(Edmonton) This summer, NASA's MESSENGER spacecraft took stunning pictures of the Earth and the moon from its orbit around Mercury (the popular science blog Bad Astronomer wrote about them, as well as photos sent by the CASSINI spacecraft).
But this spring, two University of Alberta scientists were looking at Mercury. Professor Robert Rankin and graduate student Jan Paral created a sophisticated computer simulation that explains unique behaviour in Mercury's magnetosphere. The results were published in the science journal, Nature Communications.
Rankin and Paral used data taken by MESSENGER to understand an asymmetry in the Kelvin-Helmholtz Instability (KHI), which controls and regulates how the energy and mass of solar wind plasma are loaded into Mercury's magnetosphere. The asymmetry created patterns that had not been predicted by astronomers.
"The KHI is key to understanding how Mercury's magnetosphere is affected by the solar wind," said Rankin, who supervised the development of the hybrid-code that Paral developed during his PhD. "When the KHI and asymmetry was first observed, we quickly determined that ion gyration must be a factor," said Rankin, who then turned to Paral for the simulation work.
"Jan's development of the code was a monumental task," Rankin said. "He had to choose and implement the correct algorithms. He had to make them work on massively parallel computers at IBM Watson Labs (where Paral spent some time) and subsequently on WestGrid (the computer clusters located at the University of Alberta). He had to test and validate the code. Last, but not least, he had to solve the problem of the KHI asymmetry."
Paral's code is now being used to study the magnetic fields around objects that, like Mercury, have a weak magnetic field, including Earth's moon, Mars, Venus and comets.
"We currently have a project funded by the Canadian Space Agency to examine how lunar dust is charged and transported over the moon's surface," said Rankin. Paral's plasma-based code is applicable because lunar dust particles are so small, they can be classified as plasma. "The code Jan developed is being used by one of our graduate students, Hossna Gharaee, to quantify the space environment around the Moon that dust is exposed to."
Rankin and Clare Watt, who recently completed a postdoctoral posting at UAlberta and is now a faculty member at the University of Reading, developed techniques that will allow the group to study how dust is levitated and transported over the "atmosphere" of the Moon. This study could be important to future missions to the moon.
"NASA has said that dust on the Moon presents the most significant challenge to astronauts on the Moon," said Rankin. "It coats spacesuits and equipment, gets into lungs, and is a general hazard."
Rankin and Paral's work was supported by funding and computing access provided by Canada's Advanced Network and Research Innovation Network (CANARIE), the National Science and Engineering Research Council (NSERC), the Canadian Space Agency (CSA) and WestGrid, the IBM corporation, and the Academic Information Communications Technologies (AICT) group at the University of Alberta. Chris Want at AICT helped produce the animations that accompany Paral's simulations.