The graphite epoxy motor (GEM), designated as the GEM-60, will be used to augment the Delta IV Medium-plus launch vehicles. The test culminated 29 months of design, fabrication, and testing work by employees from Boeing, Alliant Techsystems (ATK) and a number of critical suppliers, including Moog.

Moog manufactures the motor's thrust vector actuation system. The solid rocket boosters for the Delta IV vehicles are the newest addition to the ATK GEMs, which are used on each member of the Boeing Delta family of launch vehicles.

Measuring 60 inches in diameter, the Delta IV GEM-60 boosters are the largest in the group. ATK also supplies GEM-46 and GEM-40 solid rocket motors for the Boeing Delta II and Delta III rockets, respectively.

The Boeing Delta IV line includes the Delta IV Medium, Delta IV Heavy and three variants of the Medium vehicle, known as Medium-plus, which have been introduced to meet the growing needs of the commercial market for reliable and affordable access to space.

Each of the three configurations of the Delta IV Medium-plus vehicle retains the Delta IV common booster core (CBC) and is distinguished by the number of GEM-60 motors attached to the CBC, as well as the size of the upper stages and payload fairings.

The Delta IV Medium-plus can lift up to 14,475 pounds (6,565 kilograms) to geosynchronous transfer orbit. The first Delta IV launch is scheduled for 2001.