The effects of Comet Siding Spring on the atmosphere of Mars
The data collected from the missions Mars Express (ESA), MAVEN and MRO (NASA) have also allowed us to analyze the properties of the nucleus of Comet Siding Spring
Three probes dedicated to the study of the Red Planet have recently had the opportunity to conduct observations very close to a comet that has made a fly-by of Mars.
The special circumstance occurred on October 19 and the probes in question are Mars Express and Mars Atmosphere and Volatile Evolution Mission (MAVEN) and Mars Reconnaissance Orbiter (MRO) of the NASA.
C / 2013 A1, the comet from the Oort Cloud, one of the most remote regions of the Solar System, has approached the Red Planet within a radius of 139,500 kilometers, a distance that is less than half of what separates the Earth from the Moon.
The data collected by the three probes have shown that debris from the comet have influenced the ionosphere of Mars with the addition of a strong layer of ions, while the powders from Siding Spring have been vaporized in the atmosphere of the planet with a consequent meteor shower.
This debris then have caused a temporary change, but significant, in the upper atmosphere of Mars and probably have also caused perturbation in the longer term. The encounter between Mars and Siding Spring has allowed scholars to gather valuable information also on the properties of the nucleus of the comet.
The singular “appointment” between the two celestial bodies has been documented by the three probes in different manners.
Mars Express, thanks to the instrument MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding), noted a sharp increase in the density of electrons in the ionosphere of Mars as a result of the approach of Siding Spring. This phenomenon, found at an altitude less high than usual, could come from tiny particles from the comet, burned in the atmosphere of Mars.
MARSIS is a radar subsurface that brought a little flag in the orbit of the Red Planet: in fact, realized with the help of NASA / JPL, it is part of the tools provided by the Italian Space Agency as a PI for the mission.
Even SHARAD (Shallow Subsurface Radar) radar instrument aboard MRO, speaks Italian. In fact, it was developed in Italy and provided to NASA by ASI as a PI National Instrument Facility, and highlighted the growth of the ionosphere. The images produced by the instrument are the traces left by the passage of the radar signals through the temporary layer of ions created from the dust of the comet.
The team has used SHARAD these traces to determine the density of electrons in the ionosphere on the shaded part of the planet, where the observations were conducted, was 5 to 10 times higher than usual.
MAVEN, however, has carried out surveys in two different manners. First ultraviolet spectrograph of the probe showed the upper atmosphere of Mars intense ultraviolet emission produced by ions of magnesium and iron as a result of the meteor shower. The spectrometer of MAVEN, hereinafter, has been able to determine the composition of some of the dust of the comet in the atmosphere of the Red Planet.
After ground testing and a careful review, MAVEN was successfully brought out of Safehold Mode on 22 November 2014 . The spacecraft is operating nominally in Earth-Point Mode with high-rate communications. All the instruments are safe and are currently off. The spacecraft will be monitored over the weekend to ensure a safe condition before the instruments are turned back on
The instrument has identified eight different types of metal ions, which include sodium, magnesium and iron, and delivering the first direct analysis of the composition of powders of a comet from the Oort Cloud. The three probes, after highlighting these immediate effects, will continue to investigate on a long-term period.