June 17, 2013
The universe is under no obligation to make sense to us, and yet here you are — a collection of atoms that somehow learned to think, to...
Dry Ice Sled Streaks on Mars
Birthday · June 17, 2013
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APOD published June 17, 2013. Full image credits are on the original APOD entry below. A publication-date match, not a photo taken on your date. Independent of NASA.
What creates these long and nearly straight grooves on Mars? Dubbed linear gullies, they appear on the sides of some sandy slopes during Martian spring, have nearly constant width, extend for as long as two kilometers, and have raised banks along their sides. Unlike most water flows, they do not appear to have areas of dried debris at the downhill end. A leading hypothesis -- actually being tested here on Earth -- is that these linear gullies are caused by chunks of carbon dioxide ice (dry ice) breaking off and sliding down hills while sublimating into gas, eventually completely evaporating into thin air. If true, these natural dry-ice sleds may well provide future adventurers a smooth ride on cushions of escaping carbon dioxide. The above recently-released image was taken in 2006 by the HiRISE camera on board the NASA's Mars Reconnaissance Orbiter currently orbiting Mars. Astrophysicists: Browse 600+ codes in the Astrophysics Source Code Library