Lisa Pathfinder is a fundamental physics experiment that will test the technology needed to detect gravitational waves, what are sometimes referred to as ripples in the curvature of space-time. Scientists and engineers have declared the demonstrator ready to fly after more than a decade of development.
It will likely go up in November on the European Space Agency’s Vega rocket. The month marks the 100-year anniversary of when Einstein published the field equations that underpinned his Theory of General Relativity. Gravitational waves are a direct consequence of that grand idea. And although there is plenty of evidence to suggest the Universe is awash with these ripples, so far no actual detection has been made, either here on Earth or in space.
It’s not for want of trying, but the signal is expected to be very faint, even from the biggest sources. "Gravitational waves are essentially the mechanism that carries the force of gravity through the Universe," explained Esa’s Lisa Pathfinder project scientist, Dr Paul McNamara.
"They are produced by very large, violent events in the Universe, things like galaxies merging, where super-massive black holes in those galaxies come together. Supernovae, pulsars, any violent event where mass is moving. But for the space-based detectors, we’re really looking at the very big things in the Universe, the super-massive; the million solar mass objects."
Confirmation of the waves’ existence and their subsequent routine observation would open up a new paradigm in astronomy. It is one that would no longer depend on traditional light telescopes to look at and understand phenomena on the sky.
"The overwhelming part of the Universe is dark and will never be visible with electromagnetic radiation, but for all we know everything in the Universe interacts via gravity. So, ‘listening’ to gravity seems like the obvious thing to do to learn about the dark side of the cosmos," said Prof Karsten Danzmann, the co-principal investigator on Lisa Pathfinder.