New NASA Moon Orbiter, LADEE, Could Identify Mysterious Lunar Glow Seen By Apollo Astronauts
NASA's latest moon orbiter is ready to begin a mission to discover what the moon's atmosphere is made of.
Decades ago, when Apollo astronauts landed on the moon, they looked across the lunar surface to the horizon. The sun was coming up, and they saw the sky glow with streaks of light. Strange, for a place with so little atmosphere that scientists now think of it as an "exosphere." It's so thin, the molecules don't even collide.
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Now, NASA's latest lunar orbiter is ready to begin a mission to discover, among other things, what could have possibly caused that pre-sunrise horizon glow. They have their suspicions. It may have been dust, electrically charged by solar ultraviolet light. NASA hopes its new probe, which on Friday began the main phase of its scientific mission, will solve the riddle.
"Everything has been going very well during commissioning activities, even though we sometimes had to deal with unexpected events," said LADEE project manager Butler Hine in a mission update. LADEE stands for Lunar Atmosphere and Dust Environment Explorer. It's scheduled to take samples, analyze the moon's trace atmosphere and test new laser communications technology during its 100-day "Science Phase."
After its Sep. 6 launch, LADEE's computers unexpectedly shut down after downlinking its main memory as part of a laser communications demonstration. Scientists expect that lasers will be the future of space communications, replacing old-fashioned radio transmitters and massive satellite dishes with faster technology. After LADEE's laser demonstration, the processors rebooted and returned in safe mode. "This could occur for a wide variety of reasons," Hine said, "from a radiation event to a high-priority software overloading LADEE's onboard computer processor."
Everything seems to be fine now, he said.
LADEE escaped the earth's gravity in September and traveled 240,000 miles to the moon. On Wednesday, it lowered itself into the moon's gravitational field. Because of the moon's uneven pull, the orbit is oblong. LADEE — which cost $280 million and is about the size of a car — will circle the moon every two hours at a distance of between eight and 37 miles above the surface. Along the way its various sensors will be gathering data.
LADEE has three scientific instruments on board: a spectrometer to read what atmospheric materials are made of, another spectrometer to identify variations in the atmosphere, and a contraption they call the "Lunar Dust Experiment." Its job is to collect the dust samples to solve the mystery of the glow and whatever else lunar dust might tell us. With NASA now focused on deep-space probes and manned missions to Mars, it's easy to write off the moon as old news. Been there, done that.
But the moon is far from understood. "When we left the moon we thought of it as an atmosphere-less ancient surface," said John Grunsfeld, associate administrator for NASA's science mission directorate in an interview with AFP. "We have discovered that the Moon scientifically is very much alive, it is still evolving and in fact has a kind of atmosphere."
The new knowledge gained about the moon could also give us clues about other objects in space. LADEE program scientist Sarah Noble said in a statement that understanding the moon's atmosphere "will help researchers understand other small bodies in the solar system, such as asteroids, Mercury and the moons of outer planets."
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