Ever since the Voyager probes sent us the first detailed images of landscapes of our solar system more than 40 years ago, we have gradually been discovering the fascinating appearance and composition of our neighbouring planets. The photographs that have come to us from the outside show inhospitable and unusual places, but so attractive that they have even inspired a fictitious space tourism advertising campaign launched by NASA’s Jet Propulsion Laboratory.
While we wait patiently for interplanetary travel to become a reality, we search for landscapes at the ends of the Earth that look like they could be found on these extraterrestrial worlds, and that have been used as “planetary analogues” to train astronauts, prepare space probes and robots, or do research for future space missions.
1. Askja region in Iceland
A gigantic eruption on 29 March 1875 led to the current caldera of the Askja volcano in Iceland. The force of the explosion sent volcanic material all the way to Norway, Sweden, Germany and Poland, more than 2,500 kilometres away. It was not the first time this volcano had awakened. For 10,000 years, Askja has been periodically erupting in an unpredictable way, generating immense lava fields and craters, and shaping a desolate landscape reminiscent of the moon. In fact, in the 1960s, NASA considered the region’s basaltic rocks and volcanic geology to be the most Moon-like panorama they could find on Earth.
NASA chose this area for the astronauts of the successful Apollo mission to carry out training exercises for landing on the Moon. Neil Armstrong and Buzz Aldrin, the first people to step on our satellite, travelled there in 1967 to practice procedures they would have to perform in outer space, such as collecting geological samples. Last summer, NASA returned to Askja, but this time to test a Mars rover they hope to send to Mars in the spring of 2020.
2. McMurdo Dry Valleys in Antarctica
According to the European Space Agency’s catalogue of planetary analogies, the McMurdo dry valleys are the most similar place on Earth to the past and present characteristics of Mars, due to their peculiar combination of terrains, which represent the largest area of Antarctica devoid of ice. Although they don’t show the typical colour of the red planet, the dry valleys do exhibit other similarities, which include intensely cold and dry deserts, ice wedges and flows, and glaciers such as those observed on Arsia Mons, a volcano 435 kilometres in diameter located near the Martian equator.
With one of the most extreme climates on the planet —the McMurdo dry valleys harbour the coldest desert on Earth— NASA is searching there for some kind of microscopic life that could also withstand harsh Martian conditions, to get clues as to what to look for in future expeditions to Mars. In addition, NASA has used the harsh conditions of this Antarctic site to test how an inflatable habitat prototype would behave, which could serve to house a colony of astronauts on the Moon.
3. Kilauea Volcano in Hawaii
The basalt flows of the Kilauea volcano in Hawaii are reminiscent of the landscape of Venus, the hottest planet in the solar system with average surface temperatures above 400ºC. The brightest planet in the sky has a surface made up of 90% basalt, which is riddled with magmatic rocks and lava plains. Venus has no tectonic plates or water, so all its volcanoes are of the shield type, like Kilauea. These volcanoes are characterised by their enormous size and distinctive low profile, formed by successive layers of basalt that forms particularly fluid lava, which emerges in recurrent eruptions that can last for millions of years.
Shield volcanoes are so named because their shape is evocative of the typical protection borne by a warrior. Kilauea continuously expelled lava at more than 1200ºC from 1983 to 2018. The study of this volcano helps scientists learn about how volcanoes work on other planets. It especially allows us to understand the intense activity that Venus, the planet with the most volcanoes in the solar system, must have endured, and of which there is hardly any trace today.
4. Namib Desert in Africa
The south of the African continent encloses the Namib Desert, stretching over 2,000 kilometres along the Atlantic coasts of Namibia, Angola and South Africa. Its sand, gravel and earth offer a good planetary analogy for both the Moon and Mars. The dunes of the Namib, with a height of 300 metres, a length of 32 kilometres and an orange colour, are the most similar to those on Mars that we can find on Earth. Analysing their formation and movement can help us to understand the evolution of the dunes of our neighbouring planet.
The Namib Desert lacks water on its surface, but is home to underground rivers that are dry most of the year, conditions very similar to those proposed by NASA for a primitive Mars. Studying the presence of life in these conditions may allow us to recognise it more easily outside our planet.
5. Pavilion Lake in Canada
Pavilion Lake, near Vancouver in Canada, contains the most diverse microbialites, a type of bio-fossil construction that is the oldest sign of life on Earth. The study of this species of bacterial reef can reveal in detail the appearance of the first terrestrial life forms, which may help us locate them in the future in other places of the solar system, such as in the oceans found on some of the moons of Jupiter.
NASA is also studying cyanobacteria, also known as blue-green algae, which would be the descendants of the microbialites that inhabit the extraterrestrial landscape of this lake, formed by irregular green and grey mounds the size of tables, some in clusters and others alone. In a similar way to plants, although they are not so, cyanobacteria feed on sunlight and grow in shallow water.