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-perseveran...
Some info from Wikipedia:
> The rover's computer uses the BAE Systems RAD750 radiation-hardened single board computer based on a ruggedized PowerPC G3 microprocessor (PowerPC 750). The computer contains 128 megabytes of volatile DRAM, and runs at 133 MHz. The flight software runs on the VxWorks operating system, is written in C and is able to access 4 gigabytes of NAND non-volatile memory on a separate card.
Wow, such a great testament to The Unix Philosophy of building small, modular, focused tools that can be combined together to do all sorts of interesting and more complex tasks. I'm sure no one imagined using these utilities from a helicopter to retrieve rover logs to aid in diagnostics, but here we are. What a cool story.
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
(I'm kidding, the badging system is funny)
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.
Or maybe have a helicopter that can move the rover with the equipment to different locations.
I heard this line in my mind with Professor Fansworth's voice.
It does bode well for sending cheaper "nice to have" experiments on missions, though.
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.
edit: from another comment: https://news.ycombinator.com/item?id=39081718
It looks like it's just a couple of (important) components that can handle the quirks of not being radiation-hardened, but it's still significant.
> He got a quote back for $120,000. “Elon laughed,” Davis said. “He said, 'That part is no more complicated than a garage door opener. Your budget is five thousand dollars. Go make it work.’”
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
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
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.
But yeah having more helicopters might be feasible - for surveying the surface.
(Listed as 4 pounds on this official fact sheet) https://mars.nasa.gov/files/mars2020/MarsHelicopterIngenuity...
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?
(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.)
Even the combo is probably too much complexity. A heli with good imagers, spectrometers, and the ability to cart soil samples would be fantastic.
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.
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.
Does it? I thought the helicopter was just solar powered.
I should add though that the prospects of the parasites in Congress properly funding such a complex mission seem pretty low for now.
https://www.planetary.org/space-policy/cost-of-the-mars-expl...
[1] https://en.wikipedia.org/wiki/Ingenuity_(helicopter)#Avionic...
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.
See EDLCAM in https://link.springer.com/article/10.1007/s11214-020-00765-9
I am guessing the requirements for circuitry operating on Mars isn't quite as much as a spacecraft or satellite, but it is still getting hit with cosmic particles and solar radiation with no atmosphere.
HN is dominantly a web/SW crowd plus some mobile frontend, and "it uses a Snapdragon" gives many a wrong idea. In embedded device projects a lot of time is spent planning and designing around a heavy compute element running Linux like this, especially if the device has a safety concept or other mixed criticality concerns. It will have a substantial moat around it.
On HN if you say "systems architecture" most folks go "Oh you mean like, whether we use microservices?". In embedded, while there is a lot of overlap and analogues, it's also all of the above, plus power state management and other aspects. It's not very shiny, but that profession makes all your cars, airplanes and alien planet multicopters.
If you have a good head for it, it's a pretty darn good career. You might not make $500k/year like you would at google, but the money is still decent and reliable.
Plus, working on spacecraft is cool as hell.
It all makes rational sense. It just feels weird to think about Python running on Mars before there's even people there.
For LEO you can scoot by pretty easily with non-hardened solutions and better systems engineering and software. For deep space you'll need to be more clever.
https://www.northwestern.edu/magazine/spring2012/feature/roc... (Page 3)
Anyone dealing with oracle, ibm, sas, hp, Microsoft and hordes of others are not strangers to seeing a $500,000 bill for basically nothing in B2B.
We hear about the government ones cause duh.
Here's the background:
There were numerous ways in which SpaceX's strategies diverged from space industry norms, and almost all of them had direct implications for the cost of its launch systems. First, whereas most aerospace companies give their designs to myriad third-party contractors who create the hardware for them, SpaceX produced roughly 80% of its launch hardware inhouse. SpaceX builds its own motherboards and circuits, vibration sensors, radios and more. In most industries vertical integration increases the costs of firms by not enabling them to benefit from competitive bidding between efficient suppliers. In the aerospace industry, however, the entrenchment of norms around using parts specialized for the space industry ("space grade"), and the bureaucratic rules defined by government contractors, had kept supply costs high — very high. SpaceX decided instead to build many of its own parts, or to buy parts not considered "space grade" and modify them to achieve "space grade".For example, rather than paying $50,000 to $100,000 for an industrial-grade radio, SpaceX was able to build its own for $5,000, and shaved 20% of the weight off at the same time.
SpaceX's willingness to produce their own parts came as a shock to suppliers. For example,Tom Mueller recounts a time when he asked a vendor for an estimate on a particular engine valve: "They came back [requesting] like a year and a half in development and hundreds of thousands of dollars. Just way out of whack. And we're like, 'No, we need it by this summer, for much, much less money.' They go, 'Good luck with that,' and kind of smirked and left." Mueller's team created the valve themselves, and by summer they had qualified it for use with cryogenic propellants. "That vendor, they iced us for a couple of months," Mueller said, "and then they called us back: 'Hey, we're willing to do that valve. You guys want to talk about it?' And we're like, 'No, we're done.' He goes, 'What do you mean you're done?' 'We qualified it. We're done.' And there was just silence at the end of the line. They were in shock." As noted, a big factor driving savings at SpaceX is that it often builds its components out of readily available consumer electronics rather than equipment alreadydeemed "space grade" by the rest of the industry. Twenty years ago "space grade" equipment would have had far superior performance characteristics compared to consumer electronics, but today that is no longer the case-standard electronics can now compete with more expensive, specialized gear. For example, at one point SpaceX needed an actuator that would steer the second stage of the Falcon 1. The job fell to engineer Steve Davis to find the important part, and since he had never built a part like that before he sought out suppliers who could make it for them. Their quoted price for the device was $120,000. As Davis recalls, "Elon laughed. He said, 'That part is no more complicated than a garage door opener. Your budget is five thousand dollars. Go make it work.'"20 Davis ended up designing an actuator that cost $3,900. Another example is provided by the computers that provide avionics for a rocket. Traditionally NASA's Jet Propulsion Laboratory bought expensive, specially toughened computers that cost over $10 million each to operate its rockets. Musk told engineer Kevin Watson that he wanted the bulk of the computer systems for Falcon 1 and Dragon to cost no more than $10,000. Watson was floored,noting, "In traditional aerospace, it would cost you more than ten thousand dollars just for the food at a meeting to discuss the cost of the avionics."21 Watson was inspired by the challenge, however, and ended up creating a fully redundant avionics platform that used a mix of off-the-shelf computer parts and in-house components for just over $10,000. That same system was then also adapted for use in the Falcon 9.
About the actuator: Steve Davis, the twenty second hire of SpaceX, needed an actuator that would trigger the gimbal action used to steer the upper stage of Falcon1. He went to find some suppliers and got a quote a $120,000. “Elon laughed”. Davis said. “He said, ‘That part is no more complicated than a garage door opener. Your budget is five thousand dollars. Go make it work.’” Davis spent nine months building the actuator and the final actuator approved by Musk ended up costing $3900.
Seems like they don't include the engineering time in the part cost calculations - so cheating a bit!I've experienced building something in-house that is far better than what you could otherwise get. Back in the 00's I wrote a JavaScript framework because the existing ones were all crappy in a variety of ways. Even as a one-person effort (and I'm no 10x engineer) I could write something that was wayyy better in a bunch of important ways (albeit not pretty enough design). My work was engineered better than the open source and commercial frameworks that I evaluated/used. Better loading, better recovery from network and other errors, better memory behaviour, better size, better speed, better integration, better diagnostics, better browser support, better user interface, customised for our needs. It did exactly what we needed for our project and mostly worked flawlessly.
The conversion of kilograms, mass, to pound-force, weight, relies explicitly on the given acceleration of Earth's gravity, ~9.8 m/s².
Since Mars has a gravity with acceleration ~3.7 m/s², for two things that weight the same on Earth and Mars the latter would need to be larger in mass to weigh the same in pound-force.
The biggest issue though, and something I will say even having been through multiple physics courses myself I don't recall having had literally explained, is that even though "pounds" can refer to force and not mass, they are not equivalent. 1 pound-mass ≠ 1 pound-force.
It is actually converted using the Earth's standard gravitional field's force, so 1 pound-mass ≈ 9.8 pound-force.
Thus, the amount on bench's is the pound-mass amount, say 66 kg or 145 pounds-mass, which is not 145 pounds-force but actually *1421*.
It's also true even that the gravitional force can change up to as much as 0.5% depending on where on Earth you are due to the shape of the Planet.
While the joke made _me_ laugh, but it seems as you dig further there isn't often reference to pounds as a force as much as I had thought, so I even learned something from it too!
Lots more information on Wikipedia[0] around these that is particularly useful if you for any reason want to know more:
The 10x difference comes in with metric units (kg and N).
Edit: might as well mention the rocketry connection... Probably the most well-known use of pounds-force is when discussing thrust of rocket engines (and other means of jet propulsion).
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.
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!
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.
Sojourner (1997): 11 kg
Spirit & Opportunity (2004): 185 kg
Curiosity (2011): 899 kg
Perseverance (2020): 1,025 kg
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 ;
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.
Right, but why would you believe what they say? I believe they know how to launch rockets, but that doesn't mean they are telling you the reason. They may not want it public, they may want to kiss someone's a-.
If she says you can keep cool whatever needs cooling for 10% of the Boeing price, you’d better believe it.
That's not persuasive. People make things up all the time, especially stories that show how smart <powerful person> is.
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.