Author Topic: Mars 2020 Helicopter Drone  (Read 9872 times)

Online matthewkantar

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Re: Mars 2020 Helicopter Drone
« Reply #20 on: 05/15/2018 12:26 PM »
And if it sees something really compelling and lands safely, the rover will still stay away?

Offline Boost

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Re: Mars 2020 Helicopter Drone
« Reply #21 on: 05/15/2018 12:33 PM »
The drone won't be sterilized internally
I would be very surprised if JPL sends something on the surface of Mars that does not meet planetary protection requirements.

Offline Star One

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Mars 2020 Helicopter Drone
« Reply #22 on: 05/15/2018 12:37 PM »
I think that it was up to the science teams, technology demonstrations would never get done. NASA has to do science but it also has to do technology development.
Disagree. A lot of people on science teams have spent years trying to go get instruments to a high enough TRL to put on a real mission. They know the value of tech development. Also, a lot of them are huge space nerds.

I don't know why people are so bent on seeing the rover teams objections as some contrived excuse or petty malice (edit: as suggested in matthewkantar's post). Their job is to squeeze every last bit out of a $2.5+ billion machine they've been entrusted with. If the helicopter will impact their operational efficiency, it's their job to make sure decision-makers know that, even if they personally think the helicopter is super cool.

As 2020 Science Operations Lead Sarah Milkovich put it https://twitter.com/milkysa/status/995071470693838848
Quote
Welcome aboard, Mars Helicoper! We've been waiting for a final decision on this for years!   #Mars2020

(you're a cool idea even though you make my life more complicated)

Perhaps because thatís the way it comes across. Places Iíve worked people would never think to speak out in the public the way some of them have.
« Last Edit: 05/15/2018 12:42 PM by Star One »

Online matthewkantar

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Re: Mars 2020 Helicopter Drone
« Reply #23 on: 05/15/2018 05:25 PM »
And if it sees something really compelling and lands safely, the rover will still stay away?

It's not going to see anything that MRO has not already mapped.

Tech demonstrator. Not part of the operational mission.

So it's camera's resolution will be lower than MRO's?

Offline Lar

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Re: Mars 2020 Helicopter Drone
« Reply #24 on: 05/15/2018 08:28 PM »
You guys really ought to actually talk to some of the people working on Mars 2020. There's something that you're missing: the Mars 2020 team and operations are pretty much separate from the helicopter team. They're different groups, different objectives, and very different priorities. Mars 2020 is all about the science, and it's very high priority science. They view the helicopter as a sideshow tech development that is not part of their mission. And they're right. And most Mars scientists share that view.
I don't think we *can* talk to them to the level of detail we might want to. And that's a good thing because they're busy and don't have time for every fannish question, they would never get their real work done.  Fortunately we have good people that participate here that can bring the perspectives together and maybe do some interlocution in both directions. As you are doing, Blackstar.
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline theinternetftw

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Re: Mars 2020 Helicopter Drone
« Reply #25 on: 05/16/2018 04:10 AM »
Why won't they clean the inside of the Helicopter?

There are different standards for the outside of the vehicle than for the inside of a vehicle. The assumption is that anything that is enclosed is not going to transfer to the outside and the surface.

Surely that isn't the argument.  It's a reasonable standard for rovers but awful for helicopters, where innards can most definitely become outtards.  You lose your only functionality (and crank the science team irritation to 11) all by following a standard that clearly never considered this type of vehicle when being developed.

Is this really already decided and set in stone?  Is the cost so high that you would rather have the thing be useless and only ever a nuisance?

Online ccdengr

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Re: Mars 2020 Helicopter Drone
« Reply #26 on: 05/16/2018 04:22 AM »
PP requirements are complicated.  See https://planetaryprotection.nasa.gov/marsrequirements  Stuff inside has to stay within the "enclosed bioburden" limit.  What I don't know is if the helicopter is considered to potentially be "hard-impacting" or not.  I suspect not, because even the rover could end up hard-impacting in a failure.  I think they get to assume that the mission profile is normal and the helicopter isn't going to crash.

It's a coaxial anyway, so a lot of the worst failure modes probably can't happen (speaking as an R/C helicopter pilot who has crashed a certain number of times.)  Most likely is a tipover at landing, which probably won't break it open, just break the rotors.  :'(
« Last Edit: 05/16/2018 04:25 AM by ccdengr »

Offline theinternetftw

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Re: Mars 2020 Helicopter Drone
« Reply #27 on: 05/16/2018 04:39 AM »
Well Blackstar's entire rationale for not letting it do anything is it breaking open on a sample site, so if that's a real rationale and such arguments are being used to limit the helicopter's usefulness to nil, then "it probably won't break open" clearly doesn't cut it for the science team.

So if that's the case, why not clean it?

Online ccdengr

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Re: Mars 2020 Helicopter Drone
« Reply #28 on: 05/16/2018 05:29 AM »
"The science team" has very little say in helicopter operations, and essentially none in how PP is implemented.

Offline theinternetftw

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Re: Mars 2020 Helicopter Drone
« Reply #29 on: 05/16/2018 06:29 AM »
Nice quoting.

Are you sure the latter is true? If everyone on Mars 2020 wanted the benefits allowed by a helicopter that you don't necessarily have to abandon and said so, they'd be ignored?

And "X group is not in charge of PP" is definitely not an answer to "why not clean the inside?"

So why not clean the inside?
« Last Edit: 05/16/2018 07:34 AM by theinternetftw »

Online deruch

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Re: Mars 2020 Helicopter Drone
« Reply #30 on: 05/16/2018 09:06 AM »
Nice quoting.

Are you sure the latter is true? If everyone on Mars 2020 wanted the benefits allowed by a helicopter that you don't necessarily have to abandon and said so, they'd be ignored?

And "X group is not in charge of PP" is definitely not an answer to "why not clean the inside?"

So why not clean the inside?

If they haven't chosen to do so it's probably related to the budget for the tech demo.  Cleaning to the higher standard would cost X more.  The gains from doing so are insignificant to the Level 1 requirements of the project--sufficiently demonstrating the technology for potential use on future missions. 
Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

Online ccdengr

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Re: Mars 2020 Helicopter Drone
« Reply #31 on: 05/16/2018 12:39 PM »
So why not clean the inside?
The inside of the helicopter, as far as I know, will be (has to be, to meet the PP requirements) just as clean as the inside of the rover.  Read the requirements I linked to upstream.  The only thing subject to interpretation is where the rover might be allowed to drive versus where the helicopter is allowed to fly (special regions, etc.)

I think Blackstar is overstating the case for the helicopter being "just a demo".  If the helicopter works well and provides operational benefit, it will get used.  The science team isn't stupid and the support people who do much of the work are at JPL.  Of course, I suspect that the helicopter team oversold how useful the helicopter will be (haven't seen any details about the imaging system yet) but I guess we'll find out.

Offline Don2

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Re: Mars 2020 Helicopter Drone
« Reply #32 on: 05/18/2018 06:28 AM »
I the past I wasn't very keen on this helicopter, because I feared it could drive a cost or schedule blowout on the rover. It looks like NASA has found a way of doing it that doesn't pose too much threat to the rest of the project.

They way I look at this helicopter is that it is like the Wright flyer. The original Wright brothers plane didn't work very well and all it was really useful for was learning how to build something better. The Sojourner rover was similar. Falcon 1 filled a similar role for SpaceX. That is a common situation for the initial model of a breakthrough technology.

There are a couple features of the design that surprise me. One is that it doesn't need heat or power from the rover. It is autonomous except for the communication relay. If it could use a satellite relay, then it would have a theoretically unlimited range. A future model that builds on the 2020 experience could have some very interesting capabilities.

I'm also surprised that they are planning to use a lot of commercial components. Mars has a much greater day-night temperature swing than what consumer electronics is designed for. I'm quite surprised that they are able to get away with that.

The scientists are worried that it will take time away from the science mission. For political reasons it will be very difficult to park the drone as long as it continues to operate. However, this kind of flight test vehicle rarely has a long lifetime, so I don't think they scientists really have much to worry about. And it will be very cool to see it fly.

Online speedevil

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Re: Mars 2020 Helicopter Drone
« Reply #33 on: 05/18/2018 10:39 AM »
I'm also surprised that they are planning to use a lot of commercial components. Mars has a much greater day-night temperature swing than what consumer electronics is designed for. I'm quite surprised that they are able to get away with that.
Some numbers.

Looking at the the data for Curiosity, the air temperature ranges from a maximum of -30C to 10C during the day, with night at -65C to -85C.
The winter average air temperature is -60C, and summer -37C.

You do not have to search very hard to find components that are OK with -40C storage, and many specify operating temperatures near this range.
As the first example I picked, the raspberry Pi camera guarantees operation down to -20C, and specifies storage at -30C.

Once you go below -40C, parts become - if not unavailable - at least a much narrower selection.
Lithium-ion batteries normally will not be chargeable once temperature falls below around 5C, however, it is possible with electrolyte changes to drop this a little, and enable discharge over the -20C that is typical for commercial batteries.

The rover shown was around 20cm on a side, with a 7cm interior cube for electronics.
7cm of aerogel at Mars will leak 0.14W/m^2/K. For a 0.06m^2 area, 0.008W/K.

As a first stab, to keep the temperature of the electronics compartment at -30C minimum overnight, where even the modified batteries poop out, at -85C night temp, with that 55C delta, you need 0.4W.

Over 12 hours of darkness, 4.4Wh.
Compare this with the 200W*3 minutes = 11Wh - and you have numbers that indicate it is at least plausible that it can be done without heroic efforts, you may not be able to fly in winter much if at all, unless everything goes just right.
If you heat the electronics compartment to 50C at the end of the day, and the electronics weigh .2kg, you may not need any additional battery power at all to do this, due to their thermal capacity.

This is interesting, but neglects obvious heat leaks, such as the camera opening, and the wires. It at least shows it may be plausible - especially when you add perhaps not flying in winter to the internal thermal storage and add a modest amount of heat using electric power overnight.

You can also save some by 'double counting' - power spent doing navigation, comms,  or wasted in the motor controller is actually stored for warmth overnight in the thermal capacity of the batteries and circuitry.

If there is a severe dust storm, shadowed landing site, or one-day issue with your solar panel, you probably freeze and are not coming back. (a 1W RHU would be so nice)






Offline vjkane

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Re: Mars 2020 Helicopter Drone
« Reply #34 on: 05/18/2018 02:03 PM »
The helicopter will have two cameras:

Return-to-Earth (RTE) Camera. This is a rolling shutter, high-resolution 4208 by 3120 pixel sensor (Sony IMX 214) with a Bayer color filter array mated with an O-film optics module. This camera has a FOV of 47 deg (horizontal) by 47 deg (vertical) with an average IFOV of 0.26 mRad/pixel

Navigation (NAV) Camera. This is a global-shutter, nadir pointed gray scale 640 by 480 pixel sensor (Omnivision OV7251) mounted to a Sunny optics module. It has a field-of-view(FOV)of133deg(horizontal)by100deg (vertical) with an average Instantaneous Field-of-view (IFOV) of 3.6 m Rad/pixel, and is capable of acquiring imagesat10frames/sec. Visual features are extracted from the images and tracked from frame to frame to provide a velocity estimate.

My very back of the envelope calculations (trig is very ancient history for me, unfortunately) suggests that the RTE camera would have a resolution of ~2 cm from a height of 100 m, ~1 cm from 50 m, and ~0.5 cm from 25 m.  I'm sure that many the readers of this forum can do the math more properly.

Another paper that I read (but on a home computer) said that the value of small helicopters like this is future rover missions is that the higher resolution images would allow rover drivers to plan longer traverses than would be safe using just the imaging from the rover's mast cameras.  This same paper also said that larger helicopters were possible that might someday be probes in their own right.  Hence the value of demonstrating helicopter technology on this mission to enable (assuming positive results) options for future missions.

Camera specs quoted from Balaram et al. Mars Helicopter Technology Demonstrator.  2018 AIAA Atmospheric Flight Mechanics Conference.

Online speedevil

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Re: Mars 2020 Helicopter Drone
« Reply #35 on: 05/18/2018 03:43 PM »
The helicopter will have two cameras:

Return-to-Earth (RTE) Camera. This is a rolling shutter, high-resolution 4208 by 3120 pixel sensor (Sony IMX 214) with a Bayer color filter array mated with an O-film optics module. This camera has a FOV of 47 deg (horizontal) by 47 deg (vertical) with an average IFOV of 0.26 mRad/pixel

This normally costs, with the stock lens, $15 (it is out of stock at primary western vendors as it's several generations old).
Is a broadly comparable on-semiconductor part

Product brief of IMX214

The camera module is around 8*8*5mm.

I note this  article.


This is four 30s exposures, showing the milky way. (from the above article), to give an idea of some of the surprising advances in recent years.

It is moderately unlikely that nominal resolution will be achieved in flight, due to vibration.
« Last Edit: 05/18/2018 03:46 PM by speedevil »

Offline TrevorMonty

Re: Mars 2020 Helicopter Drone
« Reply #36 on: 05/18/2018 10:33 PM »
Future versions of Mars helicopter could benefit from this technology. May not be able to deliver enough power to fly without battery but should be able extend its flight time. Also an option for recharging helicopter on the ground. Would allow multiple flights a day and operation through the winter.

https://spectrum.ieee.org/automaton/robotics/robotics-hardware/laser-powered-robot-insect-achieves-lift-off
« Last Edit: 05/18/2018 10:36 PM by TrevorMonty »

Online speedevil

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Re: Mars 2020 Helicopter Drone
« Reply #37 on: 05/19/2018 01:28 AM »
Future versions of Mars helicopter could benefit from this technology. May not be able to deliver enough power to fly without battery but should be able extend its flight time. Also an option for recharging helicopter on the ground. Would allow multiple flights a day and operation through the winter.
A nuclear powered rover shooting a watt LASER at a nearby landed helicopter would easily allow it to maintain condition without heating overnight.
I'm not sure if this is sensible.

Offline maryalice

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Re: Mars 2020 Helicopter Drone
« Reply #38 on: 05/19/2018 01:15 PM »
Would this heli be smart enough (camera resolution?),, to identify the mouth of a cave or cavern on Mars?

Online speedevil

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Re: Mars 2020 Helicopter Drone
« Reply #39 on: 05/19/2018 01:30 PM »
Would this heli be smart enough (camera resolution?),, to identify the mouth of a cave or cavern on Mars?

Significant caves can probably be seen from orbit, if observed from the satellites around Mars, with a resolution of a little less than half a meter. It seems likely that any sites the rover/camera are flying in will be mapped to the highest resolution possible.

The helicopter can 3d map all the terrain it flies over (but may not be able to download all this data) with resolution of better than a centimeter.

It may in principle be able to fly very close to the entrance of a cave, and get a glimpse inside - the camera has good low light performance in some circumstances.


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