Go boldly, LISA Pathfinder

Here’s footage of the LISA Pathfinder launch, which happened at 4.04am GMT this morning. More to follow…

Update: December 11, 22:46

Fifteen years after the mission was approved, on December 3 the European Space Agency (ESA) launched LISA Pathfinder, a spacecraft that’ll test the waters for a grand experiment seeking evidence of gravitational waves, or ripples in the fabric of space-time.

The original date of launch was almost auspicious – it was delayed to a day after the 100th anniversary of the publication of Einstein’s general theory of relativity, which predicted the existence of such gravitational waves. Who said scientists can’t be romantic?

Ripples in space-time are created by the collision of huge bodies in space, such as galaxies or supermassive black holes. They’ve never been directly observed, though there are teams looking out for them from Earth.

The purpose of LISA Pathfinder is to check whether we’d be able to pick up these ripples in space-time with our experiment setup.

LISA_Pathfinder_in_space
Source: ESA–C.Carreau

The spacecraft, currently orbiting the Earth, contains two identical 2kg gold-platinum cubes separated by 38cm. The cubes will be set in perfect freefall when Pathfinder reaches its final destination, at a point between the Earth and the Sun where they’ll be isolated from all external forces but gravity.

Pathfinder will see if we can achieve the freefall. In the real experiment, which will go ahead in 2034, a set of lasers will be bounced off three cubes in freefall, separated from each other by 5 million km, to detect deviations in their motion to the accuracy of a trillionth of a metre.

The craft will reach its intended orbit, 1.5 million kilometres away from the Earth around a sweet spot called Lagrange Point 1, next February.

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