The Search for Life on Mars

The Search for Life on Mars

SPACE-X | MARS | ELON MUSK | NASA | BLACK-HOLE | COSMOS | ASTROPHYSICS | UNIVERSE |

The most successful Mars probes to date have been the two Vikings, each of which consisted of an orbiter and a lander. Viking 1 was launched on 20 August 1975, and in the following June was put into a closed orbit round Mars.

 It continued the mapping program of Mariner 9, and some of the images were very detailed; one showed a rock on which light and shadow effects gave an uncanny look of a human face – a fact which was not overlooked by scientific eccentrics. 

On 20 July 1976, the lander was separated from the orbiter, and was brought gently down partly by parachute braking (useful even in the thin Martian atmosphere) and partly by rocket braking. The landing site was Chryse, (the Golden Plain) at latitude 22 degrees North, longitude 47.5 degrees West. 

The first images showed a red, rock-strewn landscape under a pink sky; temperatures were very low, reaching a maximum of 

31 degrees C near noon and a minimum of 

86 degrees C just after dawn.

  The main task of Viking 1 was to search for life. Material was scooped up, drawn into the spacecraft and analysed chemically for traces of organic substances. The results were sent back to Earth and were at first decidedly puzzling, but it has to be admitted that no positive signs of life were found. 

The results from Viking 2, which landed in the more northerly plain of Utopia on 3 September 1976, were similar. Windspeeds were measured, and the first analyses of the surface material carried out; the main constituent is silica (over 40 per cent). 

If there is any life on Mars today it must be very lowly indeed. Whether the situation was different in the past is not certain because of the evidence of old riverbeds; at some periods Mars may have been less unfriendly than it is now, and it is at least possible that life appeared, dying out when conditions deteriorated.

 We will know for certain only when we can examine Martian material in our laboratories, and this should be possible before long; an automatic probe should be able to land there and return to Earth with specimens for analysis. It now seems that there is much more ice below the Martian surface than used to be thought. 

The Odyssey probe, launched on 7 April 2001, has confirmed that icerich soil covers much of the planet, and that the southern polar cap is composed mainly of water ice, with only an upper coating of carbon dioxide ice.

 It has been estimated that if all the frozen water were released at once, the entire surface would be covered ankle deep in water. It has been claimed that some meteorites found in Antarctica have come from Mars, blasted away from the Red Planet by a giant impact, and that they contain traces of past primitive organisms. 

This is an interesting possibility, but the evidence is far from conclusive. We do not know for certain that the meteorites are of Martian origin, or that the features contained in them are indeed indicative of past life.

THE PATH FINDER MISSION

 On 2 December 1996 a new probe was launched towards Mars: Pathfinder, which carried a small ‘rover’, Sojourner. This time there was to be no gentle, controlled landing. Pathfinder was encased in tough airbags, and was designed to land at high speed, bouncing several times before coming to rest. 

It would enter the Martian atmosphere at a speed of 26,700 kilometres (16,600 miles) per hour; the touchdown would undoubtedly be violent, so that everything depended upon the airbags. Once Pathfinder had settled down and assumed an upright position, its ‘petals’ would open, so that Sojourner could crawl down a ramp on to the Martian surface.

 It was an ambitious project by any standards, and Sojourner itself was also unusual; it was about the size of a household microwave, but it was in fact a highly sophisticated probe, capable of carrying out on-the-spot analyses of the Martian rocks.

  Data began to come through even during the descent. The Martian atmosphere was both clearer and colder than it had been during the Viking landings of 1976; at a height of 80 kilometres (50 miles) above the ground the temperature was
160 degrees C.

 But everything went according to plan, and on 4 July 1997 – America’s Independence Day – Pathfinder landed safely on the old flood plain at the end of Ares Vallis.

 After a journey of over 480 million kilometres (300 million miles), Pathfinder came down within 20 kilometres (12 miles) of the planned impact point. It was then 190 million kilometres (120 million miles) from Earth; the ground temperature reached a maximum noon value of  

13 degrees C, though it plummeted to well below 

75 degrees C during the night.

  Almost at once, the main station used its camera to transmit a panorama of the entire scene; it seemed more interesting than Chryse or Utopia had been. The site, at the end of Ares Vallis, had been carefully chosen. The valley had once been a raging torrent of water, bringing down rocks of all kinds on to the flood plain, and this did indeed prove to be the case.

 Next, Sojourner emerged and began its work (there had been a minor delay because one of the airbags had not deflated completely after landing, and had to be manoeuvred away from the ramp). The rocks around were given distinctive nicknames, such as Barnacle Bill, Yogi and Soufflé (the main station itself had already been named in honor of Carl Sagan, the American planetary astronomer who had died not long before the mission). 

Sojourner’s track marks showed that the Martian ‘soil’ might be compared with the very fine-grained silt found in places such as Nebraska, USA; the grains were less than 50 microns in diameter, which is finer than talcum powder. 

Sedimentary rocks were identified, and this was not surprising, since water had once covered the region. There was, however, one major surprise. Though the rocks were essentially basaltic, andesite was also found. This occurs on Earth at the edges of tectonic plates, for instance round the border of the Pacific, but there is no evidence that plate tectonics also applied to Mars, so that the origin of the andesite remains a puzzle.

Here are the thoughts of  billionaire CEO of Tesla on colonizing Mars.