A NASA spacecraft studying the moon’s atmosphere and dust environment, which is carrying a $6 million University of Colorado Boulder instrument, is slated to crash into the lunar surface April 21 following a successful 130-day mission.
The $280 million mission, known as the Lunar Atmosphere and Dust Environment Explorer, or LADEE, was launched Sept. 6, 2013, to orbit the moon to better understand its tenuous atmosphere and whether dust particles are being lofted high off its surface. The spacecraft was designed, developed, integrated and tested at NASA’s AMES Research Center in Moffett Field, Calif. It took a month to reach the moon and another month to enter the proper elliptical orbit and for the instruments to be commissioned.
NASA held a media teleconference today to discuss the extended mission operations, science and planned impact of the LADEE spacecraft on the moon.
“We have beautiful data,” said CU-Boulder physics Professor Mihaly Horanyi of the Laboratory for Atmospheric and Space Physics, principal investigator for the Lunar Dust Experiment, or LDEX, onboard LADEE. “We discovered that a cloud of dust permanently engulfs the moon, and that the dust density dramatically increases toward its surface,” said Horanyi, who was not involved in the media teleconference.
The CU-Boulder team, which has charted more than 11,000 impacts from dust particles since LADEE arrived at the moon in October 2013, also discovered that dust particles are regularly hurled from the lunar surface in response to impacts by tiny, high-speed interplanetary meteoroids. “When people on Earth see shooting stars, the same stream of particles also hit the moon, knocking off bursts of small particles that are detected by our instrument,” Horanyi said.
While the LADEE mission successfully completed its planned 100-day science mission in March, NASA chose to stretch the mission into an extended science phase. The spacecraft is expected to make science observations at progressively lower and lower altitudes until it drops to about three miles above the lunar surface on April 21, then makes its planned impact.
About the size of a small toaster oven, the LDEX instrument has been charting the size and individual velocities of tiny dust particles as small as 0.6 microns in diameter. For comparison, a standard sheet of paper is about 100 microns thick. A collision between a dust particle and a hemisphere-shaped target on LDEX generates a unique electrical signal inside the instrument, allowing scientists to detect individual particles, he said.
Horanyi said the dust behavior and processes discovered on the moon with LDEX are likely occurring on all other objects in the solar system that don’t have atmospheres, including Mercury, Phobos and Deimos -- the two moons of Mars -- as well as on asteroids and dormant comets. Both Phobos and Deimos have been suggested by experts as possible initial landing posts for crewed missions heading for Mars.
The success of CU-Boulder’s LDEX experiment may pave the way for new and more sophisticated dust-detecting instruments that could be developed and flown to such objects in the solar system, said Horanyi.
“Imagine if we could fly a new generation of dust experiments that could tell us not only the mass and speed of the particles being ejected from the moon or asteroid surfaces, but also their composition,” he said. “That would allow us to make a surface map of the object that would be incredibly useful if we were looking for particular resources to mine, like water or titanium.”
Horanyi also said dust-laden objects like the moon or an asteroid can be used as enormous “magnifiers,” since a gram of material hitting a surface at about 14 miles per second blasts thousands of times that amount off of the surface. “Learning about the frequency of larger and larger dust impacts will help us to predict the frequency and learn more about even bigger impacts, those in the centimeter to meter sizes, greatly improving our hazard estimates for sending spacecraft on long journeys.”
He said LASP makes a point of involving students at every level for all of its space missions. The relatively short duration and rich science return from the LADEE mission is well suited for graduate students like Jamey Szalay, for example, who plans to use the data as part of his doctoral thesis at CU-Boulder with Horanyi as his advisor.
Horanyi also is the principal investigator on CU-Boulder’s Student Dust Counter, a simpler instrument flying on NASA’s New Horizons mission that was launched in 2006 to explore Pluto and the Kuiper Belt, a massive region beyond the planets containing icy objects left over from the formation of the solar system.