Mars 2001 Odyssey Delta II Launch Vehicle

Odyssey will be launched on a variant of Boeing's Delta II rocket called the 7925 that includes nine strap-on solid-fuel motors. Each of the nine solid-fuel boosters is meter (3.28 feet) in diameter and 13 meters (42.6 feet) long; each contains 11,765 kilo-grams (25,937 pounds) of a propellant called hydroxyl-terminated polybutadiene (HTPB) and provides an average thrust of 485,458 newtons (109,135 pounds) at liftoff. The casings on the solid rocket motors are made of lightweight graphite epoxy.

The main body of the first stage houses the Rocketdyne RS-27A main engine and two Rocketdyne LR101-NA-11 vernier engines. The vernier engines provide roll control during main engine burn and attitude control after main engine cutoff before the second stage separation. The RS-27A main engine burns 96,000 kilograms (211,000 pounds) of RP-1 (rocket propellant 1, a highly refined form of kerosene) as its liquid fuel and liquid oxygen as an oxidizer.

The second stage is 2.4 meters (8 feet) in diameter and 6 meters (19.7 feet) long, and is powered by an Aerojet AJ10-118K engine. The propellant is 3,929 kilograms (8,655 pounds) of a liquid fuel called Aerozine 50, a 50/50 mixture of hydrazine and unsymmetric dimethly hydrazine. The oxidizer is 2,101 kilograms (4,628 pounds) of nitrogen tetroxide. The engine is restartable and will perform two separate burns during the launch.

The third and final stage of the Delta II provides the final velocity required to place Odyssey on a trajectory to Mars. This upper stage is 1.25 meters (4.1 feet) in diameter and consists of a Star-48B solid-fuel rocket motor with 2,012 kilograms (4,431 pounds) of propellant and a system called active nutation control that provides stability after the motor ignites. A spin table attached to the top of the Delta's second stage supports, rotates and stabilizes the Odyssey spacecraft and Star-48B upper stage before they spin up and separate from the second stage. The Odyssey spacecraft is mounted to the Star-48B by a payload attachment fitting. A yo-yo despin system decreases the spin rate of the spacecraft and upper stage before they separate from each other.

During launch and ascent through Earth's atmosphere, the Odyssey spacecraft and Star-48B upper stage are protected from aerodynamic forces by a 2.9-meter--diameter (9.5-foot) payload fairing that is jettisoned from the Delta II during second stage powered flight at an average altitude of 136 kilometers (73.6 nautical miles).