Just before the end of last term the Year 8 scholars and Mrs Lyon Taylor went to the Rutherford Appleton Laboratory to listen to a talk about the recent investigation of Comet 67P/Churyumov-Gerasimenko by the Rosetta spacecraft and the lander Philae. The talk was given by the scientist Professor Alan Fitzsimmons who was telling us about what comets are and why they are interesting. He was explaining that they are made up of mainly dust and ice which sublimes (changing from solid to gas without becoming a liquid) when it gets close to the sun on its orbit; this forms the tail of the comet. Comets look different because of their tails and how much sublimation is taking place. In contrast asteroids are made of mainly rock.
Prof. Fitzsimmons was part of the team involved in launching Rosetta 10 years ago, the spacecraft has orbited the sun and used the gravitation force of various planets to enable it to meet up with the comet earlier in 2014. After a long ‘sleep’ Rosetta was woken up when near to the comet and set about releasing the landing craft, Philae. Unfortunately, the scientists on Earth estimated the shape and relief of the dark comet incorrectly as it was hard to see from so far away. Images from Rosetta revealed that the comet actually had an unusual shape and rough, rocky surface so they then had to decide where to land Philae. The best landing site on the surface was chosen and Philae was dropped from Rosetta towards the comet, she landed correctly and because the comet had virtually no gravitation force the lander had three mechanisms to help it to hold onto the comet: ice screws, a thruster and harpoons. Unfortunately after the space craft’s long journey all three landing mechanisms failed and Philae bounced off the comet again. Philae had no way of manoeuvring so it finally came to rest after it hit what the scientists think was a cliff on the comet’s surface, unfortunately Philae also seems not to have landed on its feet, but on its solar panels. Thankfully the other equipment on Philae is still working and has sent back information, via Rosetta, about what the comet is made of and what conditions are like. Because the solar panels are covered Philae has now run out of energy and cannot collect more information. The comet is continuing to travel towards the sun, carrying Philae and being followed by Rosetta. The scientists hope that in the spring, when the comet is nearer to the sun, Philae’s solar panels will be able to collect enough light energy to power up and start collecting information again, so we will have to wait to see what happens.
It is amazing that scientists here can communicate with equipment that is so far away. The trip was very interesting and we enjoyed learning some new facts about comets.
By Daniel Ayres and Rosie Jephson