Delta III was an expendable launch vehicle made by McDonnell Douglas (later acquired by Boeing).

[4] Of its three flights, the first two were failures, and the third, though declared successful, reached the low end of its targeted orbit range and carried only a dummy (inert) payload.

Due to the continual size and mass growth of commercial satellites in the late 1980s, McDonnell Douglas realized the need for a higher-performance rocket than even their new Delta II.

[5] Multiple options for evolving the Delta II to support larger payloads were considered in the late 1980s and early 1990s, namely using higher-performing liquid hydrogen/liquid oxygen upper stages.

The third and final launch, carrying a dummy payload, was only partially successful after the RL-10B second-stage engine shut down prematurely.

[1] The first stage thrust was augmented by nine GEM-46 solid rocket boosters, sometimes referred to as GEM LDXL (Large Diameter Extended Length).

It was developed and manufactured partly by Mitsubishi Heavy Industries and was based on the second stage of JAXA's H-IIA rocket.

Boeing was in charge of preliminary design and the development of new technologies, while Mitsubishi Heavy Industries was responsible for manufacturing.

[7] A further refinement of the 5-meter diameter DCSS, known as the Interim Cryogenic Propulsion Stage, is used on the Block I Space Launch System rocket.

Control of the second stage was provided by 4 sets of hydrazine thrusters installed around the bottom of the liquid oxygen tank.