Picturing precise formation flying success
Imagine flying not one but two satellites in space, just 150 meters apart, with precision down to the thickness of a fingernail. This is the ambitious plan of ESA’s Proba-3 mission, where two spacecraft will not only fly in close proximity but also maintain their relative positions to a single millimeter for six hours at a time. The mission manager, Damien Galano, highlights the unique challenge of this formation flying, where the success will be proven by casting a shadow of one spacecraft onto another to reveal the solar corona for sustained observation. It’s a high-stakes mission that will either work or not, pushing the boundaries of space exploration.
High orbit for mission success
To overcome the challenges of flying two spacecraft in such close formation, the Proba-3 mission needed to select an ideal orbit that minimizes perturbations and gravitational influences. A standard low Earth orbit was quickly ruled out due to the need for constant thruster adjustments. Instead, a highly elliptical orbit ranging from 600 km to 60,500 km was chosen, resembling a rollercoaster loop. This orbit allows the spacecraft to move freely at the bottom, where they fly faster, and transition into active formation flying as they climb higher with reduced velocity, spending more time at the highest point of their orbit.
Driverless spacecraft
Achieving such precise formation flying requires a blend of absolute and relative positioning technologies, from startrackers to optical cameras and LEDs. The Proba-3 spacecraft will autonomously align themselves with the Sun, similar to driverless cars on Earth, due to the impracticality of human intervention at orbital distances. The mission combines multiple positioning systems like GPS receivers, radio links, and shadow position sensors to ensure the spacecraft maintain their relative positions accurately.
Flight leader and wingman
During active formation flying, the mission employs a flight leader and wingman approach, with the Coronagraph spacecraft leading and breaking formation using a propulsion system. The Occulter follows suit with its own thruster system, ensuring precise positioning and maintaining a safe distance from each other. The spacecraft will fall back to Earth after six hours, with redundant systems in place to prevent collisions. The mission is a technology demonstration showcasing the capabilities of formation flying and space observation, with a forecasted two-year lifetime due to limited propellant.
In the vast expanse of space, the Proba-3 mission represents a remarkable feat of engineering and precision, pushing the boundaries of what is possible in space exploration. The challenges of operating multiple spacecraft in such close formation highlight the ingenuity and dedication of the teams behind this mission, demonstrating the limitless potential of human innovation in the cosmos. As we look towards the skies, we are reminded of the wonders that await us beyond the confines of our planet, where dreams of exploration and discovery continue to inspire generations to reach for the stars.
