Pegasus XL version
Pegasus XL Pegasus H
The hybrid version: a standard Pegasus fitted with the XL's canted fins so it could hang under the L-1011 Stargazer that replaced the B-52. It flew four times between 3 April 1995 and 9 October 2000, orbiting the first Orbcomm satellites and the HETE-2 gamma-ray burst observatory among other payloads.
- April 3, 1995
- First launch
- 350 kg
- LEO capacity
- No
- Reusable
History
Why it existed
Orbital changed carrier aircraft in 1994, moving from NASA's B-52 to a Lockheed L-1011 bought from Air Canada and named Stargazer, which freed the company from depending on a government agency to fly. The new aircraft called for the canted fins already flying on the Pegasus XL, and there were still serviceable standard airframes in stock. The hybrid was the answer: standard body and motors, XL fins.
Four missions
It debuted on 3 April 1995 with two Orbcomm satellites and OrbView 1 — the communications constellation and the imaging programme that Orbital itself used as anchor customers to justify funding the rocket. MSTI-3 followed in May 1996 and Brazil's SCD-2 in October 1998, the latter from Cape Canaveral.
The Kwajalein flight
The last one, on 9 October 2000, flew out of Kwajalein Atoll in the middle of the Pacific and placed HETE-2 in an orbit inclined barely two degrees — precisely the kind of mission that justifies air launch, since reaching that inclination from a fixed pad would have taken a bigger rocket. HETE-2 replaced HETE-1, lost in 1996 in the only outright failure of a Pegasus XL carrying a science payload.
Retirement
With the standard airframes used up, the configuration was retired in 2000 and the programme went on with the XL alone. It remains the only Pegasus version born from a constraint of the carrier aircraft rather than from a demand for performance.