Measuring space-time

Can scientists really measure whether the Earth is in a vortex of space-time? This article from Science Blog renders a plain English explanation of the issue and the experiment to test one of Einstein's theories of relativity. From the article:

Time and space, according to Einstein's theories of relativity, arewoven together, forming a four-dimensional fabric called "space-time." The tremendous mass of Earth dimples this fabric, much like a heavy person sitting in the middle of a trampoline. Gravity, says Einstein, is simply the motion of objects following the curvaceous lines of the dimple.

If Earth were stationary, that would be the end of the story. But Earth is not stationary. Our planet spins, and the spin should twist the dimple, slightly, pulling it around into a 4-dimensional swirl. This is what GP-B [the experiment in orbit] went to space to check.