ESA's LISA Pathfinder experiment launches to explore Einstein’s General Theory of Relativity
ESA's LISA Pathfinder experiment has successfully launched atop a Vega rocket from the agency's spaceport in Kourou, French Guiana, and completed initial maneuvers required to place the probe in a low, stable orbit. The experiment will seek to observe tiny ripples in space known as gravitational waves, which were first predicted by Albert Einstein in his General Theory of Relativity.
Over the next two weeks, the spacecraft will perform six critical burns, the last of which will establish the probe at its operational location known as Lagrange point 1 (L1). L1 is a point in space located roughly 1.5 million km from Earth, at which the spacecraft would hold its position relative to our planet and the Sun, leaving it well suited to the study of gravitational waves.
Gravitational waves, as envisioned by the great Albert Einstein, are minute ripples in the fabric of spacetime caused by the movement of very massive objects such as black holes. However, the disturbances caused by even these monsters would be very difficult to detect, creating a ripple the equivalent of an atom in a million-km stretch of space.
LISA Pathfinder is essentially an attempt by ESA to validate technologies that could be used in the construction of a future full-scale observatory, that would be designed to take incredibly accurate readings of the elusive phenomena.
Once in its operational orbit at L1, the probe will release the mechanical holding mechanisms connecting two cubes, each of which are contained within a vacuum chamber in the core of the probe. The gold-platinum cubes will at their release be placed 38 cm (15 inches) apart in the most perfect free-fall ever achieved, with only the minute disturbances caused by gravity to affect their relative distance.
In order to ensure that the spacecraft does not come in to contact with the cubes owing to a force other than gravity, such as the pressure exerted on an object by sunlight, tiny thrusters will fire roughly 10 times a second to maintain the probe's position in relation to its cargo. The probe is expected to reach its final orbit roughly 10 weeks after launch.
ESA graphic displaying the maneuvers to be carried out by the probe as it transitions into its operational orbit
During LISA Pathfinder's operational life, a highly complex laser interferometer will take detailed readings of the gravity induced movement of the cubes up to within a billionth of a millimeter. Such detailed readings have never before been achieved in an experiment.
"After many years of development and testing on the ground, we are looking forward to the ultimate test, which can only be run in space," states Paul McNamara, project scientist for the LISA Pathfinder mission. "In a few weeks, we will be exploring the very nature of gravity in space, gaining the confidence to build a full-scale space observatory to study the gravitational Universe in the future."