Orbital ATK’s Pegasus XL rocket will take about eight minutes to reach orbit with NASA’s eight CYGNSS weather research microsatellites, then comes deployment of the spacecraft more than 300 miles (500 kilometers) above Earth.
The 51,000-pound (23-metric ton) rocket will drop from the belly of a modified L-1011 carrier plane, named Stargazer, flying on an east-southeast path over the Atlantic Ocean at an altitude of 39,000 feet (11,900 meters).
The Pegasus rocket, launching on its 43rd orbital mission, will fire three solid-fueled stages in succession, then release the eight Cyclone Global Navigation Satellite System spacecraft two at a time.
The images below were recorded from a previous flight.
Data source: NASA/Orbital ATK
T-00:00: Pegasus Drop
The 55-foot-long Pegasus XL rocket is released from the Orbital Carrier Aircraft off the east coast of Florida at an altitude of 39,000 feet above the Atlantic Ocean and a speed of Mach 0.82.
T+00:05: First Stage Ignition
After falling for five seconds to a distance of about 300 feet below the L-1011, the first stage Orion 50S XL solid-fueled motor of Pegasus is ignited to begin the powered journey to orbit with CYGNSS. Between drop and ignition, the Pegasus XL’s destruct system is armed.
T+00:36: Max-Q
The Pegasus XL flies through the phase of maximum aerodynamic pressure, and the Orion 50S XL continues firing, reaching a peak power level of about 163,000 pounds of thrust.
T+01:17: First Stage Burnout
The Orion 50S XL first stage motor consumes all of its solid-fuel propellant and burns out at an altitude of more than 175,000 feet, or 53.5 kilometers.
T+01:33: First Stage Separation/Second Stage Ignition
The spent first stage motor is jettisoned at T+plus 1 minute, 33 seconds, to prepare for the second stage of flight. The first stage casing falls into the Atlantic Ocean. One second later, Orion 50 XL motor ignites at an altitude of 233,000 feet (71 kilometers) to continue the flight into orbit.
T+02:12: Fairing Jettison
The 50-inch-diamter (1.3-meter) payload fairing that protected the CYGNSS satellites during atmospheric ascent is separated once heating levels drop to predetermined limits. The second stage motor continues its burn with 44,000 pounds of thrust.
T+02:48: Second Stage Burnout
The Orion 50 XL second stage motor consumes all its solid fuel, then begins a four-minute coast phase for the rocket to climb to the targeted altitude for the CYGNSS mission. During this time, the rocket’s on-board computer calculates when it needs to ignite the third stage based on the performance of the booster to this point.
T+06:37: Second Stage Separation
The Pegasus XL’s second stage separates from the third stage.
T+06:48: Third Stage Ignition
The Pegasus XL’s third stage Orion 38 motor fires for a planned 68-second burn to accelerate the eight CYGNSS microsatellites to orbital velocity.
T+07:56: Third Stage Burnout
The third stage Orion 38 solid-fueled motor burns out. The mission is targeting a circular orbit 317 miles (510 kilometers) above Earth at an inclination of 35 degrees.
T+12:56: Begin CYGNSS Spacecraft Deployments
The attitude control thrusters on the Pegasus XL’s third stage will re-orient the vehicle for the deployment of the eight CYGNSS microsatellites, which will separate in pairs at T+plus 12 minutes, 56 seconds, T+plus 13 minutes, 26 seconds, T+plus 13 minutes, 56 seconds, and T+plus 14 minutes, 26 seconds. A ground station in Kourou, French Guiana, will be monitoring the separation events.
Mission managers will be closely monitoring the weather for the first launch of astronauts aboard SpaceX’s Crew Dragon spacecraft, not just around the Kennedy Space Center, but along a corridor stretching thousands of miles across the Atlantic Ocean in case the crew capsule has to escape from its Falcon 9 rocket during the climb into orbit.
The launch from Cape Canaveral of a top secret spy satellite for the U.S. government was aborted at the last moment early Saturday as its United Launch Alliance Delta 4-Heavy rocket ignited three main engines, a dramatic cutoff of the countdown that will delay the mission by at least one week.
Engineers clad in clean suits finished stowing last-minute cargo into SpaceX’s Dragon supply ship Friday, including 40 mice and bacterial research specimens, a day before it is scheduled to blast off to the International Space Station in the first flight from the Kennedy Space Center’s historic Apollo-era launch pad 39A since 2011.
