite.”

Built by Space Systems/Loral, now known as Maxar, the Intelsat 901 satellite launched in June 2001 aboard a European Ariane 4 rocket from French Guiana with a design lifetime of 13 years. The satellite is still capable of providing services for Intelsat customers, but would need to be retired soon without the help of Northrop Grumman’s servicing craft.

The Mission Extension Vehicle takes over attitude control and propulsion responsibilities, acting like a jet pack for the customer spacecraft.

Under the terms the contract with Intelsat, the MEV 1 spacecraft will provide propulsion capabilities to Intelsat 901 to extend its usable life for five years, then return the satellite to a decommissioning graveyard orbit. At the end of the five-year service, MEV 1 could dock with another satellite in geosynchronous orbit to serve another client.

Intelsat, one of the world’s largest and oldest commercial satellite operators, signed up as the anchor customer for the Space Logistics satellite servicing program in 2016.

Satellite servicing is not new for Intelsat.

Astronauts flying on the space shuttle Endeavour installed a new upper stage on the Intelsat 603 satellite in 1992. Over the course of three spacewalks, Endeavour’s crew struggled to capture the cylinder-shaped communications satellite, which was stranded in an unusable orbit by a launch failure.

After two capture attempts turned up empty, space shuttle crew conducted the first — and so far only — spacewalk to be performed by three astronauts to grab the 4.5-ton satellite and connect a new kick motor to send it into geostationary orbit.

“Intelsat has been at the forefront of innovation and game-changing space technology for decades,” said Mike DeMarco, executive vice president and chief services officer at Intelsat, in a press release. “Pushing the boundaries of what’s possible is in our DNA here – that’s why we didn’t hesitate to sign up to be MEV-1’s first customer. We’re proud to make history with Space Logistics LLC and Northrop Grumman on this groundbreaking space milestone.”

The second Mission Extension Vehicle, set for launch in June, will also service an aging Intelsat communications satellite in geostationary orbit. The MEV 2 spacecraft will launch on top of an Ariane 5 rocket in tandem with Intelsat’s new Galaxy 30 communications satellite.

Customers can purchase MEV services on an annual basis.

For the MEV 1 mission, Intelsat is paying around $13 million per year for the life extension service, said Jacques Kerrest, Intelsat’s executive vice president and chief financial officer, in a quarterly earnings call last year.

Northrop Grumman’s satellite servicing program has weathered several corporate mergers and acquisitions. The Mission Extension Vehicle started under ATK, a precursor to Orbital ATK, which formed in 2015. Northrop Grumman acquired Orbital ATK in 2018.

Officials said the MEV design relies on existing technologies.

The navigation sensors flown on the MEV are similar to rendezvous aids used on Northrop Grumman’s Cygnus space station supply ship, and the MEV spacecraft is based on Northrop Grumman’s flight-proven GEOStar design. The MEV also uses a docking structure based on devices developed by ATK for space shuttle servicing flights to the Hubble Space Telescope.

“For us at Space Logistics, this is really just the first step,” Anderson said Wednesday. “We’ve really taken an approach here of keep it simple, incrementally improve the technologies and add new capabilities as those technologies are developed and the risks are retired.

“So we are currently working on our next generation of satellite servicing capabilities,” he said. “That consists of our Mission Robotic Vehicle and propulsion augmentation device — we call it a Mission Extension Pod. So that’s already on our horizon. We hope to have that in orbit by mid-2024. So that will bring many new capabilities for servicing, getting simple repairs, to adding augmentation devices to existing satellites.”

Intelsat 901, and the Intelsat satellite targeted by the MEV 2 mission, were never designed to join up with another spacecraft after launch. With satellite servicing now a reality, Anderson said he expects manufacturers to begin designing satellites to be repaired and serviced in orbit.

“We’ll begin designing our satellites for satellite servicing,” he said. “So rather than designing satellites for super-high reliability, like we do today, we’ll design satellites for serviceability in the future. So it will create a shift in that market.”

Other companies are pursuing satellite servicing and repair demonstration missions.

Maxar, a competitor with Northrop Grumman the satellite manufacturing business, is developing the Restore-L satellite servicing demonstration mission under contract to NASA that aims to refuel a Landsat Earth-imaging satellite, which orbits around 50 times closer to Earth than the geostationary altitude targeted by the the MEV.

Maxar was also the manufacturer of Intelsat 901, the client satellite for Northrop Grumman’s MEV 1 spacecraft.

SpaceLogistics and Northrop Grumman received technical assistance from NASA during development of the MEV, but the government provided no funding. NASA’s assistance included support tasks in rendezvous and proximity operations, management of electro-static discharges between vehicles, robotics operator training, and the development of electric propulsion systems, the space agency said.

Maxar’s Restore-L mission is more technically complex, and involves the transfer of propellant and an in-space manufacturing and assembly demonstration with robotic arms. The MEV is simpler, and it’s a purely commercial effort, but NASA and the U.S. military could be future customers for SpaceLogistics and Northrop Grumman.

Northrop Grumman is not planning to build more MEVs beyond the second extension vehicle scheduled for launch in June. But potential customers can still ask for an MEV if desired, Anderson said.

Officials instead are focusing on the next-generation satellite servicing vehicle, which could mount propulsion pods directly onto satellites, then move to another client rather than remaining docked for years at a time.

Services offered by the propulsion pods under development at Northrop Grumman could help extend operations of satellites in different orbits, and for spacecraft farther from Earth.

“We can use these for applications at low and medium Earth orbits, as well as cislunar space and Mars as well,” Anderson said. “So this need, this capability for servicing, for tugging satellites, for refueling satellites, apply in all of those all of those cases.”

Email the author.

Follow Stephen Clark on Twitter: @StephenClark1.


If you would like to see more articles like this please support our coverage of the space program by becoming a Spaceflight Now Member. If everyone who enjoys our website helps fund it, we can expand and improve our coverage further.
Do NOT follow this link or you will be banned from the site!