30 March 2015

Space for the day


Slate has an article by Phil Plait, writer of the Bad Astronomy blog and an astronomer, public speaker, science evangelizer, and author of Death From the Skies!, about Mars:
When the Curiosity rover landed on Mars, it wasn’t alone. On its way in it also dropped its heat shield, its backshell and parachute, and the rocket-powered sky crane. That last piece of hardware was pretty much what it sounds like: a platform that used rockets to hover over the surface of Mars, lowered the rover down, then blasted away to a safe distance once Curiosity was firmly down. The sky crane rose in a parabolic arc, then impacted the ground, hard, about seven hundred meters away. It was still moving horizontally, so it left a blast pattern on the surface, blowing the dust away off the ground. The dust is brighter than the rock beneath, so it left behind a dark splash pattern.
That was almost three years ago, and Mars hasn’t sat still. Weather and winds have beaten at the marks left by Curiosity’s accoutrements, and they’ve faded with time. JPL just released an amazing animation composed of images taken by the HiRISE camera on the Mars Reconnaissance Orbiter, showing the erosion of the marks over time.
As you can see, the marks have faded, most likely gradually being covered over by dust. The other pieces of hardware show similar changes (though less dramatic, given their smaller impacts); you can watch the animations for the heat shield, the backshell and parachute, and the rover landing site itself (of course, Curiosity has long since left; it’s a rover, after all).
It’s not as simple as fading, though; the marks from the sky crane have also recently darkened. It’s not clear why, though it’s possible dust blew in, then blew out again. We’ve seen the dust on Mars has done more elaborate and weirder things.
This is more than just interesting:, because we’re gearing up to send more probes to Mars, and eventually people. Understand the Martian weather will be critical. The dust is extremely fine, like talcum powder, and made of iron oxide, aka rust. It will get into everything (it coated Opportunity’s solar panels, reducing power until strong winds cleaned it off later). Understanding the dust transport mechanisms will be crucial for living on Mars as well.
Made back when the landing took place, YouTube has a video using images taken from the descent camera on the sky crane.
Rico says he's not volunteering to take the one-way trip to live there, and may not live to see it, but it will doubtless be fascinating...

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