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If you think that there is no other Life out there - then think again!

What is Life


When Did Life First Appear on Earth

How did Life First Appear

The First Inhabitants

Building blocks of life are in space

Essential Elements of Life

Window of Opportunity has increased

Panspermia, Comets the Galactic Taxis


Picture this. In the beginning a comet hurtles towards Earth. It collides with an almighty impact 3.8 billion years ago. Much of the cometry material is vapourised. But some survives including dormant microbes buried deep in the comets interior for tens of million of years. And 3.8 billion years after the impact, the phrase to describe this phenonema is coined, Panspermia.

So did life on Earth arrive on the back of a comet 3.8 billion years ago? Could life have been transported from other parts of the galaxy? The theory of Panspermia suggests that we are all descendents of aliens. We have seen how the universe appears to be teeming with the molecules which are essential for all life on Earth. But was early life indigenous to Earth or could it have arrived from space and seeded the Earth? Could our family ancestory be traced back to aliens? Many Scientists seem to think it's as viable a proposition as say, the 'primordial soup' or the 'hydrothermal vent' hypothesis. But how do these molecules get to rendezvous with a planet like Earth, and make their way down to the surface? Comets could be the answer! They may be capable of bringing both life and death to planets.

Evidence from Comets
Comets, or dirty space icebergs, to be even more descriptive, contain alot of organic material and water. We saw in 2005 how NASA's Deep Impact spaceprobe was intentionaly crashed into comet Tempel-1. The Deep Impact flyby spacecraft launched its impactor probe which then collided at 23,000 mph with the comet. The cometery material that was stirred up in the impact was analysed using the Spitzer telescope.

Comet Hale-Bopp

The spectra revealed the presence of silicates, carbonates, clay-like material and hydrocarbon compounds. Thses organic compounds as we know are essential for life to start. Indeed, ground based observatories have also arrived at these same findings on other observed comets. And in 1986, ESA's Giotto spacecraft also detected hydrocarbons on its flyby of Halley's comet. These discoveries have enormous implications, since we know organic compounds are essential for life to start.

In 2014, the ESA's Rosetta spacecraft, launched in 2004, will rendezvous with Comet 67P/Churyumov-Gerasimenko. It will release a lander onto the icy surface. The landers instruments as well as the Rosetta spacecraft itself may unlock many secrets for us. Hence the name! The chemical composition of comets is known to be similar to the chemical composition of the solar system at the time of its formation. So it's like a window to 4.5 billion years ago. But for now we must wait and see. Incidently, to accomplish this mission is no mean achievement. It is a ten year journey for Rosetta, chasing and manoeuvring into orbit around a 'cosmic bullet', playing catch-up by using gravational 'kicks' from the Earth (three times) and Mars (once).

But would organic material embedded in a comet survive an impact on a rocky planet like Earth? High impact experiments have taken place in laboratories, replicating cometry impacts. Using small grains of rock, containing microbes, scientists have shown that it is possible for some microbes to survive these extremely high impacts. The vast mayority of microbes are destroyed in the impact, but it only takes a small fraction to survive and start to replicate at rapid speeds as microbes do. These experiments further strengthen the case for panspermia and the possiblity that comets supplied the early Earth with the requisite chemical molecules, thus permitting the process of chemical evolution to take place leading to the origin of life on Earth.

An Abundance of Comets

The formation of Solar systems seems to end up with a cometery reservoir surrounding, and in the far reaches, of the solar system. Comets are concentrated in two main regions in our solar system, the Kuiper belt and the Oort cloud.

Comets orbit our sun just as the planets do. The orbits of comets will sometimes take them into the inner solar system. This can be due to collisions amongst themselves, the effects of gravity from nearby passing stars or the gravitational attraction of the planets. As a comet advances towards the sun it heats up, and essentially disintegrates, and begin to eject material. A trail of material is left which sometimes the orbit of the Earth will intersect. This we see as a meteor shower. But not all the material in the trail burns up. Some settles down through the atmosphere and reaches the surface of the Earth intact. Today its estimated that cometery dust grains contribute about 300 tonnes of organic materials to the Earth each year, Meteorites also contribute organic material. This material is sealed inside the meteorite as it plunges throught the atmosphere and its estimated that meteorites contribute about 10 kilograms of organic material annually.

The Kuiper Belt is a disk of debris in the ecliptic plane of the solar system. This 'junkyard' of material, left over from the formation of the solar system, may contain up to 100 million small icy objects, which orbit the sun beyond Neptune. This frigid and mysterious outer realm of the solar system also contains many larger objects. In fact Pluto and its moon Charon (3.6 billion miles from the sun) may actually be considered Kuiper Belt objects, as can the recently discovered Eris (9 billion miles from the sun). Though they have also been recently reclassified as dwarf planets. Comets from the Kuiper Belt are considered short-period comets which frequently return to the inner solar system.

The Oort cloud is a spherical cloud of trillions of icy objects surrounding the solar system, at a vast distance of up to two light years from the sun. Because of this immense distance the gravitational attraction of the sun is weak, and they can easily have their orbits perturbed by nearby stars or molecular clouds. This can result in some comets beginning a journey towards the inner solar system. These comets are called long-period comets.

Alien microbes arrive from space!

In 2001, in Kerala, in southern India, a strange and as yet unexplained phenomena occurred. There was 'red rain'. As 'red as blood' according to the locals. Analysis of the rain and the dust contained showed that it was 'alive', it contained a lifeform, but a mysterious lifeform! Further analysis showed that it contained life but had no DNA. It was suggested by physicist Dr. Godfrey Louis that it might possibly be extraterrestrial life. Other possible explanation were that it was due to dust from the deserts of Arabia which was in the atmosphere over Kerala, or dust from a volcanic eruption at around that time in the Philippines. Is the Red Rain of Kerala evidence of Panspermia?

There are also claims that microbes from space have been found high up in the Earth's atmosphere. High altitude balloons have collected samples from the vicinity of Hyderabad in India in 2000. Because they are 'different' that any microbes previously analysed and becasue they are so high in the atmosphere, it is unlikely that they are terrestrial microbes and may possibly be alien microbes that have drifted into the upper atmosphere from passing comet trails. But many scientists are unconvinced so the jury is still out.

Are microbes tough enough?

Can bacteria travel within comets and survive long exposure to cosmics rays, or ultra-violet rays, and extreme cold? In the 1970s the Astronomers Fred Hoyle and Chandra Wickramasinghe suggested that the universe was teeming with the building blocks of life, and that this life could travel inter-galactically. Similar to how plant seeds travel around the Earth's surface to find suitable conditions to flourish.


The survival characteristics that we see with bacteria under extreme conditions both here on Earth and on the moon would seem to suggest that it is feasible for bacteria to travel across the galaxy. The vast vast majority of instellar bacteria would probably be destroyed. But all it would require is for minute amounts of bacteria to survive the journey and arrive on a planet like Earth, seed the planet and then go forth and multiply. And we now know that the potential lifetime of bacteria is extremely long, up to 250 million years. Bacteria that were last 'alive' 50 million years before the first dinosaur appeared on Earth have been discovered in a core sample. They were contained within crystals in a type of suspended animation until 'revived' in a laboratory. Maybe bacteria are natural space travellers!

For the theory of Panspermia to have credence, we must show that life could exist in the harsh condition of space. It was once thought that outer space is just too harsh an environment for life to exist, these environments were outside the limits (we defined) of life. They were too hot, or they were too cold, or they didn't have liquid water. But scientist have began to discover microbes that live in some of the most inhospitable environments imaginable here on our own planet. These 'miracle' microbes seem equally at home in the scalding hydrothermal vents deep in the Pacific ocean as much as buried beneath the frozen wastes of the Antartic. Some examples of these microbes, so called extremophiles, which live, reproduce and indeed thrive in harsh environments on Earth are;

  • Alkaliphiles thrive in high pH environments such as in Mono lake, California. Here, Richard Hover, a NASA scientist and extremophile 'hunter' has identified microbes thriving in this extreme condition of high alkalinity with a pH of 10. In fact when they are exposed to Oxygen they can't survive!
  • Psychrophiles thrive in cold temperature. They are found in Antartica, as well as the harsh Siberian, Alpine and Artic environments.
  • Hyperthermophiles thrive in very high temperatures, and are found in hot springs and deep-sea thermal vents.

Microbes have even been discovered in a highly alkaline water in the presence of nuclear fuel rods. They are able to live and thrive in this incredibly high radiation and high alkaline environment and feed on the iron from the stainless steel of the reactor.

In fact man has participated unknownly (at the time) in panspermia. Surveyor 3 landed on the moon in April 1967. In November 1969 the Apollo 12 astronauts recovered the camera attached to Surveyor 3. And when the camera was analysed back on Earth, microbes were detected inside it. These were a common Earth microbe and were shown (how?) to have been been in the camera at launch. But how could microbes survive for 30 months, in a vacuum, with no water, in extreme cold and heat and completely unprotected from the high levels of radiation from the sun? Well apparently they are made of sterner stuff than you or I! So evidently microbes can be transferred from one planet to another (the moon) and could survive in the harsh environment of the moon. This is possibly the most important discovery of any mission to the moon! After all, isn't this the essence of panspermia?

One lesson learned from this incident is how vital it is not to contaminate the places we travel to in space. And how could we distinguish if discovered microbes were alien or some contaminant brought along with the space ship? And more importantly, we need to ensure that any samples returned to Earth in the future do not pose a biological risk to terrestrial life. Planetery Protection Officer, John D Rummel, is at the helm for NASA to do just this.

Meteors too have a part to play

Hundreds of tonnes of meteorites make their way to the Earth's surface each year. Of these, the Carbonaceous Chondrite meteorites would appear to be the most suitable taxi ride for alien bacteria, as they have been discovered to contain water and organic compounds. But do they show any evidence of life?

The Murchison meteorite, which fell in Australia in 1969 has been extensively studied. When examined under an electron micorscope, complex structures were identified, There shape along with some precise details such as reproductive structures, suggested evidence of life in that it appeared to contain the remains of living organisms. But this claim is contentious.

The Murchison meteorite contained over 100 amino acids (the protein builders), both common to Earth and alien to Earth. The chirality or handedness of the amino acids was equally left and right handed, suggesting that they were not as a result of Earth contamination as amino acids on Earth are left-handed. But the jury is still out, with many scientists convinced that you cannot just easily dismiss these discoveries as recent contamination.

Life on Europa?

Will we find life on Europa, one of Jupiters moons? There are plans to send a robot to find alien life on Europa in the near future. Europa is of great interest, because we are almost certain it has water.


It has an icy exterior but we can see the tidal cracking of the ice from high resolution photographs taken by NASA's Galileo spacecraft in 1997, similar to what can be seen on Earth. So there must be an ocean of water underneath. The planned mission is for a lander to land in a safe area, when a second stage of the lander will then melt its way thru 2-3 kms of ice. A third stage will then be able to manoeuvre in the ocean and test for the presence of life. We shall await with bated breath.