Cover Image Credits: NASA Illustration / Dennis Calaba
NASA has been testing a prototype of a flying wing aircraft that may become the first Mars Airplane.
The Preliminary Research Aerodynamic Design to Land on Mars, or Prandtl-m, is a flying wing aircraft with a twist.
Later this year, NASA plans to simulate flying in the thin martian atmosphere by dropping a prototype Mars airplane from a high altitude balloon. Dubbed the Prandtl-m ( Preliminary Research Aerodynamic Design to Land on Mars), the prototype will be released at about 100,000 feet altitude flown through the upper reaches of the atmosphere according to Al Bowers, NASA Armstrong chief scientist and Prandtl-m program manager.
The tests could demonstrate how the aircraft works in low pressure environments and lead to changes that will allow it to fold into a 4-inch by 12-inch cube.
The purpose? To deploy from a 3U CubeSat in the aeroshell of a future Mars rover.
(A CubeSat is a miniature satellite used for space research that is usually about four inches in each dimension, a 3U is three of those stacked together.)
As Bowers said:
The aircraft would be part of the ballast that would be ejected from the aeroshell that takes the Mars rover to the planet. It would be able to deploy and fly in the Martian atmosphere and glide down and land. The Prandtl-m could overfly some of the proposed landing sites for a future astronaut mission and send back to Earth very detailed high resolution photographic map images that could tell scientists about the suitability of those landing sites.
Because the Prandtl-m could ride in a CubeSat as ballast aboard the aeroshell/Mars rover piggyback stack going to Mars in 2022-2024, the additional weight would not add to the mission's cost, he said. Once in the Martian atmosphere, the Prandtl-m would emerge from its host, deploy and begin its mission.
According to Bowers, it would have a flight time of right around 10 minutes. The aircraft would be gliding for the last 2,000 feet to the surface of Mars and have a range of about 20 miles. A pretty nice way to extend exploration capabilities on Mars.
But before that happens, tests will need to be done here on Earth. As Bowers explained:
We have a number of summer community college students coming that are going to help us design and build the aircraft that will complete the first phase of the mission. We're going to build some vehicles and we are going to put them in very unusual attitudes and see if they will recover where other aircraft would not. Our expectation is that they will recover. As soon as we get that information, we will feel much better flying it from a high-altitude balloon.
In fact, Bowers credited the idea of the Prandtl-m to a brainstorming session with colleague Dave Berger, a NASA Armstrong aeronautical engineer who specializes in flow physics and propulsion and works with the Education Office. Berger and Bowers discussed a project that college students could immerse themselves in that would be extraordinary – helping to prepare a vehicle that could lead to a Mars flier was their answer.
The actual aircraft's wingspan when it is deployed would measure 24 inches and weigh less than a pound. With Mars gravity 38 percent of what it is on Earth, that actually allows us up to 2.6 pounds and the vehicle will still weigh only 1 pound on Mars. It will be made of composite material, either fiberglass or carbon fiber. We believe this particular design could best recover from the unusual conditions of an ejection.
The Flight Opportunities Program, which is managed at NASA Armstrong, has agreed to fund two balloon flights during the next few years. A sounding rocket test may follow, which would demonstrate how the flier would work on Mars.
The flights will be at one of two locations – Tucson, Arizona, or Tillamook, Oregon.
According to Bowers:
We are going to use GPS initially, but obviously there is no GPS on Mars, so later on we will have to find something else for navigation. But the little autopilot that provides the waypoint navigation, that's one of the things we're going to exercise on a research vehicle and then on the prototype that flies on a future balloon flight.
The flight test could also include some scientific research that will apply to a Mars mission - perhaps a small science payload like a mapping camera or high-altitude radiometer could be included on the first flight.
On subsequent tests, the Mars airplane may carry both payloads.
A second research flight from a balloon is planned for next year and would feature an aircraft capable of returning to the launch site on a flight that could be as long as five hours as it glides back to Earth.
As Bowers explained:
We will do the same thing again with a balloon flight to about the same altitude. On that mission Prandtl-m would actually be inside a CubeSat container. The balloon would drop the CubeSat container and then the aircraft would deploy from the container right after the drop, unfold and fly away.
Success could mean a third mission - a sounding rocket capable of going to very high altitudes.
That mission could be to 450,000 feet and the release from a CubeSat at apogee. The aircraft would fall back into the Earth's atmosphere and as it approaches the 110,000-to-115,000-feet altitude range, the glider would deploy just as though it was over the surface of Mars.
If the Prandtl-m successfully completes the 450,000-foot drop, there is a very good chance the system could be included in an upcoming rover launch and become the first Mars airplane.
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