NASAfacts

National Aeronautics and Space Administration

An aerial view of Launch Complex 39B at NASA’s Kennedy Space Center in Florida. In view on the pad is the mobile launcher that will be 

used to launch the agency’s Space Launch System with Orion spacecraft atop on Artemis missions. Photo credit: NASA/Kim Shiflett 

Significant upgrades and enhancements have been 

completed or are in progress at Launch Complex 39B 

at NASA’s Kennedy Space Center in Florida. Exploration Ground Systems (EGS) is preparing the pad to 

support the launch of the agency’s Space Launch 

System (SLS) rocket and Orion spacecraft for Artemis missions to the Moon and deep space destinations including Mars.

Pad subsystems used for the Apollo and Space 

Shuttle programs were replaced or upgraded to support the SLS and 21st century multi-user spaceport. 

The flame trench walls beneath the surface of the pad 

on the north side were upgraded with new, fire-resistant bricks. A new flame deflector has been installed. 

The energy of the rocket’s flame at liftoff will be diverted to the north side of the flame trench. The south 

side of the flame trench was repaired and will remain 

a concrete surface. The north side of the flame trench 

is about 571 feet long, 58 feet wide and 42 feet high.

Three, 600-foot-tall masts with overhead wires used 

to transmit electrical energy were installed around 

the perimeter of the pad to provide lightning protection for launch vehicles as they are processed and 

launched from the pad. The tower that holds about 

400,000 gallons of water to provide sound suppression during launch was sandblasted and repainted so 

it can continue to withstand the corrosive salt air from 

the nearby Atlantic Ocean.

Groundbreaking for a new liquid hydrogen (LH2) storage tank took place at the pad in December 2018. 

Buildup of the new tank is in progress. The new tank 

replaces the previous shuttle-era tank. The largest 

tank ever built for NASA will hold about 1.25 million 

gallons of usable LH2 to accommodate requirements 

for the SLS rocket to send Artemis missions to the 

Moon and on to Mars. 

Refurbishment at the pad included installation of new 

bypass lines and valves, removal of the heritage liqLaunch Complex 39B
National Aeronautics and Space Administration

John F. Kennedy Space Center

Kennedy Space Center, FL 32899

www.nasa.gov

FS-2021-08-726-KSC

uid oxygen (LO2) vaporizer, and removal and replacement of 

fire suppression piping around the entire pad complex. The 

catacomb roof above the pad was reinforced, a liquid hydrogen (LH2) separator vaporizer was installed, and the heritage 

Environmental Control System equipment was demolished and 

new equipment was installed.

The guiding principle behind the upgrades and modifications 

is to make the area a “clean pad,” which will allow a variety 

of companies to launch their rockets from the pad. The basics that every rocket needs remain in place, such as electrical 

power, a water system, flame trench and safe launch area. The 

other needs of individual rockets, including access for workers, 

can be met with the towers or other structures that deliver the 

rocket to the pad.

For SLS, engineers and technicians are planning to do almost 

all of their preparations inside the Vehicle Assembly Building 

(VAB) before the launcher goes to the pad. This reduces the 

amount of required time needed to be on the pad to 10 days or 

less ahead of liftoff.

Major History Facts

Apollo 10 was the first mission to begin at Launch Pad 39B 

when it lifted off May 18, 1969, to rehearse the first Moon landing. Three crews of astronauts launched to the Skylab space 

station in 1973 from Pad B. Three Apollo astronauts who flew 

the historic Apollo-Soyuz mission to link up in space also 

launched from Pad B. 

Fun Facts

• During refurbishment projects, 1.3 million feet of copper 

cables were removed and replaced with 300,000 feet of 

fiber cable.

• The water tower for the Ignition Overpressure and Sound 

Suppression System (IOP/SS) holds roughly 400,000 gallons of water, or enough to fill 27 average pools. This water 

is dumped on the mobile launcher and inside the flame 

trench in less than 30 seconds. The IOP/SS peak flow rate 

is 1.1 million gallons per minute, high enough to empty 

roughly two Olympic-size swimming pools in one minute. 

• The three lightning towers are about 600 feet tall – taller 

than the Vehicle Assembly Building, which is 525 feet tall.

• The catacomb roof was reinforced to be able to support 

25.5 million pounds - the equivalent of 2,125 average-size 

African elephants.

• The refurbished flame trench and new flame deflector 

will withstand temperatures of between 3,000 and 5,600 

degrees Fahrenheit during launch.

• More than 96,000 bricks were installed on the walls of the 

flame trench during the refurbishment project.

• The flame trench is 450 feet long; that’s equal to the length 

of about 1.5 football fields.

• The flame deflector is made up of about 150 steel plates, 

each weighing up to 4,000 pounds.

• Liquid oxygen and liquid hydrogen tanks store supercooled liquid gases (that are used for propellant) at minus 

297 and minus 423 degrees Fahrenheit, respectively.

Build-up of a new liquid hydrogen (LH2) storage tank is in progress at 

Launch Complex 39B. The new tank will hold 1.25 million gallons of usable 

LH2 to support future launches, including Artemis missions to the Moon and 

on to Mars. Photo credit: NASA/Cory Huston

Construction is complete on the main flame deflector in the flame trench at 

Launch Complex 39B at NASA’s Kennedy Space Center in Florida. Photo 

credit: NASA/Kim Shiflett