What conditions that make life possible on Earth are found missing on Mars? How have the various Mars Missions tried to overcome these inhibiting factors?
Answers
Answer:
After Earth, Mars is the planet with the most hospitable climate in the solar system. So hospitable that it may once have harbored primitive, bacteria-like life. Outflow channels and other geologic features provide ample evidence that billions of years ago liquid water flowed on the surface of Mars. Although liquid water may still exist deep below the surface of Mars, currently the temperature is too low and the atmosphere too thin for liquid water to exist at the surface.
What caused the change in Mars' climate? Were the conditions necessary for life to originate ever present on Mars? Could there be bacteria in the subsurface alive today? These are the questions that lead us to explore Mars. The climate of Mars has obviously cooled dramatically. By studying the reasons for climate change on Mars, which lacks the complications of oceans, a biosphere, and industrial contaminants, we may begin to understand the forces driving climate change on Earth. As we begin to explore the universe and search for planets in other solar systems, we must first ask the question 'Did life occur on another planet in our own solar system?' and 'What are the minimal conditions necessary for the formation of life?'
What Are We Looking For?
The planet Mars landed in the middle of immense public attention on July 4, 1997, when Mars Pathfinder touched down on a windswept, rock-laden ancient flood plain. Two months later, Mars Global Surveyor went into orbit, sending back pictures of towering volcanoes and gaping chasms at resolutions never before seen.
In December 1998 and January 1999, another orbiter and lander were launched to Mars. And every 26 months over the next decade, when the alignment of Earth and Mars are suitable for launches, still more robotic spacecraft will join them at the red planet.
With the announcement in 1996 by a team of scientists that a meteorite believed to have come from Mars contained what might be the residue of ancient microbes, public interest became regalvanized by the possibility of past or present life there. The key to understanding whether life could have evolved on Mars, many scientists believe, is understanding the history of water on the planet.
Explanation:
Has there ever been life on Mars?
What is the evidence for, and timing of, warmer, wetter past conditions?
Where is the evidence for past life likely to be found on Mars?
How do we recognize evidence of past life and sample Mars properly?
What is the geology and inventory of resources on Mars?
What is the interior structure of Mars and is the planet active today?
What do the global topography and geologic structure tell about the planet's evolution?
What are the global inventory and distribution of near surface materials and volatiles?
Should Mars be the next destination for human exploration?
Mars And Water
Mars perhaps first caught public fancy in the late 1870s, when Italian astronomer Giovanni Schiapparelli reported using a telescope to observe canali, or channels, on Mars. A possible mistranslation of this word as canals may have fired the imagination of Percival Lowell, an American businessman with an interest in astronomy. Lowell founded an observatory in Arizona, where his observations of the red planet convinced him that the canals were dug by intelligent beings - a view which he energetically promoted for many years.
By the turn of the century, popular songs told of sending messages between Earth and Mars by way of huge signal mirrors. On the dark side, H.G. Wells' 1898 novel The War of the Worlds portrayed an invasion of Earth by technologically superior Martians desperate for water. In the early 1900s novelist Edgar Rice Burroughs, known for the Tarzan series, also entertained young readers with tales of adventures among the exotic inhabitants of Mars, which he called Barsoom.
Fact began to turn against such imaginings when the first robotic spacecraft were sent to Mars in the 1960s. Pictures from the first flyby and orbiter missions showed a desolate world, pockmarked with craters like Earth's Moon. The first wave of Mars exploration culminated in the Viking mission, which sent two orbiters and two landers to the planet in 1975. The landers included experiments that conducted chemical tests in search of life. Most scientists interpreted the results of these tests as negative, deflating hopes of a world where life is widespread.
The science community had many other reasons for being interested in Mars apart from searching for life; the next mission on the drawing boards, Mars Observer, concentrated on a study of the planet's geology and climate. Over the next 20 years, however, new developments in studies on Earth came to change the way that scientists thought about life and Mars