Mars atmosphere well protected from the solar wind

Mars from NASA’s Hubble Space Telescope

The report says ‘a stronger solar wind mainly accelerates particles already escaping the planet’s gravity, but does not increase the ion escape rate’. That also raises the question of the thick Venusian atmosphere around another planet with no magnetism to speak of. Maybe some aspects of magnetosphere theory needs to be looked at again?

Despite the absence of a global Earth-like magnetic dipole, the Martian atmosphere is well protected from the effects of the solar wind on ion escape from the planet, reports Phys.org.

New research shows this using measurements from the Swedish particle instrument ASPERA-3 on the Mars Express spacecraft.

The results have recently been presented in a doctoral thesis by Robin Ramstad, Swedish Institute of Space Physics and Umeå University, Sweden.

Present-day Mars is a cold and dry planet with less than 1 percent of Earth’s atmospheric pressure at the surface.

However, many geological features indicate the planet had an active hydrological cycle about 3 to 4 billion years ago. An active hydrological cycle would have required a warmer climate in the planet’s early history and therefore a thicker atmosphere, one capable of creating a strong greenhouse effect.

A common hypothesis maintains that the solar wind over time has eroded the early Martian atmosphere, causing the greenhouse effect, and thus the hydrological cycle, to collapse. Unlike Earth, Mars has no global magnetic dipole, but the solar wind instead induces currents in the ionized upper atmosphere (the ionosphere), creating an induced magnetosphere.

“It has long been thought that this induced magnetosphere is insufficient to protect the Martian atmosphere,” says Robin Ramstad. “However, our measurements show something different.”

Continued here.