A solar powered plane that weighs less than 2.5kg may one day be flying around the atmosphere of Mars providing high-resolution imagery, anytime anywhere.
There have been other projects where spacecraft have been used for scientific exploration of Mars like "Mars Express" which covered large areas and gave images of the surface with a resolution limited to several meters. Rover's missions like "Pathfinder" or "MER", offered the ability to maneuver to scientifically interesting sites, perform analysis of soil and rock composition, but were limited in range to the immediate surroundings of the landing site.
There is a strategic gap for systems that can combine high-resolution imagery and extensive coverage, with freely selectable flight zone.
The Swiss Federal Institute of Technology in Zurich (ETH) hope that their unmanned solar airplane with its rechargeable power, lightweight sensors and scientific instruments, will cover greater areas allowing it to achieve much longer missions, anytime, anywhere around Mars.
The Sky-Sailor, prototype built at ETH, proved the feasibility of solar flight at constant altitude when it took off from MG Zugerland airfield in Niederwil, Switzerland last year. The solar cells provided enough energy to power the motor and at the same time completely charge the battery, while the airplane was following a circular trajectory at 200m above ground for just over 27 hours. Nominal flight speed was 8.97 meters per second.
The plane weighs 2.4kg and has a wingspan of 3.2m. Because weight has a major impact on the required power for leveled flight the plane uses thin silicon cells which are lighter than GaAs Triple Junction cells which would have been the preferred option because of their higher efficiency.
A total of 216 solar were installed on the wings of the demonstrator plane, providing a maximum of 90w of power. The cells were encapsulated using a flexible, mechanically favorable symmetrical laminate combined with a fiber glass reinforced plastic coating which is connected to the power circuit. This encapsulation is non-reflective so that all the sun's energy is used rather than having some reflected off.
Excess energy is stored in a Lithium-Ion battery which is mainly required during the night flight, when the solar power is below the power requirement for a leveled flight.
For flight around Mars
For a flight around Mars the plane's speed is expected to be around 40 meters per second with a distance covered of approximately 1700 km during a 12-hour period. So that the solar panels collect the maximum amount of sunlight the plane would fly ±45 above and below the Martian equator at a nominal height of about 1 to 2 km from the Martian Surface.
Other applications of solar plane
Orbiting Mars and collecting data is not the only use for Sky Sailor - because it is lightweight, low cost and simple to use, swarms of these solar planes could be easily launched by hand from places like forests to assess the fire risk over large areas ensuring that fires are dealt with rapidly reducing potential devastation. Other uses include coast or border surveillance, atmospherical and weather research and prediction, environmental, agricultural, and oceanic monitoring, imaging for the media and real-estate industries.
For more attend the conference Photovoltaics Beyond Conventional Silicon Europe and read Printed and Thin Film Photovoltaics and Batteries.
