as european bands used to mulberry, it’s the final countdown, at least for United Launch Alliance’s Delta IV Heavy, which will retire after its final flight on Thursday, March 28. The classified mission also marked the end of an era that began more than 60 years ago. ULA bids farewell to the Delta series.
The tri-core rocket is scheduled to blast off from Space Launch Complex 37 at the Space Force Station in Cape Canaveral, Florida, at 1:40 pm ET on Thursday. The weather forecast is not good, with ULA predicting a 30% chance of favorable weather. If bad weather forces a bushwalk, the ground team will try again 24 hours later. As part of the NROL-70 mission, the Delta IV Heavy is carrying a classified payload for the National Reconnaissance Office, likely a spy satellite.
In its press materials, ULA describes the Delta IV Heavy as the “most metallic” rocket yet. The reason has to do with the dramatic and even shocking way the rocket exploded. Seconds before the engines roared to life, a fireball engulfed the base of the rocket, causing a fire that scorched the outside of the booster.
This is related to excessive hydrogen combustion. Before ignition, the hydrogen fuel crawls out of the engine and up the side of the booster (it’s like starting a gas stove or propane grill – some gas has to escape before you click the ignition button). When the engine ignites, the excess hydrogen ignites, creating a brief but intense fireball.This phenomenon is actually a normal and expected parts startup process. The 2018 video (below) describes the process in more detail.
It was the last flight of the 235-foot-tall (72-meter) Delta IV heavy-lift aircraft, which debuted in 2002. This is also the end of Delta’s plan. The NROL-70 mission marks the 16th launch of the Delta IV Heavy and the 389th launch in the Delta series. according to to American space. The Delta program was established by the U.S. government in 1960 to develop a suite of expendable launch vehicles for space missions, ranging from satellite deployment to deep space exploration. ULA’s new Vulcan Centaur rocket Debut in January, aiming to replace Delta.
The two-stage Delta IV Heavy consists of three booster cores, each powered by an RS-68A engine. Each engine can produce 705,000 pounds of force at liftoff, making it one of the most powerful liquid hydrogen/liquid oxygen engines in the world. The Delta IV Heavy’s second stage uses a RL10C-2-1 engine (also fueled by liquid hydrogen and liquid oxygen) capable of producing 24,750 pounds of thrust. A 16-foot-tall (5-meter) payload fairing completes the assembly.
Although the first launch of Delta IV Heavy on December 21, 2004 was a partial failure (the virtual payload did not reach the target orbit), this was still the only blemish in a perfect launch career. Its first successful combat mission was in 2007, when it launched an NRO reconnaissance satellite into space. Notable missions include the 2014 launch of NASA’s Orion spacecraft for the EFT-1 mission (Orion is now a key component of the space agency’s Artemis program) and the 2018 launch of the Parker Solar Probe.
related articles: What to know about ULA’s new Vulcan Centaur rocket
At the time of its debut, the Delta IV Heavy was the most powerful rocket to be launched from Cape Canaveral other than the Saturn V and the Space Shuttle Launch System, according to Going to Florida today. Currently, only NASA’s Space Launch System and SpaceX’s Falcon Heavy are more powerful (Starship doesn’t count because it’s not ready for prime time). Its replacement is the 202-foot-tall (61.6-meter) Vulcan Centaur rocket, which offers greater flexibility and can be configured with zero, two, four or six solid rocket boosters to meet specific mission requirements .
So the old is out and the new is in. The Delta IV Heavy has done its part for king and country, but now it’s time for an update—and a long overdue one. Vulcan represents ULA’s first new rocket design since its founding in 2006 (ULA is a joint venture of Lockheed Martin and Boeing, inherited from its predecessor, Delta Air Lines). Sure, we’ll miss those scary fireballs at launch, but the future awaits.
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