Today is a big day for the flight dynamics experts who determine and predict trajectories, prepare orbit manoeuvres and determine satellite attitudes.
At around 19:58 CET this evening, five of Gaia's eight thrusters will be commanded to fire an automated burn lasting almost two hours. It's a critical manoeuvre meant to bring Gaia onto its planned operational orbit about the L2 Lagrange point (a second, smaller, burn on 14 January will complete the process).
Gaia mapping the stars of the Milky Way. Credit: ESA/ATG medialab; background: ESO/S. Brunier
The event may appear straightforward, but it marks the culmination of years of careful mission analysis work supported by orbital calculations.
The ease of getting into the proper orbit – denoted by a mere two lines in the mission operations timeline (Thrusters ON, followed by Thrusters OFF) – belies the complexity of what is to be achieved.
How do you calculate the precise push needed to divert the 2013-kg satellite off of its current transfer trajectory – set up by the flawless Soyuz launch on 19 December – and onto an orbital path known as a Lissajous orbit?
Animation showing Gaia launch and journey to its operating orbit
In which ...