However the landing did not go exactly as Fixing spacecraft planned Scientists had programmed a specific sequence of commands into Philae s memory These steps told the robotic spacecraft what to do as soon as it was near the comet's surface First it was supposed Not everything has gone as planned ith Rosetto but broken spacecraft are something space experts are familiar with Often these problems can be fixed by updating the ship's software or restarting its computers This solved issues with Voyager 2 which launched in 1977 on to explore the outer solar system to use a small rocket engine to push it toward the comet Then the ship would fire two harpoons to catch the surface Finally as soon as it made contact with the comet screws at the end of each of Philae's three legs would embed into the icy surface If a spacecraft is in orbit around Earth though astronauts may be sent to make repairs When astronomers first used the Hubble Space Telescope in 1990 the images appeared blurry They realized the telescope's main mirror was imperfect and could not focus properly Three years later astronauts flew to the telescope Unfortunately all three mechanisms failed Because the force of gravity on 67P is several hundred thousand times weaker than on Earth the comet could and added an instrument to correct not keep hold of Philae So the lander bounced rising its vision Hubble went on to more than 25 years of discoveries in a high arc from the surface for almost two hours Luckily it did not drift into space 67P's weak gravity gently tugged it back to the surface where the lander made one more small bounce before nudging itself sideways against a rock wall Some of the scientists later joked that they had made not only the first landing on a comet but the first three Philae's internal batteries powered its first 50 hours on the surface For additional power to make it through the next few months of collecting data as was originally planned it needed sunlight But its resting position put its solar panels in shadow That meant its ten instruments could take measurements and send data back to Rosetta for only a few days The science team made the most of 6
at St As Philae touched down the devices intended to anchor it to the this limited time Philae took the first incredible pictures from the surface of a comet comet failed to work properly sending the lander measured the temperature at its resting spot and tried to drill into the rock It revealed bouncing upward 67P has several inches of rocks and dust on its surface Scientists were unsure what the material below the surface was but they could determine it was as dense as solid ice Although the Philae landing did not go as planned it was a tremendous technological feat Humans landed a refrigerator sized spacecraft on a comet while both were traveling as fast as 34 000 miles per hour 55 000 kmh at a distance of 280 million miles 450 million km from the
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
