From June 7 to June 21, the rovers trekking across Martian soil won't hear from their controllers back on Earth. Communication between the Red Planet and Earth will be disrupted by the sun's presence.

The silence is the result of what's called the Mars solar conjunction, during which the sun bisects the line from Earth to Mars. The phenomenon, which happens every 26 months, mostly blocks the path of radio waves between the two planets, severely curtailing communications.

What isn't blocked directly by the sun's core risks being frazzled by the sun's violent solar atmosphere. To prevent devices on and around Mars from receiving garbled messages, NASA's mission controllers will limit their communication to only instances of emergency.

NASA's currently land-based Mars operations include the Spirit, Opportunity and Curiosity missions.

Though some of the rovers will continue making scientific observations during the radio silence, they will refrain from manipulating their appendages (robotic arms) and performing complex movements.

Scientific data collected by Mars' newest probe, MAVEN, will be stored and sent back to Earth once the sun is out of the way.
http://mars.nasa.gov/multimedia/videos/movies/miam20130320/miam20130320-640.mov

"Our overall approach is based on what we did for the solar conjunction two years ago, which worked well," Nagin Cox, a systems engineer at NASA's Jet Propulsion Laboratory, explained in a press release. "It is really helpful to have been through this before."

Two of the satellites orbiting Mars -- the Mars Odyssey and Mars Reconnaissance Orbiter -- will continue to collect and send data, but scientists at NASA will lower their expectations, as some of these messages are bound to be thwarted by the sun's presence.