WASHINGTON — NASA’s Opportunity rover has now traveled the length of a marathon on Mars. NASA said March 24 the rover has traveled 42.195 kilometers since landing on Mars in January 2004; it is the first spacecraft to travel that far on any world beyond Earth. The milestone comes after spacecraft controllers reformatted the rover’s memory to allow it to once again store data overnight.

Opportunity’s twin rover, Curiosity, meanwhile, has detected for the first time “biologically useful” nitrogen. An instrument on Curiosity detected nitric oxide in a sample of martian sediments that scientists believe could have been created from nitrates. The existence of nitrates on Mars adds to the evidence that the planet was once hospitable to life.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...