TacRL-2 | Pegasus XL

Lift Off Time
(Subject to change)
June 13, 2021 – 08:11 UTC | 01:11 PDT
Mission Name
Launch Provider
(What rocket company is launching it?)
Northrop Grumman
(Who’s paying for this?)
United States Space Force
Pegasus XL
Launch Location
Pegasus will be dropped somewhere west of Vandenberg Space Force Base over the Pacific Ocean
Payload mass
Up to 325 kg (717 lb)
Where is/are the satellite(s) going?
~98° Sun-Synchronous Orbit, orbital altitude unknown
Will they be attempting to recover the first stage?
No, this is not a capability of the Pegasus XL
Where will the first stage land?
The first stage will crash into the Pacific Ocean
Will they be attempting to recover the fairings?
No, this is not a capability of the Pegasus XL
Are these fairings new?
How’s the weather looking?
This will be the:
– 45th Pegasus launch
– 1st air-launched orbital launch attempt of 2021
– 53rd orbital launch attempt of 2021
Where to watch
In the unlikely case that there is a livestream, it will be listed here

What does all this mean?

Northrup Grumman will be launching the TacRL-2 payload on their Pegasus XL rocket. Pegasus XL will be dropped from the Lockheed L-1011 TriStar aircraft over the Pacific Ocean, before the payload gets lofted into Sun-Synchronous Orbit (SSO) by the three solid-propellant stages.

TacRL-2 Mission

Very little is known about the TacRL-2 payload; however, it is known that this is part of the Technology Readiness Level (TRL) program which is a service capability program. In this case, the United States Space Force is trying to demonstrate rapid response capability, giving Northrop 21 days to integrate, test, and launch the payload. The USSF chose Pegasus as Pegasus was the cheapest option. Furthermore, the USSF thought that, as Pegasus has a slow response time relative to other launch service providers, if Pegasus is able to demonstrate this, other providers will too. The USSF got a roughly 50% discount off the north of $40,000,000 launch cost for this mission, only paying $28,100,000.

What is the Pegasus XL rocket?

Pegasus is a three stage, all-solid fuel, small-lift air-launched vehicle that gets dropped from the underside of a Lockheed L-1011 TriStar aircraft. The carrier aircraft, named Stargazer, was built in 1974 and modified in 1994 to launch the Pegasus. Stargazer takes Pegasus up to an altitude of ~40,000 feet before dropping it.

Pegasus XL launch vehicle, being used on the TacRL-2 mission
Pegasus and Stargazer ahead of launch (Credit: NASA)

First Stage

The first stage of Pegasus XL is equipped with the Orion-50SXL solid rocket motor. The engine runs on hydroxyl-terminated polybutadiene (HTPB) and produces ~284 kN (63,800 lbf) of thrust. The first stage does not have any thrust vector control (TVC) systems, and instead has a wing and tail to provide lift and attitude control.

Second Stage

The second stage of the Pegasus XL uses the Orion-50XL engine. Unlike the solid rocket motor on the first stage, this engine does have TVC and produces ~160 kN (16,000 lbf) of thrust in a vacuum. The Orion-50XL engine also runs on HTPB and, like the first stage, is produced by Alliant.

Third and Optional Fourth Stage

The Pegasus XL vehicle is equipped with a Orion-38 solid rocket motor on the third stage. This motor is also built by Alliant and produces ~34.31 kN (7,710 lbf) of thrust in a vacuum and runs on HTPB.

The Pegasus XL has an optional monopropellant fourth stage; however it is not flying on this mission.

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