THE last time we spoke about the mighty midget of the Solar System, we were dismayed that over the millennia the opinions concerning man and his fate have survived. It is amply evident in the superstitious conclusions many of us hold related to horoscopes and other such frivolous matters related surreptitiously (stealthily) with planets.

Again, many amongst us maintain that the planets, stars and other celestial objects hold a key to our fate, and even our day-to-day lives. Now, fate is the cumulative outcome of our own doings (deeds) over a considerable period of time, including the acts absolutely beyond our control, like floods, earthquakes, endemics, wars and the more recently understood phenomenon, tsunamis et al.

But how can a planet — big or small — which isn’t even there in the skies for much/most of time in the course of its orbit, determine what form your and my life will take. Since this question is outside the ambit of science — and perhaps even common sense — we shall revert to the discussion on our dear little planet on scientific basis. Mars is evidently protective of its authority: it holds firmly in its grip the two little moons, tiny but fearfully named as Phobos, and Deimos, meaning, ‘fear’ and ‘panic’ respectively. The tiny moons on their part do not veer away from their parent planet by much.

Phobos (with dimensions of 27 × 22 × 18km) orbits close to Mars. Deimos is only 12km across and stays at some distance from Mars, but not much. From the desolate Martian surface at night it might appear shining as a steely dot of light, not like our own full moon which hangs in the sky like a huge and luminous football.

The interesting thing about these moons is that they are not shaped like moons i.e. round and smiling. Instead they are oddly shaped like a chipped piece of rock (or flint), flattish, dented with pock marks filled with dust and debris, cratered here and there, with the difference that the craters are big compared to the total surface, which suggests that the moons were bigger once but broke up in infancy.

For a big crater impact could force them to change course and rush out of the gravitational influence of the planet, or, crash into the planet altogether. For in my estimation, a body stays (maintains) its course provided that the body impacting it is no bigger than one thousandth its size. In the case of an intruder of comparable size, it will split open the crust of the body on which it crashes. This opening of wound on the surface of the planet, or a moon, might immediately lead to release of lava and earthquakes. Mountain ranges on many planets and their moons came to be there as a result of gashes thus caused.

On planet Earth, however, the story is different. But Earth will have to wait a little till its turn comes! Meanwhile, it is interesting to note that some craters caused by comet or asteroid impacts are so big that they cover up to about 45 per cent of the planet/moon’s surface. Yet these impacts failed to split the body at all. But then these are the vagaries which abound in astronomy. Yet, we shall have a lot more on comets and asteroids soon.

The origin of the Martian moons is no less intriguing. It appears that the moons came to be there by a cosmic accident and were not formed together with the planet. But then this appears to be the case of many moons. In all probability, the Martian moons are merely captured asteroids. Although it does not diminish their importance in any manner, the fact remains, as it evidently is, that ‘natural’ moons form quite differently i.e. they are bigger and ‘circular’. Their mass and gravity forces them to assume a round shape with the passage of time. Also, the moons tend to have come into being at the same time as the master planet itself, and possibly from the same nebular material.

On the contrary, some asteroids were ‘drawn in’ by close by planets, and remained there — shape or no shape. One important factor is the seepage or escape of gasses from deep within the interior of the body. Mass, and consequently the compression, plays a vital part in the game of formation, particularly after the planet or moon has gone through the initial stages of metamorphoses. Heavier, metallic elements gradually sink toward the bottom and lighter matter floats to the upper surface. At the same time, liquid — usually water — is ‘gassed out’, or squeezed outward on to the surface which determines the eventual fate of the planet (whether or not there will ever be life on this body).

But Mars surprised the most sceptical of the waiting scientists. Mariner 9 spacecraft made stunning discoveries about the planet: a world of giant volcanoes, huge canyons and old river beds! But our immediate concern is whether or not there is life, primarily somewhere in the Solar System besides our homily home, the planet Earth. Perhaps the one most intriguing question in astronomy is whether planets elsewhere harbour what we love to call ‘intelligent’ life.

Extra- terrestrial life, as it is popularly called, must either exist or not exist. Its consequences are striking as well as quite unpredictable. At this point in time I am reminded of the great Scottish writer, Thomas Carlyle, who is stated to have said, “... a sad spectacle. If they be inhabited, what a scope for misery and folly. If they be not inhabited, what a waste of space!”

What does planetary science say about the prospects of either situation? Meteorites have supplied some evidence of organic (carbon-based) chemistry in space. The organic molecules (complex carbon-based molecules) found in inter-stellar gas and debris offer provocative possibilities. But we must first understand what life is and under what favourable conditions life would come to exist on planets. Also important is the long process that triggered evolution of life on Earth. Along with it come many other questions that will grab our attention by and by, to which we shall try and find answers. We must understand that life is not a condition or a status, but a rather long-drawn process of chemical reactions using carbon-based molecules. Matter is taken into a system — whatever life form, whether man or animal or flora. The system in which these processes occur is the cell. All living things are composed of cells. These cells provide the body with energy and sustenance. Their numbers are large, very large. For instance, a human body comprises at least one trillion cells of a myriad variety. A cell in reality is much like a container filled with a complex variety of organic and inorganic molecules (protoplasm).

Codes for various processes of life are contained in complex molecules (such as DNA). These codes are carried in the nucleus, in the centre of the cell itself. However, it must be understood that all forms of life found in the remote reaches of the galaxy, even in other galaxies, may or may not be of the same (or common) basic structure as found here. Our minds should be open to receive form and shapes alien to our concept. The difference hinted here will form the basis of the next discussion on life in the universe and its possible forms and features, together with what is left about planet Mars.

The writer is a professional astronomer and a former head of PIA Planetaria. He can be reached at astronomerpreone@hotmail.com