But Mars is an extremely inhospitable place. Average temperatures are around -60 °C, the atmosphere is unbreathable, radiation is intense, and liquid water is almost non-existent. This is not a paradise waiting to be settled. If it is decided to send astronauts, the costs and benefits of this initiative should be carefully evaluated and whether it is worth taking this risk should be seriously considered.
Producing food and oxygen on the planet itself will significantly increase the quality of life and autonomy of the crew. Because plants can do both, several lines of research have focused on developing agricultural systems adapted to Mars. If we can achieve this; food, oxygen, beneficial compounds, and psychological benefits for those who will be away from Earth for months. Although the idea is simple, putting it into practice is not that easy.
Perchlorate Problem
Novels and movies have imagined farming on Mars as something very simple. According to the scenarios, it was enough to mix Martian soil with organic matter and plant the vegetables we wanted. The truth is much more complex. The planet’s soil is chemically hostile to both plants and humans on a global scale.
Various space missions, from Viking to Phoenix, Curiosity to Perseverance, have detected large amounts of perchlorate in the material covering the planet’s solid rock bed. Perchlorates are colorless, highly water-soluble salts that have spread across the planet in giant dust storms. Their effects are devastating: They make germination difficult, disrupt plant metabolism, and can seriously affect human health.
Mysterious Dunes: A Ray of Hope?
The Martian surface is rich in sulfates, especially gypsum. The largest gypsum formation on Mars is found in the Olympia Undae dunes near the North Pole. Polar winds may have kept this region isolated from global dust transport. The tops of these dunes have a high gypsum content, meaning they may be locally perchlorate-free safe areas. So, what do plants have to do with gypsum?
Survival Plants: Gypsophila
There are species on Earth that not only tolerate such soils, but also depend on them: Gypsophiles (gypsophila plants). These plants have adapted to soils rich in calcium sulfate, poor in nutrients, and water scarce.
Some can even use the water inside gypsum crystals. These plants are in a way “prepared” for the Martian soil, if not for the Martian climate. They can be grown successfully in a greenhouse with temperature and atmosphere control.
Pioneer Plants and Genetic Editing
Among these plants, Gypsophila struthium especially stands out. It is drought resistant, germinates quickly and easily invades vacant lands. Another important plant is Ononis tridentata, which has the ability to fix nitrogen.
Although these plants are not directly food products, they produce compounds used in medicine.
By improving the soil, they prepare the way for edible species. With genetic editing tools such as CRISPR, the salt tolerance or water efficiency traits of these plants can be transferred to tomatoes or grains.
The First Earthlings on the Red Planet
There are still many questions surrounding growing plants on Mars; such as the effects of low gravity and radiation on growth. However, the strategy proposed in a new study published in the journal Life Sciences in Space Research is this: to evaluate Martian gypsum beds as a growth environment and use gypsophilic plants on Earth as a model.
Perhaps the first Earthlings on Mars will not be us, but these hardy plants that can live in places where almost nothing else can survive.
