London, Oct 17 (IANS) The sun can block direct communication between Earth and Mars for weeks at a time, cutting off any potential mission to the red planet. The solution - satellites on special orbits around Mars.
The European Space Agency (ESA) is working on how to ensure reliable radio communication when Mars and Earth line up at opposite sides of the sun, blocking any signal between mission controllers on Earth and astronauts on Mars.

The natural alignment, known as a conjunction, happens approximately every 780 days, and would seriously degrade and even block transmission of voice, data and video signals.

Researchers have proposed an innoative solution by placing a pair of communication relay satellites into a very special type of orbit near Mars: a so-called ‘B-orbit’ (against an ‘A-orbit’, based on natural orbital laws).

However, to counter the effects of gravity and remain in place, they would have to be equipped with cutting-edge electric ion propulsion.

Such ion thrusters, powered by solar power and using tiny amounts of xenon gas as propellant, would hold the satellites in a B-orbit in full view of both Mars and Earth.

The satellites could then relay radio signals throughout the Mars-Earth conjunction season, ensuring that astronauts at Mars were never out of sync with Earth, says an ESA release.

These findings were released this week at the 60th International Astronautical Congress (IAC), the world’s biggest space event, in Daejeon, South Korea.