Mars
Mars is the fourth planet from the Sun and the seventh largest in the Solar System. A cold, dusty desert world with a thin atmosphere (mostly CO₂), the planet features extinct volcanoes, deep canyons, polar ice caps, and seasons. Mars has two small moons (Phobos and Deimos), a day just over 24 hours long, and a year lasting about 687 Earth days. It is a prime focus of robotic exploration and studies about past water and habitability.
Source: science.nasa.gov
APODs including "Mars"
The Flight Of Helios
31/08/2001
Solar-powered, remotely piloted, and flying at about 25 miles per hour, NASA's Helios aircraft, is pictured above at 10,000 feet in skies northwest of Kauai, Hawaii on August 13. This ultralight propeller driven aircraft, essentially a flying wing with 14 electric engines, was built by AeroVironment Inc. Covered with solar cells, Helios' impressive 247 foot wide wing exceeds the wing span and even overall length of a Boeing 747 jet airliner. Climbing during daylight hours, the prototype aircraft ultimately reached an altitude just short of 100,000 feet, breaking records for non-rocket powered flight. Helios is intended as a technology demonstrator, but regular, long-duration flights at that altitude could be used for environmental monitoring missions and, communications relays. In the extremely thin air 100,000 feet above Earth's surface, the flight of Helios also simulates conditions for winged flight in the atmosphere of Mars.