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Waspie_Dwarf

Martian Streaks: Flowing Sand, Not Water?

37 posts in this topic

6 hours ago, _KB_ said:

the proof is in how long they take to make simple stuff or stuff that already exists and how much they pay for it

Simple stuff? Stuff that already exists?

Where can you go to buy a Mars Rover? Where can you even go to buy Mars Rover parts? The answer is 'nowhere'.

Pretty much everything on these rovers needs to be made from scratch. And because at most only a few versions of each part are made there's no chance to amortise the cost of design, development and testing over a long production run.

So why don't they use off-the-shelf products? Because off-the-shelf products are designed to be used in Earth-like conditions. By contrast, the rovers need to be able to survive being shaken vigorously and accelerated massively during launch, survive the vacuum and radiation environment of space, survive re-entry deceleration, and then operate in the radiation, cold and un-Earth-like atmosphere of Mars, in the full knowledge that if something goes wrong you can't send anyone up there to repair it.

And that's why it's expensive.

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4 hours ago, AZDZ said:

One thing puzzles me though, why is the sand below the surface a different color?

I've been to the desert and seen these effects for myself in micro scale. I've seen conditions where moisture is present on the sand after condensing out of the air overnight.

The surface will dry as the Sun warms it up but disturb the surface before it gets too hot/dry and the moisture still present below will become visible as darkened sand.

You don't even need the desert to see this effect. Go outside on any morning the conditions are right, find and turn over a rock to see the darker bottom because of condensate.

Look at THIS image. Note sand build up from slides, affirming the new explanation. Now note some appear dried and some appear to still be wet! 

HERE we see a collection of slide streaks in varying degrees of drying.

So I can agree sand slides may be at least partially responsible for these effects, but to rule out liquid as a cause of the dark areas seems disingenuous at worst, trolling the haters, at best.

The same thing was found on the Moon - kicked up soil from below the surface was found to be darker than the material on the surface. IIRC (it's covered somewhere in the Apollo Lunar Surface Journal) the theory astronaut-geologist Jack Schmitt came up with was something to do with particle size; that over millions of years the smaller, darker grains of soil were gradually shaken down lower and lower below the surface due to a combination of daily heating-cooling and occasional moon quakes.

Not saying that's the explanation for the soil on Mars, but it's an explanation that doesn't require water.

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2 hours ago, Peter B said:

The same thing was found on the Moon - kicked up soil from below the surface was found to be darker than the material on the surface. IIRC (it's covered somewhere in the Apollo Lunar Surface Journal) the theory astronaut-geologist Jack Schmitt came up with was something to do with particle size; that over millions of years the smaller, darker grains of soil were gradually shaken down lower and lower below the surface due to a combination of daily heating-cooling and occasional moon quakes.

Not saying that's the explanation for the soil on Mars, but it's an explanation that doesn't require water.

Interesting, I knew that the kicked up soil was a different colour, but I didn't know why. The evidence of the different coloured soil persists today in images of the Apollo landing sites taken by orbiting spacecraft, especially LRO,

It's worth pointing out though that in the case of Mars it isn't necessary to exclude water entirely from any explanation, merely flowing liquid water on the surface. THere may well be subsurface ice but this would be expected to sublime on the surface.

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8 hours ago, Peter B said:

Simple stuff? Stuff that already exists?

Where can you go to buy a Mars Rover? Where can you even go to buy Mars Rover parts? The answer is 'nowhere'.

Pretty much everything on these rovers needs to be made from scratch. And because at most only a few versions of each part are made there's no chance to amortise the cost of design, development and testing over a long production run.

So why don't they use off-the-shelf products? Because off-the-shelf products are designed to be used in Earth-like conditions. By contrast, the rovers need to be able to survive being shaken vigorously and accelerated massively during launch, survive the vacuum and radiation environment of space, survive re-entry deceleration, and then operate in the radiation, cold and un-Earth-like atmosphere of Mars, in the full knowledge that if something goes wrong you can't send anyone up there to repair it.

And that's why it's expensive.

and yet to get all those parts made without the mark up (just the raw materials) would cost a couple grand (even if they are custom made, honestly the microchips would likely be the most expensive part) that's what's called embezzlement, i mean have you ever made any machinery, i mean i suppose the price could be higher if they don't have their own manufacturing equipment, but if a organization that mainly specializes in engineering doesn't have that then it's just ludicrous, i mean i have some randomly lying around my garage even though i'm a programing student and while it may not be anything super fancy so NASA should definitely have some

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5 hours ago, _KB_ said:

and yet to get all those parts made without the mark up (just the raw materials) would cost a couple grand (even if they are custom made, honestly the microchips would likely be the most expensive part) that's what's called embezzlement, i mean have you ever made any machinery, i mean i suppose the price could be higher if they don't have their own manufacturing equipment, but if a organization that mainly specializes in engineering doesn't have that then it's just ludicrous, i mean i have some randomly lying around my garage even though i'm a programing student and while it may not be anything super fancy so NASA should definitely have some

I don't think you quite get it.

Okay, let's say I'll take your word for it that the raw materials for making Curiosity would cost "a couple of grand" (personally I reckon you're understating that figure by a smidge - for example, how much does 4.8 kilograms of plutonium-238 dioxide cost - but I'll let that go). Where does the rest of the $2.5 billion go?

Let's list a few things that contribute to the cost of the mission:

1. Putting together the case for the mission in the first place. How many work-hours went into that?

2. Designing the spacecraft. What scientific instruments are going to be included?

3. Designing the scientific instruments to be used on the spacecraft. Remember, you can't just buy these instruments off the shelf. Even instruments which have a terrestrial equivalent (like, say, a drill) have to be designed (as I explained earlier) to survive launch (acceleration and shaking), travel through an irradiated vacuum, entry into Mars's atmosphere (deceleration and shaking), and operation in an irradiated, low temperature, low pressure environment. Oh, and it has to do so with a minuscule power budget (Curiosity's RTG can produce about 100 watts, and I understand hardware drills usually need around 500 watts). So you're going to need to design a drill which is very robust, very reliable, very light, and which uses a fraction of the power that drills normally use. That's going to need everything from a specially designed motor to specially designed lubricant. How many work-hours just to design the drill, let alone all the other instruments.

4. Designing all the other non-scientific systems for the spacecraft - mobility, power, communications, robot arm, landing system and data storage come to mind but there are probably others. Remember the skycrane landing system for Curiosity? How many work-hours went into designing that baby? And remember, again, the systems had to be designed to be robust, reliable, light, and light on the power needs.

5. Testing the components. This would obviously mean that some systems would have to be redesigned as testing uncovered design flaws or unrecoverable problems. How many work-hours poring over tables of data, trying to work out whether the component worked just fine, didn't work at all, or "Um, it didn't fail but it wasn't within parameters"?

6. Integrating the whole shebang. After all, it wouldn't do if the computer memory didn't store the images just captured by the camera, or if the communications antenna got in the way of the robot arm. More design, more testing, more poring over tables of data...

7. Purchasing and customising the rocket intended to launch the rover. Those things don't come cheap.

8. Designing the trajectory for launch, the coast to Mars, and the entry profile. And the decision about the landing site...

9. Designing and testing the software to run the rover.

10. Mating the rover spacecraft to the rocket and undertaking all the pre-launch testing.

11. Actually launching the rocket; overseeing it during the coast to Mars, with occasional systems tests to make sure everything's fine, and occasional tweaks to the trajectory. And meanwhile another team is constantly testing scenarios: What do we do if a thruster fails one month out from Mars? Or one day from Mars? Where do we land if there's a dust storm at the primary landing site? How are the sims going at the communications centres in Madrid and Canberra? How's the computer upgrade going at Goldstone?

12. And now that the rover has finally survived its seven minutes of terror and safely landed, now you need a crew of how many people on duty around the world to run the mission? People in mission control to actually control the rover; experts in the offices of the contracting companies who know everything about the component they designed, built and tested; people in the communications centres in Madrid, Canberra and Goldstone; scientists in half a dozen disciplines haggling over which rock to investigate next and what tools to use; computer experts who take the raw data and both load it onto JPL's website and tidy it up so that scientists can use it.

Now I don't work in this business, so the experts will probably be able to point out another dozen things I've missed. But hopefully what I've described will give you a bit of an idea about how "a couple of grand" of raw materials turns into a $2.5 billion mission, without any embezzlement.

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13 minutes ago, Peter B said:

Now I don't work in this business, so the experts will probably be able to point out another dozen things I've missed. But hopefully what I've described will give you a bit of an idea about how "a couple of grand" of raw materials turns into a $2.5 billion mission, without any embezzlement.

You would think so, but I remember _KB_ is the same person who said he could design a space shuttle in his spare time.

 

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Sure, I could design one too but that doesn't mean it would work under all the conditions that the Rover has to go through.

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16 hours ago, Peter B said:

I don't think you quite get it.

Okay, let's say I'll take your word for it that the raw materials for making Curiosity would cost "a couple of grand" (personally I reckon you're understating that figure by a smidge - for example, how much does 4.8 kilograms of plutonium-238 dioxide cost - but I'll let that go). Where does the rest of the $2.5 billion go?

Let's list a few things that contribute to the cost of the mission:

1. Putting together the case for the mission in the first place. How many work-hours went into that?

2. Designing the spacecraft. What scientific instruments are going to be included?

3. Designing the scientific instruments to be used on the spacecraft. Remember, you can't just buy these instruments off the shelf. Even instruments which have a terrestrial equivalent (like, say, a drill) have to be designed (as I explained earlier) to survive launch (acceleration and shaking), travel through an irradiated vacuum, entry into Mars's atmosphere (deceleration and shaking), and operation in an irradiated, low temperature, low pressure environment. Oh, and it has to do so with a minuscule power budget (Curiosity's RTG can produce about 100 watts, and I understand hardware drills usually need around 500 watts). So you're going to need to design a drill which is very robust, very reliable, very light, and which uses a fraction of the power that drills normally use. That's going to need everything from a specially designed motor to specially designed lubricant. How many work-hours just to design the drill, let alone all the other instruments.

4. Designing all the other non-scientific systems for the spacecraft - mobility, power, communications, robot arm, landing system and data storage come to mind but there are probably others. Remember the skycrane landing system for Curiosity? How many work-hours went into designing that baby? And remember, again, the systems had to be designed to be robust, reliable, light, and light on the power needs.

5. Testing the components. This would obviously mean that some systems would have to be redesigned as testing uncovered design flaws or unrecoverable problems. How many work-hours poring over tables of data, trying to work out whether the component worked just fine, didn't work at all, or "Um, it didn't fail but it wasn't within parameters"?

6. Integrating the whole shebang. After all, it wouldn't do if the computer memory didn't store the images just captured by the camera, or if the communications antenna got in the way of the robot arm. More design, more testing, more poring over tables of data...

7. Purchasing and customising the rocket intended to launch the rover. Those things don't come cheap.

8. Designing the trajectory for launch, the coast to Mars, and the entry profile. And the decision about the landing site...

9. Designing and testing the software to run the rover.

10. Mating the rover spacecraft to the rocket and undertaking all the pre-launch testing.

11. Actually launching the rocket; overseeing it during the coast to Mars, with occasional systems tests to make sure everything's fine, and occasional tweaks to the trajectory. And meanwhile another team is constantly testing scenarios: What do we do if a thruster fails one month out from Mars? Or one day from Mars? Where do we land if there's a dust storm at the primary landing site? How are the sims going at the communications centres in Madrid and Canberra? How's the computer upgrade going at Goldstone?

12. And now that the rover has finally survived its seven minutes of terror and safely landed, now you need a crew of how many people on duty around the world to run the mission? People in mission control to actually control the rover; experts in the offices of the contracting companies who know everything about the component they designed, built and tested; people in the communications centres in Madrid, Canberra and Goldstone; scientists in half a dozen disciplines haggling over which rock to investigate next and what tools to use; computer experts who take the raw data and both load it onto JPL's website and tidy it up so that scientists can use it.

Now I don't work in this business, so the experts will probably be able to point out another dozen things I've missed. But hopefully what I've described will give you a bit of an idea about how "a couple of grand" of raw materials turns into a $2.5 billion mission, without any embezzlement.

1. don't know how many work hours but the people were definitely over payed

2. designing it in self should cost weary little

3. again designing things isn't that expansive

4. again designing isn't that expansive

5. this points fair enough

6. integrating stuff's pretty easy the average engineer could do it, especially if the thing is well designed

7. wasn't that on a separate budget report? fine you got me there, let's ram up the price a little bit

8. you can outsource that to any high end computer, writing the algorithm to do that should take under a hour

9. fine that's fair we programmers do ask for a fair amount of money, let's add a couple grand to the sum

10. that shouldn't be too expansive unless someones embezzling money

11. Launching the rocket does have it's costs but the overseeing mission center seams a bit over payed

12. You really don't need that many people, and you certainly don't need to pay them nearly as much

fine i supose that there are some expenses that i didn't consider but that still leaves over 1 billion unaccounted for

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4 hours ago, _KB_ said:

1. don't know how many work hours ....

Yeah, its well known that you dont know much about space agencies and aerospace in general.

Quote

...but the people were definitely over payed

Please back that claim by figures and not by an empty phrase only.

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Back on topic please, _KB_, enough is enough.

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On 11/28/2017 at 2:13 PM, Peter B said:

The same thing was found on the Moon - kicked up soil from below the surface was found to be darker than the material on the surface. IIRC (it's covered somewhere in the Apollo Lunar Surface Journal) the theory astronaut-geologist Jack Schmitt came up with was something to do with particle size; that over millions of years the smaller, darker grains of soil were gradually shaken down lower and lower below the surface due to a combination of daily heating-cooling and occasional moon quakes.

Hmm. Not sure Schmitt's theory is correct, I thought bigger particles sink leaving the finer dust at the surface. 

On 11/28/2017 at 2:13 PM, Peter B said:

Not saying that's the explanation for the soil on Mars, but it's an explanation that doesn't require water.

But yeah, I do remember seeing darker regolith kicked up by men on the Moon. IIRC, the official explanation for the darker bits , given way back in the days of those missions, was that color was 'bleached' out of the top 'soil' by solar radiation relentlessly baking the surface. When disturbed the darker stuff below was exposed. It's what makes activity at Lunar landing sites visible in orbital imagery. 

I suppose I can buy the same thing occurring on Mars, but it has to be occurring faster than millions of years given sandstorms would obliterate evidence seen in my linked images. Those faded sand-slides cannot be that old.

 

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On 25/11/2017 at 0:51 AM, Peter B said:

My understanding is that scientists want to keep rovers away from any location with water. The reason is that these rovers haven't been well enough sterilised to guarantee they won't contaminate such a wet location with Earth bugs.

What is the protocol in such a scenario that Mars becomes contaminated by the rovers?

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