Delta IV Heavy: Exploring the Unique Features of this Final Flight
After nearly a decade of serving as the top dog in American space launches, the Delta IV Heavy is preparing for its 16th and final flight. This rocket, dubbed as “the most metal of rockets” by United Launch Alliance (ULA), has left an indelible mark on the history of space exploration. As the priciest commercially-made rocket globally, the Delta IV Heavy has been the backbone of the US military’s space missions for over two decades. But what sets this rocket apart from the rest? And why is its last flight such a big deal for the space industry?
One of the standout features of the Delta IV Heavy is its unique choice of fuel: super-chilled liquid hydrogen. This fuel, while tricky to handle, proves to be incredibly efficient. When ignited with liquid oxygen in its three RS-68 engines, the hydrogen creates a fiery spectacle that rises up into a towering flame. The rocket’s cores, wrapped in orange foam insulation, resemble giant toasted marshmallows. This foam not only adds to the dramatic visual effect but also shields the rocket from the intense heat of the fireball.
With over 2 million pounds of thrust, the Delta IV Heavy shoots skyward from Cape Canaveral. The center core’s RS-68 engine adjusts its power to save fuel, while the side boosters burn through theirs in under four minutes. After shedding its side boosters into the Atlantic, the center core burns for another 90 seconds before detaching. The upper stage’s RL10 engine then kicks in to propel the rocket’s classified payload into a high orbit around Earth.
The final launch of the Delta IV Heavy was initially scheduled for Thursday, 28 March. However, a ground pump issue on a gaseous nitrogen pipeline caused a delay and subsequent rescheduling. Engineers are currently troubleshooting the issue, and a new launch date for Monday, 1st of April, has been requested. The launch can be watched live on ULA’s official YouTube channel.
In terms of size and power, the Delta IV Heavy is unmatched. Unlike its smaller counterpart, the Delta IV Medium, the Heavy version combines three Delta IV core stages. These rocket engines generate a staggering 702,000 pounds of thrust. Each engine weighs around 14,876 pounds and stretches a whopping 204 inches (17 feet) in length. Fueled by a combination of liquid hydrogen and liquid oxygen, the Delta IV Heavy puts on quite a show before liftoff, with flames engulfing it as the hydrogen gas ignites and burns off.
The Delta IV Heavy’s final launch marks the end of an era for the Delta rocket family. It is the 45th flight of the Delta IV and the 16th in the Heavy configuration. The Delta IV, which first flew in 2002, has undergone significant transformations since its predecessors in the Cold War-era Thor program. Originally created as a satellite launcher, the Delta IV became the primary launch vehicle for military satellites. Its Heavy version has played a crucial role in launching hefty military and intelligence-gathering satellites.
However, the retirement of the Delta IV is imminent, with ULA’s new Vulcan Centaur ready to take its place. The Vulcan Centaur offers a cheaper and more powerful alternative, with the flexibility to attach multiple solid rocket boosters. ULA is also exploring ways to make the Vulcan Centaur reusable in the future, potentially slashing costs even further.
As the Delta IV Heavy prepares for its final flight, it leaves behind a legacy of groundbreaking space missions and significant contributions to national security and scientific endeavors. While it may be bidding farewell, its impact on the space industry will continue to be felt for years to come.
