SCIENTISTS have proposed a variety of ways to maintain a human presence on Mars - and terraforming is the key, they say.
Nasa is looking into ways to house astronauts and construct habitats on the Red Planet.
After the Moon, Mars is regarded as the next rational place that could sustain human life.
Researchers have found evidence that liquid water once flowed on the planet's surface, from possible river valleys and erosion to branched tributaries.
This discovery sparked an interest in terraforming Mars or otherwise modifying the planet to make it habitable.
However, scientists must pass through a series of hurdles before the red planet is deemed a fitting place to live.
The planet's atmosphere is only about 1% as dense as Earth's and virtually devoid of oxygen.
The lower the density of an atmosphere, the less heat it retains. On Mars, the nightly temperature can plummet to negative 150 degrees Fahrenheit or negative 101 degrees Celsius.
Scientists have considered ballasting the planet's surface with water-bearing comets and asteroids, using nuclear engines to guide them.
The process would release gases trapped beneath the surface into the atmosphere and simultaneously release water from the comets.
While the proposition may seem far-fetched, Nasa has demonstrated it is possible.
The agency's Double Asteroid Redirection Test smashed into an asteroid in September 2022, proving a kinetic impactor could deflect asteroids on a collision course with Earth.
Despite the promising results, scientists would have to find a way to direct many huge asteroids toward Mars to see results.
Going hand in hand with the sparse atmosphere is the temperature problem.
Scientists have considered using enormous mirrors to reflect sunlight onto Mars, in the form of 200,000-ton Mylar disks stretching 155 miles long.
The same greenhouse gases that pollute Earth are key to warming Mars and making it a suitable place to live.
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Researchers propose concentrating mirrors on the planet's polar caps to melt the ice and release the carbon dioxide contained within.
Eventually, the rise in temperature would release greenhouse gases like chlorofluorocarbons - though this would take many years.
If such an idea were to pan out, scientists would first have to find a way to assemble such large mirrors, which would most likely be constructed in space.
Another endeavor is growing plants on Mars, both to convert carbon dioxide to oxygen and serve as a food source.
Settlers would first have to devise a way to shield plants from the planet's extreme temperatures.
Next, they would have to find a substrate because there is no usable soil on Mars.
The red planet is covered in nutrient-poor material called regolith, which also contains perchlorates - harmful chemicals found in Earthly fireworks and explosives.
Scientists must find a way to fertilize regolith, most likely by adding enzymes that can withstand harsh conditions.
Extremophilic phosphatase is one possibility already used in industrial agriculture.
Genetically engineered microbes are another, though any additives would have to be imported from Earth.
If plants are able to thrive on Mars, contributing to the atmosphere, this could later lead to the introduction of more complex organisms.
