Wouldn’t an airship be a more viable option for a long term mission on Mars?
No because you get blown about by the winds. That has led to many destroyed zeppelins on Earth. Can’t afford that on Mars. No ground crew to secure it.
[deleted]
JPL's Plan for the Next Mars Helicopter
51–60 of 114 posts
Re: JPL's Plan for the Next Mars Helicopter
#52Earlier quoted context omitted.
I was thinking about a rigid body vacuum airship, landing would be easy because all you need to do is lose the vacuum which can be done with a valve and cost no power. Taking off again can be done over days so you can power it with solar panels if you can’t fit an RTG. I honestly don’t think winds would be that much of an issue they won’t be strong enough to structurally damage the airship they’ll blow it off sure bu…
I'm not aware of any vacuum container that is strong enough to resist buckling while being light enough to be buoyant.
Well, you have low pressure and low gravity working both for you and against you in this case. It doesn't have to be very strong, because atmospheric pressure is so low. But also, the lifting power is also very low, so it would have to be far less dense than a vacuum container would have to be to work on earth.
Low gravity means you need less lift, but low gravity also means the weight of the surrounding air is less so you need more volume. I guess that cancels out.
I suspect it's not practical in atmosphere as thin as Mars, but maybe with a light enough or strong enough material it's possible? At any rate, you'd need an enormous volume just to lift relatively small payloads. And, just filling a balloon with hydrogen would probably make more sense in almost any situation.
At least one good thing Mars has going for it in terms of airships is that CO2 is more dense than Earth's atmosphere. Even nitrogen would be a weak lifting gas on Mars (though it's not available in abundance there as far as I know).
Wikipedia has some useful background information: https://en.wikipedia.org/wiki/Vacuum_airship
Re: JPL's Plan for the Next Mars Helicopter
#53Lots in here, taking me time to unpack. Kind of blue-sky - 30kG is heavy, so maybe its all moot - who's going to dedicate that much mass to this project. Any geology it does, will be contaminated by rotor wash scrubbing the surface material when it lands. Is that an issue? Maybe its a benefit. Can it really react to sample inaccessible places? What is the response time between capturing an image of a face, and gettin…
I interviewed Bob and wrote this article, so I can answer a few of these.
I think JPL's idea is that MSH would be a dedicated helicopter mission, rather than piggybacking on some other mission, so it wouldn't be eating up the mass budget of another lander or rover.
Similar to Ingenuity, the flights would be autonomous but the science wouldn't be. MSH would fly up to a cliff face (or whatever), take pictures, land, ask Earth where to sample, and then make a second flight to do the sampling.
MSH would be able to communicate with orbit directly and would not need rover or lander support.
Re: JPL's Plan for the Next Mars Helicopter
#54"You'd shoot a little projectile from the drone that embeds itself in the cliff wall, and then you'd reel it back in with a sample." Is that what would happen? How does the embed de-embed itself? How does the reeling in not end up pulling the drone closer to the cliff?
I asked Bob about this. There are a bunch of options, but one way to do it is that you use a hollow projectile that takes a core sample, and then you just reel back in the core while the rest of the projectile stays in place.
Re: JPL's Plan for the Next Mars Helicopter
#55For me, the value of ingenuity has not been the fact that it flies but rather that is designed to be operated in a far more risky way than a traditional rover. A mission that consisted solely of a single larger helicopter would be far more risk averse. It would travel shorter distances, move slower and have so much redundancy built in that there is likely to be little mass dedicated to the scientific instruments.
The most likely way for MSH to get funded in the near term is as part of NASA's sample return goals. 5kg of science payload is not insubstantial, but even if MSH's primary instrument was just a sampling tool, it could still do some unique stuff. It could collect otherwise inaccessible samples from across a very wide area, and then bring them all back to a centralized location, which a rover can't do very well.
Re: JPL's Plan for the Next Mars Helicopter
#56Earlier quoted context omitted.
I was thinking about a rigid body vacuum airship, landing would be easy because all you need to do is lose the vacuum which can be done with a valve and cost no power. Taking off again can be done over days so you can power it with solar panels if you can’t fit an RTG. I honestly don’t think winds would be that much of an issue they won’t be strong enough to structurally damage the airship they’ll blow it off sure bu…
And how would that be packed into a landing shell?
Just thinking about some solutions - origami of both load baring hard materials and connecting flexible ones, or even do something whacky like have a composite fabric balloon that you inflate and the impregnate with resin insitu then when the resin hardens you have a large shell that can be emptied to create a vacuum.
Re: JPL's Plan for the Next Mars Helicopter
#57Earlier quoted context omitted.
But the zeppelin must be much larger for the same mass (and remember buoyancy is ALSO lower in Mars’ gravity).
Same holds true for a helicopter… before ingenuity no one knew if a helicopter could even fly on Mars.
That’s not accurate. You can do math to show a helicopter can fly on Mars. And a helicopter benefits from the lower gravity, which doesn’t help a zeppelin (as buoyancy is also reduced by gravity but lift force is independent of gravity). So even though lift for both a zeppelin and a helicopter include a density term, the zeppelin is about a factor of 3 worse.
Since helicopters already outcompete zeppelins on Earth, on Mars where helicopters have a factor of 3 advantage over zeppelins, it’ll have an even harder time.
It’s equivalent to a zeppelin at around 100,000 ft at Earth. Possible, but not very practical.
Re: JPL's Plan for the Next Mars Helicopter
#58Earlier quoted context omitted.
Same holds true for a helicopter… before ingenuity no one knew if a helicopter could even fly on Mars.
That’s not accurate. You can do math to show a helicopter can fly on Mars. And a helicopter benefits from the lower gravity, which doesn’t help a zeppelin (as buoyancy is also reduced by gravity but lift force is independent of gravity). So even though lift for both a zeppelin and a helicopter include a density term, the zeppelin is about a factor of 3 worse. Since helicopters already outcompete zeppelins on Earth, o…
It’s not about the math it’s about the engineering, NASA did the maths and a 40m diameter evacuated airship can carry a substantial payload on Mars, we however have no real clue on how to build it from an engineering perspective.
If you would’ve asked people 10 years ago about flying helicopters on Mars plenty of them would say it’s not possible not because the math doesn’t work out, but because of what requirements the math spits out.
I can do the math for a helicopter for galactic hydrogen, it doesn’t mean engineering can make one. However a vacuum airship on Mars is very much possible, it’s just a heck of an engineering challenge but if you want to get to large payloads not to mention any substantial flight time it’s by far more realistic than a helicopter.
Re: JPL's Plan for the Next Mars Helicopter
#59Earlier quoted context omitted.
terrestrial birds which would all have far too low of a lift to weight ratio on mars to ever have any hope of flying. The current mars helicopter is pretty incredible
Yes, to be pedantic about it, but I didn't say "send birds" or "do exactly what birds do", I said to look to them for ideas. Eliminate every extra gram, optimize aerodynamics and control for the purpose (c.f. owls vs. quail vs. hummingbird vs. woodpeckers) and go from there. Don't try to build a flying machine around power source that is essentially a hunk of dense metal.
just pointing out that you'd have to go to much further lengths than birds on earth have gone
Re: JPL's Plan for the Next Mars Helicopter
#60Earlier quoted context omitted.
Yes, to be pedantic about it, but I didn't say "send birds" or "do exactly what birds do", I said to look to them for ideas. Eliminate every extra gram, optimize aerodynamics and control for the purpose (c.f. owls vs. quail vs. hummingbird vs. woodpeckers) and go from there. Don't try to build a flying machine around power source that is essentially a hunk of dense metal.
just pointing out that you'd have to go to much further lengths than birds on earth have gone
No, you're just missing the point of my argument with and arguing pedantics by insisting on a literal reading what I said.