Letters to the Editor Humans Letters from the June 18, 2005, issue of Science News By Science News June 14, 2005 at 10:03 am - More than 2 years ago Share this:Share Share via email (Opens in new window) Email Share on Facebook (Opens in new window) Facebook Share on Reddit (Opens in new window) Reddit Share on X (Opens in new window) X Print (Opens in new window) Print Road worriers “Navigating Celestial Currents: Math leads spacecraft on joy rides through the solar system” (SN: 4/16/05, p. 250) gives the casual reader the distorted view that one could travel the solar system at will by using these methods. These are generally small perturbations on the much larger primary propulsion requirement that is fixed by standard two-body orbital mechanics.