TUCSON, Ariz. (AP) — NASA couldn't send commands Tuesday to the Phoenix Mars lander because of a radio glitch, delaying a second day of activities, officials said.

NASA said the problem was minor and workers were trying to fix it.

Phoenix, the latest spacecraft on Mars, communicates with Earth through two NASA orbiters circling the planet.

One of them, the Mars Reconnaissance Orbiter, turned its radio off, possibly because of a cosmic ray, said Fuk Li, manager of the Mars exploration program for NASA's Jet Propulsion Laboratory in Pasadena, Calif.

Li said the orbiter was programmed to respond as it did.