To a Fiery End
To a Fiery End
The Legacy of the Delta IV Heavy
Ricky Whitmore
The date is Tuesday, April 9th, 2024, at 12:53PM EST. The pad at Space Launch Complex 37B erupts with flame and a thunderous roar. This pad, on this day, will see the final launch of the mighty Delta IV Heavy.
The Delta rocket family has been a staple of the American space program since the 1960s starting with the original Delta series (Lettered A-N). Following this series was the Delta II, which flew 155 missions until its retirement in 2018, and the short-lived Delta III, which only flew 3 missions (one of which succeeded). Enter the Delta IV, which had two variations. The Delta IV Medium flew for the first time in November 2002, and was retired in 2019. The Delta IV Heavy flew for the first time in December 2004, and was retired this past April, marking the official end of this monumental program.
The Delta IV Heavy Rocket. Image Credit: US Space Force.
Delta IV Heavy was part of the fleet of United Launch Alliance (ULA), which is a merger between Boeing and Lockheed Martin. Delta IV Heavy was a tri-core, 2 stage rocket, which stood at 236 feet tall (72 meters). The first stage consisted of three booster cores, each of which was powered by an RS-68A engine, which together produced over 2 million pounds of thrust at liftoff. The second stage is comprised of the Delta Cryogenic Second Stage (DCSS), which is powered by an RL10C rocket engine. On top of the DCSS sits the payload, encased in a 3-piece fairing, inspired by the fairings of the old Titan Rockets.
Breakdown of a Delta IV Heavy Rocket. Image Credit: United Launch Alliance.
Over the course of 16 launches Delta IV Heavy mainly launched payloads for the United States National Security Apparatus, however there were two very notable exceptions. In December of 2014 the rocket launched NASA’s Orion space capsule into orbit on a mission called “EFT-1”. This mission was designed as an orbital and re-entry test of the Orion spacecraft which will be used to carry future astronauts to the moon as part of NASA’s Artemis Program. Then in August of 2018 a Delta IV Heavy vaulted NASA’s Parker Solar Probe into space. The probe was designed to fly around, and through the solar corona to gather data on our solar system’s star.
Delta IV Heavy Launches NASA’s Orion Space Capsule. Image Credit: United Launch Alliance.
But perhaps what Delta Heavy is most widely known for are its rusty, orange-colored boosters, and the fact that it lights itself on fire before liftoff. A few seconds before liftoff the engines are started in a staggered order, and they erupt with flame, burning off excess hydrogen fuel from the rocket. These roaring flames climb up the boosters of the rocket which gives Delta Heavy the iconic, charred look as it flies off the pad. The boosters themselves are covered in a rusty colored foam, which protect the boosters from the scorching flames of the hydrogen burn off. This fiery pre-launch show has earned the Delta IV Heavy the nickname, “The Most Metal Rocket in the World”.
Delta IV Heavy Hydrogen Burn off. Image Credit: United Launch Alliance.
The Delta family of rockets has been retired to make room for ULA’s Vulcan rocket, which has already flown two successful missions to date. Vulcan combines the capabilities of the Delta IV and ULA’s other rocket (the Atlas V) into one rocket, and does so cheaper. The average cost per launch of the Delta IV Heavy came in at a whopping $350 million dollars, Vulcan can do the same job for significantly less money per launch.
Watching a Delta Heavy launch is a quintessential experience for any rocket enthusiast. There’s something incredible about watching this beast of a rocket ignite the air around it, to see the fiery inferno crawl its way up the side of the booster cores, and to hear the unearthly roar as it lifts off towards the skies. For my part, Delta IV Heavy is my favorite launch vehicle, I was sad to see it retired. But I will always have the memories of the launches I was able to see. And as ULA moves forward to its Vulcan rocket, let us not forget the rockets of their past, including the mighty Delta IV Heavy.
As always feel free to write to me at rickyew2112@gmail.com, or find me on X @Rickyew2112
Sic Itur Ad Astra
(Thus, They Journey to the Stars)