New Horizon Mission was commissioned in 2006 to study the
objects of Kuiper belt region beyond the Neptune and Pluto-Charon, binary
planet. Solar system has three classes of planets- the inner rocky or terrestrial planets (Earth, Mars, Mercury and Venus)
the gas giants (Jupiter, Saturn,
Uranus and Neptune) dominated by thick molecular hydrogen atmospheres and the ice dwarfs of the Kuiper belt that has
solid surfaces with significant icy material (frozen water, nitrogen, carbon
dioxide, methane or carbon monoxide). There are large numbers of ice dwarfs than
the rocky and gas giants put together but no space craft has been sent to them.
New Horizon Mission is set to fill that gap. The ice dwarfs are small planets
whose growth stopped when they attained sizes of 200 to 2000 kilometres
diameter. These are ancient relics from which giant planets have formed 4
billion years ago. Hence they have great deal to teach about planet formation.
With this mission US has made history of sending space probes to all the
planets of the solar system. Galvanised by success of Orion spacecraft NASA is very
keen to work on this New Horizon Mission.
Launched from the Cape Canaveral, on Jan 19th 2006
by Atlas V 551 rocket, the 8 year interplanetary cruise included a flyby of
Jupiter in 2007. It crossed the orbits of Saturn in 2008, Uranus in 2011 and
Neptune in August 2014. Following its encounter with Neptune it entered into a
slumber to be woken up after a 99 day break on Dec 6th 3am EST to
gear up for six month Pluto encounter. It has cruised 3 billion miles (4.8
billion kilometres) and spent two-thirds of its journey in hibernation over the
course of 18 separate hibernation periods ranging from 36 to 202 days in
duration. The probe has been pushed into hibernation so often to reduce wear
and tear and operation costs. Every few months the probe was awakened for a check
up where by it would send weekly blips to the mission known as ‘green beacons’
to say that it’s not dead. Pluto’s encounter would start technically from Jan
15th 2015 during which it will probe Pluto and its five moons (Charon, Nix, Hydra, Kerberos and Styx) for
the next six months. After Pluto the mission plans to send the probe past two
icy objects in the Kuiper belt, the ring of cosmic belt which lies beyond
Neptune by 2018 or 2019 provided funds are sanctioned to the mission.
The $728 million mission has seven objects on board to study
the geology and topography of Pluto and its largest moon Charon. To map the
surface compositions and temperatures, study Pluto’s atmosphere and any
undiscovered moons and rings in the dwarf planetary system. Pluto and Charon
are together referred to as binary planets. The term is used to refer to any
pair of worlds that are similar in mass. Pluto discovered in 1930 is classified
by International Astronomical Union as a dwarf planet.
New Horizons mission is highly sophisticated and the smallest
space probe ever sent into the Solar System. Great care and precision were exercised
in selecting miniature components and instruments capabilities to fit in relatively
smaller pay load. The instruments on board include-Alice, an Ultraviolet Spectrometer,
LORRI, a camera; Ralph, a multi-spectral imager with five channels; LEISA, an
infrared spectrometer; REX, an instrument which sends radio signals to Earth;
Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) to monitor
the ions escaping atmosphere of Pluto; Venetia Burney Student Dust Counter to gauge
the distribution of size and particle density of ions and Solar Wind of Pluto
the analyser of Solar Wind which is sensitive to particles of low energy. By
July 14th New Horizons will be nearest to Pluto’s surface, roughly 6200
miles away. Message from Earth takes four hours to reach the Pluto despite
travelling at light speed. Since the mission is operating at four billion kilometres
distance from Earth in deep space communication mode, transfer of data might be
very slow. Sometimes communication may be impossible when it is focusing on
certain points. Scientists expect silence for two weeks when it is too close to
Pluto.
Following the wakeup of New Horizons Mission from slumber
there is palpable excitement among scientists as this ambitious mission is going
to unravel unprecedented information and images about Pluto.
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