Delta II

Thirty-nine metres tall on a 2.44 metre core, with 4,822 kilonewtons at liftoff. The payload figure is the 7920-9.5 taking 5,030 kilograms to a 185 kilometre circular orbit at 28.7 degrees out of Cape Canaveral, which is the number in ULA's own payload planners guide. The company web page quotes a much lower figure with no reference orbit attached to it, and that one gets misquoted constantly.

The staging trick looks like a mistake and is not. A Delta II carried nine solid strap-ons and lit only six of them on the pad, holding the other three until the first set burned out and fell away. It is an inelegant way to buy a second stage of solid thrust without paying to carry a second stage, bolted onto a first stage descended from a 1960 Thor missile.

It flew 155 times, with 153 successes and a closing run of 100 consecutive missions without a failure. That record is the argument for boring incrementalism: almost nothing on the vehicle was new at any point, and the parts that were new arrived one at a time.

What it carried is the real legacy. The GPS constellation, Spirit and Opportunity, Kepler, Dawn, and finally ICESat-2 on 15 September 2018 from Vandenberg. For twenty years, if a NASA mission was going to another planet and did not need a heavy lifter, it went on one of these.

It was killed by size and by cost, not by failure. Its price went from roughly 51 million dollars in 1987 to something like 137 million by the end, while its five tonne slot got squeezed from above by the larger government launchers and from below by Falcon 9. A fixed cost that will not fall is fatal in a market where everyone else's is falling.