Despite enormous strides of humankind is making in the trip to Mars, getting there is only the beginning of the journey.
Ultimately, the mission is to make the Red Planet livable to humans.
There are multiple challenges to this goal, one of which is that Mars' freezing temperatures mean that liquid water can't exist on the planet.
While scientists such as Carl Sagan have previously suggested vaporizing the polar ice caps to raise the planet's global temperature, further research has shown that this wouldn't provide the required change in atmospheric levels to make the Mars habitable.
Now, a group of scientists from Harvard University has found a new path to terraforming Mars. Instead of transforming the entire planet in one massive undertaking, the new research in the journal Nature Astronomy is proposing a more regional approach and changing Mars bit by bit through silica aerogel.
"This regional approach to making Mars habitable is much more achievable than global atmospheric modification," explained lead author Robin Wordsworth of the Harvard John A. Paulson School of Engineering and Applied Sciences. "Unlike the previous ideas to make Mars habitable, this is something that can be developed and tested systematically with materials and technology we already have."
The Magic Of Silica Aerogel
Mars' polar ice caps are a mixture of water ice and frozen carbon dioxide, the latter of which allows sunlight to penetrate it and traps heat at the same time. This means that there are pockets of warming occurring beneath the ice in the summer.
Wordsworth revealed that the scientists thought about this solid-state greenhouse effect and wondered if it could be used to create habitable regions on Mars. To do so, they would have to find a material that could minimize thermal conductivity, while transmitting as much light as possible.
One of the most insulating materials around, silica aerogels are 97 percent porous and used in a number of engineering applications in aeronautics, such as the NASA Mars Exploration rovers.
"It wouldn't require large amounts of energy or maintenance of moving parts to keep an area warm over long periods of time," said Laura Kerber of NASA's Jet Propulsion Laboratory, describing the effect of silica aerogel as "passive."
In models and experiments, the research team demonstrated how a thin layer of silica aerogel could increase average temperatures of mid-latitudes on Mars to reach Earth-like temperatures.
According to Wordsworth, no additional technology would even be necessary: the material could simply be spread across a large surface area and there would be permanent liquid water underneath.
Challenges To The Mission
The results of the experiments are promising, but there are still various challenges remaining before scientists could begin using silicon aerogel on the Red Planet.
For instance, NASA noted that large quantities of aerogel is needed to produce a significant region with permanent liquid water. It would also take about two Mars years or four Earth years of warming. Logistics issues, such as the shipping and storing of the material, would also need to be resolved.
Wordsworth pointed out that ethical questions would also have to be explored in terraforming other planets.
"If you're going to enable life on the Martian surface, are you sure that there's not life there already? If there is, how do we navigate that," Wordsworth asked, adding that as soon as humankind commits to inhabiting Mars, these types of questions are inevitable.