Back in January 2005, the European Space Agency’s Huygens
probe parachuted onto Saturn’s moon, Titan.
Thanks to a detailed analysis over seven years later,
researchers have pulled together what happened to the probe at touchdown. The
analysis is providing clues as to the very nature of the Titan’s surface.
The bottom line: The lander did not “splat” down – rather,
it bounced, slid and wobbled to its resting spot.
Scientists reconstructed the chain of events of Huygens
landing by analyzing data from a variety of instruments that were active during
the impact, in particular changes in the acceleration experienced by the probe.
Detailed looks at the motion of the Huygens probe seconds
after landing suggest that Huygens dug a hole 12 cm deep, before bouncing out
onto a flat surface. The probe, tilted by about 10 degrees in the direction of
motion, then slid 30–40 cm across the surface.
Stefan Schröder of the Max Planck Institute for Solar System
Research led the work, along with E. Karkoschka and R. Lorenz, publishing their
findings in Planetary and Space Science.
Final resting place
The study shows that the probe slowed due to friction with
the surface and, upon coming to its final resting place, wobbled back and forth
five times, with each wobble about half as large as the previous one.
Huygens’ sensors continued to detect small vibrations for
another two seconds, until motion subsided nearly 10 seconds after touchdown.
Had the probe impacted a wet, mud-like substance, its
instruments would have recorded a ‘splat’ with no further indication of
bouncing or sliding.
The surface must have therefore been soft enough to allow
the probe to make a hole, but hard enough to support Huygens rocking back and
forth.
“We also see in the Huygens landing data evidence of a
‘fluffy’ dust-like material – most likely organic aerosols that are known to
drizzle out of the Titan atmosphere – being thrown up and suspended for around
four seconds after the impact,” says Schröder.
The Cassini–Huygens mission is a cooperative project of
NASA, the European Space Agency and the Italian Space Agency. The Jet
Propulsion Laboratory, a division of the California Institute of Technology in
Pasadena, manages the mission for NASA’s Science Mission Directorate,
Washington, D.C.
Take a look at the landing based on the new research by going to:
http://www.esa.int/esaCP/SEMJP13S18H_index_0.html
By Leonard David