Are we alone in the universe or is there life on other planets? And perhaps even as close our next door neighbor, the planet Mars?
Mars itself is – because it is further away from our heat source the Sun – a cold desert planet. So far without any signs of life nor liquid water on the surface.
In 2002 the Mars Odyssey Orbiter discovered that large amounts of frozen, below the surface, water (ice) might be present on Mars’ North pole. As water is an essential prerequisite for any life to exist, the Phoenix Mars Lander was dispatched to investigate. The Phoenix landed, safely and as scheduled, on May 25th, 2008. Now it is in the process of using its robot arm to scoop samples of Mars’ soil and examine these in its onboard lab for the presence of water and other substances as well as any signs of current or past life.
What can we expect to find? Could there be any life on Mars?
In many ways, Mars – just like Earth – is a very privileged planet. It is orbiting a steady burning star (our Sun) of the right size and age to provide a rather constant source of light and heat. Mars – just like Earth – is also in a perfectly suited solar system. Of the right age and providing protection from comets and asteroids through the presence of much larger planets (especially Jupiter) in its outer orbits. And Mars – just like Earth – is located at the likely only possible location in its galaxy (the Milky Way) that will provide enough building materials but is not in a (too) heavy populated area of solar systems. The vast, vast majority of solar systems in our (and other) galaxies are located near the center or on the spiral arms. These areas are overcrowded and therefore life destroying collisions (like on a busy intersection of highways) occur quite often. Only planets in solar systems in-between spiral arms (like our solar system) stand even a chance to provide a ‘safe’ environment for life to exist.
So, Mars is off to a promising start and in a much better situation that any other planet we know that might have a chance to be habitable for life. But that does not mean that it is perfect for life (like Earth is).
For starters, it is too cold. Even the simplest organic life forms require average temperatures above freezing and not exceeding the boiling point of water. Mars is therefore too cold with is average temperature below 0 degrees Fahrenheit.
And life requires liquid water. Water – and the presence of at least another 26 essential elements – is a prerequisite to even consider the possibility of life. Therefore the engineers at NASA targeted the Mars polar region not expecting to find current life but perhaps evidence of past life during a time when Mars might have been closer to the Sun and therefore having a more life-inviting temperature.
Still even the presence of liquid water and all other required elements, like carbon, oxygen, nitrogen and so on are not enough to make a planet potentially habitable. Studying life on Earth we now understand and appreciate that organic life also requires other conditions to be ‘just right’, like rotation speed, mass and gravity of the planet, presence and composition of an atmosphere, magnetic field around the planet, volcanic activity, plate tectonics, axial tilt, shape of the orbit, ozone levels and so on.
And if all these conditions at some time in Mars’ history might have all worked out, then that does not automatically imply that life also ‘developed’. Having all the building blocks of life present does not ‘automatically’ build life. Just like the presence of all building materials for a house on a property not ‘automatically’ erects a beautiful residence.
It is exciting to learn more about our universe and the complexity of life by using our most advanced scientific skills to study our neighboring planet. Let us just make sure that we objectively interpret the knowledge we have gained and will gain through the Phoenix Mars Lander and subsequent projects: our Earth is extraordinary uniquely positioned and composed to allow for life to exist. So uniquely and against all statistical odds that it gives a remarkable but resounding testimony to the words of Israel’s King David who wrote almost 3000 years ago:
“The heavens declare the glory of God” (Psalm 19:1)