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#26 2019-05-20 14:30:56

JoshNH4H
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From: Pullman, WA
Registered: 2007-07-15
Posts: 2,501
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Re: ISRU Atmospheric Entry

Hey th,

In your proposal for rental heat shields, do you expect that the heat shields will be returned to orbit once used?  Or are you thinking that they will be a one-use deal?

Once we have an adequate manufacturing base on the Moon I believe that it makes more sense for them to be disposed, as it's likely to be cheaper and easier to dispose of them on Earth than to send them back up.

In that case it's not a rental so much as a sale, although I'm sure appropriate organizations will spring up as-needed to provide entry services to those who need them.


-Josh

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#27 2019-05-20 17:20:02

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 15,058

Re: ISRU Atmospheric Entry

The shield material type will be the issue just as much as the destination for the replacement to be rented.

Say the earth bound ship needs a heat shield for use once on the moon the materials for a pica version will be hard to come by but for a mars return vehicle we do not have any issues.

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#28 2019-05-21 10:57:38

tahanson43206
Member
Registered: 2018-04-27
Posts: 577

Re: ISRU Atmospheric Entry

For JoshNH4H ... thank you for picking up on the rental heat shield idea ...

Just FYI ... I'm hoping you will be interested in the question of how to analyze heat shield functionality at the level of individual molecules.  It is my understanding that most work done on heat shields or on aerospace projects in general, is done at the macro level.  That approach works so well that there would not seem to be a reason to depart from it.  I've been interested in quantum level interactions of individual particles since I first learned about the evolving field, some decades ago. It seems to me that to write a computer program that accurately models the real world, software engineers need to define individual elements that are then "realized" digitally, so that the sum of all the interactions looks like flows in the real world.

In the article about JP Aerospace (noted a day or so ago in the newmars book topic), the author points out that plasma flowing past a heat shield contains energy (or expresses energy) that might be harvested. 

Earlier in this sequence, kbd512 pointed out that infrared radiation occurs as molecules are accelerated energetically in random directions.  Certainly visible light is evident by observation of the human eye.   The deceleration of a vehicle transitioning from orbital velocity to subsonic flight represents an exchange of energy that currently is entirely lost to heat.

Below your quote, I'll take up your helpful question.

JoshNH4H wrote:

Hey th,

In your proposal for rental heat shields, do you expect that the heat shields will be returned to orbit once used?  Or are you thinking that they will be a one-use deal?

Once we have an adequate manufacturing base on the Moon I believe that it makes more sense for them to be disposed, as it's likely to be cheaper and easier to dispose of them on Earth than to send them back up.

In that case it's not a rental so much as a sale, although I'm sure appropriate organizations will spring up as-needed to provide entry services to those who need them.

Thank you (again) for picking up on this topic.

What I had in mind initially was a vehicle that would function like a tugboat, but in the space environment, the needs of the arriving vehicle would extend to more than just a gentle nudge from time to time.

I am imagining a fleet of return-to-Earth vehicles stationed at appropriate locations to catch regular traffic from the asteroid belt, from Mars and the Moon, and eventually elsewhere.

The problems to be solved are severe, but (it seems to me) the business opportunity is significant.

The first income stream would be the simplest to explain, and (perhaps) the least difficult to implement.  The concept there would be to assist miners by accepting responsibility to corral incoming rocks (or bags of rocks) and to land them gently at the desired location on Earth.

Chemical boost would deliver the heat shield return vehicle to a trajectory designed to intersect with an incoming shipment, and ion engines would sustain the propulsion and guidance needed to achieve match, and then to guide the loaded vessel to an atmospheric entry at the time and location requested by the customer.

To pay for this service, I would propose a standard fee of 10% of the value of the payload, or some minimum amount to cover expenses, if the payload turns out not to be as valuable as thought at the time of shipment.

It would seem to me to make sense for the landing company to include as part of its service factoring the shipment to maximize the market value, and thus to maximize the 10%.

For landing passenger or perishable freight, the challenges would be greater, and potentially much greater.  However, since there will be several months notice of plans to carry passengers or perishable freight from Mars, it should be possible to follow the model described above, to position the heat shield to match velocity and vectors with the customer vessel, attach it firmly, and then take on the duty of managing the high intensity phase of deceleration.

It would seem reasonable (to me at least) to separate the heat shield "tug" from the customer vessel after the heating phase is passed, so that the customer vessel can land however it was designed to land.

There might exist a business case for customer and tug operator to agree on a full landing service.

If you are interested in considering this initiative further, I'm thinking about how a business might be designed to compete in this new arena.

The NewMars forum is as good a place as any to expose ideas along these lines to a global audience, some members of whom can be expected to become the entrepreneurs who have what it takes to harness talent and resources to bring such a business into existence.

(th)

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#29 2019-05-21 14:09:11

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 3,492
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Re: ISRU Atmospheric Entry

On the notion of "understanding" hypersonic aerodynamics from a molecular viewpoint.  I'd recommend against that in favor of just using the well-established empirical correlations.  What tahanson43206 described is known as the "Newtonian flow" model,  which does not apply through the bulk of entry,  only the very earliest portion above something like 60-70 km.  Even in the altitude range where it applies,  it predicts stagnation pressure coefficient as 2,  when the test results say 1.8,  so it is only crude-ballpark to begin with.

On the notion of cheap heatshields for the moon-to-Earth flight:  if you can keep the ballistic coefficient fairly low,  and avoid bouncing off the atmosphere by fine trajectory control,  you might get away with low-density alumino-silicate ceramic,  but for one use only. 

My fabric-reinforced form,  from the 2013 Mars Society convention paper,  would be the one you want.   The base material for the fiber and flake manufacture should be available on the moon.  The form I used was water-based cure,  which might be available a few places on the moon.  What's missing is carbon,  with which to blacken the surface coating for high emissivity,  although you could fairly easily get that from human sewage by anaerobic heating.

You won't be able to reuse the heat shield,  because on a from-lunar trajectory,  you won't be able to keep the surface under 2350 F (the solid phase change temperature).  It will crack upon cooldown.  But you might stay under 3350 F (the meltpoint) if your ballistic coefficient is not too high and your entry angle is 2 degrees or less relative to local horizontal. 

For cargo,  I'd recommend a blunt capsule shape with a very-gently-radiused (not quite flat) heat shield,  and a fairly strong tumble-home angle (~30+ degrees),  so that you can "fly" the capsule at angle of attack.   Use downlift initially (to avoid bouncing off) until your speed drops below 8 km/s,  then roll or pitch for uplift after that,  varying angle of attack for a small amount of range control.  You can roll or yaw for a small amount of cross-range capability.  We've done that since the Gemini program. Apollo worked that way.

You could do people that way,  too,  but it will be a rough ride.  Apollo came back at a nominal 10.9 km/s,  at a max entry angle below local horizontal of 2 degrees.  The peak gee pulse was 11.  Shallower,  peak gees is smaller,  but the risk of bounce-off is higher.  It's a tradeoff that depends upon the specifics of the vehicle design.

GW

Last edited by GW Johnson (2019-05-21 14:16:32)


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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#30 2019-05-21 16:35:20

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 15,058

Re: ISRU Atmospheric Entry

Sounds like a cold plasma shield barrier which is going to breakdown over time and increasing pressure flow. Even with a magnetic property materials and a strong field to hold it in place I do not think we can generate that much power to have it last.

If the only reason for a replacement shield at the destination to be mounted is to lower launch mass from earth its not going to be much of a gain in launch payloads....

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#31 2019-05-21 19:04:51

tahanson43206
Member
Registered: 2018-04-27
Posts: 577

Re: ISRU Atmospheric Entry

For GW Johnson ...

Thank you for your reply and suggestions ...

GW Johnson wrote:

<snip>
On the notion of cheap heatshields for the moon-to-Earth flight:  if you can keep the ballistic coefficient fairly low,  and avoid bouncing off the atmosphere by fine trajectory control,  you might get away with low-density alumino-silicate ceramic,  but for one use only. 

My fabric-reinforced form,  from the 2013 Mars Society convention paper,  would be the one you want.   The base material for the fiber and flake manufacture should be available on the moon.  The form I used was water-based cure,  which might be available a few places on the moon.  What's missing is carbon,  with which to blacken the surface coating for high emissivity,  although you could fairly easily get that from human sewage by anaerobic heating.
<snip>
For cargo,  I'd recommend a blunt capsule shape with a very-gently-radiused (not quite flat) heat shield,  and a fairly strong tumble-home angle (~30+ degrees),  so that you can "fly" the capsule at angle of attack.   Use downlift initially (to avoid bouncing off) until your speed drops below 8 km/s,  then roll or pitch for uplift after that,  varying angle of attack for a small amount of range control.  You can roll or yaw for a small amount of cross-range capability.  We've done that since the Gemini program. Apollo worked that way.
<snip>
GW

Regarding the need for carbon for emissivity ... does it make sense to carry the carbon to the Moon, if the greater part of the shield is to be fabricated from lunar materials?  A vehicle will need to make the trip anyway, to pick up shields, and it will (most likely) carry needed supplies for the on-station crew, so I would imagine allocating a portion of the payload to carbon would be possible.

Can the water be reused (for the water based cure)?  If so, carrying a supply to the lunar surface for the project might make sense.

***
Looking at the larger picture, does the concept of developing a business around handling landings for miners shipping payloads to Earth make sense to you?

Thanks again for help with this initiative!

PS ... I went to the Mars Society Convention archive and found one of your papers from 2011, but it did not appear to be the one you are thinking of from 2013.

That said, it's good to see the 2011 paper available for study.

(th)

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#32 2019-05-21 20:56:18

kbd512
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Registered: 2015-01-02
Posts: 2,717

Re: ISRU Atmospheric Entry

A series of MWCNT tape windings with proper alignment, along with an outer "forest" / covering of aligned tubes (facing outwards- these would only be a millimeter in length or so, and layered if necessary- this can actually generate some electricity because the heating effect does not propagate through the material) could be made to ablate away into Carbon dust (CO2, ultimately) and the metal slug / projectile to be returned to Earth for further processing would be protected well enough from reentry heating to prevent the payload from melting during reentry.  Please note that these are just CNT-based tapes, NOT COMPOSITES (in other words, pure carbon with no resins or polymers or other materials embedded therein).  The same technique could be used in heat shields for spacecraft.

For single use, the obvious advantages are that only Carbon is required to make these heat shields, Carbon is relatively common throughout the solar system, the tapes can are thin and light, they're poor out-of-plane conductors, they're not nearly as brittle as ceramics or phenolic impregnated ablators (more damage tolerant in simple terms and strictly speaking, no adhesives are required since they can be woven into or around a support structure), they can be wrapped around very sharp edges (you can hammer a sheet of the tape into a block of wood with a razor blade and that won't affect its mechanical strength, let alone cut it), and they have extremely high melting points, especially for MWCNT's that inhibit the entry of Oxygen molecules into the microstructure of the multi-walled tube.

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#33 2019-05-22 09:00:52

tahanson43206
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Registered: 2018-04-27
Posts: 577

Re: ISRU Atmospheric Entry

For kbd512 re #32 ...

Thanks for this (new to me) information, about (what sounds like) a self-liquidating heat shield that even Greenies should appreciate, because the only debris left behind (as I understand it) is CO2, and ** that ** is being scarfed up (meanwhile) by carbon scavengers which pull CO2 from the atmosphere.

I found an article (somewhere) recently that indicated some serious investor attention is going towards atmospheric carbon capture.  Your postings here had heightened my interest in the topic.

However, I'm hoping you will elaborate a bit on #32 ... Specifically, in light of the asymmetrical nature of most asteroid chunks that might be heaved towards Earth by hard working miners, I am wondering how a hard working Safe Landing Company crew could prepare the package for integration into a landing attachment.

Your wording above seems to imply wrapping the object in a shroud of heat resistant material.

My vision (until now) has been of (somehow) embedding a payload in a landing craft with a heat shield.  The duties of a cargo master in the Air Force would be similar to what I am imagining would be needed for a payload landing craft.  The mass would need to be distributed so that the vehicle is stable during descent, so (I am imagining) parts of the payload would be removed and positioned properly, until the desired center of mass is achieved.

For landings on Earth, it might turn out that good old reliable parachutes would be a part of the landing technology, but as the mass of incoming payloads increases, parachutes by themselves might not be sufficient.

As you can see, I am trying to continue development of the business case for a specialization in landing payloads from space, much as mariners on Earth have developed a robust family of tugs and related ancillary vehicles to service commercial ocean-going vessels.

(th)

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#34 2019-05-22 10:55:50

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 3,492
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Re: ISRU Atmospheric Entry

tag: CeramicHeatShield

The ceramic stuff I used was a Cotronics pipe insulation paste and an aircraft fire curtain cloth.  The paste was short fibers and flakes as a water-based paste that you mold onto things by hand.  Most folks do a heat gun cure or an ambient-exposure cure,  out in the open,  and get a higher density,  more like some other ceramic materials. 

I dd this as an oven cure within closed (but not sealed) tooling,  at a temperature slightly above water boil point.  This (I think) created steam that had to wormhole its way out of the layup,  thus creating the lowered density I saw in my finished parts. 

Either way the water doesn't stay in the finished part,  it evaporates.  So water recovery and re-use is at least theoretically possible. 

The density of my parts resembled the densest commercially-available styrofoams.  My effective thermal conductivity was low,  because of the high porosity fraction.  Not quite as low as NASA's similar material,  but in the same general ballpark.

The fire curtain fabric is a commercially-available item from Nextel.  It is made of the same alumino-silicate minerals as the paste,  just in fiber form.  These are twisted into threads,  combined as twines,  and woven,  like any other fabric.  I used it in alternating layers of paste and a fabric wraps.  Once I had a cured part,  I coated its surface for air impermeability.  My parts made fabric-reinforced like that,  were far stronger than NASA's shuttle tiles.  Without the fabric reinforcement,  they were just as fragile as NASA's.

I don't have any solid characterization numbers for this,  because I did this for an experimental fuel-air burner with a subsonic ram inlet. The ceramic insulation just worked.  So I used it. 

Without the fabric reinforcement,  the liner shattered the first time I pushed the burner into rich blowout instability (low-audio frequency high-amplitude near 1 atm pressure oscillations were too much for it).  It spit the hot pieces out the tailpipe and started a grass fire.  Fun day!

With the reinforcement,  the liner survived many accumulated hours of burn (1 burn over an hour,  and none less than a few minutes) with 3000-3500 F combustion gases,  and hundreds of rich blowout instability events. These were not high altitude tests,  so the combustor pressures were always a bit over 1 atm.

The materials I used are considered obsolete now (I ran these tests in the 1984-1985 time frame),  but if you ask,  they are still available. 

The surface coating was a ceramic adhesive paste (also water-based) from Cotronics.  All these materials were a bright white color.  That’s low emissivity in the visible light wavelengths.  Spectrally,  these minerals are NOT gray,  however.  Long wave IR thermal emissivity was high,  while short-wave IR thermal emissivity and visible emissivity was quite low.

A few years ago,  I checked with Cotronics to see if the adhesive paste could be dyed black with carbon soot addition.  They had never had that question before,  but thought it would be doable and would probably work.  I had that in my pocket for the 2013 Mars Society convention paper,  which presented this as a possible heat shield material for a Mars lander.

This sort of concept might be adapted to use other minerals for the fibers and flakes,  such as basalt.  I'd stay with water-based pastes,  and the closed tooling above-boiling cure approach,  for the low density.  I do not know the detailed chemistry of the water-based heat cure,  but this stuff does stick together well. 

For use as an external heat shield panel,  you will need the strength of the fabric reinforcement.  If you let the fabric protrude out the edges of the cured panel,  you can hang onto that fabric for redundant retention.  I put that in the 2013 paper.

Very experimental,  but there's some practical promise there for a successful materials development.

GW

Last edited by GW Johnson (2019-05-23 18:37:09)


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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#35 2019-05-23 07:13:18

tahanson43206
Member
Registered: 2018-04-27
Posts: 577

Re: ISRU Atmospheric Entry

For GW Johnson re #34 ...

Thank you for this long post, with what I interpret as the essence of an approach well worth study and potential further development.

Please add a tag to #34 ... a suggestion might be: CeramicHeatShield

That way, a search for ceramic will work, or heatshield will work.

The idea would be to try to create a tag that readers can remember, AND which FluxBB can see as unique.

I liked your mention of basalt, which ties the suggestion from JoshNH4H into the overall theme.

The carbon would have to be imported if the product is manufactured on the Moon, but it doesn't sound (to me at least) as though the carbon is a significant fraction of the mass.

I also like the implication that the shield material can be laid over a form (such as a stock lifting body shape) like fiberglas.

The curing at just over the boiling point of water sounds comparatively inexpensive to me, and if the process is performed inside a tent the moisture would presumably find it's way to the walls where it would freeze with lunar vacuum outside.  It would then be available for collection after the cure is complete.

For a vibrant asteroid mining economy, the manufacture of lifting bodies for Earth landings would (presumably) become a production line operation.

The electronics should be recoverable, so it can be lifted back up from Earth after a successful delivery.  The lifting body itself might have some residual value as a feedstock for some downstream process, but in the scenario I am seeing right now, it would not be worth trying to reuse it.

I'd be interested if anyone in the forum has a suggestion for making the lifting body itself from lunar materials.

The regulatory structures on Earth and near space need to be worked out in detail in order for this set of ventures to go forward.  It seems inevitable to me that the United Nations or a similar global regulatory agency is needed.  This economic activity is going to be multi-national, and it needs to be set up to avoid monopoly by any one Nation.   The sooner work on that starts, the better.

To head off objection, it seems to me the responsibility of each Nation for the space activities of its citizens would remain in place. What I see is extension of the already existing conflict resolution mechanisms that (apparently) exist now. 

When an asteroid hunting venture heads out from Earth, it would be helpful to know that the landing and regulatory concerns are already being handled by third parties.

For JoshNH4H re #26 ....

It appears I've come around to the view you wrote in your post.  The greater part of the landing vehicle would be disposable, while the expensive electronics and propulsive equipment could be salvaged for refurbishment and return to the Moon for re-use.

As my concept for a payload landing system evolves, I am seeing the need for thrusters to adjust course during descent.  The propulsion package to match orbit with the incoming payload would remain in space and eventually make its way back to the Moon for another mission.

(th)

Last edited by tahanson43206 (2019-05-23 07:55:31)

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#36 2019-05-23 08:05:45

tahanson43206
Member
Registered: 2018-04-27
Posts: 577

Re: ISRU Atmospheric Entry

Following up on GW Johnson's post #34 above ...

The formula offered for a heat shield which could be manufactured on the Moon for asteroid mining payload delivery to Earth includes Carbon.  This element is not in great abundance on the Moon, but it IS available in considerable quantities in the form of carbonaceous asteroids.

However, landing carbon on the Moon will (presumably) require a method more adroit than just slamming a rock into the Moon.  That might work today, but it is not a good long term strategy.  An ion engine might be an appropriate solution for the trip in towards the Moon, and a chemical "tug" might be the optimum solution for the landing itself.

In fact (come to think of it) .... asteroid miners might do better by supplying the Moon with Carbon and other elements needed by a growing community, than by supplying the Earth, depending upon what they find when they reach their hunting fields.

For SpaceNut ... I asked Mr. Google about asteroid mining companies, and was astonished at the number of citations that showed up.

This activity might warrant it's own topic, if you do not already have one.

These companies would be the potential market for a payload landing service.  Certainly at this point I would imagine they are planning to handle their own landing procedures, but a well designed third party service might prove attractive, especially if the service includes (a) management of regulations including ITAR for US based companies, and (b) assistance with factoring.

Nations that showed up in my quick glance at the citations included Japan, Scotland, the UK and the US.

Edit: This 2012 article captures the scope of potential of asteroid mining:
http://www.astronomysource.com/tag/rare … asteroids/

Rare Earths (of which China is currently the predominant supplier) is an issue in the current trade talks.
(th)

Last edited by tahanson43206 (2019-05-23 11:23:41)

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#37 2019-05-23 17:31:13

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 15,058

Re: ISRU Atmospheric Entry

I think asteriods are sort of a second choice for materials to make into the things we need as they are raw but any mining would be just small chunks of it as we do not have the propulsion to move such objects to where we would want them.

Nasa had on its plate an asteriod mission which turned into a boulder movement to the lunar orbit which disappeared into being cancelled...

At one point in a minimal designed diameter the concept of a folding hetshield to which would be deployed while enroute to any destination requiring one was to allow for a larger mass delivery than a small one would have been capable of.

Replacement shield made from mars would work for earth return but that is due to the vehicle needing to replace the one which had been used to land on mars. Of course that vehicle would also need a new first stage under it to get off from mars.

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#38 2019-05-23 18:39:46

GW Johnson
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From: McGregor, Texas USA
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Posts: 3,492
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Re: ISRU Atmospheric Entry

tag "CeramicHeatShield" added to my post 34 above.  Hope it helps.

Consider heating human sewage anaerobically to get a source of carbon on the moon.  If there are people on the moon,  there is sewage to heat.  There is your carbon,  without specifically having to ship it in. 

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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#39 2019-05-23 19:05:34

SpaceNut
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From: New Hampshire
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Posts: 15,058

Re: ISRU Atmospheric Entry

Other sources of carbon from waste is plastics which are used to contain all of the items we wished to keep clean.

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#40 2019-05-23 23:57:54

JoshNH4H
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From: Pullman, WA
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Re: ISRU Atmospheric Entry

The amount of carbon involved here really is very small. A layer of carbon 100 micrometers thick is usually more than enough to change the optical properties of a surface. At the density of amorphous carbon that works out to about 200 grams per square meter.  Could maybe get away with closer to 50.


-Josh

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#41 2019-05-24 00:24:24

louis
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From: UK
Registered: 2008-03-24
Posts: 4,565

Re: ISRU Atmospheric Entry

This sounds a possible line of development. But everything would depend on the economics of asteroid mining which, at present, don't seem to be there - it still being much cheaper to mine on Earth and ship stuff around by boat, train and truck.


tahanson43206 wrote:

Today I'd like to add to the topic (ISRU Atmospheric Entry) a development of a possibility brought up in post #23 .... the possibility was for rental heat shields.

A logical extension of that idea is a business comparable to the tugboat industry, which (according to www.briannica.com) was invented in 1736 in England.

As vehicles move back and forth between orbit and the surfaces of planets, a business opportunity will exist for those who chose to specialize in the capability to bring a deep space going vessel safely to the surface.

The company (of which I am sure there will ultimately be many) will bid for the opportunity to attach a landing craft to the deep space vehicle, to take it through atmospheric deceleration and on to a landing site.

In order for this concept to work, it will make sense for dimensions of vehicles to land to become standardized, just as commercial containers are standardized today on Earth.

However, as discussed in multiple posts in other topics as well as this one, the BIG market for this service would (presumably) be delivery of arriving payloads from the asteroid belt (or other celestial sources) to be delivered safely to the surface of the destination planet.

In that case, the miner would add a radio tag to the payload and send it toward Earth, after signing a contract with a capture and land company.

The landing company would secure a percentage of the value of the payload, and (since it would make sense to combine functions) it would (most likely) attend to the details of securing the best price for the payload.

(th)


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

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#42 2019-05-24 04:52:03

tahanson43206
Member
Registered: 2018-04-27
Posts: 577

Re: ISRU Atmospheric Entry

For GW Johnson ... re #38 .... Bingo!   FluxBB returned 25 posts when I asked it for you as the author, and the three separate words of your tag.

However, when I added the expression tag: and used the compressed value you created, I got two posts. Perfect! Thanks!

My intention is to try to build upon this foundation.

For JoshNH4H ... thanks for your estimate of the amount of carbon required for a thin coating for heat emissivity purposes.

For Louis ... thanks for your contribution to the forward view needed for a successful company (or set of competitors) to be created.

Please expand upon post #41 ... Of the present forum members, it appears to me you may be the best qualified to characterize the potential market for asteroid mining.  Earlier in this topic, or not long ago in a related one, it was suggested that there might be significant amounts of nickel available for collection on the Moon.  There are (I gather) plenty of other elements which are valuable on Earth which could be sifted from lunar regolith.

Please include the potential for lunar mining for delivery to Earth, along with your analysis of asteroid mining opportunities.

In post #41 you used the expression "don't seem to be there".  For my sake, and (hopefully) to enlighten forum readers who are not informed as well as you are, please expand upon that, to help us understand what is needed to satisfy the need.

(th)

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#43 2019-05-24 17:38:49

SpaceNut
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From: New Hampshire
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Posts: 15,058

Re: ISRU Atmospheric Entry

Any asteriod will need a break away control rocket pulse just like a sled dog followed by what we term as a spacetug to keep it moving slowly with ion push to its final destination...much like bfr its going to take fuel and energy to make it happen.
Mining in space is not new its just somethig that we have not done as of yet.

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#44 2019-05-25 08:46:32

tahanson43206
Member
Registered: 2018-04-27
Posts: 577

Re: ISRU Atmospheric Entry

For SpaceNut ... Thanks for an interesting set of mental images !!!

SpaceNut wrote:

Any asteriod will need a break away control rocket pulse just like a sled dog followed by what we term as a spacetug to keep it moving slowly with ion push to its final destination...much like bfr its going to take fuel and energy to make it happen.
Mining in space is not new its just somethig that we have not done as of yet.

The rapid advance of artificial intelligence and robotics may provide a transformation of the science fiction "accepted practice" of imagining hardy humans who can tolerate long periods of isolation in their quest for riches.  I'm starting to think that the benefits of programming a set of automata to look for interesting asteroids, to examine candidates closely, to select the most promising, and to return it to Earth (or other destination as needed) are going to far outweigh the benefits of sending crew to perform those tasks.

In recent years science fiction writers have made increasing use of probes, so that now it is a rare story that does not include them.

Since the topic-within-a-topic that I am pursuing is the market potential for companies that specialize in landing, the opportunity I see here is to contract with the owners of a probe that is returning with an asteroid to meet the shipment, secure it, and return it to Earth.  Preferably, the return would be to the exact location on Earth specified by the client, in cooperation with global authorities.

An issue I have not seen discussed so far is contamination of the Earth by objects thus retrieved from elsewhere in the Solar System.  I would expect that global authorities (and certainly the United States if it is the responsible state) will want to be sure the gleaming chunk of unobtainium scheduled for landing next Tuesday is not carrying microbes that will wipe out the population.

There may be a market opportunity for companies set up to quarantine incoming shipments.  How ** that ** would be negotiated in the fractious human political climate of the immediate future is an exercise for the most optimistic among us.

(th)

Last edited by tahanson43206 (2019-05-25 08:50:16)

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#45 2019-05-25 09:45:09

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 15,058

Re: ISRU Atmospheric Entry

What you are describing is a trade route where the destination of the commodity is brought to where its needed for trade to make what is needed with it. Not all destinations will be Earth bound unless you are thinking of early orbital construction for building outward as a first staging effort.

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