NASA to Mars rover:  Phone home or else.

The space agency said it will reach out to contact the Mars rover Spirit a final time Wednesday after a series of unanswered attempts.

NASA speculates that an extreme Martian winter may have frozen the rover’s communication apparatus or weakened its energy level, hindering its ability to communicate.

In a press release Tuesday, NASA said, in essence, what we have here is a failure to communicate.

"We no longer believe there is a realistic probability of hearing from Spirit," Dave Lavery, NASA’s program executive for solar system exploration, said in the release.

Created for a three-month mission, Spirit landed on Mars in January 2004 and exceeded its intended life span by several years, giving scientists an in-depth look at the surface conditions of the red planet.

But there have been obstacles - namely massive dust storms, paralyzing sandboxes and plain ol' feisty weather that has challenged the rover's functionality.

Over most of the past seven years though, despite various violent conditions, Spirit has always managed to re-establish connection.

Not this time.

The last transmission received by the rover was March 22, 2010, NASA said.

The rover program will now focus its energies on Spirit’s twin rover, Opportunity, which landed 21 days after Spirit. Also, NASA is prepping the November launch of Curiosity, a bigger, more-tricked out rover (six 20-inch wheels?) slated to arrive on Mars in mid-2012.

As for Spirit, NASA said any communication from the rover will basically be relegated to voice mail.

“The Deep Space Network may occasionally listen for any faint signals when the schedule permits," Lavery is quoted in the release.