Paris, Nov 22 : Scientists have used the European Space Agency's (ESA's) Mars Express to produce the first crude map of aurorae on Mars, which are a powerful tool with which scientists can investigate the composition and structure of the Red Planet's atmosphere.
The aurorae on Mars were discovered in 2004 using the SPICAM ultraviolet and infrared atmospheric spectrometer on board Mars Express.
These displays of ultraviolet light appear to be located close to the residual magnetic fields generated by crustal rocks on Mars.
They highlight a number of mysteries about the way Mars interacts with electrically charged particles originating from the Sun.
Now, Francois Leblanc, from the Service d'Aeronomie, IPSL/CNRS, France and colleagues have announced the results of coordinated observation campaigns using SPICAM, the MARSIS sub-surface sounding radar altimeter's radar, and the energetic neutral atoms analyser, ASPERA's electron spectrometer on Mars Express.
They have observed nine new auroral emission events, which have allowed them to make the first crude map of auroral activity on Mars.
According to the researchers, the aurorae seem to be located near regions where the martian magnetic field is the strongest.
This suggests, although it does not prove, that the magnetic fields help to create the aurorae.
On Earth, aurorae are more commonly known as the northern and southern lights. They are confined to the polar regions and shine brightly at visible as well as ultraviolet wavelengths.
The existence of similar aurorae is well known on the giant planets of the Solar System. They occur wherever a planet's magnetic field channels electrically charged particles into the atmosphere.
The aurorae are caused by charged particles, in this case most probably electrons, colliding with molecules in the atmosphere.
The electrons almost certainly come from the Sun, which constantly blows out electrically charged particles into space.
Known as the solar wind, this constant stream of particles provides the source of electrons to generate the aurorae, as suggested by MARSIS and ASPERA.
But how the electrons are accelerated to sufficiently high energies to spark aurorae on Mars remains a mystery.
"It may be that magnetic fields on Mars connect with the solar wind, providing a road for the electrons to travel along," said Leblanc.
"There's now a large domain of physics that we have to explore in order to understand the aurorae on Mars. Thanks to Mars Express we have a lot of very good measurements to work with," he added.