‘Imagine working on the same project for over two decades. That’s what the dedicated team at the European Space Agency (ESA) have been doing with the Rosetta Spacecraft project. You’ll be hearing more about Rosetta in the coming months as the satellite nears its final destination, comet 67P/Churyumov-Gerasimenko and attempts to send the Philae Lander to the surface of the moving object.
Previous visits to comets demonstrated the valuable scientific properties of these ‘dirty snowballs’, and Rosetta was constructed by ESA to continue this research in a way never attempted before.
The International Rosetta Mission was approved way back in 1993. Since then scientists and engineers from all over Europe and the United States have combined knowledge and effort to build an orbiter, accompanying lander and scientific equipment to send to a comet.
Rosetta began the ten year trek to the comet in February, 2004 after a false start in January the year before. No rocket is strong enough to send the satellite directly to the comet, so Rosetta has been bouncing around the inner solar system. It entered the asteroid belt twice and received gravitational boosts from fly-bys of Mars and Earth.
In June 2011 Rosetta entered a hibernation mode to limit consumption of power and fuel, and minimise operating costs. During this three year phase, only a computer and several heaters remained active to ensure that the satellite didn’t freeze. The trajectory took the craft over 800 million km from the Sun. There was no communication with the spacecraft until earlier this year when Rosetta was ‘woken up’.
The probe is now near the comet, matching its orbit and the Osiris camera system on board has begun taking photos of the target. The first image was released on 3 July revealing the uneven shape of the comet. Osiris will map the surface and collect data about the chemical composition to find the best spot for the Philae Lander to touch down and attach harpoons to secure the craft to the surface.
In addition to the Philae Lander Rosetta carries a suite of scientific instruments to the comet. The lander will be ejected onto the comet’s surface, a one-way trip to collect data and make observations. Landing Philae is an unprecedented event; engineers don’t know whether the surface will be hard rock or a thick bed of dust. The touchdown to the comet will be a slow one but even a smooth landing could have enough momentum to cause the lander to rebound. The comet only has a fraction of the gravity of Earth and it may not be enough to hold the 21kg payload.
The Rosetta Satellite and Philae Lander journey has clocked up more than 6 billion kilometres in travel and on August 6 it will come within 100km of the comet. This fascinating project is still developing and it will be with bated breath that we watch Philae Lander launch to the comet in November. Keep an eye on the ESA website for the latest news. http://www.esa.int/Our_Activities/Space_Science/Rosetta