LADEE

Firsts

LADEE was the first lunar mission launched from NASA's Wallops Flight Facility in Virginia.

Key Dates

Sept. 7, 2013: Launch

Oct. 6, 2013: Entered lunar orbit

April 18, 2014: Impact on lunar surface

In Depth: LADEE

NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE), the first mission in the Lunar Quest series, was designed to orbit the Moon, and to study its thin atmosphere and the lunar dust environment—specifically to collect data on the global density, composition, and time variability of the exosphere.

By studying the Moon’s exosphere—an atmosphere that is so thin that its molecules do not collide with each other—LADEE’s instruments helped further the study of other planetary bodies with exospheres such as Mercury and some of Jupiter’s moons.

LADEE was put into a low parking orbit around Earth after launch on a Minotaur-V rocket from the NASA Wallops Flight Facility in Virginia—the first lunar launch from that location. The Minotaur’s fifth stage (with a Star 37FM solid motor) fired at 03:43 UT to boost the payload into a highly elliptical Earth orbit of 120 x 170,600 miles (200 × 274,600 kilometers) at a 37.7-degree inclination.

LADEE took a path to lunar orbit used by several other recent lunar spacecraft that involved flying increasingly larger Earth orbits (in this case, three orbits) over a period of a month, with the apogee increasing until it was at lunar distance.

On the third orbit, on Oct. 6, as LADEE approached the Moon, it fired its engine and entered into an initial elliptical lunar orbit with a 24-hour period. On Oct. 9 and Oct. 12, additional burns brought LADEE down into a 146 x 155-mile (235 × 250-kilometer) orbit. These events occurred during the period when the U.S. government—and therefore NASA—shut down briefly, before reopening Oct. 16.

On Oct. 18, LADEE used its lunar laser communications demonstration experiment (LLCD) to transmit data to a ground station 239,000 miles (385,000 kilometers) away.

On Nov. 20, LADEE successfully entered its planned equatorial orbit of about 12 × 37 miles (20 × 60 kilometers), allowing the probe to make frequent passes from lunar day to lunar night.

When China’s Chang’e 3 spacecraft landed on the Moon in December, LADEE (more specifically, it’s neutral mass spectrometer) was used to observe the specific masses of the substances (such as water, nitrogen, carbon monoxide and hydrogen) that would be expected to be found given the operation of Chang'e 3's lander operation in near-lunar space. LADEE’s data indicated no effects—no increase in dust, no propulsion products, etc.—that could be attributed to Chang’e 3.

In another experiment involving another spacecraft, NASA’s Lunar Reconnaissance Orbiter (LRO) took a photo of LADEE in orbit at 01:11 UT Jan. 15, 2014.

LADEE's 100-day science mission, during which the spacecraft collected an enormous amount of data, had formally ended by early March 2014. The three science payloads worked fulltime during this period: the ultraviolet and visible light spectrometer (UVS) acquired more than 700,000 spectra of the exosphere. The neutral mass spectrometer (NMS) positively identified argon-40 in the atmosphere (first identified by an Apollo surface experiment 40 years before). Finally, the lunar dust experiment (LDEX) recorded more than 11,000 impacts from dust particles from a dust cloud engulfing the Moon.

LADEE's orbital altitude was gradually lowered in anticipation of its planned impact on the Moon. Controllers lowered LADEE’s orbit to within about 1 mile (2 kilometers) of the lunar surface to ensure impact.

On its penultimate orbit April 17, LADEE swooped as low as 980 feet (300 meters) above the lunar surface.

Contact was lost at 04:30 UT April 18 when LADEE moved behind the Moon. Controllers estimated that the spacecraft probably struck the Moon on the eastern rim of Sundman V crater between 04:30 and 05:22 UT at a speed of about 3,600 miles (5,800 kilometers) per hour.

On Oct. 28, 2014, NASA announced that LRO had successfully imaged the impact location of LADEE on the far side of the Moon.

- Credit: NASA

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