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Mars Flier Prototype
SEWilco writes "BBC News reports that a full-scale prototype of a Mars flier will be built. The ARES glider will unfold in midair for a mission which may cover 850 km (528 miles). I wonder if its huge wings would allow it to be tossed back in the air by a storm in that thin air, although probably not by "winds of a few m/sec"."
Go here for the ARES website itself
-- Some days you're the dog; some days you're the hydrant.
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Free your mind.
Ares is in competition with three other Mars exploration proposals for a Nasa launch in 2007. The final selection of one, or possibly two, missions will be made later this year.
It isn't necessarily going to Mars.
I don't need no instructions to know how to rock!!!!
On one hand you are correct: the Pathfinder would be efficient in the Martian atmosphere, as it is roughly equivalent to the Earth's atmosphere at 100,000 feet altitude, a domain where the Pathfinder can stay for hours.
But you have to take into account that the luminosity on Mars is around 40% of that on Earth, and solar panels are likely to collect dust as well. also, it is supposed that there are violent winds blowing on Mars.
First, in reference to your comments on structural and weight limitations, the actual force born by the wings is far less, since there is far less gravity. In addition, while the thinner air is certainly a hindrance to how much lift can be acheived with the same area, it also means that the stresses that must be absorbed from turbulence and the like are probably a lot less.
In reference to unfolding wings, these have, I recall, been tested on Earth, so if they work in our dense air and stronger gravity, they should be fine on Mars. If I knew a link I'd post it; you can probably find more with google.
Finally, you talk a lot about control system algorithms. However, there are a number of reasons that Unmanned Autonomous Vehicles are simpler when flying than when driving. There are a couple of relevent articles in this month's Popular Science, as well as a very good one in the New York Times magazine from a few weeks ago that I just finished reading. If you think about it, the amount of leeway available in the air is far greater than that on the ground; whereas a car driver must maintain precision navigation within a few feet on a road and avoid obstacles and the like, a pilot can, during cruise, simply trim out the plane's elevators, maintain a proper heading, and get by without even an autopilot. If he drifts off by a few hundred feet altitude or a few degrees heading, it doesn't really matter. This is why we already have numerous UAV's in the air in the military (such as the well-known Predator drone) and why Boeing 777s and the new Airbus 330 (isn't that it?) both can supposedly fly without even needing a pilot, in an emergency.
In comparison, DARPA is working with a few contractors to develop UAV ground vehicles, but is really nowhere near production stage.
My knowledge about gliders specifically is limited, my personal experience being limited to powered planes, but I would imagine that with a fair level of accuracy, finding thermals and gaining altitude should not be all that difficult, since most of the control software already exists in some form or another.
Actually, the Mars version has a small hydrazine thruster on the back. It doesn't glide, it is powered flight.
They say it will cover 850km (500mi). No speed range is given but I would think it would take a a few hours.
You're right, though, that a long-duration balloon could cover even more territory.
Actually, the original poster was wrong. It clearly states under the "Platform" section of the site that the ARES is an "autonomous powered airplane", and one of the artist renditions shows blue exhaust from some kind of jet propulsion (not that an artists rendition is worth much, but I doubt they would allow much artistic license in this case).
Having said that, in 1989 the French and the USSR started work on Mars 96, a spaceprobe that would have sent a balloon to Mars.
Mars 96 would have sent a 65kg probe to the surface which would have been slung below a helium balloon. During the day, the Sun would warm the gas and increase bouyancy. The balloon would drift in the Martian winds taking panoramic photographs and making meteorological measurements.
As the Sun set, the gas would cool, the balloon would sink and come to rest on a long semi-rigid tail that would have kept the balloon clear of the surface so that it would not have become damaged. The tail would have contained sensors that would have performed geological tests on the Martian surface.
Sadly the mission was cancelled in the budget crisis that followed the collapse of the Soviet Union.
Best wishes,
Mike.