On 19th January 2006, an unmanned spacecraft called New Horizons set off on a journey from Earth to the dwarf planet Pluto. After travelling for over nine years, it reached its destination in July 2015 and sent back oodles of information and pictures of the small and distant world and its moons. New Horizons is still active, exploring what lies beyond Pluto. Here is its story so far…
In 1930, American astronomer Clyde Tombaugh discovered a distant object beyond the orbit of Neptune, the eighth planet in the solar system. The object was soon after confirmed to be a planet and became the solar system’s ninth planet. It received the name Pluto after an English schoolgirl suggested it.
Pluto is a very tiny object, smaller than any of the other planets in the solar system. It’s even smaller than Earth’s moon. It is also extremely far away, orbiting the Sun at a maximum distance of, although its elliptical orbit means that it can also come as close to the Sun as. This is still a long long way away though, not somewhere you’d be able to get to in a hurry. Due to its small size and huge distance from Earth, the best way of learning more information about it is to visit it.
In 1957, a small satellite called Sputnik was launched into space. It didn’t go very far, just travelling around Earth for a few months before falling out ofits orbit and burning up in Earth's atmosphere as it descended. Sputnik’s launch signified the start of the age of space exploration. It didn't take long until scientists were able to send spacecraft to objects like the Moon and nearby planets like Mars, Venus and Mercury. Over time, scientists discovered that they could go even further into space. They came up with a technique called gravity assist. This is where a spacecraft can use the gravity of a planet to gain speed and then fling itself off to continue on its journey. Gravity assist is explained in more detail here. It meant that spacecraft could travel great distance without the need of lots of rocket fuel.
During the 1970s and 1980s, two spacecraft called Voyager 1 and Voyager 2 were able to visit all of the Outer Planets – Jupiter, Saturn, Uranus and Neptune – using gravity assist (and a rather fortuitous positioning of the planets at the time) to get from one planet to the next with ease. Both Voyagers were launched on their way to the Outer Planets, or Gas Giants, in 1977. Voyager 1 visited Jupiter and Saturn, before going off on a journey out of the Solar System, a journey that it is still making. Voyager 2 visited all four Gas Giants, reaching Jupiter in 1979 and finishing with Neptune in 1989. It is also now on its way out of the Solar System. Remarkably, even though they are forty years old and so far away from Earth, both Voyagers are still working and still phone home every now and again to tell us where they are! My last mobile phone only lasted one year. Broke after I dropped it on the floor. Oh well, anyway, after Voyager 2’s encounter at Neptune, it meant that the only planet in the Solar System that had yet to be visited by a space craft was Pluto.
It was in 2001 that NASA finally made the decision to pay Pluto a visit. They held a competition to select a mission to Pluto which was won by the team behind New Horizons. Although the mission was very nearly cancelled due to lack of funds, it managed to secure enough support to convince the money men to allow it to go ahead. What's $700 million anyway? Walmart made $486 billion in 2016. With that amount of money, it could send almost 700 New Horizons spacecraft to Pluto!
New Horizons took off from Cape Canaveral in Florida on 19th January 2006 and began its journey by travelling at a whopping 16.26 kilometres a second. It passed by Earth’s moon only nine hours later, much quicker than the three days it took the Apollo astronauts to get there in the 1960s and 1970s, a definitely much quicker than my car. In fact, New Horizons was travelling so fast that it set a new record for the fastest manmade object to be sent from Earth. It reached Jupiter in February 2007 where it built up even more speed by using the gravity assist method. While passing Jupiter, it took a few pictures of the planet and some of its moons. A year later, in June 2008. it passed the orbit of Saturn (but not Saturn itself) making it the first object since Voyager 2 in 1981 to go beyond the orbit of Saturn.
For most of its journey, New Horizons has been asleep, although it has been nudged every year or so to check it was still okay. It was woken up from its slumber in December 2014 to prepare itself for its date with Pluto.
In addition to cameras to take photographs of Pluto and its moons, plus anything else that may be of interest in the area, New Horizons contains a bundle of scientific instruments to provide us with useful information about the objects that it visits. Prior to New Horizons, the only pictures we had of Pluto and its moon were unclear and blurry, and it was impossible to make out any surface features.
Other than the many scientific gizmos and gagdets onboard New Horizons, the space craft also carries a CD containing the names of over 400,000 people that were sent to NASA in an online competition (I'm sure I entered that - maybe there's a bit of Bob the Alien in the outer reaches of the solar system), a piece of SpaceShipOne - the world’s first commercial space plane, a US flag, some of Clyde Tombaugh’s ashes and a quarter coin from Florida. There's probably not going to be much to buy out there, so 25 cents should be plenty.