Waking Up Keys to the Early Solar System Soviet astronomers discovered 67p in 1969 On June 13 2015 ESA mission controllers received incredible Why would humans want to visit a comet These dusty icy rocks come from the outskirts of our solar system where temperatures cold all have the are so liquids frozen solid Water and other compounds that exist news Data sent back by the Rosetto spacecraft was telling them Philoe had woken up after months of sitting on the comet's surface without power They realized the comet had gotten close enough to the sun that the lander's solar panels could finally generate the electricity needed for Philae to function Astronomers were thrilled Philoe was now poised to provide exciting new data on the changes the comet underwent as it made its closest approach to the sun as liquids on Earth are ice in this region The cold comet filled region surrounding the outer solar system is known as the Oort cloud If a large object such as an asteroid or planet passes near the Oort cloud the object s gravitational pull disturbs the comets it passes Some of these frozen comets will be thrown into the inner solar system As a comet nears the sun our star s heat turns those ices directly to gas Astronomers can observe jets of these gases escaping a comet s surface The gases form a coma or cloud that cloaks the comet s nucleus or rocky body The gases also stretch out in the opposite direction from the sun in a long tail Comets often also have a second tail containing dust This tailed dusty object is what people commonly think of when they think of comets Rosetta watched 67P transform as it heated up on the way to its closest approach to the sun in August 2015 That is one of the goals of this space mission to study how a comet goes from a rocky snowball to a glowing ball with a gaseous tail trailing it across the sky After nearing the sun 67P will be 8
Visiting Other Comets Rosetto was the first mission to orbit a comet explosion gave astronomers an opportunity to study but it was not the first mission to visit one Giotto the comet's material They found more powdery dust another ESA spacecraft studied a comet three at the surface than expected NASA also operated decades earlier This mission's target was a more Stardust which captured thousands of dust particles well known comet 1P Halley better known as Halley's from Comet 81P Wild in January 2004 The mission comet Giotto studied this object during a flyby in returned those samples to Earth two years later The 1986 from approximately 375 miles 600 km away samples strongly suggested the presence of liquid water on the comet contrary to the usual belief that Two decades later in July 2005 NASA's Deep Impact comets never warm enough for their ice to melt spacecraft hurled a probe into Comet 9P Tempel The flung out past Mars to the most distant part of its orbit It will spend years drifting through space before it approaches the sun again Another major goal of the mission is to learn what materials make up those icy rocks Comets come from the far reaches of our solar system Scientists think that area harbors the same type of materials that made our Earth and the rest of the solar system more than 4 billion years ago But the sun's light is faint where comets come from That keeps the ingredients of the solar system in a deep freeze hibernating for billions of years Once a comet nears our sun and those ices melt the space rock becomes a window to the early solar system Astronomers know the early solar system was a hectic place Comets thrown from the Oort cloud were flying through the inner solar system Some of them likely slammed into the young Earth Scientists think comets and their closer to Earth cousins asteroids may have brought water to our planet billions of years ago This water now fills the oceans seas and lakes providing nourishment for life 10
Rosetta has detected water carbon monoxide A Long Journey carbon dioxide ammonia methane methanol and nitrogen at 67P Some of the comet s water however contains a different form of hydrogen in its molecules compared to the water and ice found on Earth This From conceiving the earliest plans for the mission Rosetto's journey to 67P took more than two decades means comets such as 67P could not have brought water to our planet It is still possible other types The ESA first approved the project in 1993 It was originally scheduled for a January 2003 launch But in late 2002 the same type of rocket that would launch Rosetto exploded early into its flight This forced the rocket company Arianespace to spend time investigating the problem Rosetta's launch was delayed 14 months of comets and asteroids could have dampened the early Earth Rosetta's Early Finds Philae did not land until November 2014 but Rosetta first approached the comet a few months earlier One Rosetta finally launched on March 2 2004 taking more than ten years to arrive at 67P It flew in a long looping path toward the comet Rosetta swung by Earth three times and Mars once using the planets powerful gravitational pulls to slingshot it into the right direction Scientists put Rosetta into hibernation in June 2011 and woke it up a few months before meeting up with 67P of the orbiter s many discoveries happened in July 2014 once the craft was close enough to the comet to take clear images of it Scientists were surprised to see 67P is shaped a bit like a rubber duck with two large sections connected by a relatively narrow area Astronomers had long expected it to be a simpler object perhaps shaped like a rounded football or a loaf of bread Scientists are still unsure whether this odd shape results from two smaller rocks slamming into each other or from one single comet that has been eroded away for billions of years 11
