LISA pathfinder takes to the skies

ESA’s LISA Pathfinder blasted off on 3 December at 04:04 GMT (05:04 CET) on a Vega rocket that delivered it to a low-Earth parking orbit. From there, the satellite will perform a series of six critical burns with its own propulsion system over the coming week, to raise the highest point of its orbit and eventually start the cruise towards its operational orbit around the Lagrange point L1, 1.5 million km away from Earth towards the Sun.

An experimental satellite, LISA pathfinder will test a technique to detect ripples in space and across time, adding a new perspective for viewing and understanding the universe.

From a vantage point 93 million miles (1.5 million km) from Earth, the European-built spacecraft, is expected to break ground in the search for the ripples, known as gravitational waves, caused by fast-moving, massive celestial objects such as merging black holes.

Black holes are so dense with matter that not even photons of light can escape the powerful gravitational effects.

“This will really open up a new window into the universe. God knows what we will learn,” said European Space Agency deputy mission scientist Oliver Jennrich.

Like light, gravity travels in waves. Unlike light, gravitational waves bend the interwoven fabric of space and time, a phenomenon conceptualised by physicist Albert Einstein a century ago. Before Einstein’s general theory of relativity, gravity was seen as a force between two bodies.
In the pre-Einstein view of physics, if the sun disappeared one day, people on Earth would feel it instantly. In Einstein’s view, the effects would not be felt for eight minutes, the time both light waves and gravitational waves take to travel from the sun to Earth.
So far, attempts to detect gravitational waves using Earth-based detectors have been unsuccessful.

Massive objects such as black holes bend space and time more than smaller bodies like the sun, similar to how a bowling ball warps the surface of a trampoline more than a tennis ball.

“There’s a whole spectrum of gravitational waves, just like there’s a whole spectrum of electromagnetic waves,” said astrophysicist Ira Thorpe of NASA’s Goddard Space Flight Center.
An operational gravitational wave observatory under development would require three satellites, flying in a triangle formation about 621,000 miles (1 million kilometres) apart. The satellites would contain small metal cubes that would oscillate as a gravitational wave passes through.

Using a laser to measure tiny changes in distance between the cubes, scientists hope to track the subtle flexing of space and time. LISA (Evolved Laser Interferometer Space Antenna) Pathfinder will demonstrate the concept with two metal cubes 15 inches (38 cm) apart inside a single spacecraft.

The spacecraft is expected to reach its operational orbit in February 2016 and, after final checks, it will begin its six-month scientific mission at the beginning of March.
The mission, designed to last six months, cost about 400 million euros ($423 million).

https://lisapathfinder.org/