Rosetta spacecraft with its numerous distinctions has
enthralled the scientific community with its spectacular accomplishments till
now. It is on the verge of making a momentous history in Space explorations if
it succeeds in sending out the lander Philae probe onto to the surface of the
Comet 67P/ Churyumov-Gerasimenko on November 12th. In its illustrious
decade long solar mission, Rosetta, the brainchild of the European Space Agency
(ESA) triumphantly accomplished all its tasks with meticulous accuracy. It is
now poised to enter the last and crucial phase of its mission of sending the
landing craft Philae to the icy comet surface.
In what is termed as the most scientifically challenging
mission in the history of the space explorations so far, scientists will be
aiming to accomplish a near impossible feat. In common parlance, mission
experts are trying to transfer an object from one speeding bullet train to
another. At nearly 500million Kilometres distance from earth, between Mars and
Jupiter, a robotic probe of 100kg Philae lander will be ejected from the space
craft Rosetta and land on the Comet surface which it has been chasing from 6th
August 2014. Both of them are flying at a speed of 65,000 km an hour. The task
is onerous as crucial details like the densities, surface atmosphere of the
Comet and other details of the landing site are not known. Moreover, the unusual
double lobed shape of the Comet is not known until the recent images have been
sent little earlier. Ever since its launch in 2004, Rosetta used the gravity of
Earth and Mars as a slingshot to enter the Comet’s trajectory. In August,
Rosetta became the first spacecraft to orbit around a comet.
Comets
are the small icy bodies which originate either in the Oort Cloud that exist
far beyond the orbit of the Pluto or from the Kuiper Belt located beyond the
orbit of Neptune and releases gas or dust. As comets dart towards sun they get
heated up and begin to outgas thus displaying visible atmosphere or Coma and
sometimes a tail posing
technical challenges for landing.
Usually the dust consists of ice, carbon dioxide, ammonia, methane and more.
Rosetta pictures indicated that surface of the comet was
highly undulated with wicked slopes and elevated rocks. Philae piggybacking on
Rosetta will separate from its mother, from a distance of 12 kilometers from
comet on 8:35 GMT with unfolded legs. The self-adjusting landing gear will
ensure Philae stays upright. It will escape the weak gravity of comet by
shooting out its harpoons into the surface. If everything goes as expected, the
confirmation signals would reach earth by 16:02 GMT.
The Philae lander will touch down on a selected site on the
Comet, Agilika named after an island in Nile. It will land on the smaller of
the comet’s two lobes. Since the mechanical details of the comet are not known,
the lander which is of size of washing machine is armed with all the structures
that can facilitate a smooth landing. Its legs would cushion the impact of
landing while ice screws on its feet would provide extra grip on the icy
terrain. A thruster will fire to cancel out the bounce and its two harpoons will
anchor the robotic probe to comet’s surface. Any technical glitch or
misalignment of the spacecraft even by 1cm can cause the probe to drift hundreds
of miles away from the target and can jeopardise entire mission. Mission
officials predict a 70% success rate. The lander has 11 instruments on board to
analyse the environment, surface and chemical properties of the comet. The
instruments can dig the surface and heat them to measure their properties.
Scientists expect to find water and other organic compounds that might provide
an insight into understanding the earth and how life on earth emerged.
Rosetta is expected to drift alongside the comet till Dec
2015. Equipped with batteries that has 60 hrs operating time, it can last till
March if sunlight and temperature are optimum for solar panels. Philae can
drill and analyse the subsurface details of the comet with the instruments its
houses and relay the data to Rosetta which is subsequently passed onto the
ground station Darmstadt, Germany. The gentle free fall is expected to
last for seven hours.
Evolutionary biologists believed that numerous comets impounded
the surface of fledging earth 4.6 billion years ago bringing with them water
and other organic compounds needed for generation of life on earth. A critical
analysis of the comet mass would help understand in detail the evolution of the
solar system. Scientists are hoping to find L-amino acids the backbone of the
proteins of the living organisms. The nerve wrecking space adventure akin to a
sci-fi fiction is tipped to mesmerize the scientific community and science enthusiasts
with its unseemly arduous task.
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