Mars may have all the elements that could support life billions of years ago but something catastrophic happened that transformed it into a lump of wasteland in space.
It was found that the Martian atmosphere, as thick as the Earth's, evaporated into space due to radiation and solar wind.
"We've determined that most of the gas ever present in the Mars atmosphere has been lost to space," Bruce Jakosky, principal investigator for the Mars Atmosphere and Volatile Evolution Mission (MAVEN) at the University of Colorado in Boulder, said.
Jakosky, also the lead author of the study, added that about 65 percent of argon present in the atmosphere has been lost to space.
The research was published in the journal Science on March 31.
The Mystery That Was Mars
The thin Martian atmosphere, with a density less than 1 percent of Earth's, makes it vulnerable to sudden daily changes of temperatures.
Previous studies have shown that Mars had the characteristics similar to Earth. The dry riverbeds and mineral formations pointed to one probable explanation — water was present on the planet.
The early Mars, as the presence of water suggests, was once covered with thick layer of gases enough to nurture life.
It has been a mystery for most what really happened through time.
Lost To Space
NASA launched in 2013 a robotic probe dubbed as MAVEN to help solve the mystery of the Red Planet.
The spacecraft began its orbit around Mars a year after its launching and had accomplished over 4,000 orbits skimming some 100 miles off the surface of the planet.
MAVEN had generated ample data for scientists to analyze. The study led researchers to focus on argon, a very stable element.
By looking into two types of argon isotopes — the lighter argon (Ar-36) and the heavier argon (Ar-38) — the scientists have found that Argon-36 was more abundant on a higher altitude, which led to being scraped by solar radiation and solar wind.
The team said the presence of two isotopes of argon at the different layers of Mars atmosphere could mean that some 66 percent of its argon had been evaporated to space since the planet's existence.
"The escape of gas to space might have played a major role...in changing the climate of Mars over time," Jakosky said.
A Process Called Sputtering
Researchers focused on argon because, as a "noble gas", it can only be scraped by the solar wind through sputtering. Sputtering happens when the particles picked up by the streams of protons and electrons from the sun would crash at high speed on Mars knocking the gas in the atmosphere in the process.
By determining how much argon was lost, the scientists could also determine the number of atoms and molecules in the atmosphere lost by sputtering.
"This discovery is a significant step toward unraveling the mystery of Mar's past environments," MAVEN program scientist Elsayed Talaat at NASA Headquarters, said.
This finding, Talaat said, could help explain not only what had caused the changes in Mars but also the "processes that can change a planet's habitability over time."
