Meteor bombardment 4 bln yrs ago may have made Earth more habitableJune 2nd, 2009 - 12:55 pm ICT by ANI
Washington, June 2 (ANI): A new study has suggested that large bombardments of meteorites approximately four billion years ago could have helped to make the early Earth and Mars more habitable for life by modifying their atmospheres.
When a meteorite enters a planet’s atmosphere, extreme heat causes some of the minerals and organic matter on its outer crust to be released as water and carbon dioxide (CO2) before it breaks up and hits the ground.
Researchers suggest the delivery of this water could have made Earth’s and Mars’ atmospheres wetter.
The release of the greenhouse gas CO2 could have trapped more energy from sunlight to make Earth and Mars warm enough to sustain liquid oceans.
In the new study, researchers from Imperial College London analyzed the remaining mineral and organic content of fifteen fragments of ancient meteorites that had crashed around the world to see how much water vapour and CO2 they would release when subjected to very high temperatures like those that they would experience upon entering the Earth’s atmosphere.
The researchers used a new technique called pyrolysis-FTIR, which uses electricity to rapidly heat the fragments at a rate of 20,000 degrees Celsius per second, and they then measured the gases released.
They found that on average, each meteorite was capable of releasing up to 12 percent of the meteorites’ mass as water vapour and 6 percent of the meteorites’ mass as CO2 when entering an atmosphere.
They concluded that contributions from individual meteorites were small and were unlikely to have a significant impact on the atmospheres of planets on their own.
The researchers then analyzed data from an ancient meteorite shower called the Late Heavy Bombardment (LHB), which occurred 4 billion years ago, where millions of rocks crashed to Earth and Mars over a period of 20 million years.
Using published models of meteoritic impact rates during the LHB, the researchers calculated that 10 billion tonnes of carbon dioxide and 10 billion tonnes of water vapour could have been delivered to the atmospheres of Earth and Mars each year.
This suggests that the LHB could have delivered enough CO2 and water vapour to turn the atmospheres of the two planets into warmer and wetter environments that were more habitable for life, according to the researchers.
According to Professor Mark Sephton, from Imperial’s Department of Earth Science and Engineering, the LHB may have been a pivotal moment in our early history where Earth’s gaseous envelope finally had enough of the right ingredients to nurture life on our planet. (ANI)
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Tags: ancient meteorite, atmospheres, bombardment, degrees celsius, early earth, extreme heat, ftir, gas co2, greenhouse gas, high temperatures, impact rates, imperial college london, lhb, liquid oceans, meteorite shower, meteorites, organic content, outer crust, study researchers, water vapour