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#26 2018-04-24 18:11:44

kbd512
Administrator
Registered: 2015-01-02
Posts: 7,362

Re: Some general observations.

Louis,

I think some intermediary steps between permanently living on a planet tens of millions of miles away and a brief series of lunar landings that took place before you and I were born may be required.  Nothing is actually ready to use yet.  We're at least 5 years out on basic technology development and prototype completion if we start today.  It'll take another 5 years of integration and operational testing after that to confirm that everything function together as intended.

Some of the major technological development efforts required and government agencies and/or companies that could be expected to develop them are shown below:

Alcoa / Baker-Hughes - Mars drilling equipment for water extraction (they've done fairly extensive test and evaluation of aluminum piping for a variety of drilling purposes and their core competencies match up very closely with what's needed for this purpose)

Boeing Network and Space Systems / Lockheed Martin Space Systems Company / Northrop Grumman Aerospace Systems - Mars Global Positioning System for precision geolocating

Dyson - Mars atmosphere pre-processors for dust separation for ISPP / ISRU and habitat cleaning vacuums

Hamilton-Sundstrand - Sabatier reactors

Honeywell / JPL / NASA - avionics software systems development and navigation

IBM - rad-hard microprocessors for computerized systems (nearly everything today)

ILC Dover - planetary exploration space suits

NASA / Desktop Metal / Markforged / Voxel - 3D printing of metal, composite, and plastic parts for contingency repairs

NASA / DOE - Radioisotope Heating Units / RHU's for keep-alive warmth and for melting ice using heated drill heads

NASA / DOE - KiloPower fission reactors for backup electrical power

NASA / Paragon SDC - CAMRAS atmospheric scrubbers and IWP waste water processors

NASA / Bigelow Aerospace - inflatable habitat modules

Orbital ATK - Solar panels and PMAD

PCI - miniature Sabatier reactors for life support

SpaceX / NASA - BFR and launch services infrastructure for use of super heavy lift launch vehicles

Tesla / Panasonic - Lithium-Ion batteries

Thales / Alenia Aerospace - Cygnus PCM cargo modules for orbital on-demand resupply missions

The Boring Company - electric high speed (relatively speaking) tunneling machines for habitat module bore holes to provide GCR protection

There's too much technology development required for a single company to handle.  All the companies listed above have core competencies that SpaceX does not.  SpaceX makes rockets, rocket engines, and pressurized spacecraft.  It's never manufactured a GPS satellite or sent any spacecraft into deep space.  A Tesla Roadster doesn't count.  I can guarantee that they know nothing about drilling operations and they purchase things like solar panels and batteries from other companies.  BFR' structure is being fabricated by a marine composites company for SpaceX because that company has the expertise required to do that and SpaceX does not.  Take the very best that industry and government research can offer and there's a decent chance that whatever is produced is suitable for playing its small but important part in this massive undertaking.

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#27 2018-04-24 20:32:47

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 28,747

Re: Some general observations.

Nicely done list kbd512,
This is also why the SLS is so expensive as well since no one company is doing everything or even trying to provide what we need via a lean mean process. Nasa is still playing with the thoughts of using the SLS and the Deep space habitat which is mostly in Boeing and Lockheeds hands with the ULA aiding in the assembly of all the pieces for getting man to Mars.

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#28 2018-04-25 04:35:30

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Some general observations.

Obviously I am not against your list, which is very useful,  but  here are some comments on it in bold: 

"Alcoa / Baker-Hughes - Mars drilling equipment for water extraction (they've done fairly extensive test and evaluation of aluminum piping for a variety of drilling purposes and their core competencies match up very closely with what's needed for this purpose)"

Probably will be required eventually. But in the early stages of settlement we can simply dig for water rich regolith with robot diggers - much quicker.  Permafrost-type regolith can be microwave into slush if necessary.  There may also be exposed glaciers where we only have to scrape off a dust layer to gain access to water ice than can then be melted and collected.

"Boeing Network and Space Systems / Lockheed Martin Space Systems Company / Northrop Grumman Aerospace Systems - Mars Global Positioning System for precision geolocating"

Not necessary for the early settlement.  We have detailed topographical detail for the whole planet now, that is enough to give you a reasonably accurate info on where you are on the planet.  We also have satellite tracking which can identify even quite small objects on the surface. Let me put it another way: why do you need GPS? Are you setting up an Amazon delivery service on Mars? No! We went to the Moon and set up shortlived bases there at locations which were pre-determined.  That was in what were virtually pre-computer days. We can now be a lot more accurate, without GPS. 

"Dyson - Mars atmosphere pre-processors for dust separation for ISPP / ISRU and habitat cleaning vacuums"

  I think too much has been made of the dust issue on Mars. First off, I see very little reason for humans to get out of a pressurised enivronment in the presence of dust.  It is really only for its historical/PR impact that people need to pad around Mars in spacesuits. For 99% of the time they will either be at base directing robot rovers or in pressurised rovers themselves. The Rovers themselves can directly connect to a secondary pressurised chamber. The passenger rovers can be equipped with a huge range of equipment so geologists can aacurately assess what is outside and take samples. Samples can be examined in a special chamber robotically back at base. If they are to brought inside the base, they can be washed to remove dust. 

"Hamilton-Sundstrand - Sabatier reactors"

I think anyone with a bit of cash and determination is going to be able to produce reliable SRs. Build in some redundancy.

"Honeywell / JPL / NASA - avionics software systems development and navigation"

  Well looking at the way both Space X and Blue Origin can land on a dime I would have thought that suggests these sorts of technologies are well advanced now.

"IBM - rad-hard microprocessors for computerized systems (nearly everything today)"

  Given the success of NASA and ESA in communicating with Mars craft, I can only assume this technology is also far advanced. 

"ILC Dover - planetary exploration space suits"

  This will in the future be important but for Mission One I see this as a limited requirement. We need a functioning space suit so we can take some pics of "feet on the ground". There may be some emergency work to carry out.  I don't think we need a revolutionary leap in space suit design for Mission One.

"NASA / Desktop Metal / Markforged / Voxel - 3D printing of metal, composite, and plastic parts for contingency repairs"

These technologies are well advanced. A lot of current research is into how to make them commercially viable, but cost is not a major issue for the early Missions.  They just need a good range of 3D printers for various tasks.   

"NASA / DOE - Radioisotope Heating Units / RHU's for keep-alive warmth and for melting ice using heated drill heads"

  By all means take some as back up but Space X's mission is going to be primarily solar powered and I am happy with that.

"NASA / DOE - KiloPower fission reactors for backup electrical power"

Unnecessary complexity.  I would stick with Musk's solar powered energy generation model. 

"NASA / Paragon SDC - CAMRAS atmospheric scrubbers and IWP waste water processors"

A lot of progress appears to have been made with these already. 

"NASA / Bigelow Aerospace - inflatable habitat modules"

This does seem an area where development has been slower than I expected.  Not sure if there have been hitches.  Of course, inflatables are not the only way to go. The BFS cargo ships are big enough to carry prefab habitats - maybe in units of 5 x 5 metres which could be bolted together and sealed both externally and internally, and then have regolith piled on top.  The units could be fully kitted out with kitchen, sleeping, bathroom, gym and office facilities etc.  Maybe take three such units at about 1-2 tonnes each. If unloading them is a problem, there may have to be multiple smaller units that get bolted together and sealed. Once the prefab units are in place, you use robot rovers to pile a protective regolith layer over them. 

"Orbital ATK - Solar panels and PMAD"

This technology is well advanced as I understand it. I think a variety of solar panels will be taken.  Orbital ATK style fan solar panels may be used for initial power requirements immediately following landing (in addition to the BFS's own arrays).  That would be a quick way of getting started and they could be carried on mobile Rovers.  Then I think you would probably lay out some state of the art high efficiency panelling to boost power availability for when your habs get under way.  After that, you will be looking at more basic solar panels - possibly on flexible rolls - to be laid out to provide enough power for propellant production (that will be a very large requirement). 

"PCI - miniature Sabatier reactors for life support"

The Sabatier reaction was discovered in 1910. Only NASA could  string this out so long!! I am sure Space X will have this covered.

"SpaceX / NASA - BFR and launch services infrastructure for use of super heavy lift launch vehicles"

Agreed, Space X is going nowhere without NASA's launch and coms facilities. That's why Musk never says anything nasty about NASA. 

"Tesla / Panasonic - Lithium-Ion batteries"

We know these technologies work on Mars.  I don't think we need any technical leaps for Mission One. But, clearly, a solar powered Mission will require a lot of batteries...maybe a couple of tonnes or so...but they of course have multiple uses...a Rover battery can still supply power to the base, if it's not being used for instance. 

"Thales / Alenia Aerospace - Cygnus PCM  cargo modules for orbital on-demand resupply missions"

I presume this is for the longer term. 

"The Boring Company - electric high speed (relatively speaking) tunneling machines for habitat module bore holes to provide GCR protection"

Desirable but not a requirement for the early missions. Heaping regolith over structures is a lot quicker and less trouble.   

"There's too much technology development required for a single company to handle.  All the companies listed above have core competencies that SpaceX does not.  SpaceX makes rockets, rocket engines, and pressurized spacecraft.  It's never manufactured a GPS satellite or sent any spacecraft into deep space.  A Tesla Roadster doesn't count.  I can guarantee that they know nothing about drilling operations and they purchase things like solar panels and batteries from other companies.  BFR' structure is being fabricated by a marine composites company for SpaceX because that company has the expertise required to do that and SpaceX does not.  Take the very best that industry and government research can offer and there's a decent chance that whatever is produced is suitable for playing its small but important part in this massive undertaking."

I've read that Space X have a lot of vertical integration in their company - that is, they make a lot more of their stuff themselves than do most rocket companies. But, remember, they have achieved that from zero in 2002.  Even so they have 3000 suppliers, I have read.  It is a huge undertaking, no one is denying that.  But of course Space X has the huge benefit of 21st century computer technology whether it comes to CAD, monitoring equipment, detecting failures, planning and implementation.  Thousands of pieces of equipment fail on any rocket and any complex mission. Failure is part of the deal. The crucial thing is to plan for failure, to have fixes, to have back up and to invest heavily in all mission critical failure points. 


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

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#29 2018-04-25 07:30:13

elderflower
Member
Registered: 2016-06-19
Posts: 1,262

Re: Some general observations.

Oldfart1939 wrote:

Here's an interesting article on ISRU and fuel production on The Space Review:

http://www.thespacereview.com/article/3479/1

Shame about the confusion of Moles and kilograms.

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#30 2018-04-25 12:13:19

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 5,423
Website

Re: Some general observations.

A lot of this debate smacks of "angels on the head of a pin".  A lot more is very well-reasoned and to the point.

I think we will need both solar and nuclear power.  Suspenders and belt.  I wish there was a third practical alternative,  but right now there is not. 

I'd really like to see the sabatier and water processing equipment intended for use on Mars,  set up in the cold on Queen Elizabeth Island,  and fed stored reagents of the type to be recovered on Mars.  Objective:  demonstrate production of LCH4 and LOX,  plus drinking water and breathable oxygen.  I'd like to see it operate for one full year without a single failure in that test.  Then send two or three sets of such equipment to Mars for redundancy,  plus a boatload of spare parts. 

I don't see anybody tooling up for such a test,  yet there is still plenty of time to run it before we go bet lives on this technology.

I'd like to see ice/water processing equipment intended for Mars tested pretty much the same way.  It probably ought to be tested on a stout brine.  While we're at it on Queen Elizabeth Island,  how about testing possible techniques for ice mining?  That's most likely what we'll have to do on Mars.  If we can recover mass quantities from the permafrost there,  we can likely recover subsurface ices on Mars.

I don't see anybody tooling up to run that test,  either.  And yet,  there's still time to do it before we go.

An observation about testing from one who spent decades doing it:  more likely than not,  what result you get from your test will be something you did NOT expect.  As it turns out,  that is far more useful.  Inconvenient,  but far more useful.  Plan on running the test at least 2-3 times before results become the expected.  If Musk is successful with his BFR,  you have 4 years.  More likely 8.  But only 4-8!

I would really like to see a practical mechanical counterpressure suit developed for Mars.  It makes EVA activities far more productive,  it's launderable,  it's repairable,  and one small rip is patchable with duct tape instead of killing the wearer. 

I don't see anybody doing that either.  NASA hired the MIT gal working on it,  but took her off those duties.  Now,  nobody is working on it.  The ONLY candidates being considered are gas balloon suits from "the usual crowd of vendors".  So, is money or people's lives more important?  You judge.

GW

Last edited by GW Johnson (2018-04-25 12:15:59)


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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#31 2018-04-25 12:31:07

kbd512
Administrator
Registered: 2015-01-02
Posts: 7,362

Re: Some general observations.

louis wrote:

Probably will be required eventually. But in the early stages of settlement we can simply dig for water rich regolith with robot diggers - much quicker.  Permafrost-type regolith can be microwave into slush if necessary.  There may also be exposed glaciers where we only have to scrape off a dust layer to gain access to water ice than can then be melted and collected.

There's a reason we use drills, pipes, and pumps to suck liquids and gases out of the ground here on Earth to power entire cities.  No city on the planet obtains drinking water or fuel by baking soil in batches.  The tar sands were unprofitable in terms of unit of energy expended per unit of energy obtained until a way to use water to leech the oil out of the sand was devised.

Do the math on how much regolith you'd have to process, how large the oven would have to be, how long it would take to bake the water (NASA tests have shown that 4 hours is the optimal cycle time to obtain the most water possible), and do the math on how much power the oven would need to generate.

louis wrote:

Not necessary for the early settlement.  We have detailed topographical detail for the whole planet now, that is enough to give you a reasonably accurate info on where you are on the planet.  We also have satellite tracking which can identify even quite small objects on the surface. Let me put it another way: why do you need GPS? Are you setting up an Amazon delivery service on Mars? No! We went to the Moon and set up shortlived bases there at locations which were pre-determined.  That was in what were virtually pre-computer days. We can now be a lot more accurate, without GPS.

I fly a little Cessna.  We use GPS to navigate.  If other methods worked better, then we'd use those methods.  They don't, so we don't.

louis wrote:

I think too much has been made of the dust issue on Mars. First off, I see very little reason for humans to get out of a pressurised enivronment in the presence of dust.  It is really only for its historical/PR impact that people need to pad around Mars in spacesuits. For 99% of the time they will either be at base directing robot rovers or in pressurised rovers themselves. The Rovers themselves can directly connect to a secondary pressurised chamber. The passenger rovers can be equipped with a huge range of equipment so geologists can aacurately assess what is outside and take samples. Samples can be examined in a special chamber robotically back at base. If they are to brought inside the base, they can be washed to remove dust.

How many construction sites have you seen that don't generate a lot of dust?

Dust was a problem on the moon and it's a problem on Mars.  Reality says so.  You may not want to deal with reality, but the problems of the real world are still there.

How many construction sites have you seen where there aren't boots on the ground performing manual labor?

In this century, no second branch of human civilization will be built without a lot of human labor.

louis wrote:

I think anyone with a bit of cash and determination is going to be able to produce reliable SRs. Build in some redundancy.

Anyone with a bit of cash and determination can build anything, yet most companies subcontract to manufacture things they can obtain cheaper / faster / better from other companies when it's just a small part of the overall product or service provided.

louis wrote:

Well looking at the way both Space X and Blue Origin can land on a dime I would have thought that suggests these sorts of technologies are well advanced now.

SpaceX uses GPS in their rockets.  That's how both the rocket and mission control "knows" where the rocket is.  SpaceX didn't invent GPS and they don't know how to build a GPS satellite, even though they've delivered some of them to orbit.

louis wrote:

Given the success of NASA and ESA in communicating with Mars craft, I can only assume this technology is also far advanced.

It's not about how far advanced it is in this particular case, although the actual microprocessor technology used is nowhere near cutting edge.  The processors are the same architecture processors that were found in Macs more than a decade ago, except that they're not the exact same processors because the manufacturing techniques and materials used are different and the chips cost tens of thousands to millions per copy.

louis wrote:

This will in the future be important but for Mission One I see this as a limited requirement. We need a functioning space suit so we can take some pics of "feet on the ground". There may be some emergency work to carry out.  I don't think we need a revolutionary leap in space suit design for Mission One.

Mission One will involve setting up a solar array that covers slightly more surface area than 4 Nimitz class aircraft carriers moored next to each other.  What has lead you to imagine that this sort of work won't be done by humans?  This is not a satellite deploying a couple of 1 to 2 kilowatt-class arrays in a vacuum using an electric motor.  This is hundreds of individual arrays offloaded from BFR, linked together with power and data cables, and distribution buses that power something requiring megawatts of power, like the vacuum pumps and cryocoolers necessary to produce LOX and LCH4 from CO2 and H2O.

louis wrote:

These technologies are well advanced. A lot of current research is into how to make them commercially viable, but cost is not a major issue for the early Missions.  They just need a good range of 3D printers for various tasks.

Once again, it's not about how advanced the technology is.  Maybe you think there are special versions of these systems made for aerospace applications that are created just to increase the cost of the system, but I assure you that that is not the case.  Elon Musk alluded to that when he launched that Tesla into space.  He said he had no idea what would happen to the vehicle because it was never designed for use in space.  He wasn't lying about that and I'm not lying when I restated what is so painfully obvious to anyone who has ever designed or built something for an aerospace application.

An office on Earth is the most benign environment conceivable for any system to operate in.  There's no gravity loading to mess up mechanical components or crack circuit boards, there are no pressure changes or extreme thermal cycles to affect electronics or batteries, and there is no intense radiation to mess up microchips because we have a magnetosphere and substantial atmosphere to provide shielding.  None of that applies to something operating aboard a spacecraft or shipped to the surface of another planet with no magnetosphere or atmosphere to speak of.

louis wrote:

By all means take some as back up but Space X's mission is going to be primarily solar powered and I am happy with that.

RHU's don't provide electrical power.  Those little solar powered rovers couldn't generate enough heat through electricity to keep the electronics warm at night without bricking the batteries, so RHU's provided supplemental heat to keep the rovers from dying at night.  Even the nuclear powered rovers use the heat generated by both the RHU's and the RTG's to keep their electronics from dying at night.  Insulation only did so much, after which several powerful nuclear heat sources were required to "keep the lights on".

louis wrote:

Unnecessary complexity.  I would stick with Musk's solar powered energy generation model.

I wouldn't.  I don't think he would, either, given the choice.

louis wrote:

A lot of progress appears to have been made with these already.

I would agree, but they're still not ready for prime time.  According to NASA, the alternatives weigh too much, consume too much power, cost too much, and are too unreliable.  ISS uses multiple redundant backup systems of dissimilar design and regular resupply of repair parts from Earth.  I think NASA's assessment is correct.  That said, any given system is either flight ready or it's not.

At the current rate of progress, I imagine these systems will be ready for flight use in the next two to three years.  CAMRAS has already flown aboard ISS and was tested over 6 months with superb results.  It's a major improvement over the previous generation of systems.  IWP will fly this year aboard ISS.  Apart from the other improvements, IWP reclaims 98% of the input water.  Paragon's goal is 99%+.  Every liter of water or atmosphere saved becomes incredibly important when resupply is not practical.

louis wrote:

This does seem an area where development has been slower than I expected.  Not sure if there have been hitches.  Of course, inflatables are not the only way to go. The BFS cargo ships are big enough to carry prefab habitats - maybe in units of 5 x 5 metres which could be bolted together and sealed both externally and internally, and then have regolith piled on top.  The units could be fully kitted out with kitchen, sleeping, bathroom, gym and office facilities etc.  Maybe take three such units at about 1-2 tonnes each. If unloading them is a problem, there may have to be multiple smaller units that get bolted together and sealed. Once the prefab units are in place, you use robot rovers to pile a protective regolith layer over them.

The colonists can't live in BFR's.  They need permanent habitable structures erected on Mars so the BFR's can come and go as required.

louis wrote:

This technology is well advanced as I understand it. I think a variety of solar panels will be taken.  Orbital ATK style fan solar panels may be used for initial power requirements immediately following landing (in addition to the BFS's own arrays).  That would be a quick way of getting started and they could be carried on mobile Rovers.  Then I think you would probably lay out some state of the art high efficiency panelling to boost power availability for when your habs get under way.  After that, you will be looking at more basic solar panels - possibly on flexible rolls - to be laid out to provide enough power for propellant production (that will be a very large requirement).

There is no PMAD for multi-megawatt systems.  Orbital ATK is working on the PMAD equipment for 30kW to 300kW arrays.  ISS uses the largest array ever deployed in space.  No other arrays come close in terms of size or output.  Other companies have built various arrays for space applications, but Orbital ATK has a proven track record of performance on Mars, arrays specifically built for use on Mars, and the depth and breadth of experience required for an operational system that generates hundreds of kilowatts to a few megawatts of power.

louis wrote:

The Sabatier reaction was discovered in 1910. Only NASA could  string this out so long!! I am sure Space X will have this covered.

Only people who believe that our technology materializes from thin air would believe that some singular company actually has the technology to live on Mars.  The tech comes from a slew of companies in the US and Europe who specialize in certain types of tech development and manufacturing.

louis wrote:

Agreed, Space X is going nowhere without NASA's launch and coms facilities. That's why Musk never says anything nasty about NASA.

Mr. Musk doesn't say nasty things about the people who made SpaceX possible because they're his most profitable single customer and the only ones who invested in his company when he needed startup funding.  He rightly views his relationship with NASA as a cooperative arrangement between SpaceX and the US government.  Uncle Sam is happy to do business with him because his people produce excellent products at bargain prices.  There's nothing that's unlikeable about their relationship from either side of it.  NASA also provides technical guidance on tasks that SpaceX may not have the internal expertise to accomplish.  Mission navigation planning software provided by JPL is the only reason anyone can get to Mars to begin with.

louis wrote:

We know these technologies work on Mars.  I don't think we need any technical leaps for Mission One. But, clearly, a solar powered Mission will require a lot of batteries...maybe a couple of tonnes or so...but they of course have multiple uses...a Rover battery can still supply power to the base, if it's not being used for instance.

I never said we didn't.  I'm saying that virtually nothing is actually designed, built, and tested to work on Mars.  The solar arrays provided by Orbital ATK, the IBM processors, and the DOE RHU's are the only flight-ready items that we know for a fact will actually work on Mars because all of those things are on Mars right now and have functioned there for a decade or more.  Everything else requires more development work.

louis wrote:

I presume this is for the longer term.

If you get stuck on Mars for 1 or 2 cycles past your return date or the next BFR can't make it there on schedule (reason is unimportant), if you make orbit but can't make escape velocity and trajectory after attaining orbit (reason still unimportant), or if you have an accident and lose some supplies at some point during the mission (yet again, reason unimportant), then you need consumables in a location that makes either scenario a survivable proposition.  The only way to do that is to have multiple resupply containers in a stable low orbit around Mars.  That means a miniature space station in LMO with consumables staged there for contingency use.  In the real world, we don't pretend that everything will go according to plan.  There's a reason why we practice landing after loss of power in an aircraft.  It happens.  Stop pretending that nothing bad will ever happen and start looking at everything that could possibly happen because it's quite a list.

louis wrote:

Desirable but not a requirement for the early missions. Heaping regolith over structures is a lot quicker and less trouble.

I want a permanent solution to the problem of radiation shielding.  This is a permanent solution that requires no guess work or radiation measurement scheme.  If you're two meters below the surface, then you have Earth sea level radiation dose rates.  We know this will remain habitable 100% of the time.  The question always gets asked and the protection scheme always gets questioned by people inside or outside of NASA, so this is the ultimate answer.

louis wrote:

I've read that Space X have a lot of vertical integration in their company - that is, they make a lot more of their stuff themselves than do most rocket companies. But, remember, they have achieved that from zero in 2002.  Even so they have 3000 suppliers, I have read.  It is a huge undertaking, no one is denying that.  But of course Space X has the huge benefit of 21st century computer technology whether it comes to CAD, monitoring equipment, detecting failures, planning and implementation.  Thousands of pieces of equipment fail on any rocket and any complex mission. Failure is part of the deal. The crucial thing is to plan for failure, to have fixes, to have back up and to invest heavily in all mission critical failure points.

No company does absolutely everything themselves.  An office supply company may actually make their own pens and paper, although it's more common that they don't, but I can guarantee that a different company made their computers.

Even if Tesla is supplying the batteries, SpaceX doesn't make batteries and knows nothing about making batteries because they don't need to know how to make batteries when a secretary in their office can use her Apple iPad to order some off the internet from Tesla, UPS will ship it, Acme Trucking Co will supply a driver to deliver the batteries on behalf of UPS, and then a SpaceX electrical engineer can install it in an enclosure that he designed after he has it fabricated in the machine shop down the road that 3D printed it for him.  None of that in any way implies that SpaceX knows bean dip about batteries, trucking, or 3D printing.  They have someone on staff who knows how to install a battery in an enclosure suitable for aerospace applications and they know how to test it because that's all they need to know to use a battery in a spacecraft.

There are a confluence of technological developments required to actually go to another planet and live there, let alone thrive there.  No single company is going to make that possible.  Rocketdyne built F1 engines for the Saturn V, but never made RP-1 for their rocket engines to burn because some other company in the business of making jet fuel did that for them at a better price and with better quality than they ever could.

Can we stop with the magical thinking about SpaceX knowing everything and doing everything themselves when they're not even building the structure of BFR themselves by their own admission about that subject?  This is like listening to our son tell me he knows all about driving right before he drove the family car into the curb.

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#32 2018-04-25 17:01:00

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 28,747

Re: Some general observations.

We might be able to forgo a few of the items depending on the scale down of the crew size and goals. It also is altered by duration and how much preloading of the landing site is done. It also is changed via the end game goals and whether we do from the start set out to be able to stay and not just turn tail after each mission is complete.

The need list is great but it only can be a success via good planning of all aspects.

Plus the list is missing a ride of some size for mission exploration.

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#33 2018-04-25 17:30:00

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Some general observations.

kbd512 wrote:

There's a reason we use drills, pipes, and pumps to suck liquids and gases out of the ground here on Earth to power entire cities.  No city on the planet obtains drinking water or fuel by baking soil in batches.  The tar sands were unprofitable in terms of unit of energy expended per unit of energy obtained until a way to use water to leech the oil out of the sand was devised.

Do the math on how much regolith you'd have to process, how large the oven would have to be, how long it would take to bake the water (NASA tests have shown that 4 hours is the optimal cycle time to obtain the most water possible), and do the math on how much power the oven would need to generate.

Estimates from satellite surveys suggest that large swathes of land have around 5% of water ice in the regolith. So one twentieth of the regolith would be water, so for every 100 kgs of water you'd have to mine 2 tonnes of regolith.  Maybe we'd have a team of 10 rovers each processing 5 tonnes of regolith per sol, producing 1500 tonnes of water over 600 sols.  Of course scientists and technician may come up with different methods.  Microwaving the ground might well produce water vapour that could be captured. That could be a quicker method. We'd need to research that.

kbd512 wrote:

I fly a little Cessna.  We use GPS to navigate.  If other methods worked better, then we'd use those methods.  They don't, so we don't.

People did land Cessnas before GPS! And Cruise missiles use topographical data to navigate, not GPS.

kbd512 wrote:

How many construction sites have you seen that don't generate a lot of dust?

Dust was a problem on the moon and it's a problem on Mars.  Reality says so.  You may not want to deal with reality, but the problems of the real world are still there.

How many construction sites have you seen where there aren't boots on the ground performing manual labor?

In this century, no second branch of human civilization will be built without a lot of human labor.

Dust is a problem if you get out on the surface and then try to get back inside the hab.  There is no reason for people to be doing EVAs to put together prefab units on Mars. Ground can be cleared by rovers.  The prefab units can, if required, be bolted together using robot arms on rover vehicles.

The Apollo dust experience was based on a single tiny depressurisation chamber as far as I know.  On Mars, we can have two chambers, with one being an intensive shower and cleansing chamber. Waste water can be collected in a sealed box and then deposited outside on the next rover run.

kbd512 wrote:

  SpaceX uses GPS in their rockets.  That's how both the rocket and mission control "knows" where the rocket is.  SpaceX didn't invent GPS and they don't know how to build a GPS satellite, even though they've delivered some of them to orbit.

That's irrelevant to landing on Mars.  On Mars they will use transponders, topographical data and human monitoring because there is no GPS.

kbd512 wrote:

Mission One will involve setting up a solar array that covers slightly more surface area than 4 Nimitz class aircraft carriers moored next to each other.  What has lead you to imagine that this sort of work won't be done by humans?  This is not a satellite deploying a couple of 1 to 2 kilowatt-class arrays in a vacuum using an electric motor.  This is hundreds of individual arrays offloaded from BFR, linked together with power and data cables, and distribution buses that power something requiring megawatts of power, like the vacuum pumps and cryocoolers necessary to produce LOX and LCH4 from CO2 and H2O.

What makes you think an array can't be laid out in the clement climate of Mars by a combination of remotely controlled automated rovers, human passenger rovers and Orbital ATK style solar array fans? How does a cable get laid on the bottom of the ocean?  Do you think divers go down and place it carefully over the seabed themselves? Er no, it's done automatically under human supervision. Same will apply on Mars.

kbd512 wrote:

Once again, it's not about how advanced the technology is.  Maybe you think there are special versions of these systems made for aerospace applications that are created just to increase the cost of the system, but I assure you that that is not the case.  Elon Musk alluded to that when he launched that Tesla into space.  He said he had no idea what would happen to the vehicle because it was never designed for use in space.  He wasn't lying about that and I'm not lying when I restated what is so painfully obvious to anyone who has ever designed or built something for an aerospace application.

An office on Earth is the most benign environment conceivable for any system to operate in.  There's no gravity loading to mess up mechanical components or crack circuit boards, there are no pressure changes or extreme thermal cycles to affect electronics or batteries, and there is no intense radiation to mess up microchips because we have a magnetosphere and substantial atmosphere to provide shielding.  None of that applies to something operating aboard a spacecraft or shipped to the surface of another planet with no magnetosphere or atmosphere to speak of.

The 3D printers aren't going to be operating on board the spaceship in flight.  They will be operating on Mars in habs on the surface.  They will need to be tested for operation in Mars' conditions, but they are going to be in a temperature controlled, pressurised, radiation-resistant environment all the time.

kbd512 wrote:

RHU's don't provide electrical power.  Those little solar powered rovers couldn't generate enough heat through electricity to keep the electronics warm at night without bricking the batteries, so RHU's provided supplemental heat to keep the rovers from dying at night.  Even the nuclear powered rovers use the heat generated by both the RHU's and the RTG's to keep their electronics from dying at night.  Insulation only did so much, after which several powerful nuclear heat sources were required to "keep the lights on".

Why do you think the Rovers are going to be outside at night during the Mars mission? I would expect them to be warm and cosy in a dedicated hab. The use of RTGs to keep Rovers heated is probably a function of trying to keep weight to an absolute minimum on small Rover missions, but we are talking here about delivering hundreds of tonnes of cargo to the surface. I expect the Rovers will have large electric batteries and there may even be some capable of night working.

kbd512 wrote:

I wouldn't.  I don't think he would, either, given the choice.

Well we'll see won't we? Every indication is that the Space X mission to Mars will be almost wholly solar powered in terms of its basic energy generation.


kbd512 wrote:

The colonists can't live in BFR's.  They need permanent habitable structures erected on Mars so the BFR's can come and go as required.

You misunderstood what I wrote.  I wrote that the BFS was big enough to carry whole pre-fab (non-inflatable) habs to Mars. These could be bolted together and sealed on the surface, away from the BFS.

kbd512 wrote:

There is no PMAD for multi-megawatt systems.  Orbital ATK is working on the PMAD equipment for 30kW to 300kW arrays.  ISS uses the largest array ever deployed in space.  No other arrays come close in terms of size or output.  Other companies have built various arrays for space applications, but Orbital ATK has a proven track record of performance on Mars, arrays specifically built for use on Mars, and the depth and breadth of experience required for an operational system that generates hundreds of kilowatts to a few megawatts of power.

But there are very large control systems on the ground on Earth, including at Musk's huge battery factory. A control system for a lone craft out in space has to be 100% reliable all the time.  For a lot of the functions on Mars, they will not be critical in the same way. Your basic life support energy systems will need to be super-reliable but propellant production for instance will likely be undertaken in a number of discrete units. An outage will not destroy the mission, as long as the production plant is properly designed for safe shutdown where an outage occurs.  That's one of the advantages of solar that you can run multiple discrete generation/distribution systems.

Basically I think you are confusing the requirements of a very small system operating on a lone craft in outer space with a Mars system which will be huge in comparison with lots of discrete units, and multiple back up.

kbd512 wrote:

Only people who believe that our technology materializes from thin air would believe that some singular company actually has the technology to live on Mars.  The tech comes from a slew of companies in the US and Europe who specialize in certain types of tech development and manufacturing.

I am saying that when you look at the imperatives of WW2 and the cold war battle to be first to the Moon you see amazing technical progress. Of course, things have to be doable in the first place. But that is the point about the Sabatier reaction, it was proved doable in 1910.  Progress has been slow because it is not in the interest of the development companies for it to be fast and NASA have not shown any real sense of urgency. If they did they would have put out a tender 20 years ago, saying "Produce within 3 years a fully functioning reliable Sabatier reactor proofed for use in space, on the Moon and on Mars."

kbd512 wrote:

If you get stuck on Mars for 1 or 2 cycles past your return date or the next BFR can't make it there on schedule (reason is unimportant), if you make orbit but can't make escape velocity and trajectory after attaining orbit (reason still unimportant), or if you have an accident and lose some supplies at some point during the mission (yet again, reason unimportant), then you need consumables in a location that makes either scenario a survivable proposition.  The only way to do that is to have multiple resupply containers in a stable low orbit around Mars.  That means a miniature space station in LMO with consumables staged there for contingency use.  In the real world, we don't pretend that everything will go according to plan.  There's a reason why we practice landing after loss of power in an aircraft.  It happens.  Stop pretending that nothing bad will ever happen and start looking at everything that could possibly happen because it's quite a list.

The BFS is huge. It could easily carry enough food and other supplies for several years. I assume it will do.

kbd512 wrote:

I want a permanent solution to the problem of radiation shielding.  This is a permanent solution that requires no guess work or radiation measurement scheme.  If you're two meters below the surface, then you have Earth sea level radiation dose rates.  We know this will remain habitable 100% of the time.  The question always gets asked and the protection scheme always gets questioned by people inside or outside of NASA, so this is the ultimate answer.

It's an answer, but not sure it is the only answer and there is a psychological cost to living underground in my view.

kbd512 wrote:

No company does absolutely everything themselves.  An office supply company may actually make their own pens and paper, although it's more common that they don't, but I can guarantee that a different company made their computers.

Even if Tesla is supplying the batteries, SpaceX doesn't make batteries and knows nothing about making batteries because they don't need to know how to make batteries when a secretary in their office can use her Apple iPad to order some off the internet from Tesla, UPS will ship it, Acme Trucking Co will supply a driver to deliver the batteries on behalf of UPS, and then a SpaceX electrical engineer can install it in an enclosure that he designed after he has it fabricated in the machine shop down the road that 3D printed it for him.  None of that in any way implies that SpaceX knows bean dip about batteries, trucking, or 3D printing.  They have someone on staff who knows how to install a battery in an enclosure suitable for aerospace applications and they know how to test it because that's all they need to know to use a battery in a spacecraft.

There are a confluence of technological developments required to actually go to another planet and live there, let alone thrive there.  No single company is going to make that possible.  Rocketdyne built F1 engines for the Saturn V, but never made RP-1 for their rocket engines to burn because some other company in the business of making jet fuel did that for them at a better price and with better quality than they ever could.

Can we stop with the magical thinking about SpaceX knowing everything and doing everything themselves when they're not even building the structure of BFR themselves by their own admission about that subject?  This is like listening to our son tell me he knows all about driving right before he drove the family car into the curb.

Straw man argument.  I never said Space X do or will make everything themselves. I said they had a high level of vertical integration. I think Musk's strategy involves Space X making the stuff that Musk thinks is critical and is not being done well enough or cheaply enough by the external market. 

I wouldn't be at all surprised if Space X make their own life support equipment, but we shall see.


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

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#34 2018-04-25 22:16:05

clark
Member
Registered: 2001-09-20
Posts: 6,362

Re: Some general observations.

Some general observations:

1. High technology is required for mars sustained human habitation of mars.
2. High technology requires alloys, processed metals, plastics, microchips, advanced integrated electronics and probably a bunch of other things I don't know about.
3.  Processing plants, smelters, chemical processing plants and factory assemblies are required to create the alloys, metals, plastics, microchips, and integrated electronics.
4.  Identified supply of resources and minerals must be available to feed the smelters and processing plants to create alloys and plastics.
5. The ability to transport industrial volumes of minerals and assorted resources
6. The ability to mine high value minerals and produce the resources in a near vacuum must be possible.
7. Sustained power generation is required for all points in the logistical supply chain

The reason why this entire conversation is absurd is that is glosses over the very real logistical hurdles involved with long term habitation of mars. We have an entire world, Earth, that can produce the requisite components, but they are built on decades of investment in a far more forgiving environment.

Without addressing the logistical supply chain needs locale, you are dependent on Earth. As long as you are dependent on Earth, any system design architecture must build in a 2-3 year fail safe redundancy for fail safes.

You can forgo the safety margins, but you must then accept that more people will die.

If you want real martian colonies, figure out how to boot strap the creation of the martian microchip. It's a lynchpin.

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#35 2018-04-26 03:59:37

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Some general observations.

Commentators who fail to distinguish between short term, medium term and long term Mars settlement invariably go wrong. Let's just take one point:

"5. The ability to transport industrial volumes of minerals and assorted resources" 

When we think of "industrial volumes" on Earth, we are thinking of tens of thousands, hundreds of thousands even millions of tonnes of stuff passing through ports and factories. And that's because the population of Earth is 7 billion.  Musk's stated ambition is to create a community of one million people on Mars. That's 0.14% of Earth's population.   So even if we have an Earth-style operation, you are talking about one seven thousandth of the quantity. That's the long term.  However, the likelihood is that even in the long term Mars will have designed into its built fabric maximal recycling and the people will have a more frugal lifestyle - fewer large homes, fewer private vehicles, fewer clothing items and no paper use for instance.

When it comes to transport, Mars is in many ways an ideal planet.  It has none or very few of the inclement weather and geological events found on Earth: rainstorms, hailstorms, huge snowfalls, gales, hurricanes, earthquakes, tornadoes, tsunamis, massive floods etc.  There will be numerous roadways that can be formed over ground cleared of boulders and rovers/trucks will be able to pass over these as easily as, or more easily than, trucks travel on ice roads on Earth. The (largely robotic) rover trucks can be electric-powered,  recharging at solar powered stations along the way. The ability to transport materials will grow incrementally as the number of roadways and trucks increases in line with mining and industrial activity. There is no problem here.

Short term, there is no great hurry to create an industrial infrastructure, as far as the Space X settlement model goes. They will be bringing in hundreds of tonnes of supplies every couple of years which will more than cover the needs of the few settlers - who might number no more than 100 within say 8 years. Developing agriculture will probably be a higher priority in the first few decades.



clark wrote:

Some general observations:

1. High technology is required for mars sustained human habitation of mars.
2. High technology requires alloys, processed metals, plastics, microchips, advanced integrated electronics and probably a bunch of other things I don't know about.
3.  Processing plants, smelters, chemical processing plants and factory assemblies are required to create the alloys, metals, plastics, microchips, and integrated electronics.
4.  Identified supply of resources and minerals must be available to feed the smelters and processing plants to create alloys and plastics.
5. The ability to transport industrial volumes of minerals and assorted resources
6. The ability to mine high value minerals and produce the resources in a near vacuum must be possible.
7. Sustained power generation is required for all points in the logistical supply chain

The reason why this entire conversation is absurd is that is glosses over the very real logistical hurdles involved with long term habitation of mars. We have an entire world, Earth, that can produce the requisite components, but they are built on decades of investment in a far more forgiving environment.

Without addressing the logistical supply chain needs locale, you are dependent on Earth. As long as you are dependent on Earth, any system design architecture must build in a 2-3 year fail safe redundancy for fail safes.

You can forgo the safety margins, but you must then accept that more people will die.

If you want real martian colonies, figure out how to boot strap the creation of the martian microchip. It's a lynchpin.


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

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#36 2018-04-26 07:06:56

clark
Member
Registered: 2001-09-20
Posts: 6,362

Re: Some general observations.

i need time to reflect on the company i keep. i just can't.

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#37 2018-04-26 19:04:32

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 28,747

Re: Some general observations.

louis wrote:

Commentators who fail to distinguish between short term, medium term and long term Mars settlement invariably go wrong.

Tell me which do you feel the BFR is?

Going with a high technology that can not be repaired is also dangerous to any crew on Mars or anywhere along the route to or from earth to Mars when it breaks. So we need a robust technology that has a very high dependability to all of the items we need for mars. To call it low tech is not wuite the term I would chose but from the experience of naval component use I would say that tried and true are what we should go with as we have a track record to failure and how to go about repairing them.

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#38 2018-04-26 19:46:35

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Some general observations.

BFR is obviously short term! It will be the first Earth-Mars transit vehicle. I am sure Space X are aiming for a robust technology that has a very high dependability. 

SpaceNut wrote:
louis wrote:

Commentators who fail to distinguish between short term, medium term and long term Mars settlement invariably go wrong.

Tell me which do you feel the BFR is?

Going with a high technology that can not be repaired is also dangerous to any crew on Mars or anywhere along the route to or from earth to Mars when it breaks. So we need a robust technology that has a very high dependability to all of the items we need for mars. To call it low tech is not wuite the term I would chose but from the experience of naval component use I would say that tried and true are what we should go with as we have a track record to failure and how to go about repairing them.


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

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#39 2018-04-26 20:50:55

Oldfart1939
Member
Registered: 2016-11-26
Posts: 2,366

Re: Some general observations.

I really believe we should simply focus on "getting there and back." Everything else is fantasy.  Robert Zubrin had a reasonable and do-able proposal 29 years ago, but everyone overlooks a key part of his proposal, which is provision of artificial gravity. Absolute necessity for overall mission success.

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#40 2018-04-27 07:33:26

kbd512
Administrator
Registered: 2015-01-02
Posts: 7,362

Re: Some general observations.

louis wrote:

Estimates from satellite surveys suggest that large swathes of land have around 5% of water ice in the regolith. So one twentieth of the regolith would be water, so for every 100 kgs of water you'd have to mine 2 tonnes of regolith.  Maybe we'd have a team of 10 rovers each processing 5 tonnes of regolith per sol, producing 1500 tonnes of water over 600 sols.  Of course scientists and technician may come up with different methods.  Microwaving the ground might well produce water vapour that could be captured. That could be a quicker method. We'd need to research that.

20t of regolith per 1t of water

1,500t of water / 600 sols = 2.5t of water per sol

2.5t of water = 50t of regolith per sol

4 hours was the optimal regolith baking time, according to NASA

That means 6 batches per sol and ~8.3t of regolith per batch

The bulk density of Martian regolith is a bit over 1,000kg/m^3, but figure roughly 1 cubic meter of regolith per ton.  The regolith movers would have to collect and deliver roughly 8 cubic meters of regolith to two or more regolith roasters every 4 hours.  We could use smaller ovens like coffee roasters and load smaller regolith batches.  Fresnel lenses could limit or eliminate consumption of electrical power for heating.

Mars surface is essentially a vacuum, so heat loss from a stainless steel vacuum insulated roaster should essentially be limited to radiation.  A molten salt tank in the center of the unit could store heat to speed up the process, but it's probably not worth the added mass and engineering effort, though molten salts have the potential to extend operating hours.  A day only process would mean just 3 batches per day instead of 6.  A heated gas could power the regolith agitator and the outer walls of the unit could function as the cold sink to eliminate electrical power requirements completely.  Since this has actually been done on Earth to purify water, it should work on Mars.

A molten salt could also supply some of the process heat for SOXE to lessen electrical heating requirements.  It'd be beneficial to use solar heat transfer systems that are insensitive to the thermal and radiation degradation from the Martian surface environment, unlike solar panels, batteries, and electronics.  It'd be a lot cheaper, too.  ATK's MegaFlex panels are obscenely expensive and complicated to manufacture in quantity since the individual cells in the array are hand-selected for space applications.

Anyway, onto excavating.  A Bobcat T595 tracked loader has a rated operating capacity of about 1,000kg, which is roughly what we're after, weighs a little over 3,600kg, and is powered by a 74hp Diesel engine.  That's for general purpose Earth moving and requires serious power, hydraulics, and counterweighting to lift a loaded bucket.  The Mars version would be battery powered and this is a very specialized task that doesn't require the full functionality of a Bobcat.  It's possible to trim substantial weight off the loaders by restricting the operating characteristics of the regolith bucket and design of the machine.  We'd need far less power if we did that and no hydraulics.  I'm thinking about something that operates at below knee height of a grown man.  A person could remote operate the unit, provided it was visible to the operator.  I'd hesitate to try to develop an autonomous system if one person can visually operate several units in sequence for less cost and complexity or perhaps use one unit until the batteries are discharged, then switch to the next unit, and so on.

Minimally, a pair of such vehicles are needed to deliver 16 1t loads in 4 hours if they only operate in daylight.  We need swappable vehicle battery packs that a single person can lift.  Each vehicle would use multiple packs.  Each night, packs would be swapped and recharged on alternate days to preserve the operational life of the packs.

Someone actually made an electrically powered skid steer Bobcat, so here's a gratuitous YouTube video of that machine in action:

Electric bobcat

It seems to work well enough with a human operator at the controls.

louis wrote:

People did land Cessnas before GPS! And Cruise missiles use topographical data to navigate, not GPS.

A lot of people also crashed due to navigational errors, but go take some flying lessons or talk to a flight instructor and tell us what you learned about visual approaches.  It works a lot better with distinctive landmarks.  Lots of place on Mars don't have those.

Cruise missiles guide to their targets using a combination of inertial navigation, radar terrain mapping, and GPS.  Anyway, terrain mapping software gets confused by very similar terrain features.

louis wrote:

Dust is a problem if you get out on the surface and then try to get back inside the hab.  There is no reason for people to be doing EVAs to put together prefab units on Mars. Ground can be cleared by rovers.  The prefab units can, if required, be bolted together using robot arms on rover vehicles.

Did you notice the CGI from the SpaceX presentation where the very first thing the colonists do is get out of the BFR or ITS to take a look around.  If robots can build an entire city all on their own, then there's no need to send humans there until the city has been built.

louis wrote:

The Apollo dust experience was based on a single tiny depressurisation chamber as far as I know.  On Mars, we can have two chambers, with one being an intensive shower and cleansing chamber. Waste water can be collected in a sealed box and then deposited outside on the next rover run.

The lunar suits were significantly damaged within a few days.  Space suits are still made with the same materials.  That fine powder is a real problem.  I didn't make it up just to disagree with you about something.  Go read about it.

If any waste water is available from a washdown system, then it will be recycled.

louis wrote:

That's irrelevant to landing on Mars.  On Mars they will use transponders, topographical data and human monitoring because there is no GPS.

I've noticed that a lot of reality is irrelevant to you.  SpaceX rockets use GPS for navigation, period.

louis wrote:

What makes you think an array can't be laid out in the clement climate of Mars by a combination of remotely controlled automated rovers, human passenger rovers and Orbital ATK style solar array fans? How does a cable get laid on the bottom of the ocean?  Do you think divers go down and place it carefully over the seabed themselves? Er no, it's done automatically under human supervision. Same will apply on Mars.

Unwinding a pre-fabricated cable is not the same thing as wiring a power station, Louis.  Nobody knows exactly how long each cable has to be since the arrays may need to be unevenly spaced for reasons related to the terrain.  Presumably, a reel of power cable and hand tools to perform wiring tasks will be brought so the humans can wire the array as necessary.

Nothing is impossible, but I've never seen or heard of a robot that deploys solar panels and connects the individual array elements.  Here on Earth, a human with a job title of "electrician" does that work.  You said you wanted the humans to get enough exercise on Mars.  Guess what?  Building your own power station is both good exercise and required work.

It's like you've never heard the story about the NASA requirement for self-replicating robots to build a base on the moon.  Someone pointed out that we already had such machines and they were called "humans".

louis wrote:

The 3D printers aren't going to be operating on board the spaceship in flight.  They will be operating on Mars in habs on the surface.  They will need to be tested for operation in Mars' conditions, but they are going to be in a temperature controlled, pressurised, radiation-resistant environment all the time.

All equipment has to get to Mars without damage.  Maybe you're willing to bet your life that a 7g reentry won't damage anything, but people with more knowledge of engineering aren't quite as optimistic as you are.

louis wrote:

Why do you think the Rovers are going to be outside at night during the Mars mission? I would expect them to be warm and cosy in a dedicated hab. The use of RTGs to keep Rovers heated is probably a function of trying to keep weight to an absolute minimum on small Rover missions, but we are talking here about delivering hundreds of tonnes of cargo to the surface. I expect the Rovers will have large electric batteries and there may even be some capable of night working.

You want to keep the rovers inside the habitat, but you're sure that dust won't be a problem.  Okay, whatever.

Hundreds of tons of stuff other than heated garages for overpriced electric Bobcats will be required, but again, whatever.

louis wrote:

Well we'll see won't we? Every indication is that the Space X mission to Mars will be almost wholly solar powered in terms of its basic energy generation.

There's no indication of anything but PR hype yet.  The first time SpaceX puts anyone in space and returns them to Earth alive, I'll start to believe.

louis wrote:

You misunderstood what I wrote.  I wrote that the BFS was big enough to carry whole pre-fab (non-inflatable) habs to Mars. These could be bolted together and sealed on the surface, away from the BFS.

How many pre-fab structures have you assembled with your team of robots so you don't get your hands dirty?

louis wrote:

But there are very large control systems on the ground on Earth, including at Musk's huge battery factory. A control system for a lone craft out in space has to be 100% reliable all the time.  For a lot of the functions on Mars, they will not be critical in the same way. Your basic life support energy systems will need to be super-reliable but propellant production for instance will likely be undertaken in a number of discrete units. An outage will not destroy the mission, as long as the production plant is properly designed for safe shutdown where an outage occurs.  That's one of the advantages of solar that you can run multiple discrete generation/distribution systems.

The exact same Lithium-ion battery cells that ISS uses to store electrical power caught fire and burned to completion aboard Boeing 787's.  The only "difference" is that NASA engineered and constructed a power storage system that made the problems experienced aboard Boeing's Dreamliners nearly impossible.  Boeing didn't understand some of what NASA had done.  NASA "assumed" Boeing knew how to construct battery enclosures, but promptly shared information with them after the "thermal events", as GM likes to call them.

louis wrote:

Basically I think you are confusing the requirements of a very small system operating on a lone craft in outer space with a Mars system which will be huge in comparison with lots of discrete units, and multiple back up.

Basically, I think you're confusing requirements for something you've seen on the internet or in a store with things that actually work well or at all in space.  Please talk to some engineers who design things for use in space.

louis wrote:

I am saying that when you look at the imperatives of WW2 and the cold war battle to be first to the Moon you see amazing technical progress. Of course, things have to be doable in the first place. But that is the point about the Sabatier reaction, it was proved doable in 1910.  Progress has been slow because it is not in the interest of the development companies for it to be fast and NASA have not shown any real sense of urgency. If they did they would have put out a tender 20 years ago, saying "Produce within 3 years a fully functioning reliable Sabatier reactor proofed for use in space, on the Moon and on Mars."

There is no imperative to go to Mars.  It's a scientific curiosity that happens to fascinate a tiny fraction of the general public.  Thousands of men, women, and children were dying every day in WWII.  The imperative of WWII was to defeat our enemies to stop their murder spree.

There was no practical need for Sabatier reactors in 1910.  There is no real urgency to get to Mars because that's an imperative you made up in your head for your own personal reasons.  NASA wants to be certain, to the extent it can, that anyone we send to Mars comes back alive and in good physical condition or can live there indefinitely without undesirable health effects.

Oddly enough, state-of-the-art Sabatier reactors are only being worked on because of NASA, not SpaceX.  NASA's mission statement revolves around space exploration and technology development, not Mars colonization using LCH4 powered rockets developed by a private company.  There's no CO2 to make CH4 on the moon, so a Sabatier reactor does nothing for a lunar exploration program.  Way back when NASA had the technology to simply get to Mars, they intended to use storable liquids for descent / ascent vehicles and nuclear thermal rockets for in-space propulsion.  The Saturn V and NERVA upper stage was the closest anyone has ever come to "all the way there and back" propulsion systems.

louis wrote:

The BFS is huge. It could easily carry enough food and other supplies for several years. I assume it will do.

Stop being so lazy and do some math on what these things weigh.  Sure, the rocket can carry this, that, or the other, but it can't carry all of that in a handful of ships.  Some consideration needs to be given to what everything weighs, even with 150t payloads.

louis wrote:

It's an answer, but not sure it is the only answer and there is a psychological cost to living underground in my view.

If you intend to put 2 meters of regolith atop the habitat, then you may as well just dig a vertical hole and bury it.

louis wrote:

Straw man argument.  I never said Space X do or will make everything themselves. I said they had a high level of vertical integration. I think Musk's strategy involves Space X making the stuff that Musk thinks is critical and is not being done well enough or cheaply enough by the external market.

SpaceX has manufactured a series of small LOX/RP-1 rockets and small capsule systems.

Now they're going to build a vehicle with a pressurized volume larger than the cabin of the A380.  Try to imagine all the new problems that will be "discovered" along the way.

louis wrote:

I wouldn't be at all surprised if Space X make their own life support equipment, but we shall see.

How much time and money do they want to spend reinventing the wheel?

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#41 2018-04-27 10:33:18

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Some general observations.

Kbd,

You have some interesting ideas on regolith treatment to extract water. I think the quantities are challenging but manageable.

I think you are underestimating the power of terrain mapping. Do modern guidance system really get confused by similar terrain? Maybe in a city they would, but over "natural" ground?

Landmarks don't have to be "distinctive" in a human sense - they just have to be recognisable by computer software. But maybe that will be one of the factors affecting landing zone choice: to have an area with a couple of very distinctive features.  The human BFS will of course have the cargo BFSs as reference points if nothing else.

I can see why Space X show colonists getting out of their habs or vehicles and having a stroll around...but not strictly necessary in my view. Getting in and out of a space suit currently takes hours. It's a very intensive activity that is not likely to yield huge results. But it may be necessary for some geological survey or repair issues.

I haven't tried to deny dust is a real problem. It's most easily resolved by not undertaking EVAs. But if you do, then it would probably make sense to wear a disposable lightweight overall that goes over the suit. On Mars, unlike on the Moon in the days of Apollo, there will be the opporunity to have full vaccuum cleaning, hosing and showering facilities before anyone re-enters the main hab.

I've as yet read nothing to suggest Space X are going to put in place GPS prior to landing. There are satellites already in orbit around Mars - I suppose they might play some role in direction finding but they would not produce GPS as we know it now on Earth.

I think wiring will be built into the PV system for the most part and then there will be some cabling in addition.

You say:  "Nothing is impossible, but I've never seen or heard of a robot that deploys solar panels and connects the individual array elements.  Here on Earth, a human with a job title of "electrician" does that work.  You said you wanted the humans to get enough exercise on Mars.  Guess what?  Building your own power station is both good exercise and required work."

On Earth laying out PV panelling is an intricate job because they have to be secured against inclement weather.  That is not a factor we have to worry about on Mars. The panelling might be literally rolled out if it is flexible. If not flexible, I would expected it to be unloaded zig zag/concertina (can't think of the right analogy) fashion, so each panel is attached to the other.  I would expect there to be something like an automated gas bladder to raise the panel to roughly the desire inclination. The first PV power system though would likely be carried into position by robot rovers and be more like the "fan" design of Orbital ATK's space systems.

We could use humans, but every EVA counts as a risk and it could be v. tiring, v. repetitive work.

Accepted all equipment has to be space tested to get to Mars in working order (but there will be pressurised and non-pressurised holds and I presume anything sensitive goes in a pressurised hold, with anythin super-sensitive being surrounding by a radiation barrier. A 7G re-entry? You mean entry to Mars? How fast did the Rover craft? Most of those have worked well.

I would keep Rovers (maybe two max) in the first (most exterior) of two air lock chambers to the main human habitat. We will probably need another dedicated hab for storage/maintenance of Rovers.  My conception is that humans get around the "base" in pressurised equivalents of golf carts which have an attachment that allows them to exit to a second clean air lock chamber.

This video gives an idea of how prefab units can be handled:

https://www.youtube.com/watch?v=CuLq4O-WmxU

The units could be put on wheeled chassises and towed to the desired location under human supervision. They could have levered bolting systems that could be very easy to operate, to bring units together to form larger structures. The units would then sit flush against each other. Sealant could then be applied to the joins. Internal doorways would match allowing access from one unit to another. An air lock unit could similarly be bolted on to a hab unit.

Agreed battery safety is very important. I thought you were referring to wider control systems.

"There is no imperative to go to Mars." There was no "imperative" to go to the Moon.

"Stop being so lazy and do some math on what these things weigh."  For a crew of six at 1.5 kgs of food per day, that would be 8.1 tonnes on a 900 day/sol mission.  8.1 tonnes out of over 500 tonnes is not a large allowance for such a crucial resource. I think you would want to double it to 16 tonnes to give your a crew a chance of survival if something goes wrong with the return launch.

You might have 70 tonnes of solar power equipment and batteries, 18 tonnes of food, 20 tonnes of water, 20 tonnes of Rovers and 20 tonnes of habitat units. That would still only be under 150 tonnes of supplies - you got 350 tonnes left for other requirements.

If it is easier to dig a hole and put your hab in it, that's what will be done but I doubt it would be.


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

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#42 2018-04-27 12:17:06

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 5,423
Website

Re: Some general observations.

For entry descent and landing,  because the location and the map scale are changing so fast,  cruise missile-type tercom is useless,  and retropropulsion steering is limited because of the limited time left to touchdown.  A radar beacon helps with touchdown,  though.

There is no communication during the plasma-sheathed hypersonics,  you fly that on inertial guidance as a robot control,  or you likely miss the target by 100's,  even 1000 km. 

That puts it on precision location and timing for the retro burn that starts entry.  Here on Earth,  GPS or an earlier analogue of it has long been used for precision positioning.  It's easier to do with satellites than with ground radars,  but those are the only ways to do it that we currently know. 

There are some satellites about Mars,  and they have been used for positioning as well as signal relay,  but not being designed for positioning,  it's slow and clumsy.  That means it could only work for descents from low Mars orbit,  not for direct entries off interplanetary trajectories. 

That lack could easily be corrected with a small swarm of dedicated positioning satellites.  It's a powered deployment vehicle with the delta vee to enter Mars orbit from the interplanetary trajectory.  Something not far from the size of a Dragon (but NOT a Dragon!) could deploy a huge swarm of these things,  and a Falcon-Heavy could send it to Mars.  The same MMH-NTO storables that work for all sorts of attitude thrusters would work for this. 

Now,  Musk is concentrating upon developing his BFR/BFS transportation system.  It's not fair to expect him to take the lead in putting positioning satellites around Mars,  or to take lead turning his camps into a real city on Mars.  Somebody else needs to belly up to the bar here. 

Musk needs the positioning satellites to put more than one BFS down safely at the same site,  though.  Concentrating on building the vehicle,  I doubt they've thought that positioning issue through yet. 

I uncovered some other things Spacex likely hasn't thought through yet:  (1) how big the landing leg feet might really need to be,  (2) rough ground landing stability (static and dynamic,  especially dynamic!!!),  (3) jet blast-flung rocks (and sand) striking other vehicles or structures,  and (4) how far debris would fly from the explosion of a crashed or toppled BFS (a long way at really high speeds).

I would hope they would read things like these forums and my blog site (and others) for heads-up on things they haven't considered yet.

As for dust and grit ruining (gas balloon) space suits,  that is a long-known problem since the Apollo landings.  It ruins more than suits. 

A mechanical counterpressure suit is far less susceptible to this,  and easily launderable,  unless you screw up its design trying to design every function into one garment.  Design it as vacuum-protective underwear with an oxygen helmet and a tidal volume bag,  and wear whatever conventional outer clothing you need for the job at hand.  All are launderable.  Your helmet and oxygen (only) backpack are far easier to keep clean than any sort of gas balloon suit rig,  especially its complicated "everything" backpack.

The only things standing in the way of doing that suit design job right are the politics and lobby money of established favored contractors long used to sucking at the government tit without competition (same as it once was for inexpensive vs expensive launch).

GW

Last edited by GW Johnson (2018-04-27 12:34:24)


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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#43 2018-04-27 20:36:51

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 28,747

Re: Some general observations.

Sure lose sand will have some water but the greater level of water will be hard to mine as its frozen in the soil. That means a microwave rover with a vapor trap to catch the water as it steams out of the soil as it travels over it. Sure it can be done but who is building it to work on Mars....

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#44 2018-04-28 03:47:26

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Some general observations.

I would suggest Space X must be...unless they have some other plan to get water  (like parking up next to a proven glacier with good exposure). I think one might be able to design a digger that has a powerful microwave edged "blade" on its digging end, and so can move into the regolith and then lever up a chunk of regolith which can then be deposited in a sealed retainer at the rear of the rover.

By the way, I'm not convinced about the "4 hour optimal" baking process put about by NASA. It may be optimal in getting as much water out as possible, but we want a quick, cheap process.

There's also this which suggests direct microwaving with water capture might be more efficient  than digging. That could be the case, in which event, bring it on!

https://aip.scitation.org/doi/abs/10.1063/1.2437523

SpaceNut wrote:

Sure lose sand will have some water but the greater level of water will be hard to mine as its frozen in the soil. That means a microwave rover with a vapor trap to catch the water as it steams out of the soil as it travels over it. Sure it can be done but who is building it to work on Mars....


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

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#45 2018-04-28 04:08:37

elderflower
Member
Registered: 2016-06-19
Posts: 1,262

Re: Some general observations.

A small drilling machine and some explosive would sort out any consolidated regolith. Carbon powder and oxidiser are quite good, I understand.

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#46 2018-04-28 04:22:43

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Some general observations.

Do explosives work in the Mars atmosphere (all, none or only some)? Or would you need an oxygen supply to make them work?

elderflower wrote:

A small drilling machine and some explosive would sort out any consolidated regolith. Carbon powder and oxidiser are quite good, I understand.


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

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#47 2018-04-28 04:29:15

elderflower
Member
Registered: 2016-06-19
Posts: 1,262

Re: Some general observations.

It needs to work in rock, Louis.
It should be selected for manufacture using in-situ resources. LOX/ carbon satisfies this.
The oxidiser must be stable enough to not go off in an unscheduled manner and must not boil away before you can set off your explosion. If using LOX that means precooling the hole.

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#48 2018-04-28 05:18:41

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Some general observations.

Interesting! Sounds like that could definitely be an option then...Doesn't ISRU manufacture of explosives (is that what you are suggesting?)  add another level of unwelcome complexity to Mission One?  Carrying explosives on board the BFS might give one pause for thought...but maybe putting them in the unpressurised-oxygen free hold would be a safe option? 

elderflower wrote:

It needs to work in rock, Louis.
It should be selected for manufacture using in-situ resources. LOX/ carbon satisfies this.
The oxidiser must be stable enough to not go off in an unscheduled manner and must not boil away before you can set off your explosion. If using LOX that means precooling the hole.


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

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#49 2018-04-28 05:27:27

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Some general observations.

It seems my hunch that lasers could be used for communication with a rocket on entry during the plasma stage has some validity:

https://www.osapublishing.org/ao/abstra … 56-10-2597

This is definitely worth following up in my view. I guess the idea would be to lock the laser on to a ground station just prior to atmospheric entry using radio transponders to get an accurate location. 


GW Johnson wrote:

For entry descent and landing,  because the location and the map scale are changing so fast,  cruise missile-type tercom is useless,  and retropropulsion steering is limited because of the limited time left to touchdown.  A radar beacon helps with touchdown,  though.

There is no communication during the plasma-sheathed hypersonics,  you fly that on inertial guidance as a robot control,  or you likely miss the target by 100's,  even 1000 km. 

That puts it on precision location and timing for the retro burn that starts entry.  Here on Earth,  GPS or an earlier analogue of it has long been used for precision positioning.  It's easier to do with satellites than with ground radars,  but those are the only ways to do it that we currently know. 

There are some satellites about Mars,  and they have been used for positioning as well as signal relay,  but not being designed for positioning,  it's slow and clumsy.  That means it could only work for descents from low Mars orbit,  not for direct entries off interplanetary trajectories. 

That lack could easily be corrected with a small swarm of dedicated positioning satellites.  It's a powered deployment vehicle with the delta vee to enter Mars orbit from the interplanetary trajectory.  Something not far from the size of a Dragon (but NOT a Dragon!) could deploy a huge swarm of these things,  and a Falcon-Heavy could send it to Mars.  The same MMH-NTO storables that work for all sorts of attitude thrusters would work for this. 

Now,  Musk is concentrating upon developing his BFR/BFS transportation system.  It's not fair to expect him to take the lead in putting positioning satellites around Mars,  or to take lead turning his camps into a real city on Mars.  Somebody else needs to belly up to the bar here. 

Musk needs the positioning satellites to put more than one BFS down safely at the same site,  though.  Concentrating on building the vehicle,  I doubt they've thought that positioning issue through yet. 

I uncovered some other things Spacex likely hasn't thought through yet:  (1) how big the landing leg feet might really need to be,  (2) rough ground landing stability (static and dynamic,  especially dynamic!!!),  (3) jet blast-flung rocks (and sand) striking other vehicles or structures,  and (4) how far debris would fly from the explosion of a crashed or toppled BFS (a long way at really high speeds).

I would hope they would read things like these forums and my blog site (and others) for heads-up on things they haven't considered yet.

As for dust and grit ruining (gas balloon) space suits,  that is a long-known problem since the Apollo landings.  It ruins more than suits. 

A mechanical counterpressure suit is far less susceptible to this,  and easily launderable,  unless you screw up its design trying to design every function into one garment.  Design it as vacuum-protective underwear with an oxygen helmet and a tidal volume bag,  and wear whatever conventional outer clothing you need for the job at hand.  All are launderable.  Your helmet and oxygen (only) backpack are far easier to keep clean than any sort of gas balloon suit rig,  especially its complicated "everything" backpack.

The only things standing in the way of doing that suit design job right are the politics and lobby money of established favored contractors long used to sucking at the government tit without competition (same as it once was for inexpensive vs expensive launch).

GW


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

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#50 2018-04-28 07:24:45

elderflower
Member
Registered: 2016-06-19
Posts: 1,262

Re: Some general observations.

Rockets (chemical) are basically an explosion in a can with a hole. They all carry a combination of fuels and oxidisers that can explode when mixed (some need triggers) or monopropellants that break down by themselves (eg Hydrazine).
Most of these could be used as an explosive under the right circumstances, but I want to avoid carrying sticks of dynamite. I don't think we will be able to avoid the need to carry blasting caps, though, so a suite of robust containers with burst discs to the exterior is probably a good solution. Limited number, well cushioned, in each container-these things are much more sensitive than normal bulk explosives.

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