Remembering Clementine’s Lunar Orbit Insertion

30 years ago yesterday, the Deep Space Program Science Experiment spacecraft, dubbed “Clementine,” entered lunar orbit after executing the Lunar Orbit Insertion (LOI) maneuver to place it into a 426.9 km x 5485.1 km orbit, with an orbit period of 8 hours.

Originally launched on a Titan II(23)G rocket from Vandenberg Air force Base launch site SLC-4W on January 25, 1994, the spacecraft used an R-4D 490 Newton engine to perform the insertion. The R4D used bipropellant hydrazine (N2O4/MMH) with an Isp of 310 sec.

The LOI maneuver was planned using the software tool “Swingby” at Goddard Space Flight Center. SEE founder, Astrogator John Carrico, was on the team that both developed Swingby and used it for maneuver planning on the Clementine mission. Swingby eventually evolved into the STK/Astrogator trajectory planning tool.

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Dr. Worden was Director of NASA Ames during both the Lunar Crater Observation and Sensing Satellite (LCROSS) and Lunar Atmosphere and Dust Environment Explorer (LADEE) Missions. LCROSS launched in 2009. LADEE launched in 2013. The SEE team supported both of these missions.

Happy 30th to Clementine!

30 years ago today, the Deep Space Program Science Experiment, dubbed “Clementine,” ignited its Star-37FM solid rocket motor to leave low Earth orbit and embark on a 2.5 phasing loop trajectory to lunar orbit. SEE’s CTO, Astrogator John Carrico, was in the frozen flight dynamics facility at NASA’s Goddard Spaceflight Center, keeping a watchful eye on the spacecraft’s trajectory. Clementine returned the United States to lunar orbit after a two-decade absence and ignited a new era of lunar exploration.

Clementine was developed as a unique Department of Defense program to demonstrate dual-use technology in deep space. The mission went from inception to launch in about 22 months for a total cost of $75M. The Naval Research Laboratory designed, built, and operated the spacecraft, turning to the Flight Dynamics Division at NASA Goddard for support during the critical lunar transfer and orbit insertion phases of the mission.

At NASA Goddard, John Carrico was on the team developing Swingby, a trajectory design application tailored for multi-gravitational trajectories. While previously employed for pre-launch analyses on other deep space missions, Clementine was Swingby’s opportunity to support operational trajectory planning and re-design. When a battery anomaly threatened to strand Clementine in LEO, Swingby proved its worth. It enabled the flight dynamics team to deliver over 50 maneuver plans over a span of 8.5 days, often with as little as 12 hours lead time.

Eventually, Swingby evolved into the highly capable Astrogator trajectory planning tool included in AGI STK. The phasing loop lunar transfer pioneered by Clementine enabled subsequent small lunar missions, like NASA’s Lunar Atmosphere and Dust Environment Explorer, SpaceIL’s Beresheet, and Astrobotic’s Peregrine lunar lander. Science data returned by Clementine indicated the presence of water ice at the Moon’s South Pole.

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Join all of us here at The Astrogator’s Guild as we celebrate the 30 year anniversary of Clementine’s journey to the Moon and look forward to the next 30 years of bold, inspiring lunar exploration.