Author Topic: Ingenuity, Mars 2020 Helicopter Drone  (Read 441610 times)

Offline Don2

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Re: Mars 2020 Helicopter Drone
« Reply #40 on: 05/19/2018 08:45 pm »
The Iphone has a lower temperature limit of 0 Celsius for operation and -20C for storage. That is probably typical of the kinds of consumer electronic components from which Earth based drones are built. There are some types of Li-ion battery that will operate at -20 but they have less capacity at that temperature than at room temperature.

Automotive electronics is a pretty big market and I think they are designed for a minimum temperature of -40C. Mil-spec calls for a minimum temperature of -55C but that is probably a small market focused on airborne drones and missiles. Surface temperatures at Gale Crater get down to -80C at night, but that is a low lying site close to the equator. The 2020 landing site is likely to be higher and colder.

Using the same electronics and batteries that Earth based drones use and simply building an enclosure to keep them at 0C is one way to go. I tried to calculate the heat flow from a 7cm cube with an internal temperature of 0C insulated with 1cm of aerogel in a -80C environment. I got an answer of about 1W.

Next I calculated the radiant heat loss from the cube and got an answer of 7W assuming no insulation. That could be easily reduced with foil insulation.

Finally, I tried to estimate the heat flow along a copper electrical cable of 2cm length and and 2mm diameter with one end at
0C and the other at 80C. I assume insulation so this is just a simple one dimensional heat flow situation. I calculate a heat flow of 5W in the cable.

The bottom line is that heat losses along electrical cables are likely to pose the biggest challenge. With some cleverness, maybe the heating requirement can be kept down to 1W during the night. If a flight takes 11Watt-hours then about half the energy will go to thermal control and half to flights. A radioisotope heater would be extremely useful. Just 2 grams of pure Pu-238 can provide 1W of heat and this would allow all the electrical energy to be conserved for flight.

Offline AlexA

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Re: Mars 2020 Helicopter Drone
« Reply #41 on: 05/21/2018 03:26 pm »
Camera specs quoted from Balaram et al. Mars Helicopter Technology Demonstrator.  2018 AIAA Atmospheric Flight Mechanics Conference.
PDF download here:
https://rotorcraft.arc.nasa.gov/Publications/files/Balaram_AIAA2018_0023.pdf

On Planetary Protection it says:
All components of the helicopter must satisfy Contamination Control requirements i.e. they need to be selected to
prevent out-gassing in the vacuum of space producing products that could contaminate other spacecraft elements. In
addition all elements must also meet Planetary Protection requirements i.e. they need to incorporate treatments and
handling procedures to prevent bio-contamination of instruments and sites with Earth organisms.


Thermal control:
The helicopter must survive the cold of the night on Mars where temperatures can drop to -100 C or lower. The
most critical component is the battery which is kept above -15 C through the night as it powers Kapton film heaters
attached to the battery cells. The avionics boards in the ECM surround the battery and are also kept at an elevated
temperature by virtue of their proximity to the warm battery assembly...


Offline speedevil

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Re: Mars 2020 Helicopter Drone
« Reply #42 on: 05/21/2018 05:12 pm »
In addition - on flight / power.
Quote
The helicopter battery shown in Fig. 12 consists of 6 Sony SE US1865o VTC4 Li-ion cells with a nameplate capacity of 2 Ah. ...
The continuous tested power load capability of this batterry is 480 W with a peak power capability of 510 W. Battery voltage is in the range of 1525.2 V and the total mass of the 6 cells is 273 g.
A de-rated end-of-life battery capacity of 35.75 Wh is available for use. Of this capacity, 10.73 Wh (30%) is kept as reserve, night-time survival energy usage is estimated at 21 Wh for typical operation in the northern latitudes in the
spring season, and approximatley 10 Wh is available for flight. Assuming that 20% of the power is at the peak load of
510 W and 80% is at a continuous load of 360 W, approximately 90 sec of flight is possible. These energy projections
represent conservative worst-case end-of-mision battery performance at 0 C initial temperature. More moderate power
loads will extend the flight time.
The solar panel is made from Inverted Metamorphic (IMM4J) cells from SolAero Technologies. The cells are
optimized for the Mars solar spectrum and occupy a rectangular area with 680 cm2 of substrate (544 cm2 active cell
area) in a region centered and immediately above the co-axial rotors. This region minimally interferes with the flow
through the rotor.
The solar panel has gone from a notionally circular one in the video upthread to a rectangular panel, tilted apparantly at the approximate value for the latitude.

Online Dalhousie

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Re: Mars 2020 Helicopter Drone
« Reply #43 on: 05/22/2018 08:55 am »
On Planetary Protection it says:
All components of the helicopter must satisfy Contamination Control requirements i.e. they need to be selected to
prevent out-gassing in the vacuum of space producing products that could contaminate other spacecraft elements. In
addition all elements must also meet Planetary Protection requirements i.e. they need to incorporate treatments and
handling procedures to prevent bio-contamination of instruments and sites with Earth organisms.


This means it will be a category IVc piece of hardware - like the outbound components of the 2020 mission itself. https://marsnext.jpl.nasa.gov/scieng_plantary.cfm
« Last Edit: 05/22/2018 12:21 pm by Dalhousie »
Apologies in advance for any lack of civility - it's unintended

Offline Pete

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Re: Mars 2020 Helicopter Drone
« Reply #44 on: 05/31/2018 07:20 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 can understand disapproval if helicopter comes at cost of science payload but its not as far as I know. If helicopter is a failure then all they've lost is a few days if that from mission. With a few days of
successful flights it could save rover weeks in travel time.
Underline by me..
Of course the heli comes at some payload cost, as it is mass that needs to be moved with the lander, that could have been allocated to something else.
But do we have accurate figures for just how much mass is involved?
What is the total mass for the Heli, its mount on the lander, any additional needed control and comms systems, etc?

Offline hop

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Re: Mars 2020 Helicopter Drone
« Reply #45 on: 05/31/2018 08:28 pm »
Of course the heli comes at some payload cost, as it is mass that needs to be moved with the lander, that could have been allocated to something else.
could have <> would have. Payload comes in discrete chunks and is subject to cost, power and data constraints. In most cases, you can't just dial in an extra kilogram and get extra science. On top of that, the primary payload is selected well before the final masses are known.

Quote
any additional needed control and comms systems, etc?
It is virtually certain the helicopter will use data volume (and associated power) that would otherwise be used for something else. OTOH, plenty of data gets spent on things that aren't strictly required for the primary science mission.

Online Dalhousie

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Re: Mars 2020 Helicopter Drone
« Reply #46 on: 06/01/2018 12:38 am »
Of course the heli comes at some payload cost, as it is mass that needs to be moved with the lander, that could have been allocated to something else.
could have <> would have. Payload comes in discrete chunks and is subject to cost, power and data constraints. In most cases, you can't just dial in an extra kilogram and get extra science. On top of that, the primary payload is selected well before the final masses are known.

Quote
any additional needed control and comms systems, etc?
It is virtually certain the helicopter will use data volume (and associated power) that would otherwise be used for something else. OTOH, plenty of data gets spent on things that aren't strictly required for the primary science mission.

However the higher resolution imagery and higher view point has been shown in tests to have benefits in terms of planning and additional data, saving time so the net gain outweighs the cost.
Apologies in advance for any lack of civility - it's unintended

Offline deruch

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Re: Mars 2020 Helicopter Drone
« Reply #47 on: 06/01/2018 12:57 am »
Of course the heli comes at some payload cost, as it is mass that needs to be moved with the lander, that could have been allocated to something else.
could have <> would have. Payload comes in discrete chunks and is subject to cost, power and data constraints. In most cases, you can't just dial in an extra kilogram and get extra science. On top of that, the primary payload is selected well before the final masses are known.

Quote
any additional needed control and comms systems, etc?
It is virtually certain the helicopter will use data volume (and associated power) that would otherwise be used for something else. OTOH, plenty of data gets spent on things that aren't strictly required for the primary science mission.

However the higher resolution imagery and higher view point has been shown in tests to have benefits in terms of planning and additional data, saving time so the net gain outweighs the cost.

Those most intimately involved and who knew most precisely exactly what the costs and potential benefits were, were pretty unanimously opposed to the helicopter being included because in their view it detracted from the main mission for this rover.  My impression of that position was that they viewed the costs as direct and the benefits as only potentially delivered on future missions.  Given the mission plan for the helicopter, that's not too surprising as it isn't planned to operate in conjunction with the rover on this mission. 
Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

Online Dalhousie

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Re: Mars 2020 Helicopter Drone
« Reply #48 on: 06/01/2018 05:40 am »
Of course the heli comes at some payload cost, as it is mass that needs to be moved with the lander, that could have been allocated to something else.
could have <> would have. Payload comes in discrete chunks and is subject to cost, power and data constraints. In most cases, you can't just dial in an extra kilogram and get extra science. On top of that, the primary payload is selected well before the final masses are known.

Quote
any additional needed control and comms systems, etc?
It is virtually certain the helicopter will use data volume (and associated power) that would otherwise be used for something else. OTOH, plenty of data gets spent on things that aren't strictly required for the primary science mission.

However the higher resolution imagery and higher view point has been shown in tests to have benefits in terms of planning and additional data, saving time so the net gain outweighs the cost.

Those most intimately involved and who knew most precisely exactly what the costs and potential benefits were, were pretty unanimously opposed to the helicopter being included because in their view it detracted from the main mission for this rover.  My impression of that position was that they viewed the costs as direct and the benefits as only potentially delivered on future missions.  Given the mission plan for the helicopter, that's not too surprising as it isn't planned to operate in conjunction with the rover on this mission.

And your evidence for this statement is?
Apologies in advance for any lack of civility - it's unintended

Online Blackstar

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Re: Mars 2020 Helicopter Drone
« Reply #49 on: 06/01/2018 11:02 am »
Of course the heli comes at some payload cost, as it is mass that needs to be moved with the lander, that could have been allocated to something else.
could have <> would have. Payload comes in discrete chunks and is subject to cost, power and data constraints. In most cases, you can't just dial in an extra kilogram and get extra science. On top of that, the primary payload is selected well before the final masses are known.

Quote
any additional needed control and comms systems, etc?
It is virtually certain the helicopter will use data volume (and associated power) that would otherwise be used for something else. OTOH, plenty of data gets spent on things that aren't strictly required for the primary science mission.

However the higher resolution imagery and higher view point has been shown in tests to have benefits in terms of planning and additional data, saving time so the net gain outweighs the cost.

Those most intimately involved and who knew most precisely exactly what the costs and potential benefits were, were pretty unanimously opposed to the helicopter being included because in their view it detracted from the main mission for this rover.  My impression of that position was that they viewed the costs as direct and the benefits as only potentially delivered on future missions.  Given the mission plan for the helicopter, that's not too surprising as it isn't planned to operate in conjunction with the rover on this mission.

And your evidence for this statement is?


I heard the same thing from the rover program manager in early May during a public presentation before the Space Studies Board.

Offline deruch

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Re: Mars 2020 Helicopter Drone
« Reply #50 on: 06/01/2018 02:31 pm »
Those most intimately involved and who knew most precisely exactly what the costs and potential benefits were, were pretty unanimously opposed to the helicopter being included because in their view it detracted from the main mission for this rover.  My impression of that position was that they viewed the costs as direct and the benefits as only potentially delivered on future missions.  Given the mission plan for the helicopter, that's not too surprising as it isn't planned to operate in conjunction with the rover on this mission.

And your evidence for this statement is?

http://spacenews.com/decision-expected-soon-on-adding-helicopter-to-mars-2020/
Quote
...
Ken Farley, the project scientist for Mars 2020, said ... “The Mars 2020 project has done everything that is necessary to accommodate that helicopter,” he said.

If added, the helicopter would operate for only about 30 days early in the rover’s mission, Farley said. It is intended to primarily be a technology demonstration to show how such a vehicle could be a scout for future rovers or carry out additional science.

If NASA did decide to add the helicopter, it would be only after determining that its inclusion would not significantly increase the overall risk of the mission. “Everybody agrees it will not put the mission at risk,” he said. “All the decisions that are being made have to honor that.”

That doesn’t mean, though, that the project supports adding the helicopter even if it doesn’t increase the mission’s risk. “I am not an advocate for the helicopter, and I don’t believe the Mars 2020 project has been an advocate for the helicopter,” he said. That opposition is based on the belief that the helicopter will be a distraction, taking away from the rover’s primary science work, at least for a short time.

"This comes right out of science time,” Farley said. “I have personally been opposed to it because we are working very hard for efficiencies and spending 30 days working on a technology demonstration does not further those goals directly from the science point of view.
...

I recall similar quotes from others on the 2020 team.  And here's the link to Blackstar's post [locked thread] of some highlighted points from various briefings he attended re: Mars Helicopter and Mars 2020, which also track the same position:  https://forum.nasaspaceflight.com/index.php?topic=45245.msg1820797#msg1820797
Quote from: Blackstar
-The helicopter will, however, require time to operate it. That time cuts into the science mission time. There are some people who were very opposed to it because of that. Mars 2020 is a very ambitious mission with a lot to accomplish, so cutting into science time is a risk to the mission objectives.
« Last Edit: 06/01/2018 02:40 pm by deruch »
Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

Online Blackstar

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Re: Mars 2020 Helicopter Drone
« Reply #51 on: 06/01/2018 03:26 pm »
I should add that in January I went to AIAA SciTech and they had a couple of presentations from the helicopter side. One of the presenters admitted that there was opposition to the helicopter from the rover science team. So this attitude hasn't been kept secret.




Offline hop

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Re: Mars 2020 Helicopter Drone
« Reply #52 on: 06/01/2018 06:00 pm »
However the higher resolution imagery and higher view point has been shown in tests to have benefits in terms of planning and additional data, saving time so the net gain outweighs the cost.
That's the overall concept, but not for this mission. This mission is a technology demonstrator to prove they can fly the helicopter. Any operational advantage would be a bonus. I tend to agree with ccdengr that if it works super well, it might get more operational usage, but there's no expectation that it will "pay for itself" operationally on the 2020 mission.

Online Dalhousie

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Re: Mars 2020 Helicopter Drone
« Reply #53 on: 06/01/2018 10:12 pm »
Some on the science team opposed it.  Therefore not all did.  Does that subset still oppose it?  We don't know. No mention of opposition from the operations people. Not surprising since there are clear potential operational advantages.  Therefore we should not universalise opposition when in fact it came from a few people.
Apologies in advance for any lack of civility - it's unintended

Online Blackstar

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Re: Mars 2020 Helicopter Drone
« Reply #54 on: 06/01/2018 10:57 pm »
Oh brother...

I don't understand why you guys don't get it: this is a tech demonstrator. It is a SMALL tech demonstrator on a BIG mission. The people who are working on the $2.4 billion rover are looking at this thing like a fly that is buzzing around their head while they are trying to drive their car. Of course they don't think it is useful or valuable because it just gets in the way of their--pardon me while I emphasize this point a little stronger--TWO POINT FOUR BILLION DOLLAR MISSION.

This thread is exhibiting one of the classic weaknesses of all space enthusiast groups: you think that the thing that you personally think is cool is what is important, and is what the people operating space programs think is important. The industry, NASA, science, are all working on their own set of rules, not your definition of cool and important.

Offline matthewkantar

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Re: Mars 2020 Helicopter Drone
« Reply #55 on: 06/02/2018 12:39 am »
And yet NASA serves the public.

Online Dalhousie

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Re: Mars 2020 Helicopter Drone
« Reply #56 on: 06/02/2018 01:04 am »
Oh brother...

I don't understand why you guys don't get it: this is a tech demonstrator. It is a SMALL tech demonstrator on a BIG mission. The people who are working on the $2.4 billion rover are looking at this thing like a fly that is buzzing around their head while they are trying to drive their car. Of course they don't think it is useful or valuable because it just gets in the way of their--pardon me while I emphasize this point a little stronger--TWO POINT FOUR BILLION DOLLAR MISSION.

This thread is exhibiting one of the classic weaknesses of all space enthusiast groups: you think that the thing that you personally think is cool is what is important, and is what the people operating space programs think is important. The industry, NASA, science, are all working on their own set of rules, not your definition of cool and important.


You have only provided evidence that some people did not like it.  You have presented zero evidence that this opposition was universal across the team.  You have presented zero evidence that this opposition continues.

You have ignored the evidence that there are documented operational advantages to the scout.

Apologies in advance for any lack of civility - it's unintended

Offline deruch

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Re: Mars 2020 Helicopter Drone
« Reply #57 on: 06/02/2018 07:14 am »
You have only provided evidence that some people did not like it.  You have presented zero evidence that this opposition was universal across the team.  You have presented zero evidence that this opposition continues.

You mean that because there doesn't exist an official poll where each and every member of the entire Mars 2020 team, without exception, publicly voted against including the helicopter that therefore the multiple and varied statements by leading team members that they personally, and the team in general, didn't support its inclusion are therefore worthless and not representative?  Ridiculous.  In addition to the direct statements, what you seem to be discounting/ignoring is that the way people talk about the issue is indicative of the feelings of the whole team.  If an issue/decision within a team has support on both sides, when representatives talk about how the team feels their statements will always reflect that ambivalence regardless of their personal position.  So, I take the fact that the project scientist was making the statements he did to the press (i.e. the SpaceNews article I linked), as actually quite a strong signal.  IMO, even the way that statements about their readiness/preparedness for the helicopter's possible inclusion which didn't touch on the team's opinion were couched in such a way that showed they weren't in favor. 

Current, ongoing opposition opinion is a moot issue.  The helicopter is included.  Done.  And the Mars 2020 project has done everything necessary, and will continue to do so, to include it and support its achieving the set mission objectives.
Quote
You have ignored the evidence that there are documented operational advantages to the scout.
You have ignored the fact that they are constrained by being required to only consider the helicopter's approved mission.  Which lasts for 30 days and, as currently planned, will have absolutely ZERO ability to assist this particular rover.  Any claims that there are "documented operational advantages to the scout" are about the idea of having an operational scout on some future mission or about what might be possible if the helicopter is able to live past its mission lifetime and gets an extension.  Only, neither of those are germane considerations to those working this mission (beyond tentative operations planning for how to try to capitalize on the capability).  IMO, the real problem is that for M2020 to make use of the helicopter, the chopper will have to live and be operable far beyond its planned lifetime.  The early months of these rover missions never seem to make long trek drives where the route planning would be most beneficial.  That only comes once they've gotten everything working and calibrated, explored the initial landing area, characterized the rover's actual driving behavior and operation, and set out for the prime science hunting grounds.  Etc.

And yet NASA serves the public.
Which is why whether to include the helicopter or not was a decision that was taken above the level of just the Mars 2020 rover team.  That way it could be based on wider views which encompassed more than just the narrow requirements of meeting just their science goals and could include things like potential benefits to future missions, advancing technology, and public engagement, etc.  It's the same reason they don't let a single instrument team decide how resources get allocated to the other instruments on a platform.  You'd often end up with one instrument being a glutton and everything else left sucking hind tit.
« Last Edit: 06/02/2018 03:39 pm by deruch »
Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

Offline Don2

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Re: Mars 2020 Helicopter Drone
« Reply #58 on: 06/03/2018 08:03 am »
There's a couple of things that aren't being mentioned here. I believe the science payload for the 2020 rover was cost constrained not mass constrained. So there is room in the mass budget for the drone. Congress thought the drone was a cool idea and I think they added extra funding for it. It is sensible to keep Congress happy because they control the purse strings. Advancing aerospace technology is part of NASA's mission so the drone is not off mission for NASA. A solar powered drone could have unlimited range and it is not hard to think of potential science applications for future missions.

The major resource that the drone will consume is time and telecommunication resources. If it doesn't last long, then it won't have much impact on the mission. If it lasts for a while, then hopefully the value of the scouting photos will pay for the resources it consumes. The drone isn't the only tech demonstration on the mission. The Moxie experiment will probably consume a fair amount of power. That will demonstrate the production of oxygen from CO2, which could be a very valuable capability for future missions.

The reason that the scientists are uncomfortable with the time the drone will take up is that they have a lot to get done and need a big improvement in rover productivity relative to Curiosity. I think they are aiming to collect 32 core samples from a diverse range of sites including both sedimentary and igneous rocks. Past plans mentioned a 20km traverse. Consider that in almost six years on Mars Curiosity has drilled only 16 times and covered only 18km. Consider that Curiosity is no where close to finishing the exploration of Mount Sharpe. The 2020 rover will have to at least double if not quadruple the rate of drilling if it is to get the samples collected before the rover starts to wear out. The landing site in Jezero Crater is not going to be simpler or have less science than Gale Crater. I they will struggle to get all the samples collected in time and it is understandable that they don't want any additional tasks on top of what they already have.

Offline speedevil

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Re: Mars 2020 Helicopter Drone
« Reply #59 on: 06/03/2018 09:41 am »
. I they will struggle to get all the samples collected in time and it is understandable that they don't want any additional tasks on top of what they already have.
The drone - if this is a concern and if in fact the rover does not help significantly path planning - should be operated out of the PR budget.


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