‘Stargazer’ - Last flying L-1011 Tri-Star in the world

by Cathy Hansen, special to Aerotech News
“Stargazer” is an L-1011 commercial transport aircraft, formerly with Air Canada, modified to serve as the launch platform for Orbital’s air-launched Pegasus rocket, as well as a platform for airborne research projects. The foundation for Orbital Sciences Corporation was laid in 1980. This L-1011 aircraft was purchased in 1992, modified to carry the Pegasus rocket and began work in the commercial space industry in June 1994.

Lockheed Aircraft Company manufactured 250 L-1011 Tri-Stars in Palmdale, Calif., from 1968 to 1984.

The ‘Stargazer’ L-1011 has been used to launch numerous Pegasus rockets as well as the captive carry flights of the X-34 reusable launch vehicle demonstrator. As of October 2019, 44 rockets (containing 95 satellites) have been launched from it, using the Pegasus-H and Pegasus-XL configurations.

The Pegasus rocket attach point. (Photograph by Bill Deaver)

Launching Satellites into Low Earth Orbit
The three-stage Pegasus is used to deploy small satellites weighing up to 1,000 pounds into low-Earth orbit. Pegasus is carried aloft by the ‘Stargazer’ L-1011 aircraft to approximately 40,000 feet over open ocean, where it is released and free-falls five seconds before igniting its first stage rocket motor. With its unique delta-shaped wing, Pegasus typically delivers satellites into low-Earth orbit in a little over 10 minutes.

This patented air-launch system provides customers with unparalleled flexibility to operate from virtually anywhere on Earth with minimal ground support requirements. Pegasus launches have been conducted from six separate sites in the U.S., Europe and the Marshall Islands, the first time a space launch vehicle has demonstrated such operational flexibility.

Photograph by Kevin Cleyhens (Northrop Grumman photograph)

Scaled Composites Manufactures Pegasus Control Surfaces in Mojave
Wings and control surfaces for the Pegasus air-launch system are manufactured at Scaled Composites in Mojave, Calif., Pegasus has been providing launch services for technology demonstrations, scientific investigation and communications missions since 1990 with numerous missions launched from the L-1011 “Stargazer” carrier aircraft that is based at Mojave Air and Space Port.

Orbital Sciences Move to Mojave
‘Stargazer’ was previously based at Meadows Field in Bakersfield, but was plagued with winter fog conditions. I remember inviting Marty Mosier and Mark Gamache (Orbital employees at the time) to speak at Bakersfield Council Navy League in 1998 and during that time I invited them to bring their L-1011 to Mojave Airport. I described our clear blue skies, long beautiful runways and friendly management. Next thing I knew, they were on the phone to Airport General Manager, Dan Sabovich. One thing led to another and now they call Mojave Airport home.

Pegasus attached to the Stargazer. (Courtesy photograph)

Double Keel Structure
The Lockheed L-1011 has an unusual double keel structure that the vertical fin of the Pegasus XL fits between. The fin goes in the space formerly occupied by the lower deck galley. The rest of the vehicle is carried entirely below the fuselage of the ‘Stargazer.’

There is an interesting story, relayed by L-1011 crew, on how this aircraft received the name ‘Stargazer.’ It is a tribute to the television series Star Trek: The Next Generation fictional starship, the USS Stargazer.

Cygnus Spacecraft
The Antares rocket with the Cygnus spacecraft was launched from NASA’s Wallops Flight Facility in Virginia by ‘Stargazer.’ This was part of NASA’s Commercial Orbital Transportation Services (COTS) program to deliver cargo to the International Space Station. Orbital performed eight cargo missions to the ISS. The maiden flight of Cygnus spacecraft was completed Sept. 2013. The cargo included student experiments, food and clothing.

Cygnus approaches the International Space Station and is grappled by the crew using the station’s robotic arm. It is then installed on the bottom side of the station’s Harmony node. After delivering cargo to the station, Cygnus destructively reenters Earth’s atmosphere.

The Stargazer cockpit. (Courtesy photograph)

Orbital Sciences merges with Alliant Techsystems (ATK)
In 2015, ‘Stargazer’ was re-painted to reflect Orbital Sciences’ merger with Alliant Techsystems (ATK). The Orbital ATK mission is cost effective insertion of small satellites into low Earth orbit.

CYGNSS (Cyclone Global Navigation Satellite System)
The constellation of eight Cyclone Global Navigation Satellite System (CYGNSS) spacecraft that was launched by the Pegasus rocket on Dec. 15, 2016, to measure the winds inside hurricanes, giving scientists insight into their formation, intensification and life cycle.

The Stargazer L-1011 makes an appearance at Plane Crazy Saturday at the Mojave Air and Space Port. (Photograph by Cathy Hansen)

L-1011 ‘Stargazer’ presentation at Plane Crazy
At a Plane Crazy Saturday event in January 2017, Ed Dunlap, manager, L-1011 Ground and Flight Operations, described some issues that delayed the first intended launch. Ever the optimist, he said that he believed there was a reason that all didn’t go as planned and actually saved the entire mission.

While he and his crew were battling some mechanical problems with the aircraft, NASA decided to recheck the payload of satellites and found some complications that they were able to remedy. Had that glitch not been found, the satellites would not have launched correctly and the whole mission would have been a failure.

Solid-fueled rocket motors for the Pegasus mission arrived at Orbital ATK’s Vandenberg processing facility. Don Walter, Orbital ATK’s Chief Pilot for the company’s Pegasus Air Launch Program, Ed Dunlap and crew then flew the ‘Stargazer’ from Mojave to Vandenberg to mate the Pegasus underneath the aircraft. They then flew to Cape Canaveral for a launch over the Atlantic Ocean.

So many details, so many years of engineering and design and everything had to work perfectly and it did.

Ed Dunlap makes a presentation at Plane Crazy Saturday in January 2017. (Photographs by Cathy Hansen)

Northrop Grumman acquires Orbital ATK
According to Wikipedia, ‘Stargazer’ appeared in Northrop Grumman livery in 2018, following their acquisition of Orbital ATK. ’Stargazer’ launched the Ionospheric Connection Explorer on Oct. 11, 2019. The launch was originally scheduled for June 2017 but was scrubbed when an anomalous piece of vehicle data was observed during a ferry flight. The data was related to the rudder position of the Pegasus XL rocket and was observed during a routine in-flight vehicle checklist. The launch was delayed multiple times throughout 2017, 2018 and 2019, finally occurring Oct. 11, 2019.

‘Stargazer’ is off on another mission, and departed Mojave Air and Space Port last week. Ed Dunlap reported in an email to me, “How long we keep Stargazer flying depends on potential launch contracts and component support. We are estimating through 2023.”

‘Stargazer’ is the last flying L-1011 in the world.