Back to Article List From the December 2007 issue How do gravity assists work? Alex Forbes, Castro Valley, California By Astronomy Staff | Published: December 1, 2007 By passing near a large body, a spacecraft can radically alter its speed and trajectory without expending any fuel. This may sound like a free lunch, but it isn’t.
Cosmology, Science Why is the universe expanding faster than predicted? A cosmologist explains what we know
