Europe's powerful new galactic surveying mission, Gaia, has given itself a gentle thruster burn, placing it in a bizarre region of gravitational stability known as Lagrangian Point "L2." The mission, which is designed to gather data for the most precise 3D map of our galaxy to date, arrived at its destination at 10:30 a.m. EST (16:30 Central European Time) on Tuesday.
Usually when a spacecraft goes into orbit, it orbits something - but in the case of L2, there's nothing there. And yet the Lagrangian Points are superb anchor points for spacecraft that shun more orthodox orbits.
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L2 is located in a direct sun-Earth line, 1.5 million kilometers from our planet's surface away from the sun. It is constantly shaded from solar radiation by Earth's shadow, making it the perfect hitching post for highly sensitive space telescopes that need a region of calm to operate.
"Lagrange points are special - it's true there's nothing there," says Markus Landgraf, a mission analyst at ESOC, ESA's operations center in Darmstadt, Germany. "They are points where the gravitational forces between two masses, like the sun and Earth, add up to compensate for the centrifugal force of Earth's motion around the sun, and they provide uniquely advantageous observation opportunities for studying the sun or our Galaxy."