[HN Gopher] JPL's Plan for the Next Mars Helicopter
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JPL's Plan for the Next Mars Helicopter
Author : samizdis
Score : 109 points
Date : 2021-08-10 18:21 UTC (4 hours ago)
(HTM) web link (spectrum.ieee.org)
(TXT) w3m dump (spectrum.ieee.org)
| zabzonk wrote:
| > Aerial mobility gives you reach, range, and resolution
|
| Sounds like the 1st Cav in Vietnam - cower, you tentacled Martian
| fiends!
| JoeAltmaier wrote:
| Lots 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 getting a
| response from Earth saying "take a sample!"? Is it even within
| the battery life/flight time?
|
| Can it range outside the rover line of sight? What about radio
| relay to the orbiter? Surely it can't track that itself,
| especially in flight. That level of independence may be a pipe
| dream.
|
| I'm in favor of a drone element to the next mission, as long as
| it doesn't instantly get lost or broken.
| srcmap wrote:
| Wonder if it is practical to design Helicopter with nuclear
| battery similar to the rover....
| perihelions wrote:
| That'd be difficult in Mars' atmosphere -- but the planned
| *Titan* helicopter will actually be RTG powered:
|
| https://en.wikipedia.org/wiki/Dragonfly_(spacecraft)#Design_...
|
| https://news.ycombinator.com/item?id=18947350 ( _" NASA May
| Decide This Year to Land a Drone on Saturn's Moon Titan"_)
|
| https://news.ycombinator.com/item?id=20337042 ( _" A technical
| look at the Dragonfly Titan mission"_)
|
| > _" Flight on Titan is aerodynamically benign as Titan has low
| gravity and little wind, and its dense atmosphere allows for
| efficient rotor propulsion.[35] The radioisotope thermoelectric
| generator (RTG) power source has been proven in multiple
| spacecraft, and the extensive use of quad drones on Earth
| provides a well-understood flight system that is being
| complemented with algorithms to enable independent actions in
| real-time.[35]"_
| nharada wrote:
| Awh, I thought that meant infinite flight time, but it
| appears instead it carries the RTG along to recharge Li-ion
| batteries at night.
| Sharlin wrote:
| Yeah, unfortunately power density is not exactly where RTGs
| shine.
| jvanderbot wrote:
| Obligatory plug for Dragonfly:
| https://www.nasa.gov/dragonfly/dragonfly-overview/index.html
|
| You _can_ use nuclear power similar to the rover if the lift /
| weight isn't prohibitive. That means a bigger copter in a
| thicker atmosphere and lower gravity. Since the power is
| generated by temperature gradients, cold helps too.
|
| Perfect for Titan.
| cratermoon wrote:
| Much too much mass. The atmosphere on Mars is 6.518 millibars.
| Look to the structure and mass of terrestrial birds for a
| guide.
| scrumbledober wrote:
| 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
| cratermoon wrote:
| 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.
| mhh__ wrote:
| Plutonium is really heavy, if you were to do that it strikes me
| that you'd be better off having some kind of wireless charging
| device which the helicopter lands on (But at that point why not
| solar power).
|
| You'd probably already need some batteries anyway as I'm
| guessing that the transient spikes in power usage would
| probably exceed any RTG you could fit in a helicopter anyway.
| science4sail wrote:
| A radioisotope thermoelectric or betavoltaic generator would
| probably be too heavy for a helicopter, so you'd probably need
| something a lot more intense than simple radioactive decay.
| zabzonk wrote:
| Do you see any nuclear-powered aircraft flying around on Earth?
| ezconnect wrote:
| No, because it's easy to refuel here on earth and there's no
| easy way to refuel a helicopter on Mars.
| jvanderbot wrote:
| If we didn't have oxygen and oil, we probably would.
| mhh__ wrote:
| You can't buy aviation fuel on Mars, though.
| gambiting wrote:
| Earth also doesn't have any nuclear powered rovers driving on
| the surface and yet Mars does. Might have something to do
| with the fact that the risk to humans on Mars is _slightly_
| lower than on Earth,no?
| zabzonk wrote:
| Yes, but also that you can't refill with gas on Mars. And
| of course we do have nuclear powered vehicles cruising
| around on Earth. We have also had nuclear powered bombers
| and cruise missiles, none of which were exactly successful,
| but not even the US DoD has ever suggested a nuclear
| powered helicopter. It would be a great introduction to our
| relationship with Mars if one of the first things we ever
| did was to spill plutonium across its surface when the helo
| crashed (as it would, eventually).
| spullara wrote:
| Not that likely even in the event of a crash.
|
| https://en.wikipedia.org/wiki/Radioisotope_thermoelectric
| _ge...
|
| "This incident resulted in the NASA Safety Committee
| requiring intact reentry in future RTG launches, which in
| turn impacted the design of RTGs in the pipeline."
| wongarsu wrote:
| French EVs are over 70% nuclear powered. We just keep the
| nuclear generators stationary and use battery buffers in
| the car to save weight.
|
| You might argue it's about risk, but that didn't seem like
| such a huge deal when we tried to make nuclear cars and
| planes back in the 50s. RTGs are just incredibly
| inefficient, and properly shielded fission reactors are
| incredibly heavy.
| micromacrofoot wrote:
| We also don't see any nuclear-powered rovers driving around
| Earth, so I don't think this is a helpful way to make a
| point.
| CapitalistCartr wrote:
| We developed them during the Cold War. The issue was the
| massive release of radiation behind them. Don't fly it over
| your own country. But they can cruise for days!
| dogma1138 wrote:
| Wouldn't an airship be a more viable option for a long term
| mission on Mars?
| Robotbeat wrote:
| 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.
| dogma1138 wrote:
| That destroyed zeppelins because there are things they can
| crash into especially during take off and landing and the
| winds are strong enough to rip them apart it's not true for
| Mars.
|
| The winds are to weak because of the thin atmosphere and
| there aren't that many things to crash into.
| Robotbeat wrote:
| But the zeppelin must be much larger for the same mass (and
| remember buoyancy is ALSO lower in Mars' gravity).
| [deleted]
| dogma1138 wrote:
| Same holds true for a helicopter... before ingenuity no
| one knew if a helicopter could even fly on Mars.
| trothamel wrote:
| Airships seem somewhat vulnerable to the weather, in practice,
| as they're always flying. A nice thing about a helicopter is
| you can land, and it's a station until you take off again.
| mikepurvis wrote:
| I don't think we know too much at this point about how
| Ingenuity will survive dust storms-- I see a reddit thread on
| this but not much else:
|
| https://www.reddit.com/r/space/comments/lo6k73/what_will_hap.
| ..
|
| If there was a dedicated mission for a much larger
| helicopter, it would obviously be important for it to have a
| story for weathering these things.
| dogma1138 wrote:
| The weather isn't that of an issue due to the thin
| atmosphere. You can land an airship by compressing the
| lifting gas into a liquid. If you can get enough power
| reserve at least to do that.
|
| The main issue would be the size of the balloon but honestly
| if we can make some origami rigid airframe a vacuum airship
| might actually work.
|
| At that point controlling buoyancy is also less of an issue
| from a power perspective since you don't need a large power
| reserve to land, and when you are on the ground you can wait
| until you have enough power to create sufficient vacuum in
| the airship.
| rtkwe wrote:
| In general trying to create a vacuum airship is a loosing
| game because you have to add so much support to prevent it
| from collapsing that you can't win the race between volume
| and weight to achieve buoyancy. The thinner atmosphere is a
| bonus to decreasing the force for a given volume but you
| simultaneously have to increase the size of the 'balloon'
| since it's displacing less air for every unit of volume so
| it has to get bigger which increases the surface area
| further.
|
| Doing some quick math using the ideal shape of a sphere:
| Mars surface atmosphere is ~1/60th as dense as the Earth's
| so you'll wind up with 23x the surface area which at the
| reduced surface pressures of mars you'd be looking at
| around 15% of the total forces you'd have to resist. For a
| sphere that might just push it into the realm of possible
| options but to get to a 'pure' vacuum you need very fancy
| and heavy pumps that need cryogenic cooling beyond the
| difficulty of doing this with an actual blimp shape.
| FreeFull wrote:
| I imagine with Mars's thin atmosphere, it'd be hard to get
| enough buoyancy to lift off.
| modshatereality wrote:
| It won't work at high altitude until we start polluting
| there. What is air density in one of those nice big craters
| though?
| jvanderbot wrote:
| The atmo is very thin, making the balloon huge relative to the
| gondola. Some people are quite enthused about it anyway.
| Including myself.
|
| http://www.gaerospace.com/space-exploration/planetary-aerobo...
|
| With a thick atmo, plenty of sun, and not too much heat / cold
| in the upper layers. Venus is a _great_ place for balloons.
|
| https://www.nasa.gov/vision/universe/solarsystem/venus-20070...
| dogma1138 wrote:
| 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 but not break it apart, and
| crashing into things isn't as much of a risk at any
| reasonable altitudes no buildings no trees, sure there are
| cliffs and mountains but that can be solved with altitude.
| jvanderbot wrote:
| And how would that be packed into a landing shell?
| jbay808 wrote:
| I'm not aware of any vacuum container that is strong enough
| to resist buckling while being light enough to be buoyant.
| skybrian wrote:
| Mars air seems a bit thin for that?
| dylan604 wrote:
| "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?
| polynomial wrote:
| mainly, precise tolerance engineering.
|
| ofc we don't already know the exact composition and hardness of
| said cliff walls, so your question stands.
| tablespoon wrote:
| 30kg flying on Mars? Wow! How massive is this thing gonna be.
| Ingenuity is already 1.2 metres across, so it's not exactly
| small. This thing is gonna be massive.
| aboodman wrote:
| > 30kg flying on Mars? Wow! How massive is this thing gonna be?
|
| It's gonna be 30kg.
|
| Sorry, I'll show myself out =P
| barbegal wrote:
| For 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.
| rtkwe wrote:
| The issue is it has to be pretty big to carry much in the way
| of scientific instruments to begin with. Right now there's no
| scientific instruments on Ingenuity beyond the camera and that
| is only really useful for surveying the ground. Also Ingenuity
| can be risky because it's goal is to test the craft itself so
| they take risks with it to see how well the design performs at
| the edges of it's flight envelope.
| tomato44 wrote:
| Jack Parsons will just have to do some real funky stuff to get
| more plans and technology to make this real :)
| verytrivial wrote:
| Why do so many website disable zoom? Why?!
| BotJunkie wrote:
| If you're looking for a better resolution version of the
| concept image, as far as I know there isn't one. The original
| is here, and it's not great: https://www-
| robotics.jpl.nasa.gov/tasks/showBrowseImage.cfm?...
| verytrivial wrote:
| I just wanted to see the folding concept at the given
| resolution, just bigger, like God and my pinch gesture
| intended. No cigar.
|
| Opening the image in another tab then zooming then I suddenly
| wonder why on Earth this is required. I know it's not malice,
| but there must millions of people with sub 20:20 vision who
| don't want to enable the screen magnifier when pinch is
| ALREADY A THING.
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