Clementine (spacecraft)

Clementine was a space satellite designed for a 1994 mission planned jointly by the US National Aeronautics and Space Administration (NASA) and what was then known as the US Strategic Defense Initiative Organization (SDIO), which became the Ballistic Missile Defense Organization (BMDO). The spacecraft's main objective was to demonstrate how well a set of specially designed sensors and other instruments held up under space conditions. The spacecraft was also intended to gather scientific observations of the Moon and the near-Earth asteroid 1620 Geographos. Clementine only partly reached its goals. It was able to provide data on the effectiveness of the onboard equipment and completed photographic and other observations of the moon. However, a computer malfunction left the spacecraft unable to complete its mission of gathering information on the asteroid.

Background

On January 25, 1994, a Martin Marietta Titan IIG ballistic missile was launched from the Vandenberg Air Force Base in Santa Barbara County, California. Part of its payload, or cargo, was the Clementine satellite. The spacecraft was the first object launched toward the moon by the United States in more than twenty years. It was named Clementine because it only carried enough fuel to complete its mission and was never intended to return to Earth. Instead, as in the lyrics of the American folk song "My Darling Clementine," the craft would be "lost and gone forever."

Sometimes referred to as the Deep Space Program Science Experiment (DSPSE), Clementine was the first of several missions intended to test and showcase new, less expensive ways of conducting scientific research and space exploration. The entire Clementine mission—including design, equipment, launching, mapping and data review conducted after the mission and mission control—cost $80 million and took twenty-two months to plan. The scientists working on the mission felt that the information gathered was comparable to what could have been accomplished by a mission with crew. In contrast, in 2005 scientists started working on a plan to send four astronauts to the Moon and back by 2018. Although that mission was scrapped, NASA unveiled the Artemis Program in 2017 with the goal of landing humans on the moon again in 2026.

After its launch, Clementine spent some time in Low Earth Orbit (LEO) before achieving lunar orbit on February 19, 1994. Between then and April 22, Clementine orbited the Moon, taking nearly two million photographs with various types of cameras. Clementine left lunar orbit and was heading toward the Geographos asteroid when a processor in one of the onboard computers malfunctioned on May 7. The malfunction caused one of the satellite's thrusters to fire continuously until it exhausted that thruster's fuel supply. Unable to correct its position to remain on a stable course, the satellite was sent into a spin of 80 revolutions per minute (RPM). As a result, Clementine was unable to collect any useful images or observations of the asteroid and that portion of the mission was aborted. However, the craft continued sending back readings on the performance of the equipment until it used all remaining fuel.

Overview

The Clementine satellite was compact, measuring 1.4 meters (about 1.5 yards) in diameter by 1.8 meters (just over 2 yards) in length and weighing 24 kilograms (about 53 pounds) including fuel. It had two solar arrays and used an automated data transfer system, or telemetry, to communicate with the NASA Deep Space Network and several US Department of Defense (DOD) satellite tracking systems. The Clementine spacecraft and mission were designed by the Naval Research Laboratory (NRL) with assistance from NASA's Goddard Space Flight Center and Jet Propulsion Laboratory. The special sensors used in the mission were designed and calibrated by Lawrence Livermore National Laboratory (LLNL).

Clementine carried some of the DOD's most up-to-date technology for determining distances and detecting and tracking objects. This included specialized sensors and six different types of cameras, which Clementine used to capture and record data. An onboard computer allowed the spacecraft to apply this new, lightweight technology to use the Moon and its own discarded booster rocket to compute its location in space and provide tracking information. This demonstrated the effectiveness of the equipment for use by the DOD in tracking any potential threats, while also testing the suitability of the equipment for deep space use.

Although gathering information for the DOD was Clementine's primary mission, its secondary mission created the most excitement for scientists. Clementine carried six types of specialized cameras: ultraviolet/visible light, near-infrared, high resolution, LIDAR (light detection and ranging), long-wave infrared, and two wide-angle star trackers that combine compasses with cameras to detect distant stars. Together, these cameras captured almost two million photographs of space and the surface of the Moon using fourteen different areas of the light spectrum, from near ultraviolet to infrared. These images included all visible and invisible light wavelengths and provided the most detailed look at the Moon's surface up to that point. The expanding development of Internet technology at the time allowed NASA's scientists to share the images with the public, one of the first times the average person could see such images.

Impact

These new and more detailed images of the Moon gave scientists the best available information on the makeup of the Moon's surface and allowed them to make key discoveries related to the Moon and the formation of the universe. The single largest discovery to come out of the Clementine mission was the finding of ice in some of the Moon's craters. In 1996, scientists announced that data obtained by Clementine showed that there might be ice on the Moon, an indication that there might once have been water there. A subsequent NASA mission in 1998 (Lunar Prospector) confirmed the presence of ice in a crater near the Moon's South Pole.

Although Clementine was disabled before it could complete its full mission and map the Geographos asteroid, it still demonstrated the value of this new, less expensive way of exploring space. For this, the mission and the people behind it received numerous awards, including one from then US President Bill Clinton, as well as accolades from a number of science publications and societies. Although the Clementine satellite was lost in space, the photos that were taken during the mission remain widely available to scientists and amateur astronomers alike.

Bibliography

"Clementine, Engineering Model." Smithsonian National Air and Space Museum, https://airandspace.si.edu/collection-objects/spacecraft-engineering-model-clementine. Accessed 22 Oct. 2016.

"The Clementine Mission." Lunar & Planetary Institute, www.lpi.usra.edu/lunar/missions/clementine/data/. Accessed 22 Oct. 2016.

"Clementine Mission." Lunar Crater Observation and Sensing Satellite, 15 July 2008. www.nasa.gov/mission‗pages/LCROSS/searchforwater/clementine.html. Accessed 17 Jan. 2023.

"Clementine Mission: 1994." US Naval Research Laboratory, www.nrl.navy.mil/clementine/. Accessed 22 Oct. 2016.

"The Clementine Satellite." Energy and Technology Review, June 1994. str.llnl.gov/etr/pdfs/06‗94.1.pdf. Accessed 22 Oct. 2016.

Dunford, Bill. "Postcards from Clementine." The Planetary Society, 25 Feb. 2013, www.planetary.org/blogs/guest-blogs/bill-dunford/postcards-from-clementine.html. Accessed 22 Oct. 2016.

Uri, John. "Thirty Years Ago: Clementine Changes Our View of the Moon." NASA, 16 Feb. 2024, www.nasa.gov/history/30-years-ago-clementine-changes-our-view-of-the-moon/. Accessed 27 Nov. 2024.

Stuart, Colin. "Artemis 1: The First Step in Returning Astronauts to the Moon." Space.com, 12 Dec. 2022, www.space.com/artemis-1-going-back-to-the-moon. Accessed 17 Jan. 2023.