European Space Agency readies LISA Pathfinder gravity observatory for launch


Gravitational waves are the yet to be detected ripples in the spacetime fabric which have been predicted by Albert Einstein in 1915 and in a bid to detect these waves if they are present, the European Space Agency (ESA) is to launch an observatory in space.

Called LISA Pathfinder, the observatory is all set for a launch later this year and pegged as a technology demonstrator, the observatory will carry out spaceborne observations of gravitational waves enabling scientists to detect the gravitational waves if they actually exist.

Gravitational waves are the ripples in spacetime fabric caused by massive bodies such as pair of orbiting black holes or massive supernova explosions.

ESA intends to take a deeper look into space and farther back in time to detect any traces of these gravitational waves using its spaceborne observatory. According to the space agency, LISA Pathfinder will test the fundamental technologies and instrumentation needed for such an observatory, demonstrating them for the first time in space.

Scientists peg powerful supernova explosions and double black holes as the source of gravitational waves as these two are possibly the most powerful events in space believed to be capable of generating the illusive gravitational waves.

Scientists say that despite the events being too powerful, the gravitational waves would simply be small perturbation in spacetime fabric. Instruments built to detect them must be capable of making exquisitely precise measurements of extremely small changes in distance between two reference objects, ESA says.

“Gravitational waves are an entirely fresh and different way to study the Universe, providing an important complement to the well-established approach of astronomy, based on observing the light emitted by celestial bodies,” says Paul McNamara, ESA’s project scientist.

In quantified terms, if there exist these small perturbations, they will cause a change of millionth of a millionth of a meter in distance between two massive celestial objects separated by around a million kilometres. This requires extraordinary measurement techniques using lasers, with the test masses flying freely in space, each shielded by a surrounding spacecraft from all extraneous influences, such as the solar wind.

ESA has designed and built the LISA Pathfinder such that it can test for those crucial underlying technologies in a single spacecraft, with the two test masses separated by only 38 cm. The aim is to prove that the masses can fly through space, untouched but shielded by the spacecraft, and maintain their relative positions to the precision needed to realise a full-up gravitational wave observatory later.

The observatory is scheduled for a launch on top of a Vega rocket later this year. After ascent on the Vega rocket, LISA Pathfinder will enter an elliptical orbit around Earth, where it will use its own propulsion system to raise the high point of its orbit.

Eventually, after about eight weeks, the spacecraft will reach its operational orbit around the Lagrange point L1, 1.5 million km from Earth towards the Sun.

There, LISA Pathfinder will begin six months of demonstrating the technology for future gravitational-wave observatories in space.