Merry Christmas, Charlie Brown: The Beagle has landed. Britain's Mars surface explorer, named Beagle 2 after the ship that took Charles Darwin on his voyage of discovery to the Galapagos Islands, landed on the Red Planet on Christmas day as Santa's sleigh was touching down on rooftops here on Earth.

Like a homesick E.T., the first thing the Beagle was expected to do was phone home. Appropriately, the first message from Mars was programmed music by British rock band Blur - Whoo hoo! Wait; hold the phone. At the time of this writing, this dog had not been heard from...but some are still hopeful.

After calling home on Christmas, the Beagle should turn its attention from the landing to its mission -- the search for evidence of life on Mars. The Beagle is expected to sniff out evidence of life from a stationary position. Like a dog on a short leash, this Beagle will dig; it has a PAW (position adjustable workbench) designed for the purpose.

It won't be until next month that American rovers, named Spirit and Opportunity, will land on Mars and start crawling over the surface in search of signs of life and answers to questions raised by the inconclusive discoveries last year by Mars orbiter Odyssey. The twin rovers, Spirit and Opportunity, are on separate missions to opposite sides of the planet:

They will look for proof that there once was water on Mars, which would mean it is possible that the planet harboured life, perhaps in its distant past.

There is intriguing evidence that water once flowed freely on Mars. Last year, the Odyssey spacecraft circling the planet found evidence that there may be life just under the dusty surface of the planet at higher latitudes.

Unfortunately, the two rovers won't be following up on those clues. The days are shorter at higher latitudes and the rovers are powered, in part, by solar energy.

Designed to work like robotic field geologists, one is to investigate a crater that looks as if it was once a lake, and the other is to land near an outcrop of deposits of an iron-oxide mineral compound usually formed in the presence of water.

The only thing we know for certain is that trips to Mars are never a sure thing:

The Mars teams have learned the hard way that getting even robotic emissaries, much less human ones, safely to the planet remains a perilous and unforgiving task.

Earlier this month, Japanese scientists gave up on their first mission to Mars, making it the first casualty of the current armada. The Nozomi ("Hope"), launched in 1998, struggled with persistent technical problems that had left it years behind schedule, low on fuel and with a crippled heating system. It was to study Mars from orbit.

"Mars has been a most daunting destination," said NASA's chief space scientist, Edward Weiler, one of several scientists who have taken to referring to Mars as the "death planet." He noted that two of every three Earth missions to the planet have failed. Only three previous attempts to land on the surface -- the two U.S. Viking craft of the 1970s and the U.S. Pathfinder in 1997 -- have succeeded.

The missions are timed to take advantage of favorable planetary alignments that occur about every two years, providing an opportunity to send more mass with less boost. This year's lineup was slightly better than usual, bringing the two worlds to their closest approach in almost 60,000 years -- about 35 million miles apart.

Mars is now almost 100 million miles away, and the spacecraft will have traveled about 300 million miles to get there.

Huh? I thought this Mars landing was timed for the release of another Peanuts Holiday Special.