Water and planets

If all goes according to plan, on July 30th an Atlas V rocket will lift off from Cape Canaveral Air Force Station in Florida carrying a rock-collecting rover named Perseverance, destination Mars.

 The intended landing spot next February is Jezero Crater, a place north of the equator that – acutely relevant to this blog — once held a lake and a river delta.

Today’s posting is about water in the universe – starting with Mars and then touching on other planets including Earth where recent research has turned up fascinating new information.

Scientists believe that billions of years ago Mars was a wet world that could have supported life. The idea behind the rover’s rock-collecting mission is that mineralized water, once analyzed, might offer clues about the past.

The surface of Mars today is mostly desert, but the planet still has water, albeit mostly of the frozen sort; recently a team of  scientists detected a Texas-size chunk of subsurface ice between the planet’s equator and north pole.

Yet a couple of years ago, astronomers reported finding a large liquid lake beneath the red planet’s surface that’s similar to underground pockets of water that have been found near Earth’s poles.

As to why there’s no longer surface water on Mars, that’s not known, but researchers this year reported finding that Martian water escapes the planet uncommonly fast in the form of vapor. The causes include the planet’s thin atmosphere and weak gravity, which partly explains why vapor in the Martian sky doesn’t cycle back to the planet in the form of rain as happens on Earth.

There are many other questions about Mars that humans would like to answer.  Hence a surge of exploration. Within the last several weeks two other Mars missions got underway – one by the United Arab Emirates and the other by China. A fourth mission organized by European and Russian space agencies was to have started this summer but was delayed for two years due to complications surrounding Covid-19.

Meanwhile, astronomers are enthusiastically talking about a relatively new find of water vapor on an Earth-size planet outside our solar system. The discovery – on a planet that’s prosaically named K2-18b – was enabled through data from the Hubble Space Telescope. Astronomers’ excitement stems from the prospect that evidence of water can mean evidence of life, no matter if it’s 111 light years away.

Meanwhile, closer to home, there’s new science about water on Earth, specifically how it got here.

 For a long time it was believed that it was asteroids that delivered water to our planet by colliding with it. Asteroids are basically rock, but they contain water, too. Frankly, I have trouble picturing it – zillions of asteroids striking our planet in its earliest years, enough to fill our oceans with water – but I’m no scientist.

 Lately, however, different thinking is getting attention, specifically that our water was a product of the massive gaseous explosions that created our solar system. Here’s  Astronomy Magazine’s report on the idea in 2019.

Bottom line: There’s much to water on our planet and other planets that we are only now discovering. It takes a certain aptitude and knowledge to grasp the science behind the findings, but lay readers aren’t necessarily left in the dark. Highly recommended: NASA’s colorful and informative site that’s named “Ocean Worlds.




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