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This is Scientific American’s 60-Second Science. I’m Cynthia Graber. This will take just a minute.

As many of us broil¹ in August heat, the Mars Rover Spirit is hunkered down to survive a far more brutal² season—a Martian winter. Spirit’s been on Mars since January 2004 and already survived previous winters, which run from May through November. With sunlight reaching Spirit at a weak angle, the rover hibernates³ and uses the scant⁴ solar power to recharge batteries and heat itself to –40 degrees.

At least, that’s what’s happened in previous winters. This winter, the game little unit just doesn’t have enough juice to keep its heaters on, so temperatures inside the rover will plunge⁵ to a frigid⁶ –67 degrees Fahrenheit⁷.

When NASA scientists began signaling Spirit on July 26, they hoped to receive a communications beep back—but so far there’s only silence.

The researchers say that in about two months sunlight will start to increase again through March 2011. If we haven’t heard from Spirit by that point, then the likelihood is that we never will. The rover was designed to work on Mars for three months, but was mobile for more than five years. Now mission scientists wait through the Martian winter to see if this ET will phone home.

Thanks for the minute. For Scientific American’s 60-Second Science, I’m Cynthia Graber.