Science experiment is bigger than the Large Hadron Collider.

In 2020 3 spacecraft will use laser fire to accurately measure the distance between them accurately enough to determine whether or not gravitational waves are real. How accurate does the measurement have to be? They will measure a distance of 3 million miles to an accuracy of 40 femtometers... roughly the distance of 15 protons side by side. This experiment will take place with the 3 spacecraft in orbit of the sun, Earth simply isn't big enough to get significant results.

We must have some incredible minds at NASA to take on a project this complex. Over 3 million miles the spacecraft would have to account for so many variables it's mind boggling, gravitational lensing from the sun should bend the laser light, open space isn't a perfect vacuum so the the light should slow down by a very small margin, redshift between 3 million miles would be incredibly miniscule, but at that accuracy very significant.... off the top of my head.

More is explained here, thanks and credit go to www.popsci.com.... again.

http://www.popsci.com/science/article/2010-05/prove-relativity-nasaesa-will-launch-universes-biggest-science-experiment