Mars is rapidly losing water when it is closest to the sun, Hubble data shows

New research from the Hubble Space Telescope and NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) mission reveals that Mars loses water more rapidly when it is closest to the sun. These seasonal changes are linked to the planet’s orbit, where increased solar heating during perihelion accelerates the escape of hydrogen atoms from the Martian atmosphere. More than three billion years ago, Mars was warm and rich in water, but today it has lost most of its water and has become a dry, desolate world.

Seasonal effects on water loss

According to According to John Clarke of Boston University, Mars loses water in two ways: by freezing into the ground or by breaking into atoms and escaping into space. The planet still holds some water in its underground reservoirs and ice caps, but much of it has been lost over time. During the Martian summer, water vapor rises into the upper atmosphere, where solar radiation splits water molecules apart. The hydrogen atoms then escape into space, carried by the solar wind.

New observations from Hubble and MAVEN

The collaboration between Hubble and MYCIAN has shown that the hydrogen escape rate is highest during perihelion, when Mars is closest to the Sun. During this period, dust storms heat the atmosphere, accelerating water loss. The MAVEN data reveal that hydrogen escape rates are 10 to 100 times higher during perihelion than at the planet’s farthest point from the Sun, called aphelion. The instruments have detected that Mars has lost enough water over its history to form a global ocean that is hundreds of kilometers deep.

This new understanding of Mars’ water loss provides crucial insight into the planet’s evolution and the potential for life in the past.