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Tue, 14 Jul 2015 - New Horizons Probe flies by Pluto

On July 14th 2015 NASA’s New Horizons probe makes its closest approach to the dwarf-planet Pluto after a journey of nine and a half years. When New Horizons was originally conceived and developed, Pluto was considered to be a true planet, and the only one as yet unvisited by a robotic probe.  New Horizons was launched on the 19th of January 2016 in the same year that the International Astronomical Union (IAU) decided that Pluto should be downgraded from full planetary status to that of a ‘dwarf-planet’ and was to be regarded as the largest of a group of icy outer-solar system objects known as ‘Kuiper Belt Objects’ . The argument over Pluto’s exact planetary status is still being contested but, however you regard it, Pluto is still a fascinating small world surrounded by a constellation of moons; and now we are set to find out a whole lot more about it.

New Horizons has successfully navigated to a window in space some 100 by 150 Km square (90 by 60 miles) from which it can study Pluto, and its collection of five moons, Charon, Styx, Nix, Kerberos and Hydra, while passing through this system with a relative velocity of some 14 Km per second. This study will involve the probe in a set of furious automatic manoeuvres, pointing its instruments at its various targets as it flashes by, and this means it will be unable to point its communications antennae at Earth while it collects data. NASA scientists will have to wait nervously till later today for the probe to stabilize, re-establish contact and pass its stored data back to Earth.

 There is a real, if small, probability that New Horizons may impact icy debris orbiting this set of distant worlds, in which case we may never hear from the probe again. In the meantime NASA has released an image taken yesterday, during final approach to fly-by, showing far more detail than anything seen before. Hopefully this is just a taste of what may be to come from New Horizons, but we can already see a history of past impacts on Pluto and it has been suggested that there are hints of tectonic activity to be seen in the image. Once through the Pluto system it is hoped that New Horizons will go on to study other distant Kuiper Belt objects.

If you want to see Pluto for yourself, the SPA News section of this website contains an article on how to find it with useful star charts and information.

Update: 21 July.

Later on July 14th the telemetry signals from the New Horizons probe was picked up by NASA, followed shortly by the first of many images and packets of scientific data. This is a slow process; the radio transmitter on the probe is low-powered and data is passed at a rate significantly slower than the speed of old 'dial-up' internet connections, partly because of the age of the technology built in to New Horizons and partly to help ensure every bit of information is transmitted without loss over the vast distances. Early images indicate that Pluto is a fascinating world with a surprisingly young surface There are signs of recent geological (or should that be Plutological?) processes producing large mountain ranges of solid water ice and vast and apparently freshly frozen plains devoid of impact sites as might be expected.

It will take around 16 months for all the images and data to be sent back to us and whole scientific careers will be built on the discoveries they reveal. I look forward to seeing those results immensely and hope that you do to.


Added by: Alan Clitherow