When it comes to space missions, no other planet has ever inspired humans to explore more than planet Mars.

International space agencies like NASA, ESA and Russia’s Roscosmos are expected to boost Martian exploration starting next year while private space agencies like SpaceX targets to send cargo to the Red Planet by 2022. On the other hand, countries such as Israel and China have already begun training for humans to adapt to the Martian environment.

However, recent studies reveal that human colonies in Planet Mars could be very difficult and even downright impossible. During a study that tried to compare both the Earth and Mars’ atmosphere and bodies of water billions of years ago, NASA scientists were able to differentiate why Earth has become a living breathing planet while Mars practically died in time.

According to Forbes, both planets had liquid water covering large portions of its surfaces at a time when the sun was still cooler. The presence of greenhouse gases basically kept both planets warm and wet with scientists concluding that organic life existed not only on Earth but in Mars as well.

However, dramatic changes in the atmosphere have resulted in very different outcomes to both Mars and Earth. Our planet remained temperate owing to its oxygen-rich atmosphere while Mars simply lost its atmosphere and with it, any sign of life.

According to the report, while Earth oceans have been pH-neutral (as evidenced by carbonate rocks precipitating out), Mars’ bodies of water were combined with the mineral, sulfur.

NASA scientists, through data gathered from the rover Opportunity's discovery of the mineral jarosite, believe that Mars is not only rich in carbon dioxide but also sulfur dioxide. This means that the water surface of Mars may have been affected by one of the strongest acids in the world.

The report said that if the oceans were acidic enough, it could have engineered the reverse reaction to what happened on Earth - sucking carbonates from land to oceans while leaving sulfur-rich deposits.

This theory, coupled with Mars’ weak magnetic field (when compared to Earth) may have been the reason the Red Planet’s atmosphere has been affected more by solar flares and other particles from the sun. This would have affected Mars’ atmosphere so much that the planet can’t retain any of its water.

Using this theory only goes to show that Earth’s space agencies have a very difficult path ahead to successfully establish a human colony on the Red Planet. The presence of sulfur and Mars’ very thin atmosphere is a challenge that could cause the human exploration of the alien planet to fail.

mars Humans are ready to reach Mars. Pictured: In this handout provided by NASA's Mars Reconnaissance Orbiter, dark, narrow streaks on the slopes of Garni Crater are inferred to be formed by seasonal flow of water on surface of present-day Mars. Photo: NASA/JPL-Caltech/Univ. of Arizona via Getty Images