18 Jun 2015: The Year of Pluto
On 13th March, 1930, the Lowell Observatory in Flagstaff, Arizona had something new for the scientific community, a new planet beyond Neptune. A ninth member of our Solar System was discovered by a 23 year old man named Clyde Tombaugh.
The search for an extra planet beyond Neptune was started with Percival Lowell, a wealthy Bostonian who had founded the Lowell Observatory in Flagstaff, Arizona, in 1894. He was sure that there is another planet beyond Uranus and Neptune by analysing the perturbations in the orbits of both the planets. He started an extensive project for finding this new planet that he named as Planet X. From 1909 to 1916 until his death, Lowell searched for the probable planet, but without any success.
The search for the Planet X resumed in 1929 with Clyde Tombaugh, then a graduate and new to Lowell Observatory. After a year of painstaking work, Tombaugh found something amazing in the January of 1930. After the first observation, several other observations are made to confirm the discovery of a new planet. And on March 13, 1930, they announced the discovery of the ninth planet of our solar system. The newly discovered planet was soon named as Pluto, after the god of the underworld by an 11 year old girl named Venetia Burney. As the time passed, astronomers slowly started to question about the status of planets in case of Pluto. After the discovery of Charon, the moon of Pluto, which is half the size of Pluto, the planet status of Pluto was in danger. Finally in 2006, the International Astronomical Union (IAU) officially created a definition of planet and Pluto wasn’t able to satisfy all the criterion. So Pluto lost it’s planet status to belong to a new family called Dwarf Planets.
Pluto is primarily made of rock and ice. It’s average distance from Sun is 39.264 AU and has an orbital period of 248 years. It’s been 85 years since the first discovery of Pluto, but we don’t know much about the planet yet. And no space mission was undertaken to go beyond Neptune, until the dawn of this century. In 2001, The National Aeronautics and Space Administration (NASA), approved the first flyby mission to Pluto, called New Horizons. The New Horizons mission is the brainchild of Alan Stern of Southwest Research Institute, who is also the principal investigator of the mission.
After several delays, New Horizons was launched on January 19, 2006, from Cape Canaveral. It set the record for the highest launch speed of a human-made object from Earth, with an Earth-relative speed of about 16.26 kilometres per second. On February 28, 2007, New Horizons made its closest approach to Jupiter. The Jupiter flyby gave gravity assist to New Horizons by increasing its speed by 4km/s. Astronomers took this opportunity to check the scientific capabilities of New Horizon. Most of the later journey was in hibernation mode to preserve on-board systems, except for brief annual checkouts. On December 6, 2014, New Horizons was brought back on-line for the encounter, and instrument check-out began. On January 15, 2015, the New Horizons spacecraft began its approach phase to Pluto, which will result in the first flyby of the dwarf planet on July 14, 2015. This makes 2015, the year of Pluto.
The New Horizons space-probe is like a grand piano in size and a satellite dish is glued to it. It is powered by a cylindrical radioisotope thermoelectric generator (RTG). The RTG contains 10.9 kg (24 lb) of plutonium-238 oxide pellets. Among many instruments, New Horizons carries instruments like LORRI (Long Range Reconnaissance Imager), SWAP (Solar Wind At Pluto), PEPSSI, Ralph, Alice and SDC (Student Dust Counter), REX(Radio Science Experiment) etc. The primary objectives of New Horizons is to characterize the global geology and morphology of Pluto and Charon and map chemical compositions of Pluto and Charon surfaces. As the New Horizons approaches Pluto, we will have our first high resolution photographs of the dwarf planet.
After passing Pluto, New Horizons will continue its mission and will try to study some of the suitable Kuiper belt objects (KBOs). New Horizons will soon follow the path of Voyager 1 and Voyager 2 to go beyond our solar system to study the outermost regions of our solar system.
The New Horizons mission is not only a space mission but it also marked the human triumph of achieving major goals towards the understanding of our solar system. Once a mere dot in the sky will open for us a whole new window of an unknown world which has been fascinating humans from centuries. NASA has recently broadcast a documentary about the New Horizons mission named “2015: the year of Pluto” describing the decade long process of reaching Pluto. We also hope that The New Horizons mission will open a new window to our understanding of the cosmos and will take us one step closer to becoming a species which hold the power to explore The Universe.