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Comment Re:GPS on Mars (Score 1) 104

I'd love to see something like that functional. It could really change what we're doing there. quadcopter or quadcopter/fixed wing hybrids, could do really well exploring the surface of Mars. It's not like there's a rush to get anywhere. They could lay out with solar panels extended for weeks to charge, and then fly for miles. It wouldn't be practical for moving lots of equipment, but it could grab samples and bring them back to the rover/base.

They'd need to take into consideration those pesky sandstorms though. It's not a great place for an aircraft, unless they can automatically secure it. Like have a screw anchor it to the ground (like a tent screw or dog tiedown), and a cover to extend over it and secure itself. Then there's the matter of digging itself out after the storm without killing the batteries.

Comment Re:GPS on Mars (Score 2) 104

That would be a cool trick. I think it will be a long long time before we see that.

GPS, and GLONASS have 24 satellites for global coverage. Galileo has 27. Beidou has 10 right now, but has limited coverage. It will have 35 when it's fully operational.

Most (all?) require ground stations to keep them updated, so it isn't just a matter of throwing some satellites up and having GPS on another planet. As I recall, GPS satellite service will degrade to unusable somewhere between 90 to 180 days. [insert obligatory apocalypse reference]

Theoretically with GPS, you can lock with 3, but that assumes a highly clock on the receiver. Our phones and GPS receivers aren't that accurate, so we require 4 satellites.

But I believe this was dumbed down for the casual reader, so they said "GPS". Using the known location of the orbital vehicle, gravitational center of mars, magnetic poles, and stars optically with a sextant, and using inertial sensors, they could put it down on a precise target.

They might use GPS for test flights here, since we have the luxury on this rock. They aren't accounting for other things with their tests right now. Like the Mars average ground level air pressure is 0.087psi. The summit of Mount Everest is 4.89psi. The highest surface air pressure they'll get on Marswould be Hellas Planitia at 0.168psi.

They're going to need some *huge* propellers on their quadcopter. Flying on Mars is like flying at just over 100,000 feet on Earth. The record for any propeller aircraft is the Boeing Condor UAV with no payload, at 67,028 feet.

The record altitude for a helicopter in Earth's atmosphere is 40,820 feet, and it also got the record for the longest autorotation when the helicopter stopped flying. :)

But other than navigation, and lack of atmospheric pressure, it could work fine. :)

Comment Re:And in other news (Score 1) 139

To tack on... ...I explain this to my wife constantly. The reason most accidents happen close to your home is exactly as you said -- most driving occurs close to your home. I use it as a reason to have her buckle up even for short trips, but it's also a lesson in our house about manipulating statistics.

Coming up next, the percentage of American's that live "near" water.

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