New Horizons has travelled over 3 billion miles over 9 years to study Pluto and its moons up close. It will pass within 6,200 miles of Pluto in July, obtaining hundreds of thousands of images and measurements to transform our understanding. Currently very little is known about Pluto, but the data from New Horizons will fill textbooks. After studying Pluto, New Horizons will continue on into the Kuiper Belt to rendezvous with another small planet years from now.

1. Nasa’s New Horizons spaceship has travelled billions
of miles in nine years to answer astronomers’
questions about the tiny world
An artist’s impression of New Horizons approaching Pluto and one of
its moons. Photograph: Nasa
Robin McKie, science editor
Sunday 12 April 201500.05 BSTLast modified on Sunday 12 April
201500.09 BST
It is the fastest spaceship ever launchedand has been hurtling towards
its target at a staggering 36,000mph for the past nine years. But
now Nasa engineers are preparing to put their robot craft, New
Horizons, on its final course – to the tiny world of Pluto.
Scheduled to reach its target on 14 July, New Horizons has already
covered more than three billion miles since its launch, a distance that
means signals from the spacecraft now take about 4.5 hours to reach our
planet.

2. And the spaceship is travelling at such a speed that even tiny grains of
dust have the potential to inflict serious damage if they strike the craft.
“We have got round that problem in a very ingenious manner,”the
mission’s principal investigator, Alan Stern, told the Observer. “We have
given the craft a bullet-proof jacket. To be more precise, we have
covered it in Kevlar, the material used to make body armour. That
shouldprotect it.”
Perched at the edge of oursolar system, Pluto has remained a
mysterious world ever since its discovery in 1930. It has an atmosphere
of nitrogen and methane and a surface temperature of about minus
230C. It is so distant that to anyone there, the sun would appear as a
single point of light, albeit a bright one. Despite its bitterly cold surface,
scientists believe it could possess an underground liquid ocean.
Pluto also has five moons, all named after characters in Greek
mythology: Charon, Styx, Nix, Kerberos and Hydra. Very little is known
about any of them, and few features can be made out on the planet’s
surface.
All that shouldchange in July when New Horizons sweeps past Pluto
and its moons, getting to within 6,200 miles of Pluto itself, and within
17,000 miles of Charon. The encounterwill be brief, however, for Pluto
has insufficient gravity to slow down New Horizons and hold it in orbit.
Instead, the probe will indulge in some of the fastest bouts of data
gathering seen in modern space travel.
“We will take hundreds of thousands of photographs and spectral
images of Pluto and its moons as New Horizons sweeps past,” said
Stern. “In fact we will gather so much information about Pluto and its
moons that it will take New Horizons until the end of 2016 to transmit
all its data back to Earth.”
That information shouldtransform ourknowledge of Pluto. At present,
astronomers would struggle to fill a single piece of paper with known
facts about the planet. By the time New Horizons has completed its
mission, they will be writing textbooks about it. “We have already begun

3. studying Pluto as we approach it, though we are still far off,” said Stern.
“There have been no surprises so far but I guarantee there will be
several by the time we get there.”
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Dwarf planet discovery hints at a hidden
Super Earth in solar system
After its encounterwith Pluto, New Horizons will speed out into
theKuiperbelt, a zone of frozen rocks and asteroids that marks the outer
solar system, and will rendezvous with anothersmall planet – yet to be
selected – in several years’ time. Our knowledge of the outersolar
system will be transformed.
It will be an intriguing mission and a fitting tribute to US astronomer
Clyde Tombaugh, who discovered Pluto. In accordance with his dying
wishes, Nasa has attached a small container – with some of his ashes
inside – to New Horizons. In a few weeks, Tombaugh will finally get to
visit the very place that made him famous.

4. New Horizons will achieve anotherimportant task, added Stern. Its data
shouldcorrect “a gross mistake that is an embarrassment to
astronomy”, he told theObserver. When the design of New Horizons was
being finished 10 years ago, Pluto was considered to be the only planet
that had not been studied by a space probe. That is why the probe was
funded and constructed.
But a few months after its launch, the International Astronomical Union
(IAU) met and decided that Pluto was not really a planet. It was too
similar to several othersmall icy bodies in the solar system and could
not be classified a full planet. So it was downgraded to dwarf planet
status.
Stern described the decision as anti-scientific. “Astronomers had found
several other worlds like Pluto, so the IAU had the choice: call them all
planets or downgrade. It chose the latter because it didn’t want to end
up with a very long list of planets in the solar system. Children wouldn’t
be able to memorise them. And that is ridiculous. We cannot memorise
all the rivers or mountains on Earth. Why do we have to remember all
our neighbouring planets. That is 19th-century thinking. Pluto is a real
planet and New Horizons is going to show it in all its glory in a few
weeks. That shouldchange their minds, if nothing else.”