Gaia’s biggest operation since launch
On Tuesday 16 July, teams at ESA’s mission control will perform an “orbit change maneuver” on the Gaia space observatory—the biggest operation since the spacecraft was launched in 2013.
Gaia is on a mission to survey more than a billion stars, charting the largest three-dimensional map of our galaxy, the Milky Way. In so doing, the spacecraft is revealing the composition, formation and evolution of our galaxy, and a whole lot more.
For the last five and a half years, the spacecraft has traveled in an orbit designed to keep it out of Earth’s shadow, around the second Lagrange point.
At 1.5 million km from Earth—four times further than the Moon – “L2′ is a fabulous place from which to do science. As the Sun, Earth and Moon are all in one direction relative to the spacecraft, the rest of the sky is free to observe.
Placing Gaia at L2 has also ensured the star-catcher’s stability, because to this day it has never passed into Earth’s shadow. This has kept the spacecraft undisturbed by any change in temperature or varying infra-red radiation that would result from an Earth eclipse.
Although at the end of its planned lifetime, Gaia still has fuel in the tank and a lot more science to do, and so its mission continues. However, its eclipse-dodging path will not. In August and November of this year, without measures to change its orbit, the billion-star hunter will become partially shrouded by Earth’s shadow.