Europe's most ambitious space mission yet, to chase down a comet and drop a lander on its surface, is finally under way after the successful launch of the Rosetta satellite, writes Dick Ahlstrom Science Editor
It was blasted aloft at 7.17 a.m. Irish time yesterday atop a European Space Agency Ariane-5 rocket, launched from the Kourou space centre in French Guiana. It was third time lucky after two launch attempts were scrapped last week.
The satellite now begins a colossal 10-year, 7,000-million kilometre journey to rendezvous with comet 67P/Churyumov-Gerasimenko by mid-2014. Scientists hope Rosetta's payload of 20 advanced experiments will give us a first-time view of the material that built our solar system 4.6 billion years ago. The lander will drill down and analyse samples from below the surface of the giant cosmic iceberg. Scientists hope it will find complex organic molecules, substances that could have provided the feedstock for life on our planet.
"We're doing something really basic. We are going back to the beginning of time," said Dr David Southwood, ESA's head of science programmes, before the launch.
The €1,200 million mission should have got under way a year ago, but the failure of a newly upgraded Ariane-5 rocket launcher on its maiden flight in 2002 forced a reschedule.
This is an exceptionally difficult mission given the complexity of the satellite's route as it chases down the comet. Getting Rosetta into orbit and then a lander on to the comet's surface in one piece will be even more difficult given the surrounding hostile environment.
Comets are often described as "dirty snowballs", loose-knit agglomerates of rock, dust, chemicals and water ice. Solar heating causes comets to eject high-speed jets of dust and particles which accumulate to form the comet's "tail" as these objects hurl through space in solar orbits.
The lander, Philae, must struggle through these jets before firing harpoons to lock itself on to the comet. It will then drill into the surface and carry out chemical analysis.
Scientists theorise that the early Earth may have been pelted by comets which delivered plentiful supplies of water, but also the chemical building blocks of life. Rosetta's visit may provide support for this theory.