LADEE, a NASA probe set to launch on Sept. 6, could answer an outstanding question in lunar history: What are "streamers"?
Dana Berry/NASA Ames
About 10 seconds before a lunar sunset or sunrise in 1972, the Apollo 17 astronauts orbiting the moon saw tall bands of lights – like thick, bright rays emanating from a sun sinking into the sea. The astronauts called that lunar light, seen on previous Surveyor and Apollo missions, “streamers,” a name that, if physically descriptive, was otherwise uninformative: No one knew what was producing the streamers.
But just before midnight on Friday Sept. 6, NASA will launch the Lunar Atmosphere and Dust Environment Explorer (LADEE) from the agency’s Wallops Flight Facility on Wallops Island, Virginia. The probe, deployed in hopes of better understanding the moon’s ultra-thin atmosphere, is also expected to answer a grand, almost mythologized question in lunar history: What was that celestial glow that Apollo 17 astronauts saw on the lunar horizon?
LADEE – about the size of a small car but about a quarter of the weight (at 800 lbs, including fuel) of a Toyota Prius – will ride into space on the back of a U.S. Air Force Minotaur V rocket, a ballistic missile that has been re-purposed as a space launch vehicle.