The Earth-like atmosphere once present on Mars was likely stripped away from the Red Planet by high-speed solar winds, causing it to transition from a warm, wet world potentially capable of supporting life to the cold, arid planet it is today, NASA scientists have revealed.
In findings that were announced at a press conference this afternoon and published in the November 5 editions of the journals Science and Geophysical Research Letters, researchers used data from the US space agency’s Mars Atmosphere and Volatile Evolution (MAVEN) mission to calculate the rate at which the Martian atmosphere was losing gas to space because of the solar wind.
According to the New York Times, the study authors found that the planet’s atmosphere has been leaking away at a rate of about one-half pound per second, and that the erosion rate significantly increases during solar storms. In fact, they found that when Mars is bombarded by particles from the sun, its upper atmosphere is being stripped away 10 to 20 times more quickly than normal.
“Mars appears to have had a thick atmosphere warm enough to support liquid water which is a key ingredient and medium for life as we currently know it,” John Grunsfeld, associate administrator for the NASA Science Mission Directorate, explained in a statement released Thursday.
“Understanding what happened to the Mars atmosphere will inform our knowledge of the dynamics and evolution of any planetary atmosphere,” he added. “Learning what can cause changes to a planet’s environment from one that could host microbes at the surface to one that doesn’t is important to know, and is a key question that is being addressed in NASA’s journey to Mars.”
Past activity from the younger sun likely decimated atmospheric gas
Under normal circumstances, the solar wind strips atmospheric gas from Mars at a rate of about 100 grams per second, and while that might not seem like much, it adds up, MAVEN principal investigator Bruce Jakosky said. Furthermore, since the erosion rate tends to spike during solar storms, his team believes that the findings indicate it would have been much higher billions of years ago, when the sun was younger and more active.
The combination of increased loss rates and higher solar storm activity rates in the past indicate that the loss of atmosphere likely played a key role in changing the planet’s climate, the authors said. Previously, scientists using the NASA Mars Reconnaissance Orbiter observed the seasonal appearance of hydrated salts indicative of the presence of liquid water on Mars, but the current atmosphere of the planet is too cold and too thin to support lakes or rivers on the surface.
Furthermore, the MAVEN data reveals that the combination of solar wind and ultraviolet light have been stripping gas primarily from three regions of the planet: down the “tail,” where solar wind flows behind the planet; in a plume above the poles; and from an extended gas cloud that surrounds the Red Planet. Based on their calculations, they believe that nearly 75 percent of the escaping gas ions come from the tail, while almost 25 percent come from the plume and a slight fraction is escaping from the extended cloud.
“Solar-wind erosion is an important mechanism for atmospheric loss, and was important enough to account for significant change in the Martian climate,” said Joe Grebowsky, MAVEN project scientist from the NASA Goddard Space Flight Center in Maryland. He added that the spacecraft is also studying “other loss processes” such as “loss due to impact of ions or escape of hydrogen atoms,” and that those factors would “only increase the importance of atmospheric escape.”
Original story, 11/04/15
After we recently heard that there’s evidence of liquid water on Mars, NASA is planning to knock our socks off again with another big announcement tomorrow.
The announcement, said to be on the “fate” of Mars’ atmosphere, will take place on tomorrow (November 5) at 2 p.m. EST.
Unfortunately, NASA’s statement is pretty sparse on details, but it does say that many participants included in the news conference are from team MAVEN.
The MAVEN mission, launched in 2013, aims to collect critical measurements of the Red Planet’s atmosphere and to assist in understanding the history of climate change on Mars. It’s attempting to measure the rate at which Mars loses its atmosphere to space, and the announcement could be important in understanding whether Mars has or ever had an atmosphere able to support life.
The announcement will broadcast live on NASA TV and online, and you can send the team any questions on social media with the hashtag #AskNASA.
Feature Image: NASA