Nasa will send helicopter to Mars to test otherworldly flight | Hacker News Reader

Nasa will send helicopter to Mars to test otherworldly flight

bbc.com

235 pointsmtuncer124 comments

Link to the underlying press release [0] which has slightly more info than the BBC article. There is a bit more background about the project at [1], with some key points being:

"The helicopter uses counter-rotating coaxial rotors about 1.1 m in diameter. Its payload will be a high resolution downward-looking camera for navigation, landing, and science surveying of the terrain, and a communication system to relay data to the 2020 Mars rover. The inconsistent Mars magnetic field precludes the use of a compass for navigation, so it would require a solar tracker camera integrated to JPL's visual inertial navigation system. Some additional inputs might include gyros, visual odometry, tilt sensors, altimeter, and hazard detectors. It would use solar panels to recharge its batteries."

[0] https://www.nasa.gov/press-release/mars-helicopter-to-fly-on...

[1] https://en.wikipedia.org/wiki/NASA_Mars_Helicopter_Scout

"The helicopter uses counter-rotating coaxial rotors about 1.1 m in diameter..."

Not to be little it but, in short, a drone.

I presume the rocket scientists are jealous ;)

Of course. It's by definition until we get someone to Mars.

I hear ya. But at 1.1m lifting an adult human might be a struggle.

Right, of course you got that. I just wanted to point out that we need to manage our expectations of such a headline due to the current state of technology. There is no way an earth-size helicopter is making it to Mars with current rocket capabilities. The thing is the size of a softball and requires those 1.1m rotors. A human carrying copter would be pointless it seems. They will probably use rocket powered hoppers or something along those lines

The funny thing is that you could almost classify most space missions as drones (or probes).

They are usually called rovers, unless they actually fly. I cannot name any single atmospheric flight on another planet, only controlled plunges.

The Vega-1 and Vega-2 balloons operated for more than 46 hours in the atmosphere of Venus as part of the Soviet Venera programme [0]

[0] https://en.wikipedia.org/wiki/Vega_program

Everyone forgets about that program, and it was incredible stuff.

NASA has been using drones since 1950, it's everyone else that's jelly.

PS: Unmanned Rockets are Drones that shoot fire.

I too found the terminology a bit weird. When I think "helicopter", i think "gigantic rotor blade with a cockpit fit for a human".

When i think "quadcopter", I think of something smaller than what NASA has proposed.

Sounds weird, because we're used to media spam. But "drone" wrt. flying machines basically has 3 popular meanings - RC multicopters, any RC aircraft, and those big RC aircrafts with surveillance cameras and Hellfire missiles. Back because multicopter mania caused all RC aircraft to be rebranded as "drones", we used to call them by category - RC plane, RC helicopter, etc. So personally, I'm totally fine with NASA using the word "helicopter" - though I expect the name that's even more cool than "drone" - an UAV.

That's what I thought too. But they've been designing this for years; so it might have started before drones got as popular as they are.

I mean, drones are just a new name for hobby aircraft. People typically associate drones with quad-copters, but people were flying tiny helicopters next to their small replica remote aircraft for decades.

I realize the FAA has official designations for what is a drone (and a lot of older hobby aircrafts may now technically be drones), but it's a word that's really come about because the field is now more accessible/affordable.

> drones are just a new name for hobby aircraft

With the minor notation that hobby aircraft are permitted in some national parks, while drones are prohibited in all. The Parks Service operates a number of model aircraft airports in some national parks.

(I'm not moaning about the perceived inequity with the "drones;" just pointing out a curiosity. I've hated drones ever since they started ruining my ability to peacefully enjoy nature.)

>it's a word that's really come about because the field is now more accessible/affordable

I think it's a word that comes about because the marketers know that douchebags will respond to pretending that they're part of some secret military high-tech spy ops program, and not flying a Chinese plastic quadcopter. "Model aircraft" is for nerds. "Drone" is for monster truck owners and wannabes.

I'll give an upvote for this. Not the most polite way of putting it, but I appreciate keeping it real.

It's a UAV if you want to get back into the subject matter we're discussing though. I do wonder how well it'll do in the Martian atmosphere, especially if it gets caught charging in a sandstorm.

To me what makes a drone a drone is the control system algorithm that keeps the aircraft stable. I thought "model aircraft " had to be operated by a sufficiently skilled operator to keep it from crashing. Whereas "drones " automate this skill and present a very simple, dummed down interface such as "go left, turn around, descend" etc

If only self-leveling was more common in drones. None of the drones I own have self-leveling, nor have any owned by other pilots that I know.

There are a multitude of ways to pilot quadcopters, combining the 4 different transmitter modes (Mode 1, Mode 2, Mode 3, Mode 4) with the different control modes (Acro, Rate, Horizon, etc). The lack of standardization can be maddening for beginners - it's like learning Git, Github, and DVCS, while learning to code.

It's always struck me, when people are panicking about some overwrought news story, how much scarier R/C helicopters are when you call them "drones".

It says a lot to how routine using satellite navigation aids has become that my first question was why they’re not using GPS.

Wait, could they use earth GPS and it would just be very innacurate?

GPS requires a bunch of satellites to be in orbit first, and we haven't sent them to Mars yet.

I meant using the known location of existing earth GPS satellites

Mars is 140 million miles away from earth on average. Even if you could detect signals from GPS satellites on earth they would all be at a single point in the sky.

However, that does bring up an interesting idea. Maybe rovers could navigate using the position of the stars? It doesn't require you to launch 4+ GPS satellites into martian orbit.

I don't see why not - automatic celestial nagivation systems are already a thing on earth, you basically have a system that uses a camera to look at the sky and it gives you an accurate position - most military planes use it as backup in case GPS ever goes down.

Good read: The Island of the Day Before by Umberto Eco

TL;DR you need to see the stars and you need to know what time it is

Earth's GPS satellites use earthward facing directional antennas, and even on Earth the signal is several dB below the noise floor, so our receivers have to use process gain to actually get anything useful out of them.

Mars is fifty million kilometers away. A GPS reliever on Mars looking for Earth satellites wouldn't be able to hear anything.

We need a bunch here on Earth so we can get a fix in a reasonable time. But all the robots on Mars move extremely slowly and infrequently. i.e. it would be fine if the bot had to wait 12+ hours for a fix, they'd probably be waiting that long regularly anyways. And it probably doesn't need to be more accurate than 0.1-1 km either.

So could we deploy, say, the first three satellites that use a modified version of GPS at first that allows you to get a very slow, inaccurate fix, but a fix nonetheless?

If you have enough time, a single satellite is enough, provided it's not in a geostationary orbit. My understanding is that this is part of the initial location of landers, but that once they're located there's no point, since it's easier to just optically determine how you moved.

On Earth, similar systems were used for the TRANSIT satellites, and the Cospas-SARSat program. The latter is really cool, as it used weather satellites in low earth orbit to find a person in distress, using a cheap transmitter that's placed on a plane, boat, or very famously, Richard Branson's watch.

The way it works is that the device transmits a very stable frequency. (Perhaps modulated by the identity of the person in trouble part of the time.) As the satellite passes by, it relays the signal to the ground in a way that preserves the doppler shift. When you know the position of the satellite and the doppler shift, you can know the closest point and the distance from it.

After a few passes of your one satellite (or multiple satellites, if you have them), you can get a location that's good enough to start search and rescue.

Of course, time has passed since this was designed in the 70s and early 80s, and now GPS has fallen in price to the point where it's everywhere. So now, the devices send GPS coordinates with the identity info.

You mean pick up the signal from earths GPS? Off the top of my head, it would require earth to be in view, and it would be very inaccurate - GPS is already less accurate the further from equator you get, as all the visible satellites are increasingly on one side of you. You'd have this problem in the extreme, as all the satellites would be clustered in a single dot in the sky. Probably also infeasible to meaningfully correct for the fact that Mars and Earth move very quickly relative to each other.

> GPS is already less accurate the further from equator you get, as all the visible satellites are increasingly on one side of you.

Not contradicting you, but just to be clear: GPS satellites are not in geostationary orbits above the equator, or even in geosynchronous orbits. Rather, they are in medium-Earth orbits and their time-averaged density over the Earth is only a little lower over the poles as the equator. At some parts of the month, there are as many visible at the poles as at the equator. See Fig. 4 here:

https://www.researchgate.net/publication/228400966_Analysis_...

The GPS Wikipedia page also has a reasonable illustration of their orbits.

Hmm, not sure I understand what you're saying. Figure 5 in that paper is the situation I'm describing: at a certain latitude (52 deg north in this case, incidentally that latitude is my 'hood) there are no satellites visible to the north. Figure 2(b) illustrates why that's bad for precision.

Sure, that's why I said I wasn't contradicting you, just clarifying. One could mistakenly read your comment and think that the coverage goes to zero at the poles ("the further from the equator you get"), but of course GPS still works pretty well there. When you get far enough north, satellites from the "other side" of the Earth come into view, so the accuracy levels off and (I think) starts increasing again with latitude.

(And I corrected my comment to refer to figure 4, not 2.)

No. GPS works only on planets surrounded by GPS satellites.

The GPS signal is already under the noise floor on Earth there is no way with present day tech that you'd be able to get the signals on Mars and besides that the math would not work because the round-off errors regarding the timing would make all satellites appear at the same point in space when looked at from Mars. The distance is hard to appreciate in terrestrial terms without getting into 'golf balls and oranges' kind of explanations.

> round-off errors regarding the timing would make all satellites appear at the same point in space when looked at from Mars

Not just timing, also space - Earth is a fraction of an arc second on Martian sky, pretty much a very small dot. All your signals would be coming from that small dot, i.e. practically on top of one another.

The whole idea of GPS is to turn a very good time reference (an atomic clock) into a space reference, by using multiple such references with known locations at once and then to send out time stamped signals. If you can't distinguish arrival times the signal origins collapse into a point. The travel time of the signal from Earth to Mars is anywhere from 4 to 24 minutes (assuming you have line of sight, which isn't the case when Mars is on the other side of the sun), with flight times that long the difference in arrival time between the signals is meaningless.

The difference in position between the satellites is at best 40,000 km (MEO orbits and satellites in opposite positions around Earth would give you the largest baseline), the difference from Mars to Earth is > 50M kilometers. So when viewed from Mars this would be like trying to triangulate your position in the United States based on signal sources spaced a very short distance apart somewhere in Moscow.

(sorry for the strained analogy)

Another problem with the approach is that of the two possible solutions that are the result from computing your location from GPS satellites one of the solutions is deep inside the Earth, which for both radio related reasons and reasons of practicality can be safely ignored. From a location in space very far away that trick no longer works so you will end up having to pick one of several answers.

Of course you could stick a GPS like transmitter into every Mars orbiter we launch from now on so that at some point there will be enough coverage locally to allow navigation, but that's a pretty expensive trick, besides that you'd also need a bunch of base stations in order to properly compute the orbits of the satellites to the required precision so that you can tell the satellites where they are.

I'm pretty sure if you're on the Earth's surface and can pick up three GPS satellites, the other solution is out in space. If you see four or more GPS satellites, there's a unique solution.

That's probably correct. I read up on GPS years ago and I remember that one of the possible solutions is intuitively wrong for a surface of the earth measurement and filled that in mentally as 'inside the earth', but out in space sounds much more logical and likely.

No.

First of all, they would need an absurdly large directional antenna to even receive GPS satellites. GPS signals are already below the noise floor on Earth's surface, and we use mathematical trickery to extract them from the background. Secondly, even that would only be possible when Earth's over the horizon at the location of the probe. Thirdly, the whole span of GPS satellites as viewed from Mars would be a small fraction of arc second, i.e. basically all coming from the one place. Lastly, there's extra light lag that you have to compensate for, that depends on relative position and orientation of Earth and Mars.

No, GPS is not suited for use in space, especially not far away from Earth. However, I read once that some Earth orbit missions did in fact look / make use of the GPS signals, as in (low) Earth orbit, they're actually easier to receive than on the ground.

The third point can be misinterpreted to make it sound like gps involves a steady tone generated from a known location like more traditional navigation aids used in aviation, rather than clocks taking advantage of our understanding relativistic effects.

While Earth is in the Martian sky, and if the signal were strong enough, a viewer could average receiving signals from over half of the constellation rather than only half a dozen. Furthermore the time signals would originate from many of the satellites moving less orthogonally to the viewer and instead moving toward and away from the viewer.

Compared to measuring the sun relative to a changing horizon, it seems plausible that an extremely precise direction and altitude relative to Earth could give even more precise location on Mars.

The distances are literally astronomical. Mars isn't just next door. It isn't like the moon where we can talk almost in real time.

Consider it like running. How far can you run in 1 second. That's the Moon. How far can you run in 21 minutes. That's Mars. It's 1260 times the distance.

If anyone has AIAA paper access (or a workaround ;), they published a ton of details on their guidance, control, and avionics designs at the beginning of this year:

https://arc.aiaa.org/doi/10.2514/6.2018-0023 https://arc.aiaa.org/doi/abs/10.2514/6.2018-1849

check ntrs?

Sounds a lot like a drone

It would have to be pretty dust/debris resistant, but could the helicopter -- or a simplified version of it -- be used to clear a lander's solar panels of dust?

I recall with previous landers, how solar charging performance would degrade, then pick up after what was surmised to have been a wind storm event.

A dusting brush would likely be more mass- and energy-efficient.

So if it falls on its side, something that has a probably a 50% chance of happening, can it get back up?

I always thought that for exploring another planet, you shouldn't really use something with wheels or wings.

Something different like small "jumping robots" would make a lot more sense in a place where you have literally the ability to do 0-hardware maintenance.

Instead of a single expensive flying robot, why not send a fleet of these little small jumping-robots instead, to more quickly and cheaply explore the area: https://www.youtube.com/watch?v=6b4ZZQkcNEo

What about jumping robots makes them maintenance-free?

Where do you get 50% from? It's got landing legs, and will be placed right-side-up to start with by the Mars 2020 rover.

All it takes is to land on the side on one rock and it's over. I would say the chance is more like 98% over the span of a few years.

Vision navigation systems are pretty effective these days - 'avoid big rocks' seems like a straightforward use case for that. And clearly the landing systems would need to account for some degree of rough terrain. The wheeled drones go through a tremendous amount of testing of the various conditions they would encounter - a flying drone would go through the same engineering rigour before it was approved for the mission.

Also, I believe most of the activity of these devices is planned out well in advance, so you could even add human review to some of that process. It could take a short flight for a few high-rez pictures, land right near (or exactly) where it took off from, send the pics back to earth for review to pick it's next landing spot.

Tiny works great for agility demos, but I doubt that there would be much agility left once you add any amount of meaningful payload. A battery that lasts longer than a demo video take, sufficiently powered uplink (no convenient wifi or low-power cellular where they are going) and all those sensors for in-situ geological experiments. Because without that, all that jumping around would not get you any data that could not be acquired much easier and with more precision using a simple overhead laser scan. Oh, and much of Mars may not be paved, that little "jump drive" surely needs a reliable surface to push back against.

OMG that little jumping robot is so cute!

I don't know.. I shudder every time I see a robot from Boston Dynamics, because I always imagine it with weaponry running/rolling down the street and killing people, with people trying to fight back but being mostly ineffective.

It's likely we'll see some nightmare uses for such technology in our lifetimes.

Neat little robot, reminds me of this animal:

https://en.wikipedia.org/wiki/Springtail

I once spotted some 'jumping dust' around a leaky faucet and it turned out that it was 100's of these little creatures. They can jump 100's of times their own height!

Very cool. They were trying to get NASA to allow them to send it when I worked at JPL a few years ago. NASA is very nervous about anything messing up the main focus of the mission.

The NASA Jet Propulsion Lab continues to excel at technology innovation in support of science.

Make bounce landing work on another planet. Make powered landing on another planet routine. Make remove vehicle operations on another planet routine. Make soft landing with a rocket sky crane routine.

So why not a blimp? I did not see any mention why they did not consider this though they did mention the Soviets using balloons on Venus. Is the air too thin to support any sort of lighter than air vehicle?

>Is the air too thin to support any sort of lighter than air vehicle?

Yes

It sounds like it might be feasible: the atmosphere on the surface of Mars is described as the equivalent of Earth at "100,000 feet" (30 km) but the record for a weather balloon is 53km, and balloons carrying people have gone as high as 40km.

The helicopter being proposed is "the size of a softball", though, and not the main focus of the mission. The high altitude weather balloons have been much bigger and would probably need a dedicated mission.

Why don't they test the helicopter at 100k feet then?

The article doesn't say whether they will or not.

Not having read the article, I am sure that they already did. Nothing gets sent beyond Earth's orbit without having gone through as much testing as is humanly possible on Earth. The cost of failure on Earth is several orders of magnitude less expensive than the cost of failure elsewhere.

I would guess that sending a test helicopter along with another rover would be to do a feasibility test for larger flight-based probes in the future. Test it now with a small helicopter, and you use 10-20 pounds of payload in order to do better wind and atmospheric studies. On the other hand, if you send a probe that uses flight as its primary mode of transportation, and some unknown unknown causes it to fail, you've scrapped the entire mission.

They might not have, because it might just fall out of the sky. It's built to overcome Mars' gravity, not Earth's.

However I agree with you, they will be testing it extensively in as close to Martian conditions as they can achieve.

> They might not have, because it might just fall out of the sky. It's built to overcome Mars' gravity, not Earth's.

A video has them flying that thing inside a pressure chamber without payload, so at least in this configuration it has enough power to overcome Earth's gravity. Probably wouldn't lift off on Earth with the payload, though.

My guess is that they test it in chambers with lowered air pressure and composition to match 100k feet?

at about 50sec into the video they appear to be doing exactly such a test in a large vacuum chamber

Forgive my ignorance, but I'd think the lower gravity would actually reduce buoyancy, so a lighter than air vehicle would have less upward force, while being at the mercy of high winds. At the same time, less gravity makes it easier for a helicopter because less lift would be required for a heavier than air vehicle.

On Mars, gravity + thin air would likely limit the usefulness. But you're spot-on with Venus. Blimps would be great there. Hell, there were articles floating a couple of years ago suggesting you could park blimp on Venus above the corrosive layers of atmosphere, and conditions there could actually support a small base that would extract necessary resources from the atmosphere, and where humans would only need light shielding (+ breathing apparatus). I'm not saying building a cloud city on Venus is a good idea now, but I do think a long-duration mission to study the atmosphere would be, as data from Venus is also useful for studying climate change on Earth.

It would be interesting to see how the helicopter handles potential dust storms which can have winds of up to 94 km/hr.[1]

1: https://en.wikipedia.org/wiki/Climate_of_Mars#Effect_of_dust...

That would be very interesting. I am pretty naive on the topic but one thing to keep in mind is that the force of martian wind is nothing like on earth as the atmosphere is around 1% as dense as ours. For reference, the winds in the Martian was one of the big literary devices used to help the story along but I don't think could actually happen

Aren't they pretty mild despite this, thanks to the very low density of the atmosphere?

They are, but this is a disaster waiting to happen anyway. Extremely high RPM, no redundancy in rotors or engines, flying in an environment full of dust and particles, having to land perfectly every time (or get damaged irreversibly), all these things add up to certain failure. It's definitely very cool, but it's not going to be nearly as reliable or useful as a land-based vehicle. Besides, aerial photos have generally little value for Mars (at least for the surface area such a drone can cover) because the atmosphere is clear and you can get great imagery from space.

So unless they want to reach an otherwise impossible to climb location, I don't see the use for it.

> Besides, aerial photos have generally little value for Mars (at least for the surface area such a drone can cover) because the atmosphere is clear and you can get great imagery from space.

I'm not buying your blanket statement. Atmosphere is not the only limitation - optics are heavy.

>optics are heavy

It depends on the optics. Modern optics for the visual range are incredibly light.

Also, since you assume optics are heavy, why do you think putting them on a drone is a good idea? You can haul a metric ton of optics in space for years (if not decades) but that drone can probably carry a handful of kg of equipment, and not that many cameras.

My point is that you can't just conclude a prior that the capabilities could be matched by an orbiter. You need bigger and thus heavier optics to match the performance of a camera on the ground from orbit. The extra mass for the drone might be less than that needed for the larger optics.

I makes me think of the Mars trilogy by Kim Stanley Robinson (best Sci-Fi book series ever!) where the early colonists run into a dust store (really _fines storm_ since the particulate mater is much smaller than dust and gets into everything) that lasts several years.

You know helicopters in Mars is totally Phillip K Dick material.

https://en.m.wikipedia.org/wiki/Martian_Time-Slip

A little more recent:

https://youtu.be/oJGJEepIOt0?t=38

It's from Red Planet (2000):

https://www.imdb.com/title/tt0199753/

Even more recent: https://youtu.be/vacjOrVqesM?list=RD7Oq-ClZ8Gbs&t=299

From the series Mars (2006) - https://www.imdb.com/title/tt4939064/.

That looks like the very same heli-drone! I had not heard of the series, thank you.

Damn, past my edit window. I mean 2016, not 2006.

Didn't see any mention on how it will be powered, are batteries even feasable?

I thought just keeping rovers warm enough to operate was quite energy consuming.

It looks like it's only going to do one brief flight, so yes, batteries probably are feasible. I'm not sure if it would require more power or less power than on Earth though since gravity is lower but so is air density for the blades to act on.

Looks like a more efficient and much faster way to explore the area if they can solve the thinner atmosphere but, if their missions are autonomous and it seems that can't be modified in real time, what happens with the mars storms?

I hope that they have a software to take measures if the air pressure or the light levels change suddenly.

Couldn't the differences in temperature between shadowed and sunny areas create turbulences?

Yes to all of this but do you assume no one at NASA has thought of any of this? Weird.

Am I assuming that? Where?

This sort of "somebody should have thought about that (and fix it), so don't say it", is probably the safe way for people working in a big company that needs to fit in a hierarchy and please their boss. We aren't in this context and have a bigger margin to freely explore any idea and talk about it. To wonder about the dust storms is a valid question.

Does this make any sense? Isn't Mars' atmosphere much thinner than Earth's? Wouldn't that count against using rotary wing crafts?

It’s about 1% the density of earths atmosphere. The craft would have to be light and have large blades, but that doesn’t seem impossible. The light atmosphere means huge blades could still spin fast without issue. It’s not easy but this is NASA we’re talking about. They made a sky crane to drop a Mini Cooper sized rover on Mars before.

Also gravity is about a third of Earth's, so that might help a little bit.

All heavier-than-air flight on Mars is subject to the same issue, but it's presumably still more efficient than using rockets. If it works, it works.

I expect the real problems would come in scaling it up; I doubt a typical helicopter rotor/head assembly would hold together under the high head speeds needed on Mars (or you could maybe use very long blades, which comes with its own problems).

The interesting thing about rotary-wing craft is that they actually work sort of independent of altitude (as long as everything stays subsonic.) As air pressure decreases, lift at a given rotor RPM decreases - but the drag on the rotor also decreases, so the RPM increases and it ends up providing the same amount of thrust. The reason helicopters on Earth haven't flown very high is not because of the rotors, but rather the engines, which require more air than is present at high altitude. For electric motors, that is not a problem.

I wonder if a sterling engine would work well for high altitude rotary-wing craft. The higher you go up the cooler the air, causing the sterling engine to be more efficient.

The big problem with stirling engines is the power-to-weight ratio; they are much heavier than internal combustion engines for the same power output, too heavy for any practical use in a flying machine.

I'm not sure that this is inherent to Stirling engines, or just the past engineering implementations. For one thing, unlike internal combustion engines, there is no need to contain an explosion (otto cycle) or flame front (diesel) so the pistons and cylinder walls can be made of lighter materials and don't need lubricant filters. In fact self lubricating graphite pistons are often used modern Stirling engines. Secondly a higher efficiency implies that more power is extracted from the fuel which indicates that the combined fuel tank and engine can be smaller and that more power will be put to doing work. Lastly, a Stirling engine usually falls short in torque, and that can be compensated for with a hybrid system that utilizes electric motors for instantaneous changes speed, where added torque is required.

Can't NASA test this in an artificial atmosphere low-pressure low-gravity room? Obviously there will be real-world concerns that are hard to simulate like slight damage from spacecraft landing and dust spun up when the copter takes off, but the article makes it sound like the low density is the big thing they're worried about.

Simulating dust kick-up would be easier than constructing a "low gravity" room.

It isn't too hard to simulate low gravity, all you need to do is move a large aircraft in the appropriate parabolic pattern. My understanding is that this is already how NASA trains astronauts for zero-g environments, and how weightlessness is done in space movies. Adjusting the path to match Mars gravity should not be difficult.

True, but you cannot test a small helicopter inside an aircraft, can you?

I don't see why not, a test that goes 10 feet up, 50 feet over, 10 feet down should be sufficient. The thing in the video looks like it could fit in a large cargo plane. Or, are you concerned about turbulance due to being in a closed space vs open atmosphere?

It might not be realistic to fly a pressure vessel large enough to simulate the low atmospheric pressure as well as the low gravity. There are probably also safety concerns; the rotors on serious R/C helicopters store enough energy to basically decapitate a human and these are probably somewhere in that neighborhood given the requirement to generate lift in Mars' atmosphere.

They've done this already: https://youtu.be/oOMQOqKRWjU?t=41s

Interesting that they didn't go the multirotor route, seems like it would cut down on development, complexity, and possibly weight. Maybe single axis counter-rotor was chosen for having a slightly better area/diameter to lift generating area ratio.

It will need smarts to fly and land, and land especially to save power while it awaits the next destination command. The land surveys can only see so much and if you land wrong on a even a small rock, you could get stuck top over

Does anybody knows what is the autonomy of this helicopter ?

Considering the lag in communication to earth, it'd have to be fully autonomous. It needs to be able to avoid obstacles, navigate visually (that article states a compass won't work with Mars's magnetic field) and find a place to land, in direct sunlight, whenever it needs to charge its batteries.

I'm sure NASA has mapped out some waypoints, but there's no way to really control the actual flight remotely without a human in orbit.

Yea, the daily flight time (3 min) is much less than signal travel time to Earth. So the entire flight needs to be autonomous.

Why not a few quadcopters like GoPro or something. I guess those are more stable and cheap.

My guess is a normal quadcopter doesn't have a big enough thrust to weight ratio in Mars' atmosphere.

Can someone check my math/physics? The atmosphere on Mars is about 1.7% as dense as on Earth, meaning that a propeller on Earth will generate 58.8x more thrust than on Mars. An aircraft on Earth will weigh 2.6x of its Mars weight. Drones probably need a thrust to weight ratio of at least 1.5 to be reasonably maneuverable. A drone that has a 1.5 thrust to weight ratio on Mars would have a thrust to weight ratio of 1.5 * 58.8 / 2.6 = 33.9. That is certainly higher than hobbyist Earth drones that I’m aware of, but not terribly hard to imagine. The craziest racing quadcopters I’ve seen have power to weight ratios of around 10.

They're not limited to commercial constraints of price and safety, so they can build it lighter, with larger and higher-RPM propellers (to the point they would break in our atmosphere), and with less battery life. But that answers the top-level question here: you can't just ship an OTC drone to Mars and expect it to work there.

This was started years ago. There are probably already plans for the next stages and quadcopters are probably on the list of ideas.

The cost of failure is so high that these ideas have to be flushed out and tested for years. There is literally no way to fix these robots once (or even if) they make it to their destinations.

Not unless we figure out how to turn off gravity or invent teleportation.

Why does the BBC use "Nasa" instead of "NASA"?

>Where you would normally say the abbreviation as a string of letters - an initialism - use all capitals with no full stops or spaces (eg FA, UNHCR, NUT). However, our style is to use lower case with an initial cap for acronyms, where you would normally pronounce the set of letters as a word (eg Aids, Farc, Eta, Nafta, Nasa, Opec, Apec).

http://www.bbc.co.uk/academy/journalism/article/art201307021...

To piggy back off this, different news outlets have their own set of rules. For example, CNET (I think) wouldn't use upper case past 4 characters Example: NASA, Nascar

Style guides also tend to ignore funky punctuation, etc. in company names. For example, it was pretty standard to drop the ! in Yahoo!. There is certainly an argument for respecting the wishes of a name's owner but it's also understandable to do otherwise for readability.

In this particular case, there are also a lot of acronyms that have entered such common usage (like radar) that capitalizing them would seem odd. And too many capped acronyms, Studly Caps, hyphenations etc. hurt readability after a while.

I always like when it’s written “Yahoo!” because I read it with an alveolar click, as /jahu!/. <https://en.wikipedia.org/wiki/Alveolar_clicks>

Using the capitalization the organization prefers seems like the best way to me. I'm sure they do it for people. The would not change the capitation of a Dutch last name for example.

It somewhat amuses me to think that "forced CamelCasing of abbreviations" is a thing outside of code. I wonder where it began.

(Personally, I find it irritating and more annoying to read, both in prose and in code.)

Well Elon has already sent a car, so a helicopter was the least they could send!

If this is the sort of experiment that is getting space on a rocket then I kind of wonder if NASA is out of ideas.

In other news, Hepatitis C is making a big comeback here in Denver. It's the sort of disease we used to laugh about being a "third world" problem back in the day. We don't use the term "third world" anymore, but we are becoming one nonetheless.

I can't stop thinking about what archaeologists will think about us in a thousand years, they will struggle so much to even come up with plausible theories, much less agree on them.

Are you a markov chain?

> If this is the sort of experiment that is getting space on a rocket then I kind of wonder if NASA is out of ideas.

No, it's just your imagination that's limited. This is a good idea to test on Mars. Want crazier stuff? Google Venus blimps, or go and find papers about flying supersonic aircraft on Mars.

> I can't stop thinking about what archaeologists will think about us in a thousand years, they will struggle so much to even come up with plausible theories, much less agree on them.

I guess you're implying we should be spending that money on Hepatitis C, to which I'll answer "no, we shouldn't", as money spent on space is pretty useful there on the margin, so you should look for sources of money elsewhere, where there's just too much of it. And if anything, archaeologists will think we've been dumb to put such absurd amounts of wealth to stupid zero sum games and entertainment, instead medical research, space exploration, and basic sciences. But that's just my guess :).

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