Fast Facts: LADEE
During an extended mission, LADEE gathered detailed information about the structure and composition of the exosphere (the thin lunar atmosphere).
- The mission proved the effectiveness of the new modular common spacecraft bus, or body, an innovation which could drastically reduce the cost of spacecraft development.
- LADEE tested also NASA's first dedicated system for two-way communication using laser instead of radio waves. The Lunar Laser Communication Demonstration (LLCD) made history using a pulsed laser beam to transmit data over the 239,000 miles from the Moon to Earth at a record-breaking download rate of 622 megabits-per-second (Mbps).
- LADEE stands for Lunar Atmosphere and Dust Environment Explorer.
|Nation||United States of America (USA)|
|Spacecraft Mass||844 pounds (383 kilograms)|
|Mission Design and Management||NASA / Ames Research Center / Goddard Space Flight Center|
|Launch Vehicle||Minotaur V (No. 1)|
|Launch Date and Time||Sept. 7, 2013 / 03:27:00 UT|
|End of Mission||April 8, 2014 / 04:30 UT|
|Launch Site||Wallops Flight Facility, Virginia, USA / Mid Atlantic Regional Spaceport (MARS) / Pad 0B|
|Scientific Instruments||1. Ultraviolet and Visible Light Spectrometer (UVS)
2. Neutral Mass Spectrometer (NMS)
3. Lunar Dust Experiment (LDEX)
4. Lunar Laser Communications Demonstration Experiment (LLCD)
The Lunar Atmosphere and Dust Environment Explorer (LADEE), the first mission in the Lunar Quest series, was designed to orbit the Moon and 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.
After insertion into low parking around Earth after launch from the Wallops Flight Facility — the first lunar launch from that location — 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 200 × 274,600 kilometers at 37.7° 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 6 October, as LADEE approached the Moon, it fired its own engine and entered into an initial elliptical lunar orbit with a 24-hour period. On 9 and 12 October, further burns brought LADEE down into a 235 × 250-kilometer orbit. These events occurred exactly during the period when the U.S. Government—and therefore NASA—shut down briefly, opening back up on 16 October.
One of the early experiments was use of the LLCD system, carried out on 18 October 2013 when the spacecraft, using the optical laser system, transmitted good data to a ground station 385,000 kilometers away.
Finally, on 20 November, LADEE successfully entered its planned equatorial orbit of 20 × 60 kilometers, allowing the probe to make frequent passes from lunar day to lunar night. When the Chinese Chang’e 3 lunar lander arrived at the Moon, LADEE (more specifically, it’s NMS 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’s operation in near-lunar space.
In the event, LADEE’s data found no effects—no increase in dust, no propulsion products, etc.—that could be attributed to Chang’e 3. Another experiment that involved another spacecraft was NASA’s Lunar Reconnaissance Orbiter (LRO) taking a photo of LADEE in orbit at 01:11 UT on 15 January 2014. Its 100-day science mission, during which LADEE collected an enormous amount of data, came formally to an end by early March 2014.
The three science payloads worked fulltime during this period: the UVS instrument acquired more than 700,000 spectra of the exosphere. The NMS instrument positively identified argon-40 in the atmosphere (first identified by an Apollo surface experiment 40 years before). Finally, the LDEX recorded more than 11,000 impacts from dust particles from a dust cloud engulfing the Moon. In early 2014, LADEE began to gradually lower its orbital altitude in anticipation of its final impact on the Moon. Controllers lowered LADEE’s orbit to within 2 kilometers of the lunar surface to ensure impact. On its penultimate orbit, on 17 April, LADEE swooped down to as low as 300 meters of the lunar surface, and contact was lost at 04:30 UT on 18 April when it 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 5,800 kilometers/hour.
Later, on 28 October 2014, NASA announced that its LRO spacecraft had successfully imaged the impact location of LADEE on the far side of the Moon.