Curiosity and the Solar Storm   
       
   Dec. 14, 2011: On Nov. 26th, Curiosity blasted off from Cape Canaveral atop an   
   Atlas 5 rocket.  Riding a plume of fire through the blue Florida sky, the   
   car-sized rover began a nine month journey to search for signs of life Mars.   
       
   Meanwhile, 93 million miles away, a second lesser-noticed Mars launch was   
   underway.  Around the time that Curiosity's rocket was breaking the bonds of   
   Earth, a filament of magnetism erupted from the sun, hurling a billion-ton   
   cloud of plasma (a "CME") toward the Red Planet.   
       
   http://science.nasa.gov/media/medialibrary/2011/12/14/twolaunches_strip.jpg   
       
   The two Mars launches of Nov. 26, 2011. On the left, a solar explosion hurls a   
   CME toward the Red Planet (Credit: SOHO). On the right, the Mars Science Lab   
   or "Curiosity" lifts off from Cape Canaveral. (Credit: Howard Eskildsen of   
   Titusville, FL)   
   There was no danger of a collision-Mars rover vs. solar storm.  Racing forward   
   at 2 million mph, the plasma cloud outpaced Curiosity's rocket by a wide   
   margin.   
       
   Next time could be different, however.  With solar activity on the upswing   
   (Solar Max is expected in 2012-2013) it's only a matter of time before a CME   
   engulfs the Mars-bound rover.   
       
   That suits some researchers just fine.  As Don Hassler of the Southwest   
   Research Institute (SWRI) in Boulder, Colorado, explains, "We look forward to   
   such encounters because Curiosity is equipped to study solar storms."   
       
   Hassler is the principal investigator for Curiosity's Radiation Assessment   
   Detector--"RAD" for short.  The instrument, developed at SWRI and Christian   
   Albrechts University in Kiel, Germany, counts cosmic rays, neutrons, protons   
   and other particles over a wide range of energies.  Tucked into the left front   
   corner of the rover, RAD is about the size of a coffee can and weighs only   
   three pounds, but has capabilities of Earth-bound instruments nearly 10 times   
   its size.   
       
   Encounters with CMEs pose little danger to Curiosity.  By the time a CME   
   reaches the Earth-Mars expanse, it is spread so thin that it cannot truly   
   buffet the spacecraft. Nevertheless, RAD can sense what happens as the CME   
   passes by.   
       
   "RAD will be able to detect energetic particles accelerated by shock waves in   
   some CMEs1," says Arik Posner of NASA's Heliophysics Division in Washington   
   DC. "This could give us new insights into the inner physics of these giant   
   clouds."   
       
   There's more to this, however, than pure heliophysics.  Future human   
   astronauts will directly benefit from RAD's measurements during the cruise   
   phase.   
       
   http://msl-scicorner.jpl.nasa.gov/Instruments/RAD/   
       
   A photo of the Radiation Assessment Detector (RAD) in the laboratory. [more]   
   "Curiosity is nestled inside its spacecraft, just like a real astronaut would   
   be," notes Frank Cucinotta, Chief Scientist for NASA's Space Radiation Program   
   at the Johnson Space Center.  "RAD will give us an idea of the kind of   
   radiation a human can expect to absorb during a similar trip to Mars."   
       
   Of particular interest are secondary particles.  Galactic cosmic rays and   
   solar energetic particles hit the walls of the spacecraft, creating an inward   
   spray of even more biologically dangerous neutrons and atomic nuclei.  RAD   
   will analyze the spray from the only realistic place to make such   
   measurements-inside the spaceship.   
       
   In this way, "RAD is a bridge between the science and exploration sides of   
   NASA," says Hassler. "The two objectives are equally exciting."   
       
   RAD was activated on Dec. 6th. Of the rover's ten science instruments, it will   
   be the only one active during the cruise to Mars.  Daily transmissions to   
   Earth will let Hassler and colleagues monitor what's going on "out there."     
   "We're very excited about the possibility of more solar storms," he adds.   
       
   As important as RAD's cruise phase measurements are, the instrument's primary   
   mission doesn't really begin until it lands on the Red Planet.   
       
   Mars has a very thin atmosphere and no global magnetic field to protect it   
   from space radiation.  Energetic particles reaching ground level might be   
   dangerous to life--both future human astronauts and extant Martian microbes.   
   RAD will find out how much shielding human explorers need on the surface of   
   Mars.  RAD will also help researchers estimate how far below ground a microbe   
   might have to go to reach a radiation "safe zone."   
       
   Solar storms are just for starters. Stay tuned to Science@NASA for the second   
   installment of this story: Curiosity and the Habitability Mars.   
       
       
   Author:Dr. Tony Phillips| Production editor: Dr. Tony Phillips | Credit:   
   Science@NASA   
       
   More Information   
   Footnote:1Posner notes that only the most powerful CMEs will still be   
   accelerating particles when they are as far from sun as Curiosity will be. For   
   a typical CME, the main thing RAD will detect is the modulation of galactic   
   cosmic rays passing through the CME.  Cosmic ray modulation could reveal new   
   information about the interior structure of these storm clouds.   
       
   Mars-Bound Rover Begins Research in Space -- NASA press release   
       
   Mars Science Lab (a.k.a. "Curiosity") -- home page   
       
   The Strange Attraction of Gale Crater -- Science@NASA   
       
   A Mars Rover Named Curiosity -- Science@NASA   
       
   Curiosity Takes Off -- Science@NASA   
       
   Credits: The Mars Science Lab mission is managed by JPL, a division of the   
   California Institute of Technology in Pasadena, for NASA's Science Mission   
   Directorate in Washington. The rover was designed, developed and assembled at   
   JPL. NASA's Launch Services Program at the Kennedy Space Center in Florida   
   managed the launch. NASA's Space Network provided space communication services   
   for the launch vehicle. NASA's Deep Space Network will provide spacecraft   
   acquisition and mission communication.   
       
       
   Regards,   
       
   Roger   
      
   --- D'Bridge 3.64   
    * Origin: NCS BBS (1:3828/7)