The solar wind has a much greater effect on Mars than previously thought, according to first results from the ASPERA-3 instrument on the Mars Express spacecraft
By: Nitzan Achsaf, window for physics
The solar wind has a much greater influence on Mars than previously thought, according to the first results from the ASPERA-3 instrument on the Mars Express spacecraft. Researchers have found that the solar wind – a supersonic plasma of charged particles flowing from the sun – can penetrate deep into the Martian atmosphere. One result of this phenomenon could be that sky and other volatile molecules could 'escape' from the planet.
Many theories have been put forward to explain how Mars changed from a hot, wet planet to a cold, dry planet. Recently, it was estimated that an amount of water, equal to the ocean that extends over the entire surface of Mars and at a depth of 14 to 34 meters, 'escaped' from Mars in the last 3.5 billion years. Unlike Earth, Mars does not have a magnetic shield to protect it from the solar wind, so particles from the Sun can play a crucial role in shaping the Martian atmosphere.
The researchers measured the solar wind that flows towards Mars, and the planetary wind that flows away from Mars. The planetary wind contains volatile substances that are energized, ionized and accelerated by the solar wind as they penetrate the Martian atmosphere. They found that the solar wind can penetrate to a depth of 270 km from the surface of Mars. Furthermore, they found that the positively charged particles of hydrogen and oxygen, which flow from Mars onwards, have an electric voltage of several kilovolts at low altitudes, which shows that they have enough energy to 'escape' the planet. According to the researchers, the combination of the hydrogen and oxygen ions that escape from Mars, can testify to the slow drying of Mars.
