Launch Complex 39B at Kennedy Space Center

Launch Complex 39B is one of the launch pads at NASA's Kennedy Space Center on the Space Coast, rebuilt by NASA's Exploration Ground Systems program to launch the Space Launch System rocket and Orion spacecraft on Artemis missions.

NASA's reference page on the complex says pad subsystems used for the Apollo and Space Shuttle programs were replaced or upgraded to support the Space Launch System and a 21st century multi-user spaceport (NASA Launch Complex 39B reference). The guiding idea is a clean pad. The basics every rocket needs, such as electrical power, a water system, a flame trench and a safe launch area, stay at the pad, while the other needs of a particular rocket, including access for workers, come with the towers or structures that deliver it to the pad, so a variety of companies can use the site.

For the Space Launch System, NASA says engineers and technicians do almost all of their preparations inside the Vehicle Assembly Building before the rocket goes to the pad, which cuts the time it needs to spend at Launch Complex 39B to 10 days or less ahead of liftoff (NASA Launch Complex 39B reference). NASA's Exploration Ground Systems page adds that the pad supported Artemis I, which sent an uncrewed Orion beyond the Moon and back (NASA Exploration Ground Systems Launch Pad 39B). Other Space Coast launch guides are listed in the Digital Towns launches section.

Pad 39B's first launch was Apollo 10 on May 18, 1969, and NASA's Artemis I page records a launch from the pad on Nov. 16, 2022.

The Apollo, Skylab and Apollo-Soyuz entries come from NASA's Launch Complex 39B reference page (NASA Launch Complex 39B reference), and the Exploration Ground Systems page names the Apollo-Soyuz Test Project in the same list (NASA Exploration Ground Systems Launch Pad 39B). NASA's Artemis I page says the mission launched from Launch Pad 39B at Kennedy Space Center at 1:47 a.m. EST on Nov. 16, 2022, and that the total mission lasted 25 days, 10 hours and 53 minutes (NASA Artemis I mission page).

Artemis II is the next mission NASA ties to the pad. In 2023 the Exploration Ground Systems page listed a new liquid hydrogen tank and an emergency egress system at Pad 39B as work in progress for Artemis II, the first crewed launch (NASA Exploration Ground Systems Launch Pad 39B). NASA's Artemis II mission page now records the first crewed Artemis flight, a crewed lunar flyby, as launched on April 1, 2026 with splashdown on April 10, 2026, carrying NASA astronauts Reid Wiseman, Victor Glover and Christina Koch and Canadian Space Agency astronaut Jeremy Hansen (NASA Artemis II mission page). That mission page does not repeat the pad name in its launch summary, so the Pad 39B link for Artemis II rests on the Exploration Ground Systems page.

NASA rebuilt Pad 39B's flame trench and flame deflector, added lightning towers, refurbished the sound suppression water tower and began a new liquid hydrogen tank to replace the shuttle-era one.

According to NASA's Launch Complex 39B fact sheet, the flame trench walls on the north side were upgraded with new fire-resistant bricks, a new flame deflector was installed, the energy of the rocket's flame at liftoff is diverted to the north side of the trench, and the south side was repaired and remains a concrete surface (NASA Launch Complex 39B fact sheet). Other refurbishment included new bypass lines and valves, removal of the heritage liquid oxygen vaporizer, replacement of fire suppression piping around the entire pad complex, a reinforced catacomb roof, a new liquid hydrogen separator vaporizer and new Environmental Control System equipment.

Some of the numbers behind that work, from the same NASA fact sheet: 1.3 million feet of copper cable were removed and replaced with 300,000 feet of fiber cable, more than 96,000 bricks went into the flame trench walls, the catacomb roof was reinforced to support 25.5 million pounds, and the flame deflector is made of about 150 steel plates, each weighing up to 4,000 pounds (NASA Launch Complex 39B fact sheet). The water tower was sandblasted and repainted so it can keep withstanding the corrosive salt air from the nearby Atlantic Ocean, according to the Launch Complex 39B fact sheet.

Pad 39B's three lightning towers are about 600 feet tall, its sound suppression tower holds about 400,000 gallons of water, and its new liquid hydrogen tank is designed for about 1.25 million gallons of usable fuel.

NASA's reference page describes the three 600 foot masts and their overhead wires as lightning protection for rockets while they are processed and launched, and calls the new liquid hydrogen tank the largest tank ever built for NASA, replacing the previous shuttle-era tank (NASA Launch Complex 39B reference). The sound suppression water is dumped on the mobile launcher and inside the flame trench at liftoff. The tank figures on the reference page date from its 2023 update, when buildup of the tank was still described as in progress.

NASA's own Pad 39B pages give two flame trench lengths and two temperature figures, and none of the pages explains the difference.

The Launch Complex 39B reference page says the north side of the flame trench is about 571 feet long, 58 feet wide and 42 feet high, and in its fun facts on the same page says the flame trench is 450 feet long (NASA Launch Complex 39B reference); the NASA fact sheet repeats both figures (NASA Launch Complex 39B fact sheet). Neither page says which measurement applies to which part of the Kennedy Space Center pad.

Heat is described two ways as well. The reference page and the fact sheet say the refurbished flame trench and new flame deflector will withstand temperatures of between 3,000 and 5,600 degrees Fahrenheit during launch, while the Exploration Ground Systems page for Launch Pad 39B says they will be exposed to a peak temperature of 2,200 degrees Fahrenheit (NASA Exploration Ground Systems Launch Pad 39B). Both statements are on current NASA pages for Kennedy Space Center, and both are given here as NASA states them.

Rockets for Pad 39B are stacked in the Vehicle Assembly Building and carried to the pad on NASA's crawler-transporter, a trip NASA put at 4.2 miles and nearly 11 hours for Artemis I.

NASA's Exploration Ground Systems page describes the Artemis I stack, the Space Launch System and Orion atop the mobile launcher, being carried from the Vehicle Assembly Building to the pad by crawler-transporter 2 for a wet dress rehearsal, a 4.2 mile journey that took nearly 11 hours, in a photo dated March 18, 2022 (NASA Exploration Ground Systems Launch Pad 39B). NASA's Artemis I page shows the same crawler outside Launch Pad 39B on Sept. 24, 2022, as teams prepared to roll the rocket back to the Vehicle Assembly Building (NASA Artemis I mission page).

Under the clean pad design, the towers or other structures that deliver a rocket bring what that rocket needs, including access for workers, and the pad supplies power, water, the flame trench and a safe launch area (NASA Launch Complex 39B reference). For the Space Launch System, NASA does almost all preparation in the Vehicle Assembly Building and plans 10 days or less at Kennedy Space Center's Pad 39B before liftoff.

NASA lists public launch viewing spots on the Space Coast from Titusville parks to Cocoa Beach beach parks, and it publishes launch schedules separately rather than on its pad pages.

NASA's See a Launch Up Close page notes that all Florida launches begin on pads at Cape Canaveral Space Force Station or Kennedy Space Center, mentions the Kennedy Space Center Visitor Complex as the closest public viewing, and lists other primary viewing locations from north to south (NASA See a Launch Up Close). In Titusville they are Marina Park at 501 Marina Road, Sand Point Park at 101 N. Washington Ave, Space View Park at 8 Broad Street, Manzo Park at 3335 S. Washington Ave (US 1), Rotary Riverfront Park at 4141 S. Washington Ave and Kennedy Point Park at 4915 S. Washington Ave. Further south NASA names the westbound SR 528 causeway over the Banana River, Jetty Park at the east end of Port Canaveral, and Alan Shepard Park, Fischer Park and Lori Wilson Park in Cocoa Beach.

For timing, NASA points to its own launch schedule and to a free Virtual Guest Program that sends schedule changes by email, and it streams launches on NASA+ (NASA See a Launch Up Close). Its tips for launch day on the Space Coast: expect heavy traffic, do not pull off alongside the road, bring drinks and snacks because launch windows can be long, and carry a flashlight for evening and early morning launches. Last verified: October 21, 2026, by re-reading NASA's Launch Complex 39B reference page, fact sheet and Exploration Ground Systems page, the Artemis I and Artemis II mission pages and the See a Launch Up Close page.