Pushing physics to the limit: Airbus Defence and Space engineers have designed and built the spacecraft and instruments for LISA Pathfinder, the technology demonstrator mission of one of the most ambitious scientific undertakings to date: proving key elements of Einstein’s theory of general relativity.
“The whole point is to show that the technological concepts developed for the detection of gravitational waves in space actually work.”
Ian Honstvet, LISA Pathfinder Project Manager
LISA Pathfinder is a unique European Space Agency (ESA) mission, requiring engineering that has never been done before. As Airbus Defence and Space UK is prime contractor, engineers in Stevenage were responsible for designing and building the overall system and platform. The Drag-Free Attitude Control System (DFACS) was developed in Friedrichshafen, as was the LISA Technology Package (LTP) under a separate ESA and DLR contract.
Together, they have created a spacecraft able to manage its own gravitational, magnetic and thermal environment, so that two test masses – identical gold and platinum cubes – follow a perfect inertial path within a delicate instrument, shielded from all disturbances except gravity. To achieve this, the spacecraft does not just transport the payload to its destination, but becomes part of the experiment itself, forming a single unit.
The challenge is immense as, even in space, there are many other forces at play apart from gravity, including radiation pressure from sunlight, charged particles from solar wind and tiny micrometeoroids impacting the spacecraft.
LISA Pathfinder‘s destination is an orbit around the first Sun-Earth Lagrangian point L1, a region of thermal and gravitational stability. Constantly illuminated by the Sun and in good communication distance from Earth, it will follow the Earth on its path around the sun.
If LISA Pathfinder is as successful as is hoped, the mission will have paved the way for the actual experiment, LISA. This ambitious mission, planned for 2035, will send a cluster of three spacecraft into space to replicate the experiment on a much larger scale. Each containing a free-flying test mass, the spacecraft will form an equilateral triangle with side lengths of about one million kilometres, creating the largest man-made structure ever in space. Precise heterodyne laser interferometry will then detect the small changes in distance triggered by gravitational waves.