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Mars orbiter spies on past probes

An image captured Jan. 29 by the High Resolution Imaging Science Experiment on NASA's Mars Reconnaissance Orbiter shows Bonneville Crater, with the Spirit rover's landing platform off to the side. Can you spot the platform? How about the Spirit spacecraft's heat shield?

Color pictures taken from Martian orbit feature the landing spots for two of NASA's dearly departed probes on the Red Planet. Can you spot the Spirit rover's landing platform in the picture?

NASA / JPL-Caltech / Cornell

The panoramic camera on NASA's Spirit rover looks back at its landing platform just after rolling onto the Martian surface in 2004.

Bonneville Crater is easy to find: That was Spirit's first big destination after its landing in January 2004, and it took weeks for the six-wheeled robot to get there. But it's harder to make out the three-petal lander that was Spirit's home base for the airbag-cushioned landing.

If you haven't spotted it yet, the lander is the small bright object in the lower left corner of the picture above, captured by the Mars Reconnaissance Orbiter's high-resolution camera on Jan. 29. The reddish tint suggests that Mars' red dust is accumulating on the platform.

MRO's High Resolution Imaging Science Experiment, or HiRISE, has taken pictures of the site before, but only in black and white.

Making out the Spirit spacecraft's heat shield, which was jettisoned during the final stage of the descent, is even more challenging. It's the bright spot at the 12 o'clock position on the rim of the 650-foot-wide crater. That heat shield was jettisoned as planned during Spirit's descent.

Spirit got a good look at the crater and plenty of other sites during its five-year, 4.8-mile trek. Don't bother to hunt for the rover in the orbital picture. It went way beyond the right side of the frame, clambering up the Columbia Hills, chronicling the planet's dust devils and turning up ample evidence of liquid water on ancient Mars.

By the time 2009 rolled around, the rover was struggling with a gimpy wheel and got itself stuck in a patch of soft Martian soil near a 300-foot-wide plateau nicknamed Home Plate. Scientists believe the rover's solar arrays were no longer able to provide enough power to keep Spirit going through the harsh Martian winter, and it fell out of communication with NASA in March 2010. After more than a year of trying to re-establish contact, NASA ended Spirit's mission.

NASA / JPL-Caltech / UA

This annotated image traces the Spirit rover's trek from its landing site in 2004 to its final resting place near a feature known as Home Plate.

Spirit's twin, Opportunity, is still in operation on the opposite side of the Red Planet, more than eight years after landing. Not bad for a couple of golf-cart-sized machines that were expected to last just 90 days.

Just as NASA was winding down its efforts to revive Spirit, HiRISE caught the glint of sunlight reflected by the rover's solar arrays. The fresh picture of the landing site serves as a renewed remembrance — but I have a feeling this won't be the last we see of Spirit. Every once in a while, it's nice to check in on the robot that did so much for planetary science

Picturing Phoenix
The same could be said for NASA's Phoenix Mars Lander. That spacecraft touched down in the Red Planet's north polar region in May 2008 and spent several months studying the frozen surface. Phoenix was the first probe to see Martian water ice close up, and watch it disappear as vapor.

Phoenix went dormant after several months of work and presumably fell prey to Mars' winter weather. But Phoenix's scientific legacy is alive and well: One study, published last August, cited Phoenix data to suggest that Martian soil might be more capable of supporting life than previously thought. Another report with a different spin came out just this month: Researchers said the soil collected by the Phoenix lander hinted at a Martian "superdrought" that lasted for hundreds of millions of years.

HiRISE snapped an amazing picture of Phoenix during its descent through the Martian atmosphere, and sent back more photos of the probe during and after its mission. The latest image was acquired Jan. 26 and released today.

NASA / JPL-Caltech / UA

A Jan. 26 image acquired by the high-resolution camera on NASA's Mars Reconnaissance Orbiter shows the Phoenix Mars Lander spacecraft in Mars' north polar region after its second Martian winter. The defunct lander is the bright spot at the center of the frame.

Will Mars orbiters still be able to see something 10, 20 or 30 years from now? Will humans ever walk where Phoenix or Spirit now sit? Feel free to reflect on the latest views of NASA's past probes in the comment section below.

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Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter or adding Cosmic Log's Google+ page to your circle. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for other worlds.