Many airplanes and helos have crashed when approaching or landing on featureless surfaces. It’s not a new problem.
Figuring out how to manage featureless surfaces is a bitch. Or even uniformly featured surfaces like strewn fields where you’re not sure whether those “pebbles” are 1cm, 10cm, or 100cm in diameter.
Ingenuity does have a laser altimeter, so it should be able to distinguish distant big rocks from nearby small ones.
We could really use GPS on Mars. Even without very accurate absolute positioning, you would get good velocity data. On Earth you easily get sub cm/s level accuracy. Maybe it wouldn’t be as good with a smaller constellation around Mars, but even 10 cm/s accuracy probably would have avoided this issue.
Sounds like 5 Doppler laser altimiters would’ve done the trick. One aimed at vehicle nadir for altitude and altitude rate.
And four more aimed at, say 45 degree down angle, and at 90 degree intervals around the vehicle’s vertical axis. Which would each provide a composite lateral + descent range & range rate that could be integrated to give a complete terrain-relative velocity vector and distance to touchdown/impact.
But all that has weight & power & compute consumption that probably exceeded Ingenuity’s very modest budgets.
The next Mars copter will be much bigger & more capable.
Better cameras might have done the trick, also. The navigation camera was only 640x480, grayscale, 10 fps. Probably limited by processing speed (the pretty pictures camera was 12 megapixels).
The setup was quite advanced… for 2018. Processing power is obviously a lot better now. And maybe some AI advancements would have helped.
Include a dispenser of thin, light, colorful “poker chips”. Drop one for reference in difficult terrain. The missions would be limited by the number of chips, but the missions are also limited by having the roter ripped off.
Things get real wacky at earthly airliner sizes. As in “not gonna happen” wacky.
Lightplane- and maybe even bizjet-sized vehicles might be doable once they can be delivered and refueled. But boy would they look weird compared to Earth airplanes of the same mission.
As @Dr.Strangelove says and cites, a copter a few feet across is not beyond the pale. Ingenuity was really pretty darn teeny (~5 x ~6 x ~7 inches of useful payload carrying fuselage) but needed relatively huge paddle-like rotors. (2 coaxial rotors of 4 foot diameter each) turning at insane RPM by earthy helo standards.
Basically it’s a question of mass flow. The atmosphere is only about 0.5% that of Earth, though you get a little extra oomph from it being CO2 rather than N2.
You can increase the speed of the flow, but that makes for an inefficient craft since power is proportional to velocity squared. Big, slow blades are most efficient, but of course there’s a tradeoff with vehicle mass.
You could make an airliner-sized craft, but it would have to be an inflatable thing that hardly weighs anything.
Somebody once described a Martian airplane as being more or less like an Earthly supersonic ocean liner. Which gives some sense of the insurmountable problems faced in actually building one.
Well, an ocean liner-sized craft that isn’t in the ocean. It’s not as bad as a supersonic ocean liner that plows through the ocean at that speed. But the scaling laws are such that to get the same behavior on Earth, a craft would have to be monstrous. If you can make it light enough, it doesn’t have to go too fast. If it’s going to be a similar density as typical Earth planes, it needs to be fast, though.
Sorta counterintuitive, but it does mean that 'copters are your best bet on Mars. A plane just has to go too fast in a linear direction to be practical. Takeoff and landing is basically impossible (especially given the lack of runways). But a 'copter can spin its blades as fast as desired. And you only have to spin up the blade mass, not the full mass of the craft.
Ingenuity may prove to already have the optimum blade geometry, or close to it. At least not without carbon nanotubes or some other high-tensile-strength material. Future craft will probably just replicate that N times, as seen in the vid above.
Yes. In one way, better than Earth since CO2 is a heavier molecule than N2/O2. But the low pressure is a problem. Without checking, I think some of our ultra-light high altitude balloon designs would work.
The problem with any direct lift solution in any atmosphere is the volume needed to do any meaningful lifting ensures the vehicle has massive drag. So you end up spending your power budget trying to move the unwieldy large lifting envelope instead of more directly providing lift via wings or rotors.
Lift is proportional to the density difference between inside and outside the envelope. The lightest imaginable “gas” is a pure vacuum. Mars’ atmosphere isn’t a vacuum, but it’s sure close to one. Regardless of what gas(ses) the atmosphere is comprised of, when there’s next to no pressure there’s also next to no density.
Many Mars pundits have made comments to the effect that
Mars has just enough atmosphere to be a big obstacle to space-style design, but not nearly enough to be useful for anything designed atmospheric-style.
The Economist this week has a fascinating piece on a range of commercial space projects in the works, including something called SpinLaunch. The photo looks like an enclosed Ferris wheel with a silo attachment. SpinLaunch’s “cargoes will be dispatched…by an armature rotating inside a vacuum chamber rather than than in a rocket. After an hour’s steady acceleration, the projectile will be fired out of the chamber at 2.2 km/s. Only when it is around 62 km up will a small motor ignite to carry it the rest of the way to orbit.” It works for its 200 kg payload.
There are a couple dozen posts in this thread about it already. Just search in-thread for “centrif”. Which will find you 9 posts, each of which is part of a flurry of posts above and below that one. Or search for “spinlaunch” itself which returns 12 posts.
The consensus is: wacky. But maybe wacky enough to work.