AND 24 OTHER AMAZING DISCOVERIES ON THE RED PLANET

1 MARS LOOKS LIKE A DEAD PLANET

Since the invention of the telescope in the 1600s, astronomers have been fascinated by the surface of Mars. It’s too far away to resolve from Earth, and the atmospheres of both planets interfere with the passage of light, but they noticed dark and light patches that moved as the year passed, speculating that they might belong to clouds, seas and even forests. In the 19th century, Italian astronomer Giovanni Schiaparelli described a series of channels that he saw in the surface of the planet, imagining that there might be water on the surface, but a mistranslation of the Italian word ‘canali’ led American scientists, most notably Percival Lowell, to believe that the Red Planet was actually covered in canals, possibly built by intelligent life.

Hopes of an Earth-like planet were dashed when NASA’s Mariner 4 captured the first ever close-up images of the surface during a flyby in 1965. The 22 stills showed craters, reminiscent of the scarred surface of the Moon, and revealed the planet to be a barren waste covered in red dust and rubble. Measurements detected no magnetic field, and barely any atmosphere. For years after, scientists thought Mars was a dead planet whose geological activity stopped billions of years ago. But subsequent missions revealed that there’s much more to Mars than meets the eye.

Schiaparelli observed ‘channels’ on Mars

© NASA; Getty; Webb

2 MARTIAN DUST IS MAGNETIC

The Red Planet owes its distinctive colouration to iron, which was detected in high quantities in the soil by the Viking landers in 1976. Its surface is coated in a fine layer of dust, which after billions of years of winds and storms has been ground down to a consistency finer than talcum powder. The Imager for Mars Pathfinder (IMP), attached to the Carl Sagan Memorial Station, which landed in 1997, used the difference in atmospheric brightness throughout the day to measure the size of the airborne dust particles, revealing that they measure about three microns in diameter on average. In 2004, NASA’s Spirit rover carried permanent magnets to the surface of the planet to probe the dust further, confirming that almost all of the dust on Mars is magnetic, whether in the air or on the ground. Two angled magnets captured particles from the atmosphere, revealing different oxides of iron, strongly magnetic dark material that is either magnetite or maghemite plus lighter, less magnetic haematite. The rover also carried a strong magnet near its panoramic camera that repelled the dust, protecting the equipment and ensuring the images remained clear.

3IT’S HOME TO THE TALLEST MOUNTAIN IN THE SOLAR SYSTEM

The first orbiter to visit Mars was NASA’s Mariner 9, tasked with mapping 70 per cent of the surface. When it arrived in 1971, the planet was engulfed in a dust storm that completely obscured the view of the ground below, and the orbiter had to wait for several months for the dust to settle. As the storm subsided, the highest points were revealed first, and four enormous volcanoes started to appear above the sinking clouds. They were large and domed in appearance, and the sides had gentle slopes reminiscent of shield volcanoes on Earth.

The tallest of the Martian shield volcanoes is Olympus Mons, measuring 624 kilometres (374 miles) across and extending nearly 26 kilometres (16 miles) above the ground. It easily dwarfs every other peak identified in the Solar System to date. For comparison, the tallest volcano on Earth, Mauna Kea in Hawaii, extends 10,200 metres (33,400 feet) above the floor of the Pacific Ocean.