A new theory suggests Mars is too small to retain water

Scientists have discovered evidence of water on Mars in the distant past, despite that the Red Planet has no liquid water on its surface today. Part of the research that scientists are conducting regarding Mars is what happened to the water they believe it had in the distant past. A new study from Washington University in St. Louis has suggested a new theory of what may have contributed to the loss of water on the planet.

The new theory suggests that Mars may be too small to keep large amounts of liquid water on its surface. NASA has images showing features in the landscape of Mars that are marked by river valleys and flood channels, so it likely had water in the distant past. Researcher Kun Wang, the senior paper author, believes there is a threshold on size requirements for rocky planets to retain enough water to enable life as we know it.

Researchers of the project studied isotopes of potassium to estimate the presence, distribution, and abundance of volatile elements on various planetary bodies in the solar system. Potassium is only a moderately volatile element, but it was chosen as a tracer to search for other volatile elements and compounds such as water.

Researchers measured the potassium isotope compositions in 20 meteorites confirmed to have originated on Mars, selected as representative of the composition on Mars. The team determined that Mars lost more potassium and other volatile's compared to Earth during its formation but retained its volatiles significantly better than the moon and an asteroid called 4-Vesta, which are smaller rocky bodies.

The team found a well-defined correlation between the size of the planetary body and the composition of potassium isotopes. The researchers also note that they don't believe Mars was wetter than Earth in the distant past, as some theories suggest.