After a 10-year chase taking it billions of miles across the solar system, the Rosetta spacecraft made history Wednesday as it became the first probe to rendezvous with a comet on its journey around the sun.
Rosetta fired its thrusters on its final approach to Comet 67P/Churyumov-Gerasimenko, known as “Chury” for short, on Wednesday morning. Half an hour after the burn, scientists announced that the craft had entered into the orbit of the streaking comet.
“After 10 years, five months and four days travelling towards our destination, looping around the Sun five times and clocking up 6.4 billion kilometers, we are delighted to announce finally ‘we are here’,” said Jean-Jacques Dordain, ESA’s Director General, in a statement.
“Europe’s Rosetta is now the first spacecraft in history to rendezvous with a comet, a major highlight in exploring our origins. Discoveries can start.”
ESA tweeted a photo of the comet after Rosetta’s maneuver. Chury and the space probe now lie some 405 million kilometers from Earth, about half way between the orbits of Jupiter and Mars, according to ESA.
The mission has now achieved the first of what it hopes will be a series of historic accomplishments. In November mission controllers aim to place the robotic lander Philae on the surface — something that has never been done before.
Previous missions have performed comet fly-bys but Rosetta is different. This probe will follow the comet for more than a year, mapping and measuring how it changes as it is blasted by the sun’s energy.
Mission controllers had to use the gravity of Earth and Mars to give the probe a slingshot acceleration to meet its target on the right trajectory. Rosetta also had to be put into hibernation for more than two years to conserve power before being woken up successfully in January this year.
Wednesday’s thruster burn was the tenth rendezvous maneuver Rosetta has performed since May to get the probe’s speed and trajectory to align with the comet’s — and if any of them had failed, the mission would have been lost, according to ESA.
Scientists hope to learn more about the composition of comets and perhaps whether they brought water to the Earth or even the chemicals that make up the building blocks of life.
“It really is such a step forward to anything that has come before,” project scientist Matt Taylor said.
Rosetta will soon begin mapping the surface of and finding out more about its gravitational pull. This will help to find a suitable landing site for Philae and allow engineers to keep Rosetta in the right orbit.
As comets approach the sun, any ice melts and is turned into an ionized gas tail. The dust produces a separate, curving tail. It’s these processes that Rosetta scientists hope to be able to study from close proximity.
Taylor explained that the survey will show the team what the comet nucleus looks like now and when it gets closer to the sun.
“We’ll be able to make a comparison to now, when its relatively inert, to when it’s highly active … making this measurement over a year when we’re riding alongside at walking pace and observing how a comet works and interacts with the sun,” he said.
“We are there for over a year to see this compete development to the extent that you may even be able to measure the decrease in the volume of the nucleus … see how much material has left the comet.”
Chury is known as a short-period comet. It reappears every six years as its orbit brings it close to the sun. Halley’s comet has a period of about 76 years and is not due to return close enough to Earth to be visible until 2061. Others only return after thousands of years.
Matt Taylor says it is unlikely that you will be able to see comet 67P with the naked eye but you can follow the progress of the mission on Rosetta’s blog.