LAUNCH VEHICLE

Overview

Lunar Prospector began its mission at Spaceport Florida's Pad 46 in Cape Canaveral, Florida. The spacecraft was launched aboard a three-stage Athena II rocket (made by Lockheed Martin Astronautics in Denvre, Colo.). After a short coast, a STAR 37 Trans-Lunar Injection (TLI) solid rocket motor ignited and propelled the spacecraft into a 105-hour transfer orbit to the Moon. During transfer, the spacecraft established its cruise attitude, deployed its science booms, fired its jets to correct any launch errors, and shortly before encountering the Moon, re-oriented the spin axis for Lunar Orbit Insertion (LOI).

At LOI, jets were fired to place the spacecraft into an initial 12-hour orbit. Following a period of health-and-status checks, the orbit period was reduced to 3.5 hours, and then to its final 118-minute circular mapping orbit. Periodic maneuvers (approximately once per month) will maintain the mapping orbit during the one-year primary mission.

Athena II

An Athena II solid-fuel rocket propelled Prospector and its TLI kick motor into its low Earth orbit. This was the maiden voyage of this double-boosted member of the Lockheed launch vehicle family. The first two stages consist of Castor 120® solid rocket motors. The third stage is an Orbus 21D® solid rocket. An Orbital Adjust Module (OAM) provides orbital correction capability and oriented the Lunar Prospector payload before separation.

Spaceport Florida

Lunar Prospector was launched from Spaceport Florida, in Cape Canaveral, Florida, on January 6,1998. One of the primary reasons mission designers chose this launch window is its proximity to an unusually long period of time free of lunar eclipses. During a complete lunar eclipse, the Earth passes between the Sun and the Moon, shadowing the the entire Moon from the perspective of the Earth. During a lunar eclipse, Prospector would have to fly in total darkness and consume large amounts of solar-generated battery power. Prospector's launch date allows the spacecraft to spend as little time as possible in Earth's shadow, minimizing battery- power drain and spacecraft cooling requirements.

The Lunar Prospector launch was the first from the Spaceport Florida complex at Cape Canaveral. The nighttime launch placed the spacecraft into a low Earth orbit. Upon achieving proper injection position, the Orbital Adjust Module (OAM) separated the payload, and the Trans Lunar Injection Stage (a Star 37 kick motor) ignited to provide additional velocity in order to achieve the Trans Lunar Injection trajectory.

Athena 1 (Lockheed Martin Launch Vehicle I)

Athena 1 on a launch pad at Vandenberg Air Force Base.