Maybe this is how meteorites travel from one planet to another

NASA has already rode these currents once--the Genesis probe followed a gravitational channel en-route to collecting solar dust in 2004. By following the gravitational current, Genesis reached its mission point with ten times less fuel than it would have needed otherwise.

Speaking at the British Science Festival at the University of Surrey in Guildford, Ross highlighted the convenience of these gravity tubes, but also noted that they must be utilized in conjunction with regular rockets. For instance, riding a gravity channel from Earth to Mars without any other boosts would take a couple thousand years.

http://www.popsci.com/military-aviation-amp-space/article/2009-09/scientists-map-out-gravitational-space-highways