A Minotaur 1 rocket powered by a surplus Cold War-era missile stage more than 54 years old is poised to blast off from the Eastern Shore of Virginia Tuesday morning, heading to orbit with three top secret spacecraft for the U.S. government’s spy satellite agency.
The solid-fueled launcher, sized to haul small satellites into orbit, is awaiting liftoff from pad 0B at the Mid-Atlantic Regional Spaceport located at NASA’s Wallops Flight Facility in Virginia. Liftoff is scheduled for 7 a.m. EDT (1100 GMT).
There is a 60% chance of favorable weather for launch Tuesday morning, according to the official launch forecast. The primary weather concerns are low cloud ceilings and cumulus clouds associated with a cold front moving through the area early Tuesday.
The Minotaur 1, assembled and operated by Northrop Grumman, is set to fly its first mission since 2013. The Minotaur rocket family is primarily geared to launch satellites for the military.
The 69-foot-tall (21-meter) rocket will is based on leftover solid-fueled motors from the U.S. Air Force’s Minuteman missile program. Designers added two Orion solid rocket motors on top of the lower two stages of a Minuteman missile to turn the bomb carriers into satellite launchers.
The Minotaur 1 rocket’s M55A1 first stage motor was cast with solid propellant in 1966 by Thiokol, now part of Northrop Grumman. The SR19 second stage motor, produced by Aerojet, was filled with its solid propellant in 1983, according to a Northrop Grumman spokesperson.
The age of the first stage likely means it is the oldest rocket motor ever used on a space launch.
After going on alert with nuclear warheads in silos during the Cold War, the Minuteman missile motors were stored at Hill Air Force Base, Utah, and refurbished there before shipping out for launch preparations.
Military teams test-fired Minuteman motors with similar ages in 2019 and 2020, and engineers verified good performance in both stages.
“We are using these decommissioned assets, taxpayer-funded assets, and we’re taking them and we’re able to launch government-sponsored payloads, which to me is actually one of the coolest things about our Minotaur 1 rocket,” said Kelly Fitzpatrick, a Northrop Grumman senior guidance, navigation and control engineer.
The mission set for launch Tuesday is designated NROL-111. While the satellites on-board the Minotaur 1 rocket are classified, NRO officials held a pre-launch press conference last week to preview the mission.
“We certainly cannot get into any specifics for national security reasons, but I can tell you that there are three spacecraft that will be launched on this mission,” said Col. Chad Davis, director of the NRO’s office of space launch. “NRO payloads and capabilities, in general, are the nation’s eyes and ears in space, being able to deliver that exquisite intelligence information from space that our warfighters and national decision-makers need.”
NRO satellites collect high-resolution optical and radar imagery of sites around the world, eavesdrop on communications from U.S. adversaries, and help track worldwide military activity.
In 2016, the Space Force’s Space and Missile Systems Center, then part of the Air Force, selected a Minotaur 1 rocket for the NROL-111 mission. The launch contract awarded to Orbital ATK, since acquired by Northrop Grumman, was valued at $29.2 million.
Airspace warning notices indicate the Minotaur 1 rocket will head southeast from Wallops Flight Facility, likely targeting an orbit a few hundred miles in altitude at an inclination of around 50 degrees to the equator, according to Marco Langbroek, a Dutch archaeologist and expert tracker of military satellites.
The Minotaur 1’s first stage will ignite as the five-hour countdown strikes zero at Wallops. A hydraulic thrust vector system will steer the rocket on a trajectory over the Atlantic Ocean as the first stage burns through its pre-packed propellant to generate more than 200,000 pounds of thrust.
After exceeding the speed of sound in less than 30 seconds, the Minotaur will shed its spent first stage motor casing about a minute into the mission. The Minuteman second stage will ignite at the same time and burn for 72 seconds, accelerating the rocket to more than 6,000 mph (nearly 10,000 kilometers per hour).
Two commercially-produced solid rocket motors will finish the job of placing the three NRO payloads into orbit.
An Orion 50XL third stage will ignite nearly two-and-a-half minutes after liftoff. The rocket’s 61-inch-diameter (1.55-meter) titanium payload fairing will jettison during the third stage burn, once the Minotaur 1 flies above the dense, lower layers of the atmosphere.
After burnout of the third stage, the rocket will coast for several minutes until it reaches the proper altitude for ignition of the fourth stage Orion 38 motor, which will place the three NRO satellites into orbit. The payloads will separate from the rocket soon after the fourth stage completes its burn.
The launch Tuesday will mark the 28th flight of a Minotaur rocket since 2000, including suborbital missions. It will be the 18th orbital launch of a Minotaur rocket, and the 12th use of the Minotaur 1 configuration. Northrop Grumman also launches the Minotaur 4 rocket family using more powerful surplus Peacekeeper missile motors.
It will be the eighth Minotaur rocket to launch from the Mid-Atlantic Regional Spaceport in Virginia. Minotaur missions have also launched from Vandenberg Space Force Base in California, the Pacific Spaceport Complex in Alaska, and Cape Canaveral Space Force Station in Florida.
The NROL-111 mission is the second launch in two days for Northrop Grumman’s rocket program.
The company’s air-launched Pegasus XL rocket fired into orbit Sunday off the coast of California with a small Space Force satellite named Odyssey. The spacecraft was developed in less than a year, and the Space Force conceived the mission as a demonstration for a “tactically responsive launch” capability.
Military officials informed Northrop Grumman of the target launch date and the mission’s orbital parameters just 21 days ahead of time. Northrop Grumman configured a Pegasus rocket already in its inventory to launch the Odyssey space surveillance satellite.
“It just shows the depth and breadth of Northrop Grumman’s capabilities that we have fairly independent teams to be able to get these two launches off in two days on opposite coasts,” said Kurt Eberly, head of the company’s launch vehicles division.
“These launches are both for the U.S. Space Force, so when they want to launch, and when the Space Force’s customer — the NRO — wants to launch, we try to be there on the day that they want,” Eberly said.
Northrop Grumman’s orbital-class rockets, which also include the Antares launcher used for space station resupply missions, have a relatively low flight rate. The launch Sunday was the first flight of a Pegasus rocket since 2019, and Antares rockets typically launch about twice per year.
But the company also launches suborbital rockets on tests of the U.S. military’s missile defense system. Eberly said Northrop Grumman plans to launch 28 rockets in 2021, and they all use the same common avionics package, from small target vehicles to the medium-class Antares rocket.
“Most of them you’re not really going to hear about,” he said. “They’re target launches for various parts of the military, but nonetheless each of those is a rocket in and of itself.”
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Source: https://spaceflightnow.com/2021/06/14/minotaur-rocket-set-to-launch-top-secret-satellites-from-virginia/
