A LASP-led and University of Colorado Boulder student-built instrument riding on NASA’s New Horizons spacecraft found only a handful of dust grains, the building blocks of planets, when it whipped by Pluto at 31,000 miles per hour last July.
Data downloaded and analyzed by the New Horizons team indicated the space environment around Pluto and its moons contained only about six dust particles per cubic mile, said LASP planetary scientist and CU-Boulder Professor Fran Bagenal, who leads the New Horizons Particles and Plasma Team.
“The bottom line is that space is mostly empty,” said Bagenal. “Any debris created when Pluto’s moons were captured or created during impacts has long since been removed by planetary processes.”
The moon is engulfed in a permanent but lopsided dust cloud that increases in density when annual events like the Geminids spew shooting stars, according to a new study led by LASP scientists at the University of Colorado Boulder.
The cloud is made up primarily of tiny dust grains kicked up from the moon’s surface by the impact of high-speed, interplanetary dust particles, said CU-Boulder physics Professor and LASP research associate Mihály Horányi. A single dust particle from a comet striking the moon’s surface lofts thousands of smaller dust specks into the airless environment, and the lunar cloud is maintained by regular impacts from such particles, said Horányi.
When NASA’s napping New Horizon’s spacecraft awakens later this week in preparation for its July 2015 encounter with Pluto, a University of Colorado Boulder student instrument onboard already will have been up for years.
The instrument, the Student Dust Counter (SDC), was designed and built to detect dust both on the interplanetary journey to Pluto and beyond, said CU-Boulder physics Professor and LASP research scientist Mihaly Horanyi, principal investigator on the effort. The SDC has been on for most of the mission—even as the other instruments primarily napped—measuring dust grains that are the building blocks of the solar system’s planets, he said.