Aerographite is a new material made of intertwined carbon nanotubes. It is one of the lightest known materials, with a density of only 180 grams per cubic meter, about 7 times lower than the air we breathe (1225 g/m3). Its other remarkable property is its "darkness", i.e. its ability to absorb light almost perfectly : less than one incident photon in 1000 is reflected. These two properties make it an ideal material for the design of photonic sails : its great lightness and its ability to absorb photon energy allow it to accelerate very efficiently when illuminated by light. This light can be laser light, as in the Breakthrough Starshot concept, or simply sunlight, as in this study.
60 days of travel to Mars and the possibility of escaping from the Solar System...
Astronomers have calculated that a spherical shell 1 metre in diameter and 0.5 mm thick released from the International Space Station ISS could reach Mars in only 60 days and Pluto in just over 4 years, with no propulsion other than sunlight.
Because of its very low density, a spherical sail with a radius of 5 metres and a thickness of 0.1 mm could even carry a 55-gram payload at a speed sufficient to escape from the Solar System.
Such a probe would be an excellent precursor for an interstellar mission to our close neighbour, Alpha Centauri, and to the telluric planet located in the inhabitable zone of the weakest of its three component stars, Proxima Centauri b.
