When Rip Van Winkle awakened from his 20-year slumber atop the Catskill Mountains, he didn't know he had missed the American Revolution. He was disturbed to find so much had changed—his wife had died, his friends had fallen in a war, and it was George Washington ruling instead of King George III. Next week, a comet-tracking Rip Van Winkle is set to wake up from a 30-month hibernation, but with one difference. Our understanding of comets hasn't changed much in this period.
The Rosetta space probe, launched by the European Space Agency (ESA) in 2004, will flicker to life on January 20 in its eccentric orbit around the Sun, between those of Mars and Jupiter. Once it becomes operational again, scientists from NASA and ESA will get it ready to start tracking the comet 67P/Churyumov-Gerasimenko (67P/C-G) before May this year. If all goes well, they will attempt to soft-land a lander on the comet in November for the first time in history.
The mission was conceived by ESA in 1993 to study comets, where they originate from, their composition, and what they say about the formation of the Solar System. Recent studies, including two from >February and >September 2013, have also shown that comets could have smuggled amino acids and hydrocarbons from other parts of the galaxy onto Earth, where their crashing billions of years ago could have seeded life.
Despite their relevance, no comet has been studied as closely as Rosetta will attempt to in the next 12-13 months.
The lander on-board Rosetta, titled Philae, carries 10 instruments provided by ESA and NASA to study the 67P/C-G properties. “The lander addresses a wide range of science aspects which are meant to solve questions of cometary science on one hand and the origin and formation of the planetary system on the other,” said Dr. Hermann Boehnhardt, Lead Scientist for Philae. He is affiliated with the Max Planck Institute for Solar System Research, Germany.
The instruments will study the landscape of 67P/C-G, its soil composition, chemical and isotopic make-up, temperature and other physical characteristics. Before it can be deployed, however, Rosetta will study the comet’s nucleus and determine a suitable landing site in August-September 2014. “This will be when the comet is about 585 million km from and travelling at a speed of 14.1 km/s with respect to the Sun,” wrote Dr. Boehnhardt.
At this stage, the comet will start to feel the effects of the Sun, which will become measurable by Philae.
Dr. Boehnhardt said that there was a possibility of Rosetta not finding a suitable landing site, or of Philae not being healthy after landing. To overcome such scenarios, the team is planning back-up missions for the lander. However, because a controlled landing is being attempted for the first time, Dr. Boehnhardt deems most problems as being unforeseeable.
Philae will relay information of what it finds to Rosetta, which will be escorting 67P/C-G to its perihelion, its closest point to the Sun in its orbit. This is expected to occur on August 13, 2015. The entire mission will end in December of that year. Dr. Boehnhardt speculated that Rosetta’s successors in the future may be designed on the basis of what we learn from Philae.
Before it went into hibernation, Rosetta studied the asteroids Steins and Lutetia in 2008-2010.
