A cosmic census got under way this morning as ESA’s Gaia mission lifted off atop a Soyuz–Fregat from the European Spaceport in Kourou, French Guiana at 9:12:19 AM GMT (10:12:19 AM CET). The 2,030 kg (4,475 lb) unmanned probe is at the start of a five-year mission to carry out a survey of one percent of one percent of the 100 billion stars that make up our galaxy as part of a project to produce the most detailed three-dimensional galactic map ever attempted.
According to ESA, the liftoff went as scheduled and without a hitch. As the rocket rose, it carried out a series of automated sequences. About 118 seconds into the flight, the four side boosters on the Soyuz fell away, and at 220 seconds the protective fairing around the Gaia spacecraft was jettisoned. At 42 minutes, Gaia separated from the Fregat third stage and after entering orbit at 88 minutes, the spacecraft began deploying its 10.5 m- (34.4 ft-) wide parasol-like sunshield.
Gaia is now in the early orbit phase of its mission as it heads into a Lissajous-type orbit around Lagrange 2 point, where the gravitational fields of the Sun and the Earth balance out, allowing the probe to maintain a stable position trailing the Earth at a distance of 1.5 million km (930,000 miles). It will carry out a six-month commissioning phase, after which it will use its instruments to chart the positions and velocities of billions of stars, as well as their brightness, temperature, and composition.
In addition, ESA expects it to discover hundreds of thousands of asteroids and comets in the Solar System, extrasolar planets, tens of thousands of brown dwarfs, up to twenty thousand supernovae, and hundreds of thousands of quasars. It carries the largest digital camera ever to have been sent into space, with a resolution of one billion pixels, and can make 40 million observations in a single day of objects one million times fainter than can be seen with the naked eye. ESA estimates that by the end of the mission it will collect one petabyte of data – the equivalent of 200,000 DVDs.
Gaia was originally scheduled to launch on November 20, but a malfunction in its X-band transponders caused a delay.