A quick test of the WEP enabled by a sounding rocket

We describe SR-POEM, a Galilean test of the weak equivalence principle (WEP), which is to be conducted during the free fall portion of a sounding rocket flight. This test of a single pair of substances is aimed at a measurement uncertainty of σ(η) < 10–16 after averaging the results of eight separate drops, each of 40 s duration. The WEP measurement is made with a set of four laser gauges that are expected to achieve 0.1 pm Hz–1/2. We address the two sources of systematic error that are currently of greatest concern: magnetic force and electrostatic (patch effect) force on the test mass assemblies. The discovery of a violation (η ≠ 0) would have profound implications for physics, astrophysics and cosmology.