A US spacecraft accidently found evidence of ice on moon while taking a complete look at lunar surface in 1994

US spacecraft Clementine, an orbiter, was launched on January 25, 1994. Its primary mission was testing spacecraft components and examining the Moon and an asteroid. The mission was successful and Clementine was able to provide about 1.6 million digital images of the Moon's surface, including the polar regions. The findings indicated that there may be frozen water hidden in a shadowed crater at the south pole of the Moon. The finding was announced by the Department of Defense in 1996.

Clementine's mission and its purpose

Clementine was the first United States spacecraft to be launched toward the Moon since 1973 when Explorer 49 was launched. It was also known as Deep Space Program Science Experiment (DSPSE). It was a component of the Brilliant Pebbles program of the Strategic Defense Initiative that was developed to test some new low-cost technologies that would allow the creation of future spacecraft.


Clementine consisted of 15 advanced flight-test hardware items and nine science-craft instruments with cameras that could see the Moon in different wavelengths and systems to measure the lunar surface. The instruments included ultraviolet/visible camera, near-infrared camera, laser image detection and ranging system, long-wave infrared camera, high-resolution camera, two star tracker cameras, bistatic radar experiment, s-band transponder doppler gravity experiment and charged particle telescope.

This spacecraft had a mass of 935 pounds (424 kg), and was managed by the Ballistic Missile Defense Organization and NASA. It was launched using Titan 2G rocket from Vandenberg Air Force Base in California.

How Clementine reached the Moon?

Clementine was launched from the West Coast of the US on January 25, 1994, at 16:34 UT, and placed in a temporary Earth parking orbit. It was then moved out of this orbit on February 3 when a solid-propellant rocket placed it on course for the Moon, where it flew two Earth flybys on February 5 and 15. Clementine was able to enter an elliptical polar orbit around the Moon on February 19, 1994. The orbital range stretched from about 270 miles (430 km) to 1,830 miles (2,950 km). The spacecraft had a flight period of about five days.

Clementine began its task of scanning the Moon. During the next two months, it was sending back about 1.6 million digital images of the Moon's surface. Many of these images are taken at 330 x 660 feet (100 x 200 meters) resolution.

The view was providing scientists who were looking for lunar water with a very good look at the Moon, including the unexplored regions around the poles. This survey was the first mission to give a complete view of the Moon from a US spacecraft.

How the Moon's ice evidence was found?

One of the most interesting discovery of this mission was made in the lunar south pole. There are craters near the poles of the Moon whose floors receive no sunlight. The reason for this is that the craters are located far to the north or south and are permanently shadowed.

Clementine's data indicated that there was an existence of ice on the lunar south pole. The finding wasn't made with the discovery of lunar water as a priority. The water in the form of ice that is found on the moon could potentially be used for life support and spacecraft propulsion, as water can be broken down into oxygen and hydrogen.

Although the 1994 finding was an indication of this, it was not an explicit observation of a large block of ice. The finding only suggested that there might be a possibility of water on the Moon.

Clementine's lunar mission ended before its asteroid goal

Clementine finished its survey of the Moon after completing 297 orbits. On May 3, 1994, controllers fired the spacecraft's thrusters to head towards asteroid 1620 Geographos; the plan was to make an Earth flyby on the way. The asteroid part of the mission, however, never happened, as on May 7 at 14:39 UT, problems developed with a computer, causing one of the spacecraft's thrusters to fire, and using all of its propellent. The spacecraft began to tumble out of control at about 80 rev/min and lost the ability to rotate. Controllers cancelled the flyby of the asteroid and attempted to send the spacecraft back toward the vicinity of the Earth.

On July 20, 1994, lunar gravity placed Clementine in a orbit about the Sun (heliocentric orbit). The mission was officially terminated on August 8, 1994. There was, however, an added twist to this story. The spacecraft happened to be in an attitude that allowed it to be powered up again. So, between February 20 and May 10, 1995 ground controllers were even able to regain contact with the spacecraft briefly.