Meanwhile, back on Mars …

JISHOU, HUNAN — Most of my posts lately have been about China, for obvious reasons, but it’s hard to abandon being a physics teacher. So, here’s a science post.

While humans have been flitting around in low-earth orbit, NASA-JPL’s Martian probes have been busy on the red planet. The arctic explorer, Phoenix, has discovered water ice in the soil and in the sky, detected snow falling from the clouds, and photographed the sun creeping up above the horizon as the martian winter approaches.

This sequence just fascinates me in particular. It shows clouds scooting through the sky, much as they would here in Earth. These are water-ice clouds, like the high-altitude cirrus clouds here.

Clouds in the martian arctic

Aside from practical issues like not having any oxygen to breath and sub-sub-zero temperatures, you could almost imagine yourself standing there watching the clouds go by.

Phoenix has been operating for more than four months, but the approaching martian winter solstice may kill the little fellow off. Temperatures are dropping to -120C (-184F), which is bad for its electronics and especially its solar panels. Carbon dioxide frost is forming on the solar panels, cutting down sunlight reaching the solar cells. And the sun itself, as it does in Earth’s arctic region, will soon dip below the horizon, not to return for three months.

So NASA-JPL scientists are trying to keep Phoenix busy every waking hour before it’s lights out for the probe. For details, visit the website.

Phoenix’s older siblings, Opportunity and Spirit, are in more temperate latitudes (which is a relative term on Mars — it’s not like they’re vacationing on Hilton Head!), still functioning well past their planned 90-day mission length. For four years (years!),tThe two rovers have been tooling along the surface, investigating rock formation, sediments (left by water activity), soil composition and atmospheric conditions. They have survived winter temperatures, powerful dust storms and momentary mechanical and computer glitches.

The rovers have pretty much clinched the idea that water at one time flowed on the martian surface, with their images of sedimentary rocks and detection of carbonates and other minerals requiring liquid water to form. Their photographs of the rocky, desert landscape have given us a far better picture of “life on Mars” than any mission before.

(Spirit’s photo of the sun setting on Mars is this blog’s header image, by the way. The same image won a “most popular” contest sponsored by the Jet Propulsion Lab.)

Rovers website link.

Two other probes have been studying the red planet from above. Mars Odyssey has found evidence of salt deposits on the surface, again indicating the existence of surface water. And the less poetically named Mars Reconnaissance Orbiter recently imaged cracks in the sandstone that once channeled water billions of years ago.

So, while the US economy slip slides into disaster and, like Gov. Sarah “Six-Pack” Palin, you watch your 401(k) bleed money, take time to vicariously visit Mars. Maybe it’ll cheer you up.

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