NASA’s LADEE Spacecraft Crashes Into The Moon – Preliminary Mission Results

An artist’s concept of NASA’s Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft crashing into the moon’s farside Thursday April 17. Credit: NASA

What it may sound like a huge disaster, destroying the $263 million dollar spacecraft was NASA’s intention from the start. At 8:59 p.m. CDT April 17, the agency confirmed the probe had impacted the moon’s surface.

The Lunar Atmosphere and Dust Explorer or LADEE (pronounced ‘laddie’) began circling the moon last fall, its mission to study dust in its extremely rarefied lunar atmosphere. Much of the dust sputters off the surface during meteorite impacts, while some may be lofted into the sky by electrostatic forces active when the sun rises along the day-night borderline called the terminator.

LADEE only had so much fuel to conduct operations at the moon. When that was used up, the mission was complete. The vending-machine-sized probe broke apart as it heated up upon impact. Many pieces likely lie scattered across and inside craters. Credit: NASA Ames/Dana Berry

Prior to crashing, mission controllers gradually lowered the spacecraft’s orbit to study the moon’s near surface dust environment in ever more detail. While the moon lacks the atmosphere to slow a spacecraft and “drag” it down to the surface (like what happens at Earth), nature worked her wonders all the same. The moon’s gravity field is “lumpy”, with lighter, less dense regions alternating with denser concentrations of rock beneath the surface. Low-orbiting probes, perturbed by variations in pull of gravity are soon brought down.

An photo taken by the star trackers aboard LADEE of the moon’s surface illuminated by a nearly full Earth along with stars in the airless sky. Credit: NASA/Ames

“At the time of impact, LADEE was traveling at a speed of 3,600 miles per hour – about three times the speed of a high-powered rifle bullet,” said Rick Elphic, LADEE project scientist at Ames. “There’s nothing gentle about impact at these speeds — it’s just a question of whether LADEE made a localized craterlet on a hillside or scattered debris across a flat area. It will be interesting to see what kind of feature LADEE has created.”

LRO photographed LADEE about 5.6 miles beneath it on Jan. 14, 2014. Image width is about 898 yards (821 meters). LADEE appears stretched because it was moving and LRO builds an image a line at a time. Credit: NASA/Goddard/Arizona State University

NASA plans to work with the Lunar Reconnaissance Orbiter (LRO) team to overfly and capture an image of the impact site. LADEE struck the moon on the farside, a safe distance from any historic landing sites, all of which have been on the lunar nearside. Because radio communications can’t be received from the farside, NASA mission controllers had to wait for an hour during each ultra-low orbital pass. If LADEE began sending data again, they knew it was still “alive”. When LADEE didn’t show up at the planned time Thursday, the mission was declared over.

A thin crescent moon. Unseen except by space probes are the dribs and drabs of moon dust that comprise the moon’s rarefied atmosphere. Credit: Bob King

Scientists will be analyzing the data from the probe for a long, long time, but there are some preliminary results:

* LADEE survived the chill-inducing lunar eclipse earlier this week, demonstrating the spacecraft’s ability to endure low temperatures and a drain on batteries as it, and the moon, passed through Earth’s deep shadow.

* LADEE’s Lunar Dust EXperiment (LDEX) experiment detected an increase in the number of dust particles in the moon’s exosphere during the Geminid meteor shower in mid-December 2013.  The LDEX dust impacts are thought to be due to the ejecta, or spray, of particles that result when the Geminid meteoroids slam into the lunar surface. The exosphere or dilute lunar atmosphere contains dust particles as well as gases from the solar wind.

* The Ultraviolet and Visible light Spectrometer (UVS) carried out a series of before and after observations looking for effects of the Chinese Chang’e 3 landing in December and meteor showers. Analysis revealed an increase in sodium connected with the Geminids, as well as evidence of increased light scattering due to dust but no clear signal from the Chang’e 3 landing.

The UVS also has been monitoring specific wavelengths of light emitted by atomic oxygen, and has seen emissions that may indicate the presence of both iron and titanium in the lunar exosphere. All three are elements found in the lunar soil called regolith but have never been seen in the moon’s atmosphere before.

5 Responses

  1. caralex

    Bob, is there a lot of static in the moon’s thin atmosphere? I remember reading that the Apollo astronauts had dust clinging to their suits – I got the impression it was like that annoying static cling that sometimes happens, when your clothes stick to you! If I’m right, how does it happen on the moon?

    1. astrobob

      Great question. The sun’s energetic X-rays and UV radiation knock out electrons from the elements composing the dust giving them a positive charge. That makes the dust cling happily to space suits.

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