The Red Planet bleeds. Not blood, but its atmosphere, slowly trickling away to space. The culprit is our sun, which is using its own breath, the solar wind, and its radiation to rob Mars of its air. The crime may have condemned the planet's surface, once apparently promising for life, to a cold and sterile existence.
Features on Mars resembling dry riverbeds, and the discovery of minerals that form in the presence of water, indicate that Mars once had a thicker atmosphere and was warm enough for liquid water to flow on the surface. However, somehow that thick atmosphere got lost in space. It appears Mars has been cold and dry for billions of years, with an atmosphere so thin, any liquid water on the surface quickly boils away while the sun's ultraviolet radiation scours the ground.
Such harsh conditions are the end of the road for known forms of life. Although it's possible that martian life went underground, where liquid water may still exist and radiation can't reach.
The lead suspect for the theft is the sun, and its favorite M.O. may be the solar wind. All planets in our solar system are constantly blasted by the solar wind, a thin stream of electrically charged gas that continuously blows from the sun's surface into space. On Earth, our planet's global magnetic field shields our atmosphere by diverting most of the solar wind around it. The solar wind’s electrically charged particles, ions and electrons, have difficulty crossing magnetic fields.
"Mars can't protect itself from the solar wind because it no longer has a shield, the planet's global magnetic field is dead," said Bruce Jakosky of the University of Colorado, Boulder. Jakosky is the Principal Investigator for NASA's MAVEN mission, which will investigate what is responsible for the loss of the martian atmosphere. NASA selected the MAVEN (Mars Atmosphere and Volatile Evolution Mission) on September 15, 2008.
Mars lost its global magnetic field in its youth billions of years ago. Once its planet-wide magnetic field disappeared, Mars' atmosphere was exposed to the solar wind and most of it could have been gradually stripped away. "Fossil" magnetic fields remaining in ancient surfaces and other local areas on Mars don't provide enough coverage to shield much of the atmosphere from the solar wind
Although the solar wind might be the primary method, like an accomplished burglar, the sun’s emissions can steal the martian atmosphere in many ways. However, most follow a basic M.O., the solar wind and the sun’s ultraviolet radiation turns the uncharged atoms and molecules in Mars' upper atmosphere into electrically charged particles (ions). Once electrically charged, electric fields generated by the solar wind carry them away. The electric field is produced by the motion of the charged, electrically conducting solar wind across the interplanetary, solar-produced magnetic field, the same dynamic generators use to produce electrical power.
An exception to this dominant M.O. are atoms and molecules that have enough speed from solar heating to simply run away, they remain electrically neutral, but become hot enough to escape Mars' gravity. Also, solar extreme ultraviolet radiation can be absorbed by molecules, breaking them into their constituent atoms and giving each atom enough energy that it might be able to escape from the planet.
There are other suspects. Mars has more than 20 ancient craters larger than 600 miles across, scars from giant impacts by asteroids the size of small moons. This bombardment could have blasted large amounts of the martian atmosphere into space. However, huge martian volcanoes that erupted after the impacts, like Olympus Mons, could have replenished the martian atmosphere by venting massive amounts of gas from the planet's interior.
It's possible that the hijacked martian air was an organized crime, with both impacts and the solar wind contributing. Without the protection of its magnetic shield, any replacement martian atmosphere that may have issued from volcanic eruptions eventually would also have been stripped away by the solar wind.
Although the solar wind might be the primary method, like an accomplished burglar, the sun’s emissions can steal the martian atmosphere in many ways. However, most follow a basic M.O., the solar wind and the sun’s ultraviolet radiation turns the uncharged atoms and molecules in Mars' upper atmosphere into electrically charged particles (ions). Once electrically charged, electric fields generated by the solar wind carry them away. The electric field is produced by the motion of the charged, electrically conducting solar wind across the interplanetary, solar-produced magnetic field, the same dynamic generators use to produce electrical power.
An exception to this dominant M.O. are atoms and molecules that have enough speed from solar heating to simply run away, they remain electrically neutral, but become hot enough to escape Mars' gravity. Also, solar extreme ultraviolet radiation can be absorbed by molecules, breaking them into their constituent atoms and giving each atom enough energy that it might be able to escape from the planet.
There are other suspects. Mars has more than 20 ancient craters larger than 600 miles across, scars from giant impacts by asteroids the size of small moons. This bombardment could have blasted large amounts of the martian atmosphere into space. However, huge martian volcanoes that erupted after the impacts, like Olympus Mons, could have replenished the martian atmosphere by venting massive amounts of gas from the planet's interior.
It's possible that the hijacked martian air was an organized crime, with both impacts and the solar wind contributing. Without the protection of its magnetic shield, any replacement martian atmosphere that may have issued from volcanic eruptions eventually would also have been stripped away by the solar wind.
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