Virgin Orbit’s “Start Me Up” mission may have ended up in failure earlier in this last week — but it is not the first time that the UK has been involved in horizontal launches. In 1994, a British firm undertook the conversion of a passenger airliner into a first-stage launch pad, just like Cosmic Girl, the modified Boeing 747-400 used by Virgin Orbit. In the nearly three decades since, this craft — dubbed the “Stargazer” — has launched a grand total of 45 Pegasus rockets, carrying nearly 100 different satellites up into Earth orbit — including NASA craft designed to study space weather.
Stargazer started her life as a Lockheed L-1011 TriStar wide-body, tri-jet airliner built in early 1974 for service with Air Canada.
Eighteen years later, however, she was purchased by the Orbital Sciences Corporation — now part of the aerospace firm Northrop Grumman — to be modified into a launch pad for the Pegasus launch vehicle, the first air-launched orbit rocket.
Today. Stargazer is the only L-1011 airframe still considered to be airworthy.
Orbital Sciences is said to have considered various other craft for use as a launch pad before settling on the L-1011 — including the Boeing 747, McDonnell Douglas DC-10 and the Boeing B-52G Stratofortress.
The first few Pegasus rockets were deployed from a NASA-owned B-52 Stratofortress.
Marshall Aerospace of Cambridge, England implemented the retrofit of the L-1011 to accommodate the Pegasus launch system, at which point she was renamed Stargazer.
The name was chosen as an homage to the then recently-concluded science fiction television series “Star Trek: The Next Generation”.
In the series, USS Enterprise-D captain Jean-Luc Picard, played by Patrick Stewart, was formerly the captain of another starship named the “USS Stargazer”, which appeared in the 1987 episode “The Battle”.
The naming choice also referenced the fact that Picard’s first officer, William Riker (Jonathan Frakes), had served on a vessel called the USS Pegasus — the same name given to Orbital Sciences’ launch vehicle.
Pegasus, which consists of three solid propellant stages and an optional fourth stage, is designed to be released from a carrier aircraft at an altitude of around 39,000 feet.
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Unlike with Virgin Orbit’s Cosmic Girl, where the LauncherOne rockets are held under a wing, on Stargazer the Pegasus rockets are slung underneath the main fuselage.
Also unlike LauncherOne, the first stage was equipped with a wing to help provide lift while passing through the Earth’s atmosphere.
Stargazer’s first launch was also the maiden flight of the larger-sized Pegasus XL rocket, which was just under 58 feet long and capable of carrying a payload of up to 976 lbs.
Alongside its assorted Pegasus launched, the Stargazer has also been used to transport NASA’s aborted X-34 hypersonic test plane — and to conduct research flights.
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The airliner is capable of carrying a payload of 51,000 lbs to an altitude of 42,000 feet.
In 2010, Stargazer was further retrofitted, with its original 42,000 pound-thrust RB211-22B turbofans replaced with 50,000 pound-thrust ones.
The mobile launch pad has remained active, with launches in recent years including NASA’s hurricane forecasting Cyclone Global Navigation Satellite System (CYGNSS) in late 2016.
In October 2019, meanwhile, Stargazer assisted with the launch of NASA’s Ionospheric Connection Explorer — a satellite designed to investigate the region of the upper atmosphere where space and earthly weather meet.