NROL-129 | Minotaur IV

Northrop Grumman will be launching a classified national security payload (NROL-129) on its missile-derived Minotaur IV rocket vehicle, from the Mid-Atlantic Regional Spaceport (MARS) at Wallops Island, Virginia.

The Minotaur family of rockets has been in service since 1984, but none have flown at all over the last three years. This is the first flight of a Minotaur IV from Wallops and is also the first time that a Minotaur rocket has been used for a U.S. National Reconnaissance Office (NRO) mission.

Lift-Off  (Time) (Window)
(Subject to change)
July 15, 2020 – 13:00 UTC (Start of launch window)
Mission Name and what it is
NROL-129, National Reconnaissance Office Launch 129
Launch Provider
(What rocket company is launching it?)
Northrop Grumman
(Who’s paying for this?)
U.S. National Reconnaissance Office (NRO)
Minotaur IV
Launch Location
Launch Area 0 B, Mid-Atlantic Regional Spaceport (MARS), Wallops Island, Virginia, USA
Payload mass
Undisclosed, up to 1735 kg (3825 lbs)
Where are the satellites going?
Low Earth Orbit
Will they be attempting to recover the first stage?
No, this is not a capability of the Minotaur family of rockets.
Where will the first stage land?
It will not land but instead crash into the Atlantic Ocean.
Will they be attempting to recover the fairings?
No, this is not a capability of the Minotaur.
This will be the:
  • 2nd flight for Northrop Grumman for 2020 
  • 93rd mission for Northrop Grumman for life
  • 1st flight of Minotaur IV in 2020
  • 7th flight of Minotaur IV in life 
  • 1st launch of Minotaur IV from Wallops Island
Where to watch
Official live stream

Mission Overview

This mission marks the first time that a Minotaur IV rocket has launched from the Wallops Island launch facility. It’s the first flight of a Minotaur rocket in over three years. The mission is classified as the customer is the U.S’ National Reconnaissance Office (NRO). For these missions, all that is usually known about them is the name of the flight.

MARS, Wallops Island, Virginia
MARS, Wallops Island, Virginia. Credit: Northrop Grumman.

The launch is taking place from the MARS facility on Wallops Island, Virginia. This site is already used by Northrop Grumman for launching its Antares vehicle when sending Cygnus spacecraft resupply missions to the International Space Station. Soon, RocketLab will also be using this facility for launching its Electron rocket as well.

What about the NROL-129 payload?

Due to the classified nature of the mission, little is publicly known about the payload. However, given the name of the agency, we can safely speculate that it’s a reconnaissance (spy) satellite used for observing the goings-on in other countries. Whilst other classified payloads most certainly do exist, they have historically been launched by the Air Force (or since last year the Space Force).

Traditional spy satellites have often been large vehicles, such as the KH-11 (or “Key Hole”) family of vehicles, that look remarkably similar to the Hubble Space Telescope. These satellites could have a mass between 12,000 kg and 20,000 kg.

Technological advancements since the time of the Key Hole design of the 1970s, plus the size of the rocket and its payload capability, tell us that this payload is considerably smaller than what we may be used to thinking a reconnaissance satellite should look like. Improvements in electronics and electro-optics, particularly in miniaturization, have seen a reduction in size over the years for virtually all types of satellite.

Minotaur IV rocket on launch pad
Minotaur IV rocket on the launchpad. Credit: USAF

Minotaur IV Rocket

Minotaur IV is a variant of the Minotaur class of launch vehicles, all of which are derived from intercontinental ballistic missiles (ICBMs) – namely the Peacekeeper and Minuteman. They are manufactured by Northrop Grumman Innovation Systems, formerly Orbital ATK and Thiokol Propulsion before that. The Minotaur IV rocket has been flying payloads since 2010, with a 100% success rate over six flights so far.

The Minotaur I and II rockets are based on the Minuteman missile, whereas the Minotaur III-V range of rockets is based on the Peacekeeper missile.

The entire family of Minotaur rockets exclusively use solid rocket motors for propulsion. The use of SRMs reflects their ICBM heritage, which required them to be storable and rapidly ready to launch for deterrent purposes during the Cold War. The Minotaur IV, in particular, is designed to reach Low Earth Orbit with a medium mass payload.

The Minotaur IV is a four-stage rocket, comprising:

  • SR118 first stage
  • SR119 second stage
  • SR120 third stage
  • Orion 38 (or Star 48V) fourth stage
Graphic layout of Minoatur IV rocket
Layout of Minotaur IV rocket stages. Credit: Northrop Grumman.

First Stage

The first stage is named SR118 and has a single solid motor. This stage has 2,200 kN of thrust, or 490,000 lb.

Second Stage

The second stage, called SR119, also has just one solid motor with 1,465 kN (307,00 lb).

Third Stage

The third stage is designated as SR120 and is once again built from a single solid motor, this time with 329 kN (74,000 lb) thrust.

Fourth Stage

The fourth stage is available in two variants – Orion 38 (baseline) and Star 48V (an optional alternative). The Orion 38 has thrust of 32.2 kN (7,200 lb) and a burn time of 66.8 seconds.

The Star 48V has 68.6 kN (15,400 lb) thrust and a burn time of 84.1 seconds.

Minotaur Launch Sites

As mentioned at the top of this article, this launch marks the first time that a Minotaur IV rocket vehicle will launch from the MARS facility at Wallops. Previous launches have taken place from Vandenberg AFB (specifically SLC-8) in California, along with Kodiak (LP-1) in Alaska, and Cape Canaveral Air Force Station (from SLC-46).

  1. Note – regarding the rocket description it says: “The first stage, called SR119, also has just one solid motor with 1,465 kN (307,00 lb).”
    It should say – “The SECOND stage, called SR119, also has just one solid motor with 1,465 kN (307,00 lb).”

  2. Thanks for the article! I was wondering, what’s the propulsion mechanism for the fourth stage – though it says the entire family is exclusively solid-fueled. What does this mean for their accuracy of insertion – it seems to me that solid fuels would be a bit less reliable for precise burn duration and thrust. Would the satellite normally be able to adjust its own orbit once launched using RCSx thrusters?

    1. To the best of my knowledge, each stage has primary stage gimbal capability. How that works out in terms of final thrust, I can’t answer,

  3. I have noticed that the link to watch it is password protected, any idea of the password?

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