REAL LIFE NEWS: SCIENTISTS FIGURE OUT WHY MOST METEORITES DISINTEGRATE BEFORE LANDING
by Hazed
Earth is bombarded with meteorites but most of them burn up in the planet’s atmosphere. Even those that don’t disintegrate completely tend to explode in the air rather than just plummeting to the ground. Now scientists think they have figured out why: it’s all about atmospheric pressure.
New research suggests that air is forcing its way inside the meteorites, causing them to break up.
Exploration over the past few years has shown that many meteorites are not solid boulders but are a loose collection of rocks that have come together thanks to gravitational attraction. This means they are very porous. When they hit the lower part of the Earth’s atmosphere, the denser air is forced inside the porous meteorites and heats up massively. The pressure inside increases until eventually the object can’t take it any longer and disintegrates or explodes.
This explains the 2013 Chelyabinsk meteorite, which injured over 1,000 people when it exploded in the atmosphere. It was thought to weigh around 12,000 tons but scientists were only ever able to find around five tons of debris. The explosion must have destroyed most of its matter.
Using computer models, Jay Molesh and his team at Purdue University, Indiana, replicated the destruction of meteorites. They used software that was first developed by Los Alamos National Laboratory to model nuclear explosions.
Their simulations showed that a dense patch of air forms in front of the meteorites, and a near vacuum behind it. The pressure differential forces air into the meteorite. It becomes superheated and that leads to explosions.
Porous meteorites start to fragment at about 298 miles up, then explode around 24 miles from the surface, according to the simulations. By contrast, rocks with low porosity are still whole 22 miles up.
What does this mean? Well, we still need to worry about a giant meteorite hitting Earth, but provided it’s a porous one then it won’t be as devastating as we thought.
Source: http://www.theregister.co.uk/2017/12/11/earth_atmosphere_final_defense_against_meteorites/
