Mars Rover Hit by Radiation Storm

By: Susie77 , 5:19 PM GMT on February 24, 2012

Curiosity, the Stunt Double

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Feb. 24, 2012:

With a pair of bug-eyes swiveling on a stalk nearly 8 feet off the
ground, the 6-wheeled, 1800-lb Mars rover Curiosity doesn’t look much like a human being.  Yet, right now, the mini-Cooper-sized rover is playing the role of stunt double for NASA astronauts.

“Curiosity is riding to Mars in the belly of a spacecraft, where
an astronaut would be,” explains Don Hassler of the Southwest Research
Institute in Boulder, Colorado.  “This means the rover experiences
deep-space radiation storms in the same way that a real astronaut

Stunt Double (splash)
Curiosity doesn't look much like a human being, but the rover
turns out to be an excellent stunt double for real astronauts. [video]

Indeed, on Jan. 27th, 2012, Curiosity’s spacecraft was
hit by the most intense solar radiation storm since 2005.   The event
began when sunspot AR1402 produced an X2-class solar flare. (On the
“Richter Scale of Solar Flares,” X-flares are the most powerful kind.) 
The explosion accelerated a fusillade of protons and electrons to nearly
light speed; these subatomic bullets were guided by the sun’s magnetic
field almost directly toward Curiosity.

When the particles hit the outer walls of the spacecraft, they
shattered other atoms and molecules in their path, producing a secondary
spray of radiation that Curiosity both absorbed and measured.

“Curiosity was in no danger,” says Hassler.  “In fact, we intended
all along for the rover to experience these storms en route to Mars.”
Curiosity and the Solar Storm (rad, 200px)
A photo of the Radiation Assessment Detector (RAD) in the laboratory. [more]

Unlike previous Mars rovers, Curiosity is equipped with a
Radiation Assessment Detector.  The instrument, nicknamed “RAD,” counts
cosmic rays, neutrons, protons and other particles over a wide range of
biologically-interesting energies. RAD’s prime mission is to investigate
the radiation environment on the surface of Mars, but researchers have
turned it on early so that it can also probe the radiation environment on the way to Mars as well.

Curiosity’s location inside the spacecraft is key to the experiment.

“We have a pretty good idea what the radiation environment is like
outside,” says Hassler, who is the principal investigator for RAD. 
“Inside the spacecraft, however, is still a mystery.”

Even supercomputers have trouble calculating exactly what happens
when high-energy cosmic rays and solar energetic particles hit the walls
of a spacecraft.  One particle hits another; fragments fly; the
fragments themselves crash into other molecules.

“It’s very complicated.  Curiosity is giving us a chance to actually measure what happens.”

Even when the sun is quiet, Curiosity is bombarded by a slow
drizzle of cosmic rays—high-energy particles accelerated by distant
black holes and supernova explosions.  In the aftermath of the Jan. 27th
X-flare, RAD detected a surge of particles several times more numerous
than the usual cosmic ray counts. Hassler’s team is still analyzing the
data to understand what it is telling them about the response of the
spacecraft to the storm.

More X-flares will help by adding to the data set. Hassler expects
the sun to cooperate, because the solar cycle is trending upward toward
a maximum expected in early 2013.

As of February 2012, “we still have 6 months to go before we reach Mars.  That’s plenty of time for more solar storms.”

A stunt double’s work is never done.

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

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