November 12, 2018

Timeline for Pegasus launch of ICON satellite


If you would like to see more articles like this please support our coverage of the space program by becoming a Spaceflight Now Member. If everyone who enjoys our website helps fund it, we can expand and improve our coverage further.

Northrop Grumman’s Pegasus XL rocket will take about 11 minutes to place NASA’s Ionospheric Connection Explorer, or ICON, satellite into a roughly 357-mile-high (575-kilometer) orbit after an airborne launch off Florida’s east coast.

The nearly 53,000-pound (24-metric ton) rocket will drop from the belly of a modified L-1011 carrier plane, named Stargazer, flying on an easterly path over the Atlantic Ocean at an altitude of 39,000 feet (11,900 meters).

The Pegasus rocket, launching on its 44th orbital mission, will fire three solid-fueled stages in succession, then release NASA’s ICON satellite into orbit to begin a mission studying how weather in Earth’s atmosphere influences plasma conditions at the edge of space in the ionosphere, a boundary that can interfere with radio communications and satellite navigation.

The images below were recorded from a previous flight.

Data source: NASA/Northrop Grumman

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.
The 57-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 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.
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 ICON. 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.
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.
The Orion 50S XL first stage motor consumes all of its solid-fuel propellant and burns out at an altitude of more than 177,000 feet, or 53.9 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.
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 237,000 feet (72.1 kilometers) to continue the flight into orbit.

T+02:10: 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 50-inch-diamter (1.3-meter) payload fairing that protected the ICON during atmospheric ascent is separated once heating levels drop to predetermined limits at an altitude of around 381,000 feet (116 kilometers). 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.
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 ICON 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+07:00: Second Stage Separation

The Pegasus XL's second stage separates from the third stage.
The Pegasus XL’s second stage separates from the third stage.

T+07:11: 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.
The Pegasus XL’s third stage Orion 38 motor fires for a planned 69-second burn to accelerate the ICON satellite to orbital velocity.

T+08:20: 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.
The third stage Orion 38 solid-fueled motor burns out. The mission is targeting a circular orbit 357 miles (575 kilometers) above Earth at an inclination of 27 degrees.

T+11:20: ICON Separation

The attitude control thrusters on the Pegasus XL’s third stage will re-orient the vehicle for the deployment of the ICON satellite. The spacecraft is programmed to begin extending its solar panel within about 100 seconds of separation from the Pegasus third stage.

Email the author.

Follow Stephen Clark on Twitter: @StephenClark1.


If you would like to see more articles like this please support our coverage of the space program by becoming a Spaceflight Now Member. If everyone who enjoys our website helps fund it, we can expand and improve our coverage further.
Do NOT follow this link or you will be banned from the site!