This article comes from the WeChat public account: SF Chinese (ID: kexuejiaodian), by the author SF.
Mars is very close to the Earth and has the potential to become a habitable place for humans in the future. However, one major drawback of Mars at present is that the temperature is too low, so scientists have come up with many ways to warm Mars up. The recent method of 'using local materials' to make aerosols proposed by scientists may be more efficient than previous assumptions.
One-third of the Martian surface has shallow water deposits, but the surface of Mars is now too cold for survival. Scientists have proposed using greenhouse gases to warm Mars up, but in fact, the greenhouse gases that are quite a headache for us on Earth are not that common on Mars.
Recently, an article published in Science Advances shows that scientists from Northwestern University, the University of Chicago, and the University of Central Florida have found a more feasible method that can'surge' the surface temperature of Mars.
According to the exploration results of the 'Curiosity' rover, we know that Martian dust is formed by the weathering of minerals rich in iron and aluminum on the Martian surface. These dust particles are very fine, with an effective radius of only about 1.5 microns and can be thrown to an altitude of 15 to 25 kilometers above the Martian surface, and sometimes even appear at an altitude of more than 60 kilometers. During the day on Mars, the aerosol composed of this dust can reduce the temperature of the Martian surface.
From this point of view, Martian dust is not suitable for heat preservation. But in this study, the scientists made a special design based on Martian dust as a prototype and created some 9-micron-long conductive nanorods. The aspect ratio of these nanorods is about 60:1, and the materials are mainly aluminum and iron. The calculation results show that the thermal infrared scattering of these nanorods is nearly isotropic, which is beneficial to the heating of the material surface.
In addition, simulation experiments show that if these nanorods settle in the Martian atmosphere, the speed is less than 1/10 of that of natural Martian dust. This means that compared to natural Martian dust, these nanoparticles are more likely to be sprayed into the high altitude and can stay in the Martian atmosphere for a longer time, with an average of up to 10 years.
If in the future, we can create a density of 160 mg/m2 of aluminum nanorods on the Martian surface, perhaps it will be possible to have liquid water in many places where there are shallow water resources (currently in the form of ice) during Mars summer.
To achieve this, we need to continuously release aerosol made of this kind of nanoparticle into the Martian atmosphere at a speed of 30 liters per second. The simulation results show that in this way, the entire Martian surface can be warmed up by 30°C within a few months and reach about -50°C - at this temperature, many microorganisms will not be a problem to survive.
Although we still need to produce hundreds of thousands of tons of aerosol, compared to the previous method of using greenhouse gases such as fluorides of carbon or sulfur to warm Mars up, the new method has a warming efficiency that is 5000 times higher.
In creating a habitable environment on Mars, the ultimate vision is to hope that life can appear on Mars. If a photosynthetic biosphere can be established on the Martian surface, maybe with the help of synthetic biology, humans can go to Mars to multiply and reproduce in the future.
However, if the Martian rock strata contain substances that are toxic and irreparable to Earth life, then Earth life may not benefit from the warming of Mars.
In addition, if there is life on Mars now, we also need to consider wh ether this method of using nanoparticles to warm Mars will threaten this life.
Warming Mars can turn the solid water resources on Mars into liquid water that is more accessible to life, but at the same time, the increase in temperature will increase the evaporation of water. Therefore, we also need to monitor whether a large amount of water resources (including ice and liquid water) stored in the pores underground on Mars are replaced by gas during the warming process.
Considering factors such as precipitation again, we need to assess whether it is worth losing so much water for the purpose of raising the temperature.
Reference:
https://www.science.org/doi/10.1126/sciadv.adn4650