R.I.P. Delta IV Heavy, 2004-2024

The very strange mission badge for the 37th Delta IV Heavy mission.

After the Space Shuttle launch vehicle retired in 2011, The Delta IV Heavy was the biggest, baddest rocket ship in the world. It had a lift capacity of 29 metric tons. Unfortunately it cost tons of money – $400 million per – to launch so its principle customer was the Department of Defense, launching big monitoring satellites on secret missions. Only two launches were non-DoD: a test of the since-abandoned Orion crew spacecraft and the launch of the Parker Solar Probe in 2018.

The Delta IV Heavy’s ignition sequence – venting a bunch hydrogen before oxygen – created a spectacular fireball every time, just a few seconds before launch.

Altogether Delta IV Heavy rockets made 37 launches and, over the two decades and over those 37 launches, the rocket had a perfect record. All 37 cargoes reached orbit. No failures.

But now it is retired. The Space Launch System, a launch vehicle only Congress likes, will replace it for a while but, really, the future is distributed launches rather than a single, massive launch. Commercial space launches are built around the idea of multiple, smaller payloads instead, “distributed” across a series of launches. SpaceX’s Falcon Heavy can manage a “mere” 26.7 metric tons. SpaceX’s Starship, still in development, will have a payload of 100 – 150 metric tons, but has not across three tests yet performed to spec.

 Captured video frame from ULA’s live broadcast, showing the three RS-68A engines poweringg the Delta IV Heavy rocket into the sky over Cape Canaveral, Florida.

The final launch of a Delta IV Heavy rocket came on April 9, 2024, a classified mission for the National Reconnaissance Office . The classified satellite was likely a type of satellite known publicly as an “Advanced Orion” or “Mentor” spacecraft. Another of the attractions of the Delta IV Heavy is that can carry the largest diameter payload of any rocket, and a payload as long as 65 feet. The Advanced Orion is a very large satellite.

The launch pad at Cape Canaveral used for Delta IV Heavy launches will likely be repurposed for SpaceX’s Starship. Environmental reviews are under way.

That’s also likely the end of the line for the line of the Delta rocket family, which has roots extending back through 389 Delta missions, starting in 1960.

Requiescat in pacem, Delta IV Heavy, 2004-2024.