Perseverance Mars Lander

[wotnot]

I was looking for a meme that closely resembled how I thought about all this Mars stuff...

[Uncle Fester]

...they won't be able to fire guns indoors? That would render the US sourced P.D. useless.
However a bullet shot outside from a normal 0.22 calibre rifle aimed up at 30-45˚ angle could reach well over 100km range and easily hit a dome and pierce it or other random targets.

[hinekadon]

very interesting what can happen as normal in our lives but on the moon or mars the differences become almost impossible what we know involves the atmosphere and gravity and its hard to get ones head around that when its not there , I wonder what effect it would have on the hidden things like emotions and ethics ???

[Uncle Fester]

very interesting what can happen as normal in our lives but on the moon or mars the differences become almost impossible what we know involves the atmosphere and gravity and its hard to get ones head around that when its not there , I wonder what effect it would have on the hidden things like emotions and ethics ???

Everything will be about staying alive and surviving and that will only work when everybody works perfectly together.
So the ethic is: You behave properly or we all die.
This might eventually lead to a kind dictatorship but initially the colony is a team of flexible and highly skilled people who all know what to do without being commanded too much.
The main emotion will be a feeling of success that we lived another day and maybe missing something from home like fresh air, water and good food.
As everyday is an achievement, people should stay in a reasonably good mood.
I know this feeling when I am 'roughing it' in the bush.
I feel quite satisfied with achieving basic things that we normally take for granted.
And some of these things are going to be an incredible achievement on Mars.


Of course a lot will change dramatically when the colonists can start to procreate.

[trash]

Dry ice is quite soft, I can crumble it with my hands.

Earth dry ice. Not Mars dry ice. There's just a slight difference there.

BTW I think it is time the stop sending these awkward rovers and just send a bunch of Boston Dynamics "Spots".

You forgot - power hungry. The advantage of a rover is power efficiency.
But in general, spot offers no advantages for Mars exploration.

[qoute]
Unlike what Trash claims, it sure got there but the lander crashed due to an engine failure in the last seconds before touchdown.
[/quote]
I didn't say it was impossible or it had not happened. It's just harder to land there and not because it has anything to do with landing sites.
It has everything to do with orbital mechanics and the energy required to just get to the landing phase.

If you approach mars equatorially, you can take advantage of Mars's orbital velocity and subtract that from your spacecraft's velocity for a fuel saving on an orbital insertion. If you try to do that in a polar orbit you do not have that saving so even the orbital approach has to be different which is another fuel consideration.
Of course you can go for a direct entry which is common, again it requires the right approach and burn. Once in the atmosphere everything is the same except for the approach speeds and angle but those are still able to be factored in. The cost is really about the fuel. Small lander it's not a lot of difference, but a big lander the cost goes up in multiples. At the end of the day they are already picking the low hanging fruit first for life anyway.

There must be an atmosphere on the moon,

There is an atmosphere but not a lot of it.
I can't remember the composition. Hydrogen and Helium make up most of it. Pressure is about 2e-12 torr which is what I call a "damn hard vacuum"
My pumps go down to 1e-7. Which "suck a balling ball through 10ft of garden hose" kind a vacuum.

However a bullet shot outside from a normal 0.22 calibre rifle aimed up at 30-45˚ angle could reach well over 100km range and easily hit a dome and pierce it or other random targets.

I'm kind of surprised it's not further than that, but I suppose it's just a .22. Have you crunched some numbers to see if it is correct?

I can't help myself, I have to crunch the numbers for fun anyway.
.22 is about 500m/s and Mars gravity about 3.7m/s/s. which means it's 135 to apogee if shot straight up.
s=ut+1/2at^2 == 500 - (0.5 * 3.7 * 135^2) = ~34km altitude.

For 45 degrees we use 354m/s. which gives us 95.5 seconds to apogee at 17km and 191 seconds flight time.
We'll ignore air friction. 191s x 354m = ~68km.

Turns out it's less. But that is an average .22 velocity I just picked.
Of course we can go magnum, hornet or my personal fave, wildcat

Now did somebody say spot?

[Uncle Fester]

You forgot - power hungry. The advantage of a rover is power efficiency.
But in general, spot offers no advantages for Mars exploration.

The rover only seems efficient because it is slow but it is also very heavy, so I will question the efficiency to work load ratio here.

Spot's base weighs 32.5kg (on Earth), lets say 50kg with arm and gun (to fire holes in the ice )
20 spots could do a hell of a lot more than a single rover and without having to be extremely careful before you consider even moving the rover a single meter. Pretty sure Spot can crawl out of small but unexpected deep craters that would bog or tip over the rover and losing a few spots won't really matter.

I did say we need to drop a power pack to charge the Spots, better in nuclear form especially for polar expeditions.
Spot (or two Spots) could also carry expansion battery packs with foldable solar panels to distant locations to increase the accessible range.
Essentially they would become the first inhabitants and workers.

Oh did I mention cost: 2.2Billion for the rover. Spot costs $74K, probably cheaper by the dozen. Plenty left for batteries, transceivers, mining tools, test equipment and drones.


EDIT: just when I was thinking about contacting JPL and Boston dynamics I did a duckduckgo search and :



I am always too late

Happened last time when I contacted them with a suggestion to install wipers on the solar panels of the Opportunity rover, kind of like those fine brushes you use to clean vinyl records that self clean themselves when they pass over an edge.
I was told the idea had merit but I had contacted them TOO LATE to allow for any further additions.
Opportunity DID fail likely due to dust eventually covering the panels but it lasted way longer than expected as the wind managed to keep them clean which was unexpected at that time.
Maybe with my wipers it could still be active today.

[hinekadon]

interesting thread very good participants intelligent conversation well done , I wish all threads were this good

[lsemmens]

interesting thread very good participants intelligent conversation well done , I wish all threads were this good

Hey! You forgot about me! I'm not that intelligent!

[hinekadon]

I was generalising still a quality thread in my opinion

[enf]

I was generalising still a quality thread in my opinion

I dunno...we started talking about Mars Exploration and ended up talking about guns......

Then again, Perseverance IS American...

[trash]

Hang onto your hat Hink, we're going to keep you amused for a while yet.

The rover only seems efficient because it is slow

No, it's efficient because it has wheels. Wheels are way more efficient than legs.
Consider the energy used to walk compared to riding a bike which carries the extra overhead of the bike's weight.

but it is also very heavy, so I will question the efficiency to work load ratio here.

Did I say wheels? Overcoming the friction of the axel for a truck takes a lot less energy than moving a leg capable of supporting the same weight.
Hehe... you're pushing shit uphill with a pointy stick, if you put wheels on it..... it ain't going to look as weird as legs either.

20 spots could do a hell of a lot more than a single rover and without having to be extremely careful before you consider even moving the rover a single meter. Pretty sure Spot can crawl out of small but unexpected deep craters that would bog or tip over the rover and losing a few spots won't really matter.

I did say we need to drop a power pack to charge the Spots, better in nuclear form especially for polar expeditions.
Spot (or two Spots) could also carry expansion battery packs with foldable solar panels to distant locations to increase the accessible range.
Essentially they would become the first inhabitants and workers.

pull that spot over to the side of the Martian autobahn !

20 spots... Lets start at the bottom.
Perseverance produces ~110W/hr it uses about half of that

Spot uses 400W/hr four times what Perseverance produces. x 20 = 8kW/hr or 192kW/day consumption.
2000 times as much power.
Where do you think you're going to get that from? The sun? Lets do those numbers.
So a day on Mars is about the same as Earth, so you can assume that because there is no cloudy weather on Mars you'll get 5 hours of useful sunlight.
But the sun is 1/4 the brightness, so that means four times as many panels.

Spots have a run time of 90 minutes, and two hours to charge which means in 6 hours of useful sunlight you get two runs of 90 minutes.
600Whr capacity charge 2 hours = 300W per spot x 20 spots = 6000W of solar. x4 to compensate for Mars sunlight means you need 24kW of solar panels on the ground.
You know how those spots weigh 32kg each, their support panels alone weigh a tonne. Did you forget the cost of the fuel to get them into space and then onto the surface, then unpack them all and ..... I think you just engineered yourself into a corner.

Space is not easy. It's hard. Spot is deigned to work on Earth. In space he's a dead dog.
The first Martian dust storm and you have a lot of dead hardware not withstanding nasty wear and tear and no servicing. Spot is also not space hardend.

So lets to the mythbusters thing and see if we can't engineer the fuuk out of spot.
We're going to probably just go with a fission reactor. The three that jump to mind are RORsat, Topaz and SNAP. You might like to consider their electric power supply, their weight and the cost and factor that up and then work out how much to put it on Mars. Suddenly that "little" fission reactor is not so little.
And again you have to scale it for the task. And still, the range is limited to the proximity of the supply. 4kph with 45min range is 3km radius.
You just cannot plunk these things down like road flaps on Mars, even the small ones.

Oh did I mention cost: 2.2Billion for the rover. Spot costs $74K, probably cheaper by the dozen. Plenty left for batteries, transceivers, mining tools, test equipment and drones.

Lets say a nice round figure like $2.7 Billion USD. And it's srvice life design is 2 years.
I'm going to be lazy here because I already know the planetary society did a summary of this large spend.

EDIT: just when I was thinking about contacting JPL and Boston dynamics I did a duckduckgo search and :

Yes, that is a much more suitable task for them. What do you think it will cost to build a Mars Spot?
The speed of travel is an advantage and a disadvantage. That on the fly processing power comes at a cost.
The tradeoff will be between idle running power and continually moving in a race against time.

Exploring caves on Mars will be not unlike snorkeling on Earth. How long can you hold your breath and swim under water out and back coving as much distance as possible. You're going to want to see Boston Dynamics do this on earth first. Start from a location outside of the cave, charge, go in and come out , recharge and go back in. You might start to see this one dimension form of exploration is rather limited. You'd think a quad copter can do that job cheaper. $74k for spot and $300 buck for a drone. Oh hang on, then why do you think it cost $85 million for a Mars RC Helicopter?
Lets face it, you know as well as I do that $74k is gunna scale

At the end of the day you engineer the best solution possible for the task to be performed with constraints on cost, size and weight. And in space there are no second chances. Every action is you last chance. Spots will surely find an application, but exploring Mars, nope it's just not their gig.

Maybe with my wipers it could still be active today.

There are a few issues there. The first is you assume they will work. That's extra weight, power and point of failure.
You might imagine if a small rover is buried, wipers are not going to help. On a big rover, big panels you need big wipers.
But this is a game you can play at home. Buy yourself a solar cell and build a cleaning system powered by the solar cell so it can clean itself when you throw fine dirt on it. Amusing how impractical this is on Earth, now imagine those scaled costs for Mars. Limit your power by four and keep the weight to a minimum.
It might just be simpler to fold them up and hibernate.

Solar panels are cheap, simple, a little heavy, limited by sunlight and a bit clumsy in terms of spacecraft power supplies.
The bottom line is that wipers are probably just not practical.

As Rovers get bigger, so does their demand for power. RTG's are smaller, but low power with limited lifespans.
They behave a bit like pocket sized 24 hour solar panels. With batteries you bank the power budget to a point.

Fission reactors are heavier but offer more power but also need more shielding for their operation and are limited by their fuel.
Each has advantages and disadvantages. The Juno mission is a good example of where they weighed up these options and went with Solar for one reason more than others. There wasn't enough fuel available.

[Tiny]

But, but, but?

Traditional Mars rovers are limited mostly to flat surfaces, but many scientifically interesting Martian regions are only reachable by crossing very rough terrain or descending below ground. Walking robot "dogs" are well-suited for such challenges — even if they fall down, they can get back up again.
"Toppling does not mean mission failure," the scientists said during the presentation. "Using recovery algorithms, the robot can self-right from a multitude of falls."
A Mars Dog would also be roughly 12 times lighter than current rovers and would be capable of traveling much faster, reaching normal walking speeds of 3 mph (5 km/h) during terrestrial tests. To put that into perspective, the Curiosity rover rolls along the Martian surface at about 0.09 mph (0.14 km/h), the researchers reported.

From Festers link =

[Uncle Fester]

Trash, I think you need to learn to think a bit outside of the box.

BTW the active time for the Opportunity rover was expected to last only 90 days:
So anything that could significantly increase that time using something as simple as wipers, which could be done with very light weight materials would have been worth it.
It came as a surprise for all that the Mars winds did the job instead.



Some of the major issues I have in your argumentation for a rover is the lack of speed and limited coverage area, wheels are only good on a road or relatively even surfaces.
One Spot can cover more in a single hour than the rover in a day, possibly a lot more.
Then you are also fully ignoring that gravity on Mars is roughly 1/3 of ours which significantly reduces the power Spot consumes there(it weighs less). I won't say 3 time less because it still has to deal with the same inertia as on Earth but 50% less would be realistic.
I have no info about Perseverance but Curiosity moves 1.68km in 12 hours. Spot moves 10km in 2 hours and still has 1hour reserve.
Hence they ARE significantly more efficient.

So that 90 minutes would look more like 3 hours on one charge and then let it charge over the strongest sun period for the rest of the day, means a smaller panel. Foldable Solar panels don't weigh much. As mentioned earlier Spot could carry it's panel to a more distant location and work from there.
Spot can clean them or fold them up before the dust storm.
Spot can crawl itself out of a pile of dust after or while there is a dust storm.
Already too much dead (rover) hardware lying around on Mars.

Modifying Spot for space is not going to cost anything near 2.7 billion and after that it is a production item for many future missions and they are obviously not going to be sent individually in large supportive FedEX boxes in styrofoam but all crouched and strapped down to a platform with a self releasing mechanism "Ready To Go", that is not a great engineering feat.
Anyhow despite your almost unfathomable pessimism they are on it.

You really ARE scared of Spot, aren't you

[Uncle Fester]

Just want to clarify again that it is rather pointless to search for traces of life on any open surface on Mars or even a meter deep in the ground due to perchlorates found wide spread which has been demonstrated to have been created with the help of strong UV radiation due to lack of an Ozon layer on Mars.

Caves are protected from UV light and likely may contain very little perchlorate or none at all and life would have survived much longer inside them, maybe exist even in some microbial form today. Water could also to be trapped in some subterranean form inside as well.

Caves also provide very useful shelter for future manned missions and colonisation.

And then there are these

Bring on the Spots to sniff out those caves and tubes ASAP !

[lsemmens]

Bluddy Hell Trash! You are letting facts get in the way of good story!!!!!

[Uncle Fester]

Bluddy Hell Trash! You are letting facts get in the way of good story!!!!!

Facts that ignore other facts will always be fiction until reality judges.

[trash]

Trash, I think you need to learn to think a bit outside of the box.

The problem with thinking outside of the box is you tend to ignore what's inside the box and why.
What you're saying is "Take a risk". Ok.. it also often means to try something different.
Well they certainly did that with the skycrane. I wouldn't have thought of that.

Thinking outside the box. Nope. RTG is in the box. It cost more but has less dust issues.

Some of the major issues I have in your argumentation for a rover is the lack of speed

So impatient. What's your rush, not a lot changes on Mars in a human lifespan.

and limited coverage area,

Everything is limited. But lets compare. Spirit traveled about 8km on Mars, Curiosity about 20km and Oportunity about 45km.

Spot (the earth version can operate for 90 minutes at 4kph. That's 6km out and dead.
Or 3km radius if you go out and return to recharge.

wheels are only good on a road or relatively even surfaces.

That's a good generalisation but as you might have noticed, Mars is relatively rough depending on the scale you look at it and it doesn't consider the size of the wheels. Of course you might also be overestimating the ability of legs. We tend to consider that kind of engineering with respect to steps.
Imagine a planet of steps, what does a good robot use to get around?

One Spot can cover more in a single hour than the rover in a day, possibly a lot more.

That is definitely true. But we know you're well aware of that tradeoff with speed. You can deal from the bottom of the deck, it's not like we don't know you're doing it If speed is the advantage, then a probe is designed for speed. If speed is not a critical consideration then how fast you finish a game of golf does not improve your score. Though personally the sooner golfers got the hell off my landing runways the better.

Then you are also fully ignoring that gravity on Mars is roughly 1/3 of ours which significantly reduces the power Spot consumes there.
Hence they ARE more efficient.

You know I can tell when you just make shit up. I mean come on... have you not read Tytower's posts and seen my use of my modified scientology E-meter. (their pathetic version of a lie detector) I call mine the B-meter.

Lets start with the most basic of physics. F=ma. To accelerate a mass on Earth requires the same energy on Mars. You'll notice Gravity has nothing to do with it.
And if you think the friction is different.... again. The dirt and bearing also have the same friction as on Earth as Mars.

You legged robot might use less force to lift itself in lower gravity, but that overhead still exists while a wheeled robot does not have to lift itself to move.
That overhead lessens as the robots climb and you don't get a free lunch on the decent. Wheels get that

You might consider backing this argument up a bit and asking why the Earth bound spot doesn't use wheels?
Well the main reason is it looks cool. It also opens up consideration for legged robot applications we might not have considered.
So while legged robots might not be practical on Mars, what we learn from them on Earth can then be applied to the best applications in space either in part or whole.

So that 90 minutes would look more like 3 hours on one charge

Your premise on efficiency was wrong. Your robot died because you miscalculated something. At least you made that mistake on Earth and not on Mars

means a smaller panel.

Nope. You have the rover in front of the dog. Your charging time doesn't change even if you did have a more efficient robot.
Who do you think you're fooling here? You get more range for the same power or the same range for less power. Not BOTH.
Pick one, do you want longer range or a smaller battery?

Foldable Solar panels don't weigh much. As mentioned earlier Spot could carry it's panel to a more distant location and work from there.

Riiight. So now you're losing that speed advantage (if it actually was one).
But it is an interesting thought experiment.
If you have a short range robot that is detatched from it's prime clumsy power source but also capable of moving it.
So thinking about it, if it is capable of moving it's power source, what is the advantage of disconnecting from it?
Taking it with you is an advantage because you don't have to go back to recover it. Reconnaissance might be a reason, I'm not sure if it is an advantage in it's own right. Access to a restricted space not possible with the power supply would be an advantage.

Spot can clean them or fold them up before the dust storm.

That seems feasible. How do you propose it cleans them? On earth we use Meth addicts at traffic lights to clean sheets of glass. The key ingredient in that equation is not Meth, Coin or even a Squidgee. It's water. Without water Meth addicts can become very unpredictable.

Spot can crawl itself out of a pile of dust after or while there is a dust storm.

Oh, the B-meter started moving again. That is an assumption and a shortcut to failure.
Have you seen something that is not a robot climb out of an engulfing material?
Do you think there might be a better strategy than wasting limited power?

Already too much dead (rover) hardware lying around on Mars.

What are you implying here? That failure is unacceptable? That equipment should last forever? That sending robots to Mas is bad?

Modifying Spot for space is not going to cost anything near 2.7 billion

That is true, because that is for the entire mission.
That also includes what my customers would call "stuff". You know, cheap stuff like spectrometers, cameras, space grade radiation hardened components and a couple of jaycar 555 timers.

Anyhow despite your almost unfathomable pessimism they are on it.

You might be mistaking my high engineering standards for a high bar you think it is impossible to get over.
It's better to be on Earth making mistakes and wishing your robot was on Mars than having your robot on Mars wishing you'd made the mistakes on Earth.
It's not pessimism, it's just rationalism of reality. Sometimes you can't just do whatever you like and instead have to chose from the best set of limited set of options. And doing something cool does not mean it is the best thing to do. Though sometimes, you might send a Tesla to Mars rather than a cheap block of concerete because it does the same job and is cool.

You really ARE scared of Spot, aren't you

Oh fvck yeah... those things are killing machines. They need to be removed from this planet and put on another of their own where they can fight it out for my amusement with no hope of building their own spacecraft and looking for new things to kill.

[Uncle Fester]

You know I can tell when you just make shit up. I mean come on... have you not read Tytower's posts and seen my use of my modified scientology E-meter. (their pathetic version of a lie detector) I call mine the B-meter.

Oh dear, you always like to show off with your BS-meter but now you just fell deep down a rabbit hole lava tube with your following comments:

Lets start with the most basic of physics. F=ma.

OK, 7th grade Physics, you got that right.

To accelerate a mass on Earth requires the same energy on Mars. You'll notice Gravity has nothing to do with it.

Incorrect!

Gravity in this case has a hell of a lot to do with it.
We have both established that Spot is not a little wagon with wheels on a smooth flat track that is typically used for high school year 7 experiments to demonstrate F = ma, which in that case merely deals with inertia and friction. Then little Fester did something naughty to annoy his teacher and tilted the tracks upwards.

To keep Spot's body above the ground it's legs need to constantly counteract the acceleration of 9.81ms^-2 on Earth, even if it looks like it is moving perfectly lateral.
Even when it is not moving, energy is required to maintain that height.
It may be possible to lock up the legs when it is stationary using worm gears in the DOFs but that would make it slow and far less agile than you see it
in operation, so I doubt they use worm gears.
Another possibility is closing valves in a hydraulic system but AFAIK Spot uses electrical servo motors for the DOFs.

However the mechanics of a leg or robotic arm here is a lot different than lets say hovering a drone that weighs 32kg where 400W would be way to weak.
Regenerative force and friction from the geared down motors help to counteract the force of gravity and I assume that Spot is so sophisticated that it can use this kind of regenerative braking in the DOFs while it is walking to charge the battery in short bursts with each step where the mechanics allow for that.

But remove power from the all the DOF servos and Spot will immediately go limp and collapse because of gravity.

On Mars Spot has to counter act only 3.72ms^-2. That makes a huge difference for this kind of movement.
While it is climbing up on rocks the power consumption will only marginally increase while it also has to deal with the inertia of raising it's body but only at a relatively low speed.

Neil Armstrong's steps on the Moon where not just ' a giant leap for mankind' he could literally do giant leaps as he only weighed 1/6 of his weight on Earth.
Humans are slightly better designed than Spot as they can keep their legs fully stretched while they are standing and only a small amount of energy is then required to keep balance.
Spot's legs are always flexed ready to prance. Despite this energy hungry state I assume that is the preferred condition for Spot's abilities, but maybe they might modify that for the space version.
I would think keeping stretched out legs would be better than having the Spots crouch in the dust every time they go idle for shorter periods of time.

And if you think the friction is different.... again. The dirt and bearing also have the same friction as on Earth as Mars.

Incorrect!

Bearing:
A vehicle weighs roughly 3 time less on Mars than on Earth
Therefore the load on the bearings of that vehicle on Mars is roughly 3 times less. This applies of course to the Rover just as much as to Spot's DOFs.
Everybody knows if you put too much load on a bearing it can get so hot that it will seize up.
It might come as a surprise to you but the balls in a ball bearing deform under load. This deformation energy is transferred to heat.

Dirt:
When a wheel sinks into loose dirt it does so because of it's weight. The higher the weight the deeper it's wheel or foot will sink in and therefore
the more dirt it has to displace while it moves and that will require a lot more energy.


Conclusion:
Spot can indeed run with less power on Mars, possibly even built lighter as it can get away with smaller powered DOFs and achieve a better range on a single charge rather than two charges each day, allowing it to spend more time each day to replace that single charge with a smaller panel.