7 ms·

NASA regains contact with mini-helicopter on Mars

407 points by Tommstein 3y ago

simion314 3y ago
We will use more helicopters instead of rovers for new missions ? Or larger crafts would be much harder or riskier to use ? Or maybe have a helicopter that can move the rover with the equipment to different locations.
- wyldfire 3y ago
  The existing helicopter is extremely small and light, IIRC. less than one kg. So it definitely won't be picking up a 900kg rover, even if you tried to scale it up somehow. The atmosphere is just too thin to support anything but a minimal payload. But yeah having more helicopters might be feasible - for surveying the surface.
  - mmbop 3y ago
    Is there a problem of scaling this up to say a 20kg payload? I’m not an aeronautical engineer, so I guess what I’m asking is if there is some problem scaling up flying machines in an extremely thin atmosphere?
    - deleted 3y ago
      [deleted]
    - nortlov 3y ago
      In a thin atmosphere, lifting a heavier payload needs bigger rotors or increased RPM, which increases power demands and structural stress. The challenge is to keep the vehicle light enough to fly while also making it sturdy enough to carry the payload and survive environments.
      - mmbop 3y ago
        Ok - this makes sense to me. Also taken into account the context that anything going to space needs to be light at this point in time. Hopefully we don’t have that restriction forever :)
      - D13Fd 3y ago
        Why can’t “more rotors” be another solution?
        swells34 3y ago
        This is what I'm thinking too. A number of posts above talked about physical limits based on speed of sound and rotor length. Cool, so add two rotors, or four.
        nortlov 3y ago
        For sure, that’s another way to decompose “bigger rotors”. It would probably be appropriate to dive into a conversation about Ingenuity’s design goals, requirements, and the trades performed to end up with what they got.
    - Robotbeat 3y ago
      It scales up to 20kg, yes.
    - wongarsu 3y ago
      One issue might be rotor span. Ingenuity has pretty big rotors to counter the thin atmosphere (about 4 feet top-to-tip). On earth rotor sizes are limited by the speed at the wing-tip. Once you make the rotor too long the tips start approaching supersonic speeds, giving you all kinds of weird mach effects. To make matters worse, the speed of sound is about 30% lower on Mars compared to near earth's surface.
      - mmbop 3y ago
        Oh interesting! I can see how that would be a harder problem (although not insurmountable since some planes on earth have supersonic propellers). Just a quick edit - wow, u didn’t realize the span was already 4ft! Anything much larger could definitely be hard to pack inside a fairing!
      - jessriedel 3y ago
        Yea good point. Apparently the blade tip speed on Ingenuity is Mach 0.6-0.7!
        skovati 3y ago
        Interesting note about this: the speed of sound on Mars is only ~70% of that on Earth, due to less atmospheric density. Might change your Mach numbers!
        Metacelsus 3y ago
        It's not due to less density, but rather a different gas composition (CO2 vs. N2+O2).
        algas 3y ago
        Let's run the numbers! The speed of sound in an ideal (calorically perfect) gas is given by a = sqrt( gamma * R * T ) where gamma is the ratio of specific heats (thermodynamic property of a gas, which may vary with temperature), R is the individual gas constant, and T the temperature of the fluid. All of these are going to be different on Mars versus on Earth: Earth: R = R_atm = 287 J / (kg * K) gamma = 1.44 T = 293 K (taking room temperature as an average temperature) Mars: R = R_CO2 = 188 J / (kg * K) gamma = 1.37 T = 210 K (from a quick google, about -60 deg C) If the Martian and Earth atmospheres were at the same temperature, then the speed of sound on Mars would be 80% that of the speed of sound on Earth. Given the temperature difference, the speeds of sound are a_mars = 232 m/s a_earth = 347 m/s So yes, much of the difference is due to the composition: the Martian atmosphere has a higher atomic weight, which leads to a lower individual gas constant, and decreases the speed of sound. However, a substantial amount of the difference is simply due to the different temperatures on the surfaces of the two planets.
    - jessriedel 3y ago
      I don't know the answer to your question, but for context here are the weights of Mars rovers: Sojourner (1997): 11 kg Spirit & Opportunity (2004): 185 kg Curiosity (2011): 899 kg Perseverance (2020): 1,025 kg
      - mmbop 3y ago
        I know these are much larger - I’m just really curious about the dynamics of scaling up rotorcraft & why it is problematic. ie - do rotor physics become impracticality large or fast at some point for materials science, or is it purely a space problem for rocket launches.
        jessriedel 3y ago
        Oh for sure, it's a great question.
        IamTC 3y ago
        I have led efforts building Chinook style tandem rotors with 2 sets of blades from a size like the Trex 800, powered by a 2 stroke engine, as well as 40kg max takeoff quad-planes with both electric quadrotor and 2 stroke engine (for forward motion). But because I was the main lead and pushing the pace so fast, I wished I did it with a more rigorous aero-engineering to it. I started both projects with barely any experience developing aircraft. Thinking about your question, here are my 2 cents: The biggest thing I stugged with is how the vibrations and the accompanying harmonics on the sytem as the rotors spin up and down. I could see it on the logs as the rotors spin through certain Hz, there's would spikes in virbational ampiltudes at predictable frequencies. As the blades get bigger the forces (probably) goes up. Sometimes, these frequecies (especially the lower ones) are at the range where its very hard to find the right materials to damp it out of the control and sensing electronics. Ingenuity probably deals with a virbration range that well into the hundreds/thousand of Hz and I do remember that renge is not a difficult range to damp out, vis a vis the low tens of hertz. Also, the harmonics is related to ground resonance. I had built my tandem with "skids" that are rigidly attached to the rest of the frame. When the system made contact with the ground on just one skid, that one skid becomes a pivot, the vibration has no where to go and I witnessed first hand, first time, what ground resonance can do to mechanical systems. I can never forget seeing M4 through to M8 hex holt beads being sheared clean off after the resonance event. Only later did I find out that in full scale systems, they have dampeners between the main body and the skids of the aircraft. See https://m.youtube.com/watch?v=IIC-oBzLYhQ https://m.youtube.com/watch?v=IIC-oBzLYhQ ; Staying in flight is not as hard. But getting the ssytem to land and spin down proerly was big pain without understanding ground resonance and its effect on mechanical design. When I saw the little puny legs of Ingenuity, this experience of mine came into mind and I was glad they had legs like to damp out vibrations as it came down to land. Then there is the relation between the mechanical vibration regimes of the system, the polilng rates of the foundational flight sensors and the freqency of the main flight stability and movement control loop itself. With bigger systems, the cables (for signal and power) could run longer too (becoming long long antennas), which means you can run into problems with noise of various origins. If I'd do it again, something like CAN bus would probably be something I look at seriously. Bigger systems also draws more power, and that can have an impact on how much management is needed for noise. Bigger power draw usually also means heavy power store & delivery system, which affects CG management, when then means you can't move things around to management noise. At some point, I felt like I was doing dancing a multi-factorial show. I wished I could be clearer. Perhaps someone more qualified can chime in.
    - jvanderbot 3y ago
      Here's a paper that describes what the next gen could/should be. The lead author is the head of Mars heli, IIRC. https://ieeexplore.ieee.org/abstract/document/9843501 https://ieeexplore.ieee.org/abstract/document/9843501 In short: 30kg heli, 5kg payloads. Other designs by collaborators are closer to 20kg. It's probably possible to transport a few of these on the existing lander technology, which would be awesome. The scholar.google.com keywords you want are "Mars Science Helicopter" and a good touchpoint author is T. Tzanetos or S. Withrow-Maser Ames and JPL were still collaborating on this when I worked there.
  - Firaxus 3y ago
    I was surprised to learn that it’s actually a fair bit heavier. I was lucky enough to get to attend a talk by the head of the Ingenuity program, and he mentioned how the mass ballooned a bit to something under 5 pounds. (Listed as 4 pounds on this official fact sheet) https://mars.nasa.gov/files/mars2020/MarsHelicopterIngenuity_FactSheet.pdf https://mars.nasa.gov/files/mars2020/MarsHelicopterIngenuity...
- surfpel 3y ago
  That's the goal, yes. Depending on the destination, naturally. Here's what's planned for Titan: https://en.wikipedia.org/wiki/Dragonfly_(spacecraft) https://en.wikipedia.org/wiki/Dragonfly_(spacecraft)
  - jvanderbot 3y ago
    Was going to post this. Titan is such a wonderful place for a nuclear powered helicopter. Much better than rover/submarines/floaters, IMHO. A balloon would also have been excellent, but the extra mobility from helis is going to be amazing.
- wongarsu 3y ago
  Ingenuity was just a technology demonstrator. I think it demonstrated the technology splendidly, so we are likely to see more helicopters on Mars in the future. Not sure if Nasa has said yet which roles they see for future Mars helicopters. The initial idea behind Ingenuity was to use them as scouting vehicles for rovers. Of course rovers improved a lot too, with better autonomous driving. But with a Mars rover driving about 100 meters/yards per day scouting helicopters are still useful. Maybe we will also see Helicopters carrying more instruments themselves. But I imagine in the beginning that's mostly better imaging instruments. Weight is still an issue for flying things, no matter the planet. But maybe we will see some future missions that instead of a car-sized rover and one tiny helicopter have a fleet of helicopters with a small support-rover for exploring wider areas.
- jessriedel 3y ago
  I think the current plan is that helicopters will be very light with minimal instrumentation and will be used mostly to scout ahead for rovers. The rovers will be much heavier and include many instruments. (Of course, all of NASA's long-term plans for Mars would be completely disrupted if Starship lowers the cost-per-kg of delivering equipment by two orders of magnitude, which arguably is likely.)
  - kibwen 3y ago
    Making it more economical to escape Earth's gravity well isn't going to alter the physics of the Martian atmosphere or the relative utility of copters vs rovers for Martian exploration. Which is to say, even if you stationed humans on Mars, they'd still be exploring remotely via copter/rover pairs, just no longer with a human-to-robot latency measured in tens of minutes.
    - wongarsu 3y ago
      However we might be willing to drive a lot more agressively if we know we can get a mechanic out to a stuck rover. Similarly, cheaper delivery might make a large number of smaller more disposable vehicles more appealing for many missions, just like what happened to satellites in the last decade.
    - jessriedel 3y ago
      If you increase the mass and/or number of vehicles by 100x, a bajillion things will change.
- jvanderbot 3y ago
  A heli that can move a rover is basically worse than a heli that has rover instruments and a few wheels. You have extra weight and parts and complexity for hitching and carrying that you can just avoid by giving a small rover flying ability. Even the combo is probably too much complexity. A heli with good imagers, spectrometers, and the ability to cart soil samples would be fantastic.
- jvanderbot 3y ago
  Surfacing a comment: Here's a paper that describes what the next gen could/should be. The lead author is the head of Mars heli, IIRC. https://ieeexplore.ieee.org/abstract/document/9843501 https://ieeexplore.ieee.org/abstract/document/9843501 In short, future designs target ~30kg heli, 5kg payloads. Other designs by collaborators are closer to 20kg. It's probably possible to transport a few of these on the existing lander technology, which would be awesome. The scholar.google.com keywords you want are "Mars Science Helicopter" and a good touchpoint author is T. Tzanetos or S. Withrow-Maser
  - two_in_one 3y ago
    > Other designs by collaborators are closer to 20kg. It's probably possible to transport a few of these on the existing lander technology, which would be awesome. Actually it could be like 50 of them. Plus some ground robots to put together solar farm. And wooh... we get the first extra terrestrial permanent base
    - jvanderbot 3y ago
      Well size is the limiting factor for fliers, since they like to have broad surfaces with low weight. But I think you're referring to some, ahem, untested possible landing vehicles ... in which case, yeah, you have a lot of robots. For the solar farm assembly case, It's actually a lot easier to have a teleoperated robot doing the work, a few astronauts in orbit doing the operation / construction. In the case of building things, you want as much space / weight landed to be the thing being built, not the builders, per se.
  - Keysh 3y ago
    Non-paywalled article about the concept, including renderings of the hexacopter design: https://spectrum.ieee.org/the-next-mars-helicopter https://spectrum.ieee.org/the-next-mars-helicopter
- deadbabe 3y ago
  Why not some helium balloon type craft that could float along with low power for longer periods of times? Could cover vast distances? Descend into fertile plains looking for samples?
  - Jabbles 3y ago
    Helium's lifting capability is proportional to the density of the atmosphere, which is very low on Mars.
    - bloopernova 3y ago
      Is it viable to use vacuum instead of helium?
      - nilsherzig 3y ago
        Wouldn't you need something with some amount of pressure to stop the "shell" you plan to float from collapsing?
      - anticensor 3y ago
        What if we use hydrogen, which is halfway between helium and vacuum?
    - deadbabe 3y ago
      Hydrogen it is.
      - M95D 3y ago
        Hydrogen leaks.
- somenameforme 3y ago
  Minimizing moving parts, so much as possible, when dealing with hardware tens of millions of miles away, let alone with a 13 minute delay in 1-way messaging, is generally smart. And Mars' atmosphere is so thin that these rovers will never be moving any meaningful payload, so their only real use case is as a scouting type system. But they also add very little value there given the existence of orbiting satellites. Even the Mars Recon Orbiter (from 2005) captures images in the < 1m resolution range. IMO NASA wanted to try to deal with the sort of 'oh boy... another rover' fatigue and saw the drone as a way to spice things up with some passable science arguments behind it, and a relatively minimal cost. Further supporting this is that the helicopter wasn't an initial part of the plan - it was strapped on at the 'last minute', speaking in government time. In any case, I would comfortably wager against us seeing more drones in future missions, at least to Mars.
- analog31 3y ago
  In the shorter term, I see the helicopter as making the rover more capable, by finding routes and destinations of interest. And the rover makes the helicopter more capable by providing a recharging station. So they're both at their best when working as a system. Maybe a rover can support multiple choppers.
  - p1mrx 3y ago
    > the rover makes the helicopter more capable by providing a recharging station Does it? I thought the helicopter was just solar powered.
    - analog31 3y ago
      That's cool. Thinking about it, there must be a tradeoff. The rover could support more massive batteries, but then "docking" between the two machines would have to be utterly reliable.
- dotnet00 3y ago
  IIRC as a result of Ingenuity's success, one of the proposals for the Mars sample return mission architecture involved several helicopters to retrieve Perseverance's sample canisters (it drops them as it goes along, so that there's no worry about how to get the samples out of the rover in the future). I should add though that the prospects of the parasites in Congress properly funding such a complex mission seem pretty low for now.
Kye 3y ago
Didn't this use mostly off the shelf parts? If so, I wonder how this will impact costs on future missions. If they can do more with consumer hardware, they can save budget to apply toward more science.
- artemonster 3y ago
  Yes, it did. I like the sentiment but I wonder how much conflict of interest would undermine this idea. Imagine how many companies are involved in developing space grade one-off hardware! Also, why would a highly bureaucratic structure undercut the amount of money that they themselves are asking for (and receiving) out of a budget? Savings are not aligned with the interest of such structure. Its not that for the amount you have saved you can allocate rest of the funds for something else (usually this is how it works with publicly funded projects AFAIK)
  - foota 3y ago
    Well maybe they could start doing bigger and better missions, if they can reliably pull it off.
  - augusto-moura 3y ago
    This also drops the bar for other space agencies, from other countries and private alike. Getting cheaper hardware also means more launches and more testing. Instead of sendind a multi million project to space, you can send basically a smartphone (an epheumism, ofc) and some big antennas, and do it in bulk
  - icegreentea2 3y ago
    Every bit of money and platform resources (rad hardened CPUs are giant, slow and power inefficient compared to even semi modern COTS) is money and resources that NASA can spend on scientific payload on the same platform. NASA absolutely does have some incentive to find savings in control hardware and software. Finally, while Ingenuity does use a non-hardened Snapdragon, many other of its critical electronics components are still rad-hardened. The FPGA and dual MCUs (that actually do the low level control and I/O I assume) are both rad hardened. In addition, the COTS components that were used where screened by NASA for their performance in radiation. The Snapdragon is really just there to control the radio, and do image processing. Critically, these are functions that have -some leeway- for timing, giving the option to just restart the Snapdragon if a watch dog detects a problem. All of this to say is that rad-hardening isn't going away, but will probably stick around in many critical niches. What Ingenuity absolutely do is validate that modern COTS processors have a role to play in radiation elevated environments, including in semi-critical applications.
xeromal 3y ago
I actually go to the gym with one of the guys who worked(s) on this copter/drone. Super cool guy
- daed 3y ago
  How much can he bench?
  - jvm___ 3y ago
    On Earth or Mars?
    - pimlottc 3y ago
      I don’t think you’re supposed to hold your breathe when lifting…
      - dylan604 3y ago
        Just like your not supposed to puff your cheeks when playing an instrument, but that never stopped Dizzy Gillespie. More of a suggestion than a rule
        analog31 3y ago
        Gillespie also exemplified why the rule against puffing your cheeks is more than just a suggestion.
      - liamwire 3y ago
        Jokes aside, you absolutely are. Bracing properly is a critical skill in both olympic weightlifting and traditional strength training.
        pimlottc 3y ago
        Ah, shows how much I know about lifting... in general I've always been reminded to keep breathing when exercising.
csdreamer7 3y ago
On Jupiter Broadcasting there was a lot of interviews on how this was a Linux powered device and could be the first of many new Linux devices on Mars by JPL. If I remembered correctly they used a space hardened Power cpu with an ancient version of Yocto since the newer versions of it did not have working drivers. When the rover had an issue they actually used the helicoptor's userspace command line GNU utilities to debug and get logs from the rover to send to Earth. Also, this makes Mars the second planet that uses Linux more than Windows as noted by the tweet in the linux below. :-) https://www.theverge.com/2021/2/19/22291324/linux-perseverance-mars-curiosity-ingenuity https://www.theverge.com/2021/2/19/22291324/linux-perseveran...
- dylan604 3y ago
  > If I remembered correctly they used a space hardened Power cpu If you're remembering correctly, then I'm misremembering in that this has essentially a Snapdragon chip and not a rad hardened CPU at all
  - eric__cartman 3y ago
    They used the hardened PowerPC for the rover, similar to previous mars rovers and the Snapdragon chip for the helicopter.
  - csdreamer7 3y ago
    Maybe I am misremembering the interview. Maybe the person said that they used to use a hardened IBM power chip?
    - Denvercoder9 3y ago
      This information is pretty widely available, e.g. on Wikipedia [1], no need to go off memory. Flight control is done by an FPGA, the main CPU is a Snapdragon 801 running Linux, and it uses Zigbee to communicate with the rover. [1] https://en.wikipedia.org/wiki/Ingenuity_(helicopter)#Avionics https://en.wikipedia.org/wiki/Ingenuity_(helicopter)#Avionic...
okasaki 3y ago
[flagged]
pimlottc 3y ago
It was probably just stuck in a tree.
- deleted 3y ago
  [deleted]
- cubefox 3y ago
  Or a Martian canal.
wait_a_minute 3y ago
Yeah! Let's go NASA, Godspeed! USA, USA, USA!!! Not only has it already exceeded its objectives, but now it may generate even more useful data for new objectives...does anyone know if NASA maintains any kind of engineering blog or stream where we can learn more details about what went wrong and how they reconnected?
patall 3y ago
For me, being listed as a contributor to Ingenuity is one of the highlights of my career in software development. I mean, I just fixed a bug in some python library, but that was enough to get the GitHub Ingenuity badge. And when ever I am asked for a fun fact about myself, I can answer: some of my code is flying on Mars :)
- mlsu 3y ago
  Ingenuity is running Python?
  - Rebelgecko 3y ago
    The vehicle itself is mostly C++ but there's lots of python in the ground station and data processing
    - varelse 3y ago
      [dead]
    - jeffparsons 3y ago
      Wow, I somehow never imagined that even NASA's technology choices would be influenced by "all the data stuff being for Python". But I guess if it's all sandboxed and any errors are reversible... then why not? It all makes rational sense. It just feels weird to think about Python running on Mars before there's even people there.
      - zelphirkalt 3y ago
        GP stated, that there is a lot of Python based stuff on the ground though, as I read it. Not necessarily on Mars.
        jeffparsons 3y ago
        Ah, I see. I read "ground station" as hardware on the ground on Mars, as opposed to on the helicopter itself.
standardUser 3y ago
I'm curious how long they expected it to remain in working condition. NASA has a habit of underestimating lifespans by a comical amount. It will be like "we expected the rover to operate for 10 weeks and that was 6 years ago". I think the most extreme example is Voyager 1, which was on a 5-year mission that reached nearly 50 years.
- cwillu 3y ago
  “We need the rover to operate for 10 weeks and will be discredited as an organization if it fails at 9” is what causes that. It's not necessarily a bad thing.
- CuriousCosmic 3y ago
  They planned for three 90 second flights prior to launch. After those worked they transitioned over to longer "operations demo" flights and those were extended tentatively out to 12 flights. After the 21st flight they just stopped manually allocating labor and funding to the project for a set number of flights and instead gave them a running budget for indefinite continued operations. So while "strictly speaking" they planned for three 90 second flights. There was the unstated assumption that it'd be used for much more than that as long as it actually worked effectively.
  - foobar1962 3y ago
    It sounds as though mission life has as much to do with funding for ground staff (not something I ever considered) at least as much as it has to do with the life expectancy of deployed hardware.
    - CuriousCosmic 3y ago
      Yep. For example, Spirit and Opportunity were part of the Mars Exploration Rovers mission. 2/3 of that mission's total cost was the development, manufacture, and launch of the rovers themselves. Which more or less "per unit" works to 1/3 of the total mission cost per rover. The other third of that mission cost was staffing for the (15 year) ongoing mission from when it passed the initial mission parameters to when opportunity finally was deemed dead in 2018. https://www.planetary.org/space-policy/cost-of-the-mars-exploration-rovers https://www.planetary.org/space-policy/cost-of-the-mars-expl...
HPsquared 3y ago
So did it crash, or freeze?
Trekker666 3y ago
> "Good news today," NASA's Jet Propulsion Laboratory (JPL) wrote on X, formerly Twitter, late Saturday. I heard this line in my mind with Professor Fansworth's voice.

407 points by Tommstein 3y ago

We will use more helicopters instead of rovers for new missions ? Or larger crafts would be much harder or riskier to use ? Or maybe have a helicopter that can move the rover with the equipment to different locations.

wyldfire 3y ago
The existing helicopter is extremely small and light, IIRC. less than one kg. So it definitely won't be picking up a 900kg rover, even if you tried to scale it up somehow. The atmosphere is just too thin to support anything but a minimal payload. But yeah having more helicopters might be feasible - for surveying the surface.
- mmbop 3y ago
  Is there a problem of scaling this up to say a 20kg payload? I’m not an aeronautical engineer, so I guess what I’m asking is if there is some problem scaling up flying machines in an extremely thin atmosphere?
  - deleted 3y ago
    [deleted]
  - nortlov 3y ago
    In a thin atmosphere, lifting a heavier payload needs bigger rotors or increased RPM, which increases power demands and structural stress. The challenge is to keep the vehicle light enough to fly while also making it sturdy enough to carry the payload and survive environments.
    - mmbop 3y ago
      Ok - this makes sense to me. Also taken into account the context that anything going to space needs to be light at this point in time. Hopefully we don’t have that restriction forever :)
    - D13Fd 3y ago
      Why can’t “more rotors” be another solution?
      - swells34 3y ago
        This is what I'm thinking too. A number of posts above talked about physical limits based on speed of sound and rotor length. Cool, so add two rotors, or four.
      - nortlov 3y ago
        For sure, that’s another way to decompose “bigger rotors”. It would probably be appropriate to dive into a conversation about Ingenuity’s design goals, requirements, and the trades performed to end up with what they got.
  - Robotbeat 3y ago
    It scales up to 20kg, yes.
  - wongarsu 3y ago
    One issue might be rotor span. Ingenuity has pretty big rotors to counter the thin atmosphere (about 4 feet top-to-tip). On earth rotor sizes are limited by the speed at the wing-tip. Once you make the rotor too long the tips start approaching supersonic speeds, giving you all kinds of weird mach effects. To make matters worse, the speed of sound is about 30% lower on Mars compared to near earth's surface.
    - mmbop 3y ago
      Oh interesting! I can see how that would be a harder problem (although not insurmountable since some planes on earth have supersonic propellers). Just a quick edit - wow, u didn’t realize the span was already 4ft! Anything much larger could definitely be hard to pack inside a fairing!
    - jessriedel 3y ago
      Yea good point. Apparently the blade tip speed on Ingenuity is Mach 0.6-0.7!
      - skovati 3y ago
        Interesting note about this: the speed of sound on Mars is only ~70% of that on Earth, due to less atmospheric density. Might change your Mach numbers!
        Metacelsus 3y ago
        It's not due to less density, but rather a different gas composition (CO2 vs. N2+O2).
        algas 3y ago
        Let's run the numbers! The speed of sound in an ideal (calorically perfect) gas is given by a = sqrt( gamma * R * T ) where gamma is the ratio of specific heats (thermodynamic property of a gas, which may vary with temperature), R is the individual gas constant, and T the temperature of the fluid. All of these are going to be different on Mars versus on Earth: Earth: R = R_atm = 287 J / (kg * K) gamma = 1.44 T = 293 K (taking room temperature as an average temperature) Mars: R = R_CO2 = 188 J / (kg * K) gamma = 1.37 T = 210 K (from a quick google, about -60 deg C) If the Martian and Earth atmospheres were at the same temperature, then the speed of sound on Mars would be 80% that of the speed of sound on Earth. Given the temperature difference, the speeds of sound are a_mars = 232 m/s a_earth = 347 m/s So yes, much of the difference is due to the composition: the Martian atmosphere has a higher atomic weight, which leads to a lower individual gas constant, and decreases the speed of sound. However, a substantial amount of the difference is simply due to the different temperatures on the surfaces of the two planets.
  - jessriedel 3y ago
    I don't know the answer to your question, but for context here are the weights of Mars rovers: Sojourner (1997): 11 kg Spirit & Opportunity (2004): 185 kg Curiosity (2011): 899 kg Perseverance (2020): 1,025 kg
    - mmbop 3y ago
      I know these are much larger - I’m just really curious about the dynamics of scaling up rotorcraft & why it is problematic. ie - do rotor physics become impracticality large or fast at some point for materials science, or is it purely a space problem for rocket launches.
      - jessriedel 3y ago
        Oh for sure, it's a great question.
      - IamTC 3y ago
        I have led efforts building Chinook style tandem rotors with 2 sets of blades from a size like the Trex 800, powered by a 2 stroke engine, as well as 40kg max takeoff quad-planes with both electric quadrotor and 2 stroke engine (for forward motion). But because I was the main lead and pushing the pace so fast, I wished I did it with a more rigorous aero-engineering to it. I started both projects with barely any experience developing aircraft. Thinking about your question, here are my 2 cents: The biggest thing I stugged with is how the vibrations and the accompanying harmonics on the sytem as the rotors spin up and down. I could see it on the logs as the rotors spin through certain Hz, there's would spikes in virbational ampiltudes at predictable frequencies. As the blades get bigger the forces (probably) goes up. Sometimes, these frequecies (especially the lower ones) are at the range where its very hard to find the right materials to damp it out of the control and sensing electronics. Ingenuity probably deals with a virbration range that well into the hundreds/thousand of Hz and I do remember that renge is not a difficult range to damp out, vis a vis the low tens of hertz. Also, the harmonics is related to ground resonance. I had built my tandem with "skids" that are rigidly attached to the rest of the frame. When the system made contact with the ground on just one skid, that one skid becomes a pivot, the vibration has no where to go and I witnessed first hand, first time, what ground resonance can do to mechanical systems. I can never forget seeing M4 through to M8 hex holt beads being sheared clean off after the resonance event. Only later did I find out that in full scale systems, they have dampeners between the main body and the skids of the aircraft. See https://m.youtube.com/watch?v=IIC-oBzLYhQ https://m.youtube.com/watch?v=IIC-oBzLYhQ ; Staying in flight is not as hard. But getting the ssytem to land and spin down proerly was big pain without understanding ground resonance and its effect on mechanical design. When I saw the little puny legs of Ingenuity, this experience of mine came into mind and I was glad they had legs like to damp out vibrations as it came down to land. Then there is the relation between the mechanical vibration regimes of the system, the polilng rates of the foundational flight sensors and the freqency of the main flight stability and movement control loop itself. With bigger systems, the cables (for signal and power) could run longer too (becoming long long antennas), which means you can run into problems with noise of various origins. If I'd do it again, something like CAN bus would probably be something I look at seriously. Bigger systems also draws more power, and that can have an impact on how much management is needed for noise. Bigger power draw usually also means heavy power store & delivery system, which affects CG management, when then means you can't move things around to management noise. At some point, I felt like I was doing dancing a multi-factorial show. I wished I could be clearer. Perhaps someone more qualified can chime in.
  - jvanderbot 3y ago
    Here's a paper that describes what the next gen could/should be. The lead author is the head of Mars heli, IIRC. https://ieeexplore.ieee.org/abstract/document/9843501 https://ieeexplore.ieee.org/abstract/document/9843501 In short: 30kg heli, 5kg payloads. Other designs by collaborators are closer to 20kg. It's probably possible to transport a few of these on the existing lander technology, which would be awesome. The scholar.google.com keywords you want are "Mars Science Helicopter" and a good touchpoint author is T. Tzanetos or S. Withrow-Maser Ames and JPL were still collaborating on this when I worked there.
- Firaxus 3y ago
  I was surprised to learn that it’s actually a fair bit heavier. I was lucky enough to get to attend a talk by the head of the Ingenuity program, and he mentioned how the mass ballooned a bit to something under 5 pounds. (Listed as 4 pounds on this official fact sheet) https://mars.nasa.gov/files/mars2020/MarsHelicopterIngenuity_FactSheet.pdf https://mars.nasa.gov/files/mars2020/MarsHelicopterIngenuity...
surfpel 3y ago
That's the goal, yes. Depending on the destination, naturally. Here's what's planned for Titan: https://en.wikipedia.org/wiki/Dragonfly_(spacecraft) https://en.wikipedia.org/wiki/Dragonfly_(spacecraft)
- jvanderbot 3y ago
  Was going to post this. Titan is such a wonderful place for a nuclear powered helicopter. Much better than rover/submarines/floaters, IMHO. A balloon would also have been excellent, but the extra mobility from helis is going to be amazing.
wongarsu 3y ago
Ingenuity was just a technology demonstrator. I think it demonstrated the technology splendidly, so we are likely to see more helicopters on Mars in the future. Not sure if Nasa has said yet which roles they see for future Mars helicopters. The initial idea behind Ingenuity was to use them as scouting vehicles for rovers. Of course rovers improved a lot too, with better autonomous driving. But with a Mars rover driving about 100 meters/yards per day scouting helicopters are still useful. Maybe we will also see Helicopters carrying more instruments themselves. But I imagine in the beginning that's mostly better imaging instruments. Weight is still an issue for flying things, no matter the planet. But maybe we will see some future missions that instead of a car-sized rover and one tiny helicopter have a fleet of helicopters with a small support-rover for exploring wider areas.
jessriedel 3y ago
I think the current plan is that helicopters will be very light with minimal instrumentation and will be used mostly to scout ahead for rovers. The rovers will be much heavier and include many instruments. (Of course, all of NASA's long-term plans for Mars would be completely disrupted if Starship lowers the cost-per-kg of delivering equipment by two orders of magnitude, which arguably is likely.)
- kibwen 3y ago
  Making it more economical to escape Earth's gravity well isn't going to alter the physics of the Martian atmosphere or the relative utility of copters vs rovers for Martian exploration. Which is to say, even if you stationed humans on Mars, they'd still be exploring remotely via copter/rover pairs, just no longer with a human-to-robot latency measured in tens of minutes.
  - wongarsu 3y ago
    However we might be willing to drive a lot more agressively if we know we can get a mechanic out to a stuck rover. Similarly, cheaper delivery might make a large number of smaller more disposable vehicles more appealing for many missions, just like what happened to satellites in the last decade.
  - jessriedel 3y ago
    If you increase the mass and/or number of vehicles by 100x, a bajillion things will change.
jvanderbot 3y ago
A heli that can move a rover is basically worse than a heli that has rover instruments and a few wheels. You have extra weight and parts and complexity for hitching and carrying that you can just avoid by giving a small rover flying ability. Even the combo is probably too much complexity. A heli with good imagers, spectrometers, and the ability to cart soil samples would be fantastic.
jvanderbot 3y ago
Surfacing a comment: Here's a paper that describes what the next gen could/should be. The lead author is the head of Mars heli, IIRC. https://ieeexplore.ieee.org/abstract/document/9843501 https://ieeexplore.ieee.org/abstract/document/9843501 In short, future designs target ~30kg heli, 5kg payloads. Other designs by collaborators are closer to 20kg. It's probably possible to transport a few of these on the existing lander technology, which would be awesome. The scholar.google.com keywords you want are "Mars Science Helicopter" and a good touchpoint author is T. Tzanetos or S. Withrow-Maser
- two_in_one 3y ago
  > Other designs by collaborators are closer to 20kg. It's probably possible to transport a few of these on the existing lander technology, which would be awesome. Actually it could be like 50 of them. Plus some ground robots to put together solar farm. And wooh... we get the first extra terrestrial permanent base
  - jvanderbot 3y ago
    Well size is the limiting factor for fliers, since they like to have broad surfaces with low weight. But I think you're referring to some, ahem, untested possible landing vehicles ... in which case, yeah, you have a lot of robots. For the solar farm assembly case, It's actually a lot easier to have a teleoperated robot doing the work, a few astronauts in orbit doing the operation / construction. In the case of building things, you want as much space / weight landed to be the thing being built, not the builders, per se.
- Keysh 3y ago
  Non-paywalled article about the concept, including renderings of the hexacopter design: https://spectrum.ieee.org/the-next-mars-helicopter https://spectrum.ieee.org/the-next-mars-helicopter
deadbabe 3y ago
Why not some helium balloon type craft that could float along with low power for longer periods of times? Could cover vast distances? Descend into fertile plains looking for samples?
- Jabbles 3y ago
  Helium's lifting capability is proportional to the density of the atmosphere, which is very low on Mars.
  - bloopernova 3y ago
    Is it viable to use vacuum instead of helium?
    - nilsherzig 3y ago
      Wouldn't you need something with some amount of pressure to stop the "shell" you plan to float from collapsing?
    - anticensor 3y ago
      What if we use hydrogen, which is halfway between helium and vacuum?
  - deadbabe 3y ago
    Hydrogen it is.
    - M95D 3y ago
      Hydrogen leaks.
somenameforme 3y ago
Minimizing moving parts, so much as possible, when dealing with hardware tens of millions of miles away, let alone with a 13 minute delay in 1-way messaging, is generally smart. And Mars' atmosphere is so thin that these rovers will never be moving any meaningful payload, so their only real use case is as a scouting type system. But they also add very little value there given the existence of orbiting satellites. Even the Mars Recon Orbiter (from 2005) captures images in the < 1m resolution range. IMO NASA wanted to try to deal with the sort of 'oh boy... another rover' fatigue and saw the drone as a way to spice things up with some passable science arguments behind it, and a relatively minimal cost. Further supporting this is that the helicopter wasn't an initial part of the plan - it was strapped on at the 'last minute', speaking in government time. In any case, I would comfortably wager against us seeing more drones in future missions, at least to Mars.
analog31 3y ago
In the shorter term, I see the helicopter as making the rover more capable, by finding routes and destinations of interest. And the rover makes the helicopter more capable by providing a recharging station. So they're both at their best when working as a system. Maybe a rover can support multiple choppers.
- p1mrx 3y ago
  > the rover makes the helicopter more capable by providing a recharging station Does it? I thought the helicopter was just solar powered.
  - analog31 3y ago
    That's cool. Thinking about it, there must be a tradeoff. The rover could support more massive batteries, but then "docking" between the two machines would have to be utterly reliable.
dotnet00 3y ago
IIRC as a result of Ingenuity's success, one of the proposals for the Mars sample return mission architecture involved several helicopters to retrieve Perseverance's sample canisters (it drops them as it goes along, so that there's no worry about how to get the samples out of the rover in the future). I should add though that the prospects of the parasites in Congress properly funding such a complex mission seem pretty low for now.

Kye 3y ago

Didn't this use mostly off the shelf parts? If so, I wonder how this will impact costs on future missions. If they can do more with consumer hardware, they can save budget to apply toward more science.

artemonster 3y ago
Yes, it did. I like the sentiment but I wonder how much conflict of interest would undermine this idea. Imagine how many companies are involved in developing space grade one-off hardware! Also, why would a highly bureaucratic structure undercut the amount of money that they themselves are asking for (and receiving) out of a budget? Savings are not aligned with the interest of such structure. Its not that for the amount you have saved you can allocate rest of the funds for something else (usually this is how it works with publicly funded projects AFAIK)
- foota 3y ago
  Well maybe they could start doing bigger and better missions, if they can reliably pull it off.
- augusto-moura 3y ago
  This also drops the bar for other space agencies, from other countries and private alike. Getting cheaper hardware also means more launches and more testing. Instead of sendind a multi million project to space, you can send basically a smartphone (an epheumism, ofc) and some big antennas, and do it in bulk
- icegreentea2 3y ago
  Every bit of money and platform resources (rad hardened CPUs are giant, slow and power inefficient compared to even semi modern COTS) is money and resources that NASA can spend on scientific payload on the same platform. NASA absolutely does have some incentive to find savings in control hardware and software. Finally, while Ingenuity does use a non-hardened Snapdragon, many other of its critical electronics components are still rad-hardened. The FPGA and dual MCUs (that actually do the low level control and I/O I assume) are both rad hardened. In addition, the COTS components that were used where screened by NASA for their performance in radiation. The Snapdragon is really just there to control the radio, and do image processing. Critically, these are functions that have -some leeway- for timing, giving the option to just restart the Snapdragon if a watch dog detects a problem. All of this to say is that rad-hardening isn't going away, but will probably stick around in many critical niches. What Ingenuity absolutely do is validate that modern COTS processors have a role to play in radiation elevated environments, including in semi-critical applications.

xeromal 3y ago

I actually go to the gym with one of the guys who worked(s) on this copter/drone. Super cool guy

daed 3y ago
How much can he bench?
- jvm___ 3y ago
  On Earth or Mars?
  - pimlottc 3y ago
    I don’t think you’re supposed to hold your breathe when lifting…
    - dylan604 3y ago
      Just like your not supposed to puff your cheeks when playing an instrument, but that never stopped Dizzy Gillespie. More of a suggestion than a rule
      - analog31 3y ago
        Gillespie also exemplified why the rule against puffing your cheeks is more than just a suggestion.
    - liamwire 3y ago
      Jokes aside, you absolutely are. Bracing properly is a critical skill in both olympic weightlifting and traditional strength training.
      - pimlottc 3y ago
        Ah, shows how much I know about lifting... in general I've always been reminded to keep breathing when exercising.

csdreamer7 3y ago

On Jupiter Broadcasting there was a lot of interviews on how this was a Linux powered device and could be the first of many new Linux devices on Mars by JPL. If I remembered correctly they used a space hardened Power cpu with an ancient version of Yocto since the newer versions of it did not have working drivers. When the rover had an issue they actually used the helicoptor's userspace command line GNU utilities to debug and get logs from the rover to send to Earth. Also, this makes Mars the second planet that uses Linux more than Windows as noted by the tweet in the linux below. :-) https://www.theverge.com/2021/2/19/22291324/linux-perseverance-mars-curiosity-ingenuity https://www.theverge.com/2021/2/19/22291324/linux-perseveran...

dylan604 3y ago
> If I remembered correctly they used a space hardened Power cpu If you're remembering correctly, then I'm misremembering in that this has essentially a Snapdragon chip and not a rad hardened CPU at all
- eric__cartman 3y ago
  They used the hardened PowerPC for the rover, similar to previous mars rovers and the Snapdragon chip for the helicopter.
- csdreamer7 3y ago
  Maybe I am misremembering the interview. Maybe the person said that they used to use a hardened IBM power chip?
  - Denvercoder9 3y ago
    This information is pretty widely available, e.g. on Wikipedia [1], no need to go off memory. Flight control is done by an FPGA, the main CPU is a Snapdragon 801 running Linux, and it uses Zigbee to communicate with the rover. [1] https://en.wikipedia.org/wiki/Ingenuity_(helicopter)#Avionics https://en.wikipedia.org/wiki/Ingenuity_(helicopter)#Avionic...

okasaki 3y ago

[flagged]

pimlottc 3y ago

It was probably just stuck in a tree.

deleted 3y ago
[deleted]
cubefox 3y ago
Or a Martian canal.

wait_a_minute 3y ago

Yeah! Let's go NASA, Godspeed! USA, USA, USA!!! Not only has it already exceeded its objectives, but now it may generate even more useful data for new objectives...does anyone know if NASA maintains any kind of engineering blog or stream where we can learn more details about what went wrong and how they reconnected?

patall 3y ago

For me, being listed as a contributor to Ingenuity is one of the highlights of my career in software development. I mean, I just fixed a bug in some python library, but that was enough to get the GitHub Ingenuity badge. And when ever I am asked for a fun fact about myself, I can answer: some of my code is flying on Mars :)

mlsu 3y ago
Ingenuity is running Python?
- Rebelgecko 3y ago
  The vehicle itself is mostly C++ but there's lots of python in the ground station and data processing
  - varelse 3y ago
    [dead]
  - jeffparsons 3y ago
    Wow, I somehow never imagined that even NASA's technology choices would be influenced by "all the data stuff being for Python". But I guess if it's all sandboxed and any errors are reversible... then why not? It all makes rational sense. It just feels weird to think about Python running on Mars before there's even people there.
    - zelphirkalt 3y ago
      GP stated, that there is a lot of Python based stuff on the ground though, as I read it. Not necessarily on Mars.
      - jeffparsons 3y ago
        Ah, I see. I read "ground station" as hardware on the ground on Mars, as opposed to on the helicopter itself.

standardUser 3y ago

I'm curious how long they expected it to remain in working condition. NASA has a habit of underestimating lifespans by a comical amount. It will be like "we expected the rover to operate for 10 weeks and that was 6 years ago". I think the most extreme example is Voyager 1, which was on a 5-year mission that reached nearly 50 years.

cwillu 3y ago
“We need the rover to operate for 10 weeks and will be discredited as an organization if it fails at 9” is what causes that. It's not necessarily a bad thing.
CuriousCosmic 3y ago
They planned for three 90 second flights prior to launch. After those worked they transitioned over to longer "operations demo" flights and those were extended tentatively out to 12 flights. After the 21st flight they just stopped manually allocating labor and funding to the project for a set number of flights and instead gave them a running budget for indefinite continued operations. So while "strictly speaking" they planned for three 90 second flights. There was the unstated assumption that it'd be used for much more than that as long as it actually worked effectively.
- foobar1962 3y ago
  It sounds as though mission life has as much to do with funding for ground staff (not something I ever considered) at least as much as it has to do with the life expectancy of deployed hardware.
  - CuriousCosmic 3y ago
    Yep. For example, Spirit and Opportunity were part of the Mars Exploration Rovers mission. 2/3 of that mission's total cost was the development, manufacture, and launch of the rovers themselves. Which more or less "per unit" works to 1/3 of the total mission cost per rover. The other third of that mission cost was staffing for the (15 year) ongoing mission from when it passed the initial mission parameters to when opportunity finally was deemed dead in 2018. https://www.planetary.org/space-policy/cost-of-the-mars-exploration-rovers https://www.planetary.org/space-policy/cost-of-the-mars-expl...

HPsquared 3y ago

So did it crash, or freeze?

Trekker666 3y ago

> "Good news today," NASA's Jet Propulsion Laboratory (JPL) wrote on X, formerly Twitter, late Saturday. I heard this line in my mind with Professor Fansworth's voice.