The Moon is very close to the Earth, so close that man has already been there, but still we are not sure if there was or could have been any living organisms there. It is believed that there is an amount of ice underneath the lunar ice caps, in shadowed areas, which would act as a deep-freezer for anything that once lived there. If protolife was there it could have lived in the water when the Moon was warmer, and froze in the water when it cooled and would be persevered by the conditions. Also as it is in shaded areas, exposure to ultraviolet light would no have degraded it.
There have been bursts of gases from the surface of the Moon, including sulphur, carbon, hydrogen and other gases. These gases are important for the production of protolife. Other gases and compounds that could harbour protolife could be frozen in the shaded areas of the Moon.
These are the reasons that give people the right to say that scientists should be sent back to the Moon to search for the remains of life in its earliest form.
However finding protolife on the Moon does not necessarily mean that life came from the Moon, some would say that it would affirm that protolife arrived on Earth from farther away. Looking at the Moon we can see that it has been battered by comets and meteorites. Comets are generally made of ‘dirty ice’ (water frozen with other chemicals in it), the water on the Moon could wholly be from comets bringing water from the far reaches of the solar system. Which could have brought life with it.
Comets and Meteorites
Comets and meteorites are important to the history of the Earth. As we can see by the Moon and other celestial bodies, we can see that there has been a lot of activity involving comets and meteorites hitting moons and planets. As comets travel in the orbits they follow, they fly through interstellar space. This is an obvious fact but the less obvious fact is that amino acids can found not only in the comets and meteors but also in the space they fly through.
Researchers began with finding out what was in the interstellar space then experimenting with them and trying to recreate the conditions that they would see in space. Almost zero pressure and temperatures as low as -260 degrees below zero, then they were illuminated with UV light similarly to conditions they would be subjected to in space. When analysing the resultant grains formed the scientists found glycine, alanine and serine among the 16 amino acids produced. These interstellar clouds act as a melting pot for the simple gases that are the building blocks of all of the planetary systems and so are available to the whole of the solar system, galaxy and universe.
These results of amino acids being created in interstellar space were achieved by two independent groups, although the groups abundances of amino acids were different, it is not seen as a problem. The differences in abundances of the amino acids created can be put down to the abundances of the original gases used.
While flying through these interstellar clouds, the comets and meteors do themselves hold amino acids. It is suspected that they hold amino acids as they have been discovered in meteorites that have fallen to Earth, but never seen in space. Some scientists say that the amino acids found in meteorites are due to contamination from the Earth. But there are reasons to believe that the amino acids are not from contamination. Firstly is the fact that amino acids with asymmetrical carbon atoms are found in D and L forms as racemic mixtures. On Earth most of which are L forms, so by assuming that the sample has been contaminated, scientists can assume that any excess of the L form is due to contamination. Another reason is the C12/C13 ratio of the organic carbon in the meteorite was higher in C13 than any Carbon found on Earth. However, this data was not found for the actual amino acids because of the relatively large amounts carbon needed from the amino acids found.
Life On Mars
Recently meteorites from Mars have been closely examined for traces of life, ALH84001 especially. This meteorite is one of a number of SNC meteorites (named after the initials of the people who found the meteorites). It is known that the meteorites have come from Mars due to the gases that have been caught in the rock. The composition of which matches the composition of the atmosphere of Mars, found by the Viking Landers. ALH84001 was found to hold carbonates that are only formed in the presence of water. Indicating that there was water on Mars in the past. The word past is a vague word to use as ALH84001 is thought to be around 4.5 billion years old. As well as the carbonates, it held tube like formations that look like fossilised organisms. These organisms would have been alive during the period when there was water on the surface of Mars.
There has also been research into a bug that is thought to have come from Mars. This bug, deinococcus radiodurans, is thought to have come from Mars due to its resistance to radiation. The bugs were exposed to radiation enough to kill 99.9% of the population, then left to recover. The first dose was only one hundredth of the lethal dose for human beings, but it took 44 cycles and up to 5000 times the original lethal dose of radiation to kill the same 99.9% of the population. Researchers calculated that it would take thousands of cycles for E.Coli to reach a similar resistance.
It is thought that these resistant bugs are from mars because of the fact that the cycle of movement of Mars’ axis would change the seasons so that these bugs would have to lie dormant for periods of time enough for them to be exposed to the radiation required to kill a large percentage of the population. Then when they come out of their dormant state, they would multiply and recover until they would have to become dormant again due to the wobble of Mars’ axis.
The Seas Of Europa
Beneath the crust of Europe lies a massive sea of water. It is known due to the study of Europa’s infrared spectrum, which shows frost of water on top of a layer of pure water ice. The surface is smooth due the gravitational forces of Jupiter and the other moons. These forces pull and contort the shape of the moons enough to give the sea enough energy to stay liquid. Enhanced pictures of the surface of Europa also show debris of meteorites that have crashed onto the surface. These meteorites could have brought protolife to Europa and perhaps extremophiles could have grown from them.
Conclusion
Discussed above are a few possibilities of extraterrestrial life elsewhere in the solar system. Possibilities for the discovery of protolife on the Moon, Comets, Mars and Europa have been discussed, however these are just a few possibilities due to the age of the solar system. The tube like structures found on ALH84001 are 4.5 billion years old, if they were once micro organisms then there was life in the solar system just as the Earth was forming.
Amino acids have been found in comets and meteorites, and they are forming in interstellar clouds in outer space. This production the building blocks of life going on all over the solar system must be going on all over the galaxy and the universe.
As the universe as we know it is infinite there must be life somewhere in the universe.
Earth is a place in which life has flourished, in that we have liquid water and a suitable climate, a moon that holds the rotation of the Earth’s axis steady. But what really makes us so special?