Brett Smith for redOrbit.com – Your Universe Online
Using ultraviolet and infrared imaging techniques, scientists have discovered that the Martian atmosphere contains particulate matter in two distinct sizes, according to a new report published in the journal Icarus.
In the study, a team of Russian and French scientists observed the transition of Mars’ northern hemisphere into summer. During this transitional phase, the Sun’s rays poke through the Martian atmosphere and the spectrometer on board the European Space Agency’s orbital station Mars Express was able to capture just how solar radiation interacts with particulates high above Mars.
The European researchers discovered that the dust in the Martian atmosphere isn’t homogenous. Rather, there are two distinct types. The first type is rougher and includes both water-ice grains and slightly smaller airborne dust. The second type of particulate is finer, and is an aerosol consisting of much smaller particles.
The researchers noted that the density quantity of both types is not that high. Even in the densest layers of the planet’s atmosphere at altitudes of 12 to 18 miles there are approximately three particles of the finer mode per cubic meter, and less than two particles of the coarser mode per one cubic meter.
The study team noted that when looking at what is considered normal on Earth, Martian air is fairly clean, adding that most rooms are dustier. However, aerosols are critical because they have an essential role in developing the planet’s climate.
Because of fine dirt particles from the upper layers of the atmosphere, ice “embryos” are produced faster, which, consequently, have a bearing on clouds’ build-up. The clouds are the reason for both precipitation and temperature on the planet’s surface. Investigating the way the dust is spread in the atmosphere of the planet with regards to the altitude and geographical coordinates is essential for understanding what is happening on Mars, the scientists said.
The study also revealed the conditions on Mars allow for dust storms that are able to lift large volumes of particles from the planet’s surface. The scientists point out that finding fine dust in the atmosphere is in opposition to prior information that indicated supersaturated steam at the same altitude.
With the extraneous dust present it would have been normal for the supersaturated steam to become further condensed and create clouds. The team speculated that crucial to this potential contradiction is that there are very low temperatures such that the growth of ice grains slows down considerably.
Answers to the many questions surrounding Mars’ atmosphere may be answered later this year when NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) mission arrives at the Red Planet.
After MAVEN enters into an orbit above Mars, its Solar Wind Ion Analyzer (SWIA) will begin sampling the small electrically charged particles in and above the planet’s wispy atmosphere. The unmanned craft will also be sampling ions from the solar wind, a magnetic field that originates deep within the Sun and radiates out toward the planets. Particles from the solar wind interact with ions in Mars’ upper atmosphere and energize them enough to escape from Mars’ gravitational pull.
Scientists have theorized that this process progressively strips Mars of its atmosphere and it has done so for billions of years.