NASA Getting Ready To Fly A Drone On Mars!

They referred to the initial test flights being 90 seconds in duration. I would not expecgt subsequent programmatic flights to be so short. UAVs operating in earth gravity and atmosphere easily get 20 times that flight time, and there is no physical reason why the power consumption on Mars would be even nearly that much higher, provided that the props are optimized for the 0.02 kg m⁻³ atmospheric density (i.e. 1/50 earth atmospheric density).

Flying is just one of the energy requirements for the drone -- it's going to have to send the data it records back to Earth and even using a Mars satellite to relay that is going to require a not insignificant amount of power and energy. Additionally, they'll need to use power and energy to keep it warm enough -- the low air density will limit convection loss but not eliminate it. Putting a lot of insulation on it is impractical though a radiation blanket is almost certain. At the other end getting rid of heat produce during flight will be another problem as the air is so thin convection will do little to limit temps during flight -- it is for this reason I think flight times will have to be kept short.

One way they might reduce weight and sensitivity to temp might be to use super capacitors instead of batteries as that would permit much higher power output and a practically unlimited lifespan relative to a small battery being over-driven to produce the power needed for flight. The downside to ultra capacitors is high self discharge.

Perhaps the biggest trouble area is dust and the impact that will have on solar energy production particularly given the fact that every flight will begin and end on loose dirt. The annual planet wide dust storms could pose a major problem if it zero's out energy production for a few days. One upside potential is that the props might help to blow off some of the dust from the storms -- OTH, those same props will blow up the dirt on the ground and onto the solar cells.


Brian
 
Land based rovers on Mars do not travel very far in a day owing to the fact that the signal delay from Mars to Earth and back is so long they can't control them from Earth -- not real-time anyway. In fact, the cumulative distance traveled by any of the rovers is less than 50km over the entire duration which in some cases is about 15 years. A drone would have some advantages there given they should have less risk of hitting something provided the mission planners review the planned flight and climb high enough to avoid hitting a boulder or hillside. So, even with the limited flight time a drone should indeed be able to cover more territory than a rover. Let's try some guesstimate on numbers here...

If the solar cells can provide 2W, and judging by the size of the panels and the much lower solar flux on Mars, and not counting the dust, and if we put the battery at, say, 40WHrs it would take 2 full days to charge it for a single flight that might cover 200m. So, maybe 100m/day or potentially 36km/year -- this would be much more than the land based rovers manage but we have to account for the limited lifespan of the battery and dust so in reality the total distance covered in its lifespan might wind up being more like 10km.

BUT....

As mentioned before, if the drone actually consumes an appreciable portion of the total charge in 90 seconds or there abouts the lifespan of the batter and therefore the drone will be very short. Also, given the minuscule weight the drone can carry as well as the very limited energy budget, the drone will be very limited in the sensors it can carry. Dust is a problem on Mars and we had a rover die last summer because of it. Every flight will begin and end on loose dirt/regolith -- anyone that's flown a drone knows what that means for dust. If dust reduces the already low energy production from the limited amount of solar cells, and remember some of the energy collected needs to go to keep the batteries and other things warm enough to function -- Mars is like a very northern latitude in the winter and gets real cold.

If the goal is a photo survey then the need for other sensors is reduced, but given the likely short lifespan the amount of ground covered would be no more and likely less than the current rovers. As an exercise to test future tech then I'm 100% OK with this, but as a tool to provide science or even photos I'd argue its viability is, well, not so good...


Brian
The triple-junction solar panels and special LiION battery formulations are likely to exceed the limits of your assumptions by a significant margin. NASA has demonstrated that the LiION cells used in other applications on mars should provide 1000 cycles with less than 15% usable capacity loss.

In any case- why might we need to assume the sole charging solution is from the panels on the AC?
 
  • Like
Reactions: sar104
Flying is just one of the energy requirements for the drone -- it's going to have to send the data it records back to Earth and even using a Mars satellite to relay that is going to require a not insignificant amount of power and energy.

I'm pretty sure that the drone is going to be communicating to the local base, and the local base communicating with earth - unless you think they are going to install a large dish antenna on the drone.

Additionally, they'll need to use power and energy to keep it warm enough -- the low air density will limit convection loss but not eliminate it. Putting a lot of insulation on it is impractical though a radiation blanket is almost certain. At the other end getting rid of heat produce during flight will be another problem as the air is so thin convection will do little to limit temps during flight -- it is for this reason I think flight times will have to be kept short.

That sounds like total speculation. The only temperature-sensitive component is likely to be the battery, and it takes very little parasitic power to warm that up.

One way they might reduce weight and sensitivity to temp might be to use super capacitors instead of batteries as that would permit much higher power output and a practically unlimited lifespan relative to a small battery being over-driven to produce the power needed for flight. The downside to ultra capacitors is high self discharge.

Except they are undoubtedly using batteries - just like the rest of the equipment there.

Perhaps the biggest trouble area is dust and the impact that will have on solar energy production particularly given the fact that every flight will begin and end on loose dirt. The annual planet wide dust storms could pose a major problem if it zero's out energy production for a few days. One upside potential is that the props might help to blow off some of the dust from the storms -- OTH, those same props will blow up the dirt on the ground and onto the solar cells.

Which is a completely different subject. I'm guessing that they may have already considered all those issues, but maybe you should give them a call, just to be sure.
 
The LiIon cells used in other applications on Mars aren't being pushed to the same power/capacity ratios required for a drone -- not even in the remote ball park equivalent!

You better believe they'll be using the best solar cells and while there are research cells that are upwards of 43% efficient I don't think the ones used will be more than about 33%. At Mars distance from the Sun the solar intensity will be about 400W/m^2 and the cells shown in the photo don't look more than 100mm x 300mm or about 0.03m^2. With 33% cells and 400W/m^2 you're looking at a bit less than 4W assuming the Sun is shinning directly on it (normal) -- integrated over a day multiply 4W by about 70% and you get about 2.6W. The mass appears to be about what the P4P is and in flight the P4P burns about 170W on average. The lower gravity on Mars should lower the power needed but the thin air will require large props spinning fast -- I'd ballpark the power needed for sustained flight at about 80W given the overhead of CPU's and comm that will be there even if the gravity were zero.

I'd love to see what the plan to limit dust on the solar cells every time they takeoff and land is, though I doubt they'll return my phone calls on the matter.


Brian
 
I can’t decide if this is an interesting intellectual exchange, or a cleverly disguised pissing contest.

;-))

Aww. I’m just having some fun. It’s an interesting read in either case. :)
 
Last edited:
  • Like
Reactions: Maddy
The LiIon cells used in other applications on Mars aren't being pushed to the same power/capacity ratios required for a drone -- not even in the remote ball park equivalent!

You better believe they'll be using the best solar cells and while there are research cells that are upwards of 43% efficient I don't think the ones used will be more than about 33%. At Mars distance from the Sun the solar intensity will be about 400W/m^2 and the cells shown in the photo don't look more than 100mm x 300mm or about 0.03m^2. With 33% cells and 400W/m^2 you're looking at a bit less than 4W assuming the Sun is shinning directly on it (normal) -- integrated over a day multiply 4W by about 70% and you get about 2.6W. The mass appears to be about what the P4P is and in flight the P4P burns about 170W on average. The lower gravity on Mars should lower the power needed but the thin air will require large props spinning fast -- I'd ballpark the power needed for sustained flight at about 80W given the overhead of CPU's and comm that will be there even if the gravity were zero.

I'd love to see what the plan to limit dust on the solar cells every time they takeoff and land is, though I doubt they'll return my phone calls on the matter.


Brian
The LiIon cells used in other applications on Mars aren't being pushed to the same power/capacity ratios required for a drone -- not even in the remote ball park equivalent!

You better believe they'll be using the best solar cells and while there are research cells that are upwards of 43% efficient I don't think the ones used will be more than about 33%. At Mars distance from the Sun the solar intensity will be about 400W/m^2 and the cells shown in the photo don't look more than 100mm x 300mm or about 0.03m^2. With 33% cells and 400W/m^2 you're looking at a bit less than 4W assuming the Sun is shinning directly on it (normal) -- integrated over a day multiply 4W by about 70% and you get about 2.6W. The mass appears to be about what the P4P is and in flight the P4P burns about 170W on average. The lower gravity on Mars should lower the power needed but the thin air will require large props spinning fast -- I'd ballpark the power needed for sustained flight at about 80W given the overhead of CPU's and comm that will be there even if the gravity were zero.

I'd love to see what the plan to limit dust on the solar cells every time they takeoff and land is, though I doubt they'll return my phone calls on the matter.


Brian
At least certain of your assumptions must be incorrect- assuming NASA and JPL (the supplier) aren’t incompetent and haven’t missinterpreted what is known about the conditions on mars and the expected performance of available technology.

From what had been revealed publicly about the project it will carry 2Ah of Sony LiION cells and fly for 90sec with a max misssion range of 600m and altitude of 10m. The stated purpose is to scout ahead of the rover it will be deployed from. Seems like a reasonable business case for its development.
 
I can’t decide if this is an interesting intellectual exchange, or a cleverly disguised pissing contest.

;-))

Aww. I’m just having some fun. It’s an interesting read in either case. :)
Reality? It might be there is little difference in the two scenarios you have proposed on most occasions- always elements of both to varying degrees.
 
Reality? It might be there is little difference in the two scenarios you have proposed on most occasions- always elements of both to varying degrees.
I haven’t posed any scenarios. Only a wee bit of humor. But... QED. ;)
 
  • Like
Reactions: Maddy
Well I think we've exhausted this and until more info is forthcoming there's little reason to continue the "pissing contest". So, I for one am signing off on this for now. If someone finds a source for more complete and up-to-date information please post a link so we can have a look at it.


Brian
 
Well I think we've exhausted this and until more info is forthcoming there's little reason to continue the "pissing contest". So, I for one am signing off on this for now. If someone finds a source for more complete and up-to-date information please post a link so we can have a look at it.


Brian
JPL mars helicopter scout as terms (google or your search engine of choice) will remove the need for a lot of assumptions.
 
According to the plan, the aircraft should hit the surface of the neighboring planet in February 2021. The Martian helicopter will not carry any research equipment. The device will be equipped with only one high-resolution color camera, with the help of which scientists will study hard-to-reach places on the planet's surface for rovers.
 
Would they still have to calibrate the drone compass?? Is it a drone that doesn't need a compass?

and also wondering that if the drone was made on Earth, than wouldn't it not fly properly on Mars?


A bit confusing....
 
  • Like
Reactions: MTO

Members online

No members online now.

Forum statistics

Threads
143,066
Messages
1,467,358
Members
104,936
Latest member
hirehackers