NASA identifies the cause of Mars' "water shortage".

After nearly a decade of orbiting Mars, NASA's MAVEN spacecraft has for the first time directly observed a process that scientists have long suspected is the primary culprit behind the Red Planet's loss of its atmosphere.

This discovery could help answer the big question of how Mars transformed from a potentially habitable world with rivers and lakes into the icy, almost atmosphere-free desert it is today.

Although Mars is currently dry and cold, its surface bears irrefutable evidence of a much "wetter" past.

Topographic features such as ancient river valleys, shallow lakebeds, and minerals that only form when water is present suggest the existence of long-lasting lakes, possibly even shallow seas, on the surface of Mars billions of years ago.

However, for liquid water to exist, Mars would need a much denser atmosphere to retain heat and maintain higher surface pressure.

Over the past decade, scientists have gathered increasing evidence that solar wind – the continuous stream of ionized particles emitted from the Sun – and radiation have eroded much of Mars' atmosphere.

One of the most important mechanisms behind this erosion is the process of "sputting." In this process, high-energy particles from the solar wind collide with the planet's upper atmosphere, transferring enough energy to neutral atoms, allowing them to escape Mars' gravity and fly into space.

Shannon Curry, principal investigator for the MAVEN mission at the University of Colorado Boulder and lead researcher on the new study, used an analogy: "It's like doing a 'bomb drop' jump into a swimming pool (hugging your knees to maximize the impact on the water's surface). In this case, the 'bomb' is the heavy ions from the Sun hurtling rapidly into the atmosphere, scattering neutral atoms and molecules."

Although sputtering has long been considered a key factor in Mars' climate change, this is the first time the process has been directly observed.

Using data collected over nine years from the MAVEN spacecraft, Curry and her colleagues documented the sputtering phenomenon that is occurring on Mars today.

According to Curry, these results establish the role of sputtering in the loss of Mars' atmosphere and in determining the history of water on Mars.

To fully determine whether sputtering is truly the primary driver of Mars' long-term climate change, scientists will need to look back billions of years into the past using models, isotopic data, and clues to ancient climates.

(VNA/Vietnam+)

Source: https://www.vietnamplus.vn/nasa-xac-dinh-nguyen-nhan-sao-hoa-can-nuoc-post1042485.vnp