A NASA space probe launched in 2001 August to collect samples of the solar wind and return them to Earth. Genesis was stationed at the L₁ Lagrangian point, 1.5 million km on the sunward side of Earth, and began collecting particles on the surface of silicon wafers in 2001 December. It continued collection until 2004 April, then returned in 2004 September to Earth, where it dropped a sample-return capsule into the atmosphere for recovery.

http://genesismission.jpl.nasa.gov/ Official mission website.