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A Mars aircraft is a vehicle for flying in the atmosphere of Mars. So far, Mars lander entry, descent, and landing systems have passed through the atmosphere. Aircraft may provide in situ measurements of the atmosphere of Mars, as well as additional observations over extended areas. A long-term goal is to develop piloted Mars aircraft.
Contents
Compared to Earth, the air is thinner at the surface (less than 1%) but the gravity is lower (less than 40%). Also, the major component of Mars air, CO2 gas, is denser than Earth air for a given pressure.
History
Before the start of Mars exploration with spacecraft, the density of Mars' atmosphere was believed to be higher than was later measured to be, leading engineers to believe that the difficulty of winged flight would be much easier than it actually is. In his " Mars Project" ("Das Marsproject") concept, Wernher von Braun proposed winged vehicles for landing human missions on Mars.
A winged rover design was proposed in the 1970s, to cover more area than the single-site Viking landers. There was a proposal by NASA in the 1990s for a Mars airplane to fly on Mars by the anniversary of the Wright Brothers's first flight, in the "Faster, Better, Cheaper" era; and the ARES Mars airplane proposal was selected as a Mars Scout Program candidate, but not selected for flight.
In 2015, a Mars aircraft was considered as on option in the re-boot of the Japanese MELOS mission. One early design proposed a wing-span of 1.2m, a mass of 2.1kg, and with the following mission profile: During the landing phase of the surface element of MELOS, the aircraft would be released at an altitude of 5 km then fly 4 minutes, covering 25 horizontal km.
Airplanes
Prototype Mars planes have flown at close to 30 km (about 98 thousand feet) altitude on Earth, and tested expandable wings that cure in ultraviolet light. For flight in Mars' atmosphere, the Reynolds number would be very low compared to flight in Earth's atmosphere. Valles Marineris was targeted for an unmanned aircraft flight and by Mars' gliders. Gliders could carry more scientific instrumentation, but cover less area. Hydrazine has been proposed as a fuel for Mars aircraft. Another possibility is taking off and landing, which could allow an aircraft to visit multiple landing sites. At one point, NASA planned a wok-sized airplane "micromission", which would piggyback on an Ariane 5 launch and use a lunar gravity assist to get to Mars. Mach 1 on Mars can be about 240 meters per second (537 mph) while it is about 332 m/s (743 mph) on Earth.
In the 1970s the Mini-Sniffer aircraft were made in several versions, including one that used a hydrazine-powered motor (so it could also operate in an all-CO2 environment).
Proposed Mars Airplane concepts include:
Balloons
Balloons may provide an alternative to parachutes, allowing for a soft landing. A balloon could allow a lander to take off and land at a new site. Two types of balloon technology are super-pressure and Montgolfiere. The super-pressure balloons try to contain the pressure caused by heating to maintain altitude. The Montgolfiere would use heated Martian air to create lift. An example of concept for Mars balloon was the Mars Geoscience Aerobot. Some work has been done to develop extremely thin, flexible solar cells that could allow a balloon's skin itself to generate power from the Sun.
Other aircraft and airborne devices
Virtual
Mars Express HRSC and MRO's HiRISE data can provide virtual Mars flyovers by draping surface pictures over 3D terrain models.