At first glance through a telescope, Mars seems like it is very much a potentially habitable planet – there are clouds, polar icecaps and an axial tilt – all of which imply seasons.
These so-called seasons and calendar are very similar to the Earth’s, only Mars’ days are thirty-seven minutes longer than our own. Though the seasons are longer because a Martian year is two Earth years, the axial tilt and day length on Mars are similar to Earth’s values. In the late nineteenth century, astronomers also noticed a “wave of darkening.” What was described was a seasonal coloring of the planet, something that also happens on a global scale.
In 1877, the Italian astronomer Giovannni Schiaparelli looked at Mars through his telescope, and found that Mars had a series of trenches, which he decided to call canali, the Italian word for “channels.” Funnily enough, people like Percival Lowell interpreted that has canals, which are artificial structures, thinking that he was implying that there were Martians out there that had dug the trenches at some point.
Unfortunately, the seasonal coloring has been attributed to seasonal dust storms; there is no plant life on Mars. Although Schiaparelli’s canali do not exist, there are smaller erosional features that could have possibly be formed by the flow of liquid water in the relatively recent past. Additionally, the channels that were discovered by Schiaparelli, were not built by Martians, which would have demonstrated that there is life on Mars; however, if these channels were formed by flowing water, though likely sporadically and in the past as appears it appears to be, then this would suggest that there were life sources available at one point in Mars’ history.
Unfortunately, with better technology and equipment, has come the definitive knowledge that there was no existing Martian life, but there are some advantages to having better equipment. The telescopes that showed that there was no life on Mars, also supported the observation of widespread seasonal color changes. This also means that while it is highly unlikely that Mars ever had civilizations, there was at least harboring plant life. However, this implication has been contradicted by scientists that have concluded that Mars’ atmosphere is dangerously thin, containing a large amount of carbon dioxide and also lacks observable oxygen or water vapor. Though some life may have still been able to exist without that, Mars’ lack of observable oxygen or water vapor in its atmosphere definitely make it uninhabitable for humans, and a poor choice for terraforming. However, if humans came up with the technology to alter the atmosphere of Mars and withstand the planet’s harsh conditions, Mars could be terraformed into being habitable.
Overall, one can conclude that Mars is currently uninhabitable for humans, as well as any other life. Though Mars may have had life many years ago, there is no clear evidence to definitely prove that. Conversely, should humans come up with advanced enough technology, terraforming of Mars could make it habitable for humans.