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#1501 2021-10-13 18:17:01

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 7,597

Re: Starship is Go...

For SpaceNut re #1600

Thanks for this very interesting report and image .... Can you compute the difference between Earth and Mars?

The air pressure is lower, but the CO2 content is higher.

Perhaps the unit that captures 900 tons of CO2 on Earth would do even better on Mars?

The company might even be willing to talk to you, if you write to them to ask.

There can't be ** that ** many people asking them about using their equipment on Mars!

(th)

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#1502 2021-10-13 19:04:25

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 23,333

Re: Starship is Go...

The air co2 is close to the same values once you alter for pressure and percentages. The main issue is the speed of the fans must be increase to gain the require force to push the atmosphere into the absorption system.

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#1503 2021-10-13 19:16:29

louis
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From: UK
Registered: 2008-03-24
Posts: 6,914

Re: Starship is Go...

You're asserting things here without providing evidence.

The only "one time use" for water is rocket fuel manufacture.

For everything else, from agriculture to hygiene to cooking,  varying degrees of water recycling are possible  - with probably 95% overall an achievable goal. Plants actually transpire etc over 97% of the water they take in.

Oldfart1939 wrote:

Louis-The scale of chemical process equipment required to process ice into usable water will astound you, as well as the quantities of starting material needed. GW gave a listing of how much water will be needed and getting a ton a day simply will not suffice. We can get Hydrogen and Oxygen from water by electrolysis, and the efficiencies are not really anywhere near quantitative. Every process has operational losses, and the efficiency is usually described by percent yield at the end. The difficult step will be getting enough CO2 to run through the Sabatier process and having hydrogen from the atmosphere.

This is a massive industrial undertaking at the scale of Starship's requirements. One Starship freighter will probably not be enough to handle a chemical processing facility in total weight and volume. A lot of this processing machinery is bulky.

Designing plants was part of what i did in industry. I designed the chemical process and with engineers, built systems that worked.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#1504 2021-10-13 22:02:05

Oldfart1939
Member
Registered: 2016-11-26
Posts: 2,237

Re: Starship is Go...

Louis-

The present project is specifically stated to provide sufficient water to produce enough Oxygen and Hydrogen for the return to Earth and also for all other uses, and extracted from ice that's contaminated by who knows what. Your assertions are also without adequate foundations. Getting water that's chemically and physically contaminated into a condition that it's pure enough for electrolysis and human consumption requires a massive amount of processing--AFTER it's been dug out in chunks from strip mining-type operations.

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#1505 2021-10-13 22:17:50

kbd512
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Registered: 2015-01-02
Posts: 4,708

Re: Starship is Go...

SpaceNut,

You need to use a different design for CO2 capture on Mars, like the Dyson vacuum design (centrifugal force), to spin the dust out of the air so that the CO2 entrainment portion of the device (the zeolite bed) is not caked with fine dust.  I wonder if there's a liquid polymer that could capture CO2.  That would also solve the problem of dust capture, because a filter media could remove the dust contamination from the polymer.

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#1506 2021-10-14 06:48:04

louis
Member
From: UK
Registered: 2008-03-24
Posts: 6,914

Re: Starship is Go...

I think my assertions are with foundation:

These craters expose “excess” ice (Dundas et al., 2015)– which is almost entirely free of dust (>99% water ice).

https://www.nasa.gov/sites/default/file … tagged.pdf

99% pure ice is what we should be aiming for and I believe it's why JPL has selected sites in that area for the first base and recommended them to Space X.

I really don't think finding water and processing it is going to be that big a problem on Mars.

Getting the carbon is much more problematic.


Oldfart1939 wrote:

Louis-

The present project is specifically stated to provide sufficient water to produce enough Oxygen and Hydrogen for the return to Earth and also for all other uses, and extracted from ice that's contaminated by who knows what. Your assertions are also without adequate foundations. Getting water that's chemically and physically contaminated into a condition that it's pure enough for electrolysis and human consumption requires a massive amount of processing--AFTER it's been dug out in chunks from strip mining-type operations.

Last edited by louis (2021-10-14 06:52:52)


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#1507 2021-10-14 09:54:05

Oldfart1939
Member
Registered: 2016-11-26
Posts: 2,237

Re: Starship is Go...

I am not considering the assumption of 99% pure water ice (determined by satellite imaging!) to be correct. i am considering the "worst case scenario. I am thinking of manufacturing copious pure water for all uses, but first things first: enough to manufacture methane and Oxygen for a return trip. I don't want dead astronauts and or colonists because of bad assumptions made based on orbital imaging.

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#1508 2021-10-14 16:34:44

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,621
Website

Re: Starship is Go...

Remote sensing has ALWAYS differed from actual ground truth.  It proved to be very,  very,  VERY (!!!) far wrong in the mid-1960's when Mariner 2 flew past Venus,  and again when Mariner 4 flew past Mars. 

With Mariner 4 at Mars what was thought to be a more-or-less Earth-like planet with a nitrogen-carbon-dioxide atmosphere at a surface pressure of 85 mbar turned out to be a meteor-cratered utterly-dry planet with a near-pure carbon-dioxide atmosphere at the near-vacuum surface pressure of 6 mbar.  That was a Pear Harbor-class shock to the remote-sensing crowd.  I remember it well.

In the years since,  remote sensing has gotten better,  but it still misses the mark,  and sometimes still rather widely!  The biggest problem I have with it,  is that detection of "water" from orbiting satellites is really detection of hydrogen atoms,  coupled with the ASSUMPTION that hydrogen-bearing masses have to be water.  That assumption is already well-known to often be wrong,  WRONG,  WRONG(!!!!!). 

There simply is NO SUBSTITUTE for real ground truth!  There never will be,  no matter how "good" the remote-sensing crowd gets.  Simple fact,  simple logic. 

Real ground truth is what the "engineering lander" concept proposal debated under the "unmanned probes" category,  in the "scouting Mars for landing sites" thread,  is all about.  And those real ground truth determinations are something never,  EVER (!!!),  done by NASA/JPL,  ESA,  or anybody else.  Not in all these decades.  Because those scientists are NOT engineers trying to keep a crew alive!  Nor will they ever be qualified for that job!

My point is that remote sensing still does not warrant risking lives on its accuracy,  not even today!!!

Sorry,  Louis,  that's just the bald truth of the matter.

GW

Last edited by GW Johnson (2021-10-14 16:43:56)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#1509 2021-10-14 19:37:14

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 23,333

Re: Starship is Go...

tahanson43206 wrote:

For SpaceNut re #1600

Thanks for this very interesting report and image .... Can you compute the difference between Earth and Mars?

The air pressure is lower, but the CO2 content is higher.

Perhaps the unit that captures 900 tons of CO2 on Earth would do even better on Mars?

The company might even be willing to talk to you, if you write to them to ask.

There can't be ** that ** many people asking them about using their equipment on Mars!

(th)

Found another that collects 4,000 tons a year

for the dyson vacuum its the opening orifice that is the issue for the collection process.

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#1510 2021-10-14 19:38:43

louis
Member
From: UK
Registered: 2008-03-24
Posts: 6,914

Re: Starship is Go...

GW/OF

This isn't just determined by satellite imaging, in fact I think it's the ground penetrating radar that is key because pure ice gives different signals from rock or impure ice.  They can tell all sorts of things from the way radar waves come back. There are also chemical signatures being given off.

But the other key fact here is that Space X plan to send cargo ships to the Mars landing site two years before humans land. There is no reason why a robot rover shouldn't be sent with those cargo ships and then be deployed to check whether the water results are reasonably accurate. If they are, then the human mission can go ahead, no problem.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#1511 2021-10-14 21:30:42

Oldfart1939
Member
Registered: 2016-11-26
Posts: 2,237

Re: Starship is Go...

If my method of extraction is used to collect ice, it will be relatively clean. I use the word relatively with caution. My system involves allowing the crude mined ice to melt in a heated environment. The water Probably dirty and possibly even a sludge, will be dewatered with a basket centrifuge that separates the solids from free flowing but still chemically impure water. Distillation is the next step in getting water pure enough for electrolysis and drinking.

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#1512 2021-10-15 15:34:20

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,621
Website

Re: Starship is Go...

Louis: 

Yes,  the hydrogen is detected with ground-penetrating radar.  It is a fairly high probability that the hydrogen is within simple water.  But,  another possibility is that it is within hydrated minerals.  You don't know until you go there and look.  There was,  is,  and always will be,  no substitute for ground truth.

The Perseverance team just confirmed this with the news release that said the ground-level views told them there definitely had been a lake in Jezero Crater,  and that views from orbit simply could not determine that with certainty. So if you don't believe me,  then ask them.

As for robots doing everything for crews on Mars,  no I don't think so.  Robots/AI can only do or perceive what it was programmed to do or perceive.  They do NOTHING outside what is in that programming.  A robot strolling into a pasture here on Earth will only see what it is programmed to look for.  It will not see the unexpected new discovery.  It simply cannot see or perceive the unexpected.  And the unexpected happens all the time.

Plus,  there's the "garbage-in,  garbage-out law" effect.  You put bad data in,  it screws up or misbehaves.  Like the driverless cars that keep turning down the dead-end residential street in San Francisco,  forcing them to turn around and drive back out.  There's bad data in whatever map they are using.  Car after car makes the same mistake  about every 5 minutes or so,  all day and all night,  for some days now.

Personally,  I believe your great faith in remote sensing and in robots/AI is misplaced.  Events on the ground (that I have nothing to with) say so,  quite clearly.

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#1513 2021-10-15 17:07:35

louis
Member
From: UK
Registered: 2008-03-24
Posts: 6,914

Re: Starship is Go...

GW,

I don't think it's a question of faith.  I think it's just that the satellites around Mars are pretty sophisticated and there is lots of cross-checking between the various instruments on board.

I think you're confusing two things there aren't you - spectrometer analysis and radar findings? Radar findings show the presence specifically of ice, not hydrogen. The radar signal from ice is very different from other materials.

My understanding is that the MRO satellite is the principal source of info on water presence. The MRO has a Spectrometer for identifying  key minerals. I think this is used to identify the chemical signatures, like hydrogen, coming from the ground. And yes you could be in the presence of hydrated minerals (although I think the experts can detect some differences). But then there are other instruments on board.

The "Mars Climate Sounder" can, amongst other things measure the amount of water in vertical columns above the ground. Presumably that helps identify the presence of water on the ground at any particular locality.

The Mars Color Imager uses ultraviolet violet as a reverse indicator of water presence through determining ozone prevalance. That too, gives a good indication of ground water presence.

Then there is the all-important radar. It is the Shallow Subsurface Radar on MRO which  can penetrate to roughly 500 metres  below Mars’ surface that gives  information about underground layers of ice. My understanding is that radar-dervied results from rock, aggregates or even impure ice are totally different from the results you get from nearly pure ice. 

On top of that, visual imagery can be used to ascertain geological features that confirm the presence of ice e.g. bulges in crater walls etc. If you were getting lots of water indicators from other instruments but no geological signs of ice presence on the ground you'd know something wasn't right. Geology doesn't lie. But of course in places like Erebus Montes there are geological signs of ice presence all over the place!

https://mars.nasa.gov/files/mro/MRO-060303.pdf

All these sorts of instruments will have been tested around Earth where you easily confirm how accurate they are at predicting presence of various materials. That is why JPL/NASA has such high confidence in them. It's not blind faith!

As for robots, we know robots are fine at a huge range of tasks including mining on Earth. Referencing software failures for AI vehicles in densely populated urban centres is meaningless (robot taxis work fine in Phoenix). The cargo Starships will be fitted with advanced coms - far better than what NASA has been using. Likewise the robots will be much much faster and more powerful. I would envision first cargo landing robot rovers to maybe weigh in at something like 1500 kgs, have powerful cameras and real time HD video connection to the cargo ships, and would possibly capable of speeds of 20 MPH. You'd probably have a bulldozer robot to clear a path of boulders where necessary. 

As for your tale from Jezero Crater there you are talking about establishing what occurred millions of years ago.

This is about what is present now. If a lake were currently present in Jezero Crater we could detect its presence with the MRO's multiple instruments.


GW Johnson wrote:

Louis: 

Yes,  the hydrogen is detected with ground-penetrating radar.  It is a fairly high probability that the hydrogen is within simple water.  But,  another possibility is that it is within hydrated minerals.  You don't know until you go there and look.  There was,  is,  and always will be,  no substitute for ground truth.

The Perseverance team just confirmed this with the news release that said the ground-level views told them there definitely had been a lake in Jezero Crater,  and that views from orbit simply could not determine that with certainty. So if you don't believe me,  then ask them.

As for robots doing everything for crews on Mars,  no I don't think so.  Robots/AI can only do or perceive what it was programmed to do or perceive.  They do NOTHING outside what is in that programming.  A robot strolling into a pasture here on Earth will only see what it is programmed to look for.  It will not see the unexpected new discovery.  It simply cannot see or perceive the unexpected.  And the unexpected happens all the time.

Plus,  there's the "garbage-in,  garbage-out law" effect.  You put bad data in,  it screws up or misbehaves.  Like the driverless cars that keep turning down the dead-end residential street in San Francisco,  forcing them to turn around and drive back out.  There's bad data in whatever map they are using.  Car after car makes the same mistake  about every 5 minutes or so,  all day and all night,  for some days now.

Personally,  I believe your great faith in remote sensing and in robots/AI is misplaced.  Events on the ground (that I have nothing to with) say so,  quite clearly.

GW


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#1514 2021-10-15 19:01:02

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 23,333

Re: Starship is Go...

So we have a value for the water to electrolysis and what we need is the electrical energy required to do so.

In general, it takes about 50 kiloWatt hours of energy to electrolyze 9 kilograms (also 9 liters) of water to produce 1 kg of hydrogen (H2) and 8 kg of oxygen (O2).

25 hrs x 300 sols is  7,500 hrs total
540,000 kg / 9 kg = 60,000
60,000 x 50 kwhr = 3,000,000 kwhr
3,000,000 kwhr / 7,500 hr = 400 kw


That's a big power source....400kw constant delivery for 25 hr sols at a duration of 300 sols to break down the Water to collect, separate and store of 540mT...

A single Krusty is 10 kw x 25 = 250 kwhr / 50kw hr = 5 x 9kg of water = 45 kg per sol x 300 sols = 13,500 kg
40 KRUSTY units would need to be supplied just to get the water divided up for hydrogen to go into the sabatier reactor...assuming the total water amount is waiting for a single unit.

So to get that number down we are going to up the number of units that break the water down to get the through put up with power source going up.

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#1515 2021-10-16 07:12:15

louis
Member
From: UK
Registered: 2008-03-24
Posts: 6,914

Re: Starship is Go...

Your figures sound about right...Space X did commission a study previously and I think they come up with a figure of 600Kws for producing the rocket fuel. But if you are using solar power that would mean you need a bigger capacity than that...1Mw or more.

No Krusty has been developed for Mars. It's a non-starter in terms of Space X's timeline and would no doubt, in any case, make launch approval even more fraught.

I think we're going to have more than 300 days. Does anyone have the figures for mission duration over the next 10 years. With cargo ships landing two years ahead of humans, you could certainly make a start with automated dehumidifiers and automatic electrolysing.




SpaceNut wrote:

So we have a value for the water to electrolysis and what we need is the electrical energy required to do so.

In general, it takes about 50 kiloWatt hours of energy to electrolyze 9 kilograms (also 9 liters) of water to produce 1 kg of hydrogen (H2) and 8 kg of oxygen (O2).

25 hrs x 300 sols is  7,500 hrs total
540,000 kg / 9 kg = 60,000
60,000 x 50 kwhr = 3,000,000 kwhr
3,000,000 kwhr / 7,500 hr = 400 kw


That's a big power source....400kw constant delivery for 25 hr sols at a duration of 300 sols to break down the Water to collect, separate and store of 540mT...

A single Krusty is 10 kw x 25 = 250 kwhr / 50kw hr = 5 x 9kg of water = 45 kg per sol x 300 sols = 13,500 kg
40 KRUSTY units would need to be supplied just to get the water divided up for hydrogen to go into the sabatier reactor...assuming the total water amount is waiting for a single unit.

So to get that number down we are going to up the number of units that break the water down to get the through put up with power source going up.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#1516 2021-10-16 09:33:06

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 1,193

Re: Starship is Go...

This would be the way to go for a small nuclear reactor in support of SpaceX propellant programme.
https://en.m.wikipedia.org/wiki/Aqueous … us_reactor

The reactor is self controlling and has been used for criticality experiments and medical isotope production for nearly 80 years now.  The low enriched uranium nitrate fuel salts would only be added after reaching Mars.  We are talking about 20-30kg of low activity materials.  Not a big issue as far as launch is concerned.  The self-controlling nature makes it easy to design, build and commission.  Longer term on Mars, heavy water AHRs can be made using Starship fuel tanks and could even make use of natural uranium mined on Mars.

Waste heat rejection could take place by running water pipes through poly tunnels, which would provide base food supply.  A 5MWth (750kWe) system, would generate enough heat to keep some 14,000m2 of greenhouse at a temperature of 30°C, 24/7.  That is enough to feed hundreds of colonists.  An elegant solution wouldn't you agree?

Last edited by Calliban (2021-10-16 09:45:02)


Interested in space science, engineering and technology.

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#1517 2021-10-16 11:04:47

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 23,333

Re: Starship is Go...

The KRUSTY reference is for a known functioning molten salt reactor that when we scale the size by 40 we get power that can only do the electrolysis but here is the kicker, the unit mass is 2.5mT so scaling it means we have eaten up the entire starship payload in fast transit to mars and with slow you might have the room for the machine to do the electrolysis and that's all.
The CO2 capture is going to be just as problematic as will the remaining items to get what we need done.

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#1518 2021-10-16 11:19:42

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 7,597

Re: Starship is Go...

For SpaceNut re nuclear power for regolith project ...

Have you asked Calliban for advice?  Your reference to something else implies to me you are not taking advantage of a member who is knowledgeable in the field.

(th)

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#1519 2021-10-16 11:23:57

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 7,597

Re: Starship is Go...

for SpaceNut .... KRUSTY is a ** solid ** block of Uranium alloy.  It has nothing to do with Sodium.

From one of a number of references Google found:

The Kilowatt Reactor Using Stirling TechnologY (KRUSTY) was envisioned as the next step toward successful deployment of a space reactor. KRUSTY was a prototypic nuclear-powered test of a 5-kW(thermal) Kilopower space reactor.2 Kilopower reactor concepts utilize heat pipes to transfer fission energy from a solid block of fuel and are intended for simple, low-power [1- to 10 -kW(electric)] space and surface power systems. KRUSTY was designed to be as prototypic as possible within the cost constraints of a 3-year, <$20 million program.

The distinctive feature of this project was use of a Stirling engine to convert thermal energy to electric power.

(th)

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#1520 2021-10-16 11:27:49

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 23,333

Re: Starship is Go...

https://ntrs.nasa.gov/api/citations/201 … 005435.pdf

1*VB61N4SZ2MvSW42H3iYobQ.png

heat pipes are sodium filled to make the power

Seems the sterling section can be scaled upward

kilopower-vs-fps-768x258.png

so 40 kw is even better for the mass

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