In the 1970s, signs were seen in the atmosphere and surface of Mars that life once had a chance there.
In April 1974: Mars may once have had an atmosphere suitable for life. Although the atmosphere is thin today, there are signs that it may have resembled Earth’s atmosphere at one time.
The Soviet Mars 6 probe, which landed on the planet Mars last month, studied the composition of the Martian atmosphere during the landing. The density of the Martian atmosphere is only one-hundredth that of Earth’s and is believed to be mainly carbon dioxide.
However, according to information published in Izvestija, the probe found that the Martian atmosphere contains tens of percent argon. – –
The relatively high proportion of argon suggests that Mars may once have had an atmosphere similar to Earth’s. The Earth’s atmosphere contains about one percent argon. – –
According to some American scientists, this could confirm the theory that conditions on Mars vary over long periods. Sometimes Mars would have an ice age, like right now, after which the climate would become warmer and wetter again.
During these seasons, life could appear on Mars. The length of such periods has been calculated to be 50,000 years. The changes are due to periodic fluctuations in the direction of the rotation axis of Mars, as a result of which the polar regions of Mars periodically receive more sunlight than usual and the polar glaciers melt.
The theory about climate variations is also supported by the canyons and troughs on the surface of Mars photographed by the American Mariner 9 two years ago. In the pictures, they are similar to the traces left by flowing water on the Earth. – –