Something strange has happened to Mars's polar ice cap. Instead of a uniform, roughly circular blob, like on Earth, the Martian version resembles a pinwheel (left), with dry, spiral troughs separating the ice sheets. There's also Chasma Boreale, the deep, dagger-shaped gouge that cuts across the pinwheel. Scientists had thought that the canyon, which is 2 kilometers deep, was carved by some catastrophic flood in the distant past. Now in two papers published tomorrow in Nature, researchers think they have solved both mysteries. Using a radar survey of the pole (right), which peered under the ice, they conclude that Chasma Boreale wasn't dug out at all. Instead, Martian winds built up the steep, canyon-like walls over millions of years. As for the pinwheel, the team reports that it likewise formed over many millennia, as strong winds pushed apart the dry ice crystals on the surface, much like winds on Earth create sand dunes.

One of NASA's three probes on the red planet has cashed in. Two years ago tomorrow, the Phoenix Mars Lander plopped down near the north pole, and for 5 months it transmitted data indicating the onetime presence of water beneath the frozen surface. Then the long and dark Martian winter interrupted communications. When spring returned last year, NASA mission controllers attempted to reestablish contact with the solar-powered probe, but 211 tries failed to detect a signal. Now, images taken by the Mars Reconnaissance Orbiter tell the tale. Not only is the lander buried by hundreds of kilograms of frozen carbon dioxide, but most likely, scientists reported today, the weight of the ice has broken off the solar panels, rendering Phoenix a relic - and maybe a candidate for display in a Martian museum by residents in some future, distant year.

Looking for long-term real estate investments? Avoid WASP-12b. The giant exoplanet, located about 600 light-years away in the constellation Auriga, is not long for its solar system. WASP-12 circles so close to its sun - it takes only a little more than an Earth day to complete one orbit - that its surface temperature exceeds 1500°C, making it the hottest alien world ever found. What's more, astronomers report in the 10 May issue of The Astrophysical Journal Letters, the planet's atmosphere is being slowly ripped away by the star's gravity. In only 10 million years or so, barely the wink of an eye on astronomical timescales, WASP-12b will boil away entirely.

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