The New Horizons became the first spacecraft to successfully fly by the dwarf planet Pluto, the last unexplored world in the Solar System. This it did after travelling a distance of nearly 5 billion kilometres since its launch in January 2006. The scientific treasure that has been returned since then by the baby grand piano-size spacecraft has already “dramatically surpassed” expectations. A satellite carrying the ashes of Clyde Tombaugh, the astronomer who discovered Pluto in 1930, confirmed Pluto’s pride of place as the largest object in the Kuiper belt: Pluto was demoted to dwarf planet status in August 2006 after the discovery of Eris, of similar size, in the Kuiper belt. Contrary to expectations, the first close-up image revealed that the surface of Pluto was not riddled with any impact craters formed by objects bombarding it. Without doubt, the surface is very young, probably less than 100 million years old, and the only way to explain this is by rejecting the grand old theory of an inert Pluto made up of ice and rock. Instead, the dwarf planet is geologically active with an internal heat source that drives the engine, and it has some yet-to-be deciphered mechanism that refreshes the surface from time to time; tidal heating can be ruled out as Pluto does not orbit any giant planet. Similarly, the existence of high mountains, possible volcanoes, fault lines, rift valleys and other features underlines the presence of active tectonics. Similar to the crater-free surface, a mountain range jutting out 3,500 metres above it is also less than 100 million years old, and is one of the “youngest surfaces seen in the Solar System”. Much like Pluto, its largest moon Charon too has a young surface with geologically diverse features. More images are expected to be sent on by the spacecraft until August next year, and these could contain invaluable information about both Pluto and its moon, and other objects in the Kuiper belt.
Getting as close as 12,500 km of the dwarf planet after travelling for nearly a decade and covering a distance of nearly 5 billion km is an extraordinary achievement; scientist Neil deGrasse Tyson likened it to “a hole-in-one on a two-mile golf shot”. With exploration being second nature to humans, it is expeditions such as these that awaken curiosity and fire our interest in science. Unlike other mega-science projects of equal importance, space exploration has always had the power to hold ordinary people under a spell. India’s m`oon mission Chandrayaan-1 and the recent Mars Orbiter Mission Mangalyaan, certainly rekindled interest in science among students. At a time when basic science appears to have become less attractive, expeditions such as these could help reverse the trend.