So we almost got hit by an asteroid on Friday…
…that no one knew about until it was 15 hours away from its closest point, about one Earth diameter away. But space is vast and trying to keep an eye on every part of it at all times is a challenge all it’s own, so it doesn’t surprise me. After all it was only 7 meters wide, not a planet killing asteroid by any means, but still a large hunk of rock and ice.
While, typically, we hope these asteroids will keep their distance, there’s a possibility that asteroids seeded life here on Earth. There’s been a surge of scientific study on asteroids and comets because they contain something once thought to be unique to Earth–amino acids, the basic building blocks of life.
In 1999, NASA launched Stardust to pass through the tail of comet Wild-2 and collect material. One of the most interesting results of the study of Stardust’s payload is the presence of glycine, an amino acid found in proteins. Amino acids have also been found in meteorites including the pieces of 2008 TC3, which impacted in Sudan last October. Even though the asteroid was smashed into numerous bits, scientists confirmed the presence of intact amino acids among the fragments.
But the curiosities don’t end there. Amino acids can be built in one of two ways that mirror each other in structure. You can have left-handed or right-handed amino acids. While life should be able to exist in either form, the two structures cannot be mixed. Scientists have found as much as 18% more left-handed amino acids in the widely studied Murchison meteorite and guess what? Life here on Earth is based on left-handed amino acids.
Think of the implications of this. If amino acids, the basic building blocks of our carbon based life forms, can be found within asteroids impacting planets and comet tails traveling around our solar system, where else in the galaxy are comets showering a trail of amino acids overhead and asteroids are on a collision course with a planet that has the right conditions to harbor life? There could be thousands of planets with the makings of life, maybe millions in this unbelievably vast universe we inhabit.
Large life forms are incredibly delicate. There are many conditions on Earth that our fragile human bodies cannot withstand, but microscopic life is tenacious. Anaerobic bacteria have been discovered in the rock walls of mine shafts two miles beneath the earth’s surface, surviving in the very crust of the earth where no light or oxygen can penetrate. I don’t believe it’s much of a stretch to consider the possibility of microscopic life, alien life, surviving under the icy surface of the potential oceans on Europa or deep in crust of a dry, dusty Mars.
In fact, large plumes of methane gas were discovered on Mars in 2003. The once thought dead planet isn’t so dead after all. Only two things can cause methane production–geologic processes and biologic processes. While it still remains to be seen which is causing the production of methane on Mars, I believe our solar system has many more treasures and surprises in store for us.
A partial list of articles, in case you are interested in reading further:
Universe Today-Asteroid buzz
Popular Mechanics-Stardust
NASA-Left-handed amino acids
NASA-Martian Methane
