Mars Rovers Catch Argon Fluctuations in Atmosphere

Scientists working with the rovers on Mars are starting a fresh study of the atmosphere around that planet using an instrument developed at the University of Chicago, the Alpha particle X-ray Spectrometer (APXS). The study was cleared after the APXS indicated fluctuations in the composition of one of the components of the atmosphere at Mars, argon. The APXS has been placed aboard the two rovers Spirit and Opportunity.

In a statement, Senior Scientist of the Enrico Fermi Institute in Chicago, Thanasis Economou said there was constant fluctuation in the quantity of argon present in Mars’ atmosphere. According to Economou, argon, owing to its low freezing point stays on in the atmosphere and is enhanced much later than other gases.

Argon stays in the atmosphere and becomes enhanced because it freezes at a much lower temperature, Economou said. Studies conducted using equipment on the Odyssey orbiter sent up by NASA showed argon concentration in the Martian atmosphere over the South Pole to be six times more in the warm seasons than at other times.

Economou attributed this to be due to the argon staying on in the atmosphere for longer times than other gases. The carbon dioxide cannot stay on so long, and drops earlier compared to the argon, causing a steady increase in the argon levels in the atmosphere until the next season.

The conclusions drawn by the scientists are based on a combination of data from two sources – the Odyssey spacecraft that is orbiting Mars and the APXS. Data related to the number of argon atoms present between the instrument and the ground comes from the APXS. The APXS data measures the amount of argon present at the ground level on Mars. This is at a micro-level.

On board the Odyssey, the gamma-ray spectrometer measures the number of argon atoms at a macro-level. It measures the quantity of argon in the air. It covers a large area, basically an air column from the upper atmosphere to the Martian surface, and across a large swathe covering several hundred miles.

Economou says these findings are critical because they indicate that at some point of time, the site probably had liquid water. The two Martian probes touched down on the planet’s surface in January 2004.