Ballistic Delivery of Supplies to Mars: Lithobraking

RobertDyck · 2021-02-03 18:41:32

GW Johnson wrote:

For "ballistic" delivery to the surface of Mars, feasibility depends upon the size of the object. Bigger objects will have higher ballistic coefficents, due to the square-cube scaling rules, even if all densities and proportions are preserved. That's just physics that applies to everybody.

I haven't read this whole discussion, but we've discussed ballistic coefficient many times. This is an image of ADEPT. It's a carbon fibre fabric that opens like an umbrella. It increases surface area to resolve the cube-square problem. This is the technology that Robert Zubrin included with his original Mars Direct plan of 1990. Yes, NASA was already working on ADEPT in the late 1980s. Baseline configuration for Mars is 40 metric tonnes payload. Mars Direct was smaller than that: 25.2 tonnes hab, 28.6 tonne ERV, taking from "The Case for Mars" 1997 soft cover edition.

SpaceNut · 2021-02-03 18:46:34

On set of topic was no parachutes, no adapt or hiad or heatshield, retro propulsion ect... only brute force landings permitted to the surface bunker buster style landing

tahanson43206 · 2021-02-03 18:53:02

For GW Johnson re #75

Thanks for adding multiple helpful insights to this topic.

SearchTerm:Aerobraking long flight through atmosphere per GW Johnson See #75 above

Your suggestion of splitting a large package into smaller components to maximize the slowing capability of the atmosphere seems quite helpful.

The idea (as I understand Void's idea, which itself is still evolving) is to maximize delivery of useful mass to the surface of Mars, while reducing the cost to the absolute minimum.

Calliban has suggested three categories of cargo to be delivered, from slugs of highly purified metal through deliveries of grain to electronics that can be packed in solid material such as bakelite(tm).

The least expensive delivery method is direct impact with the regolith at the full velocity from space, without atmosphere slowing.

That delivery method will have a corresponding increased expense for retrieval of the payload. At this point, it seems to me we have no idea what is possible.

One observation I would like to offer is that a radio transmitter can operate quite well right to the instant of impact, so a suitable radio location system would be able to record the coordinates of the impact, and the impact site would be somewhat apparent.

Plus! Earthquake triangulation would provide backup location information.

Our friends in the Military have centuries of experience delivering mass into various kinds of materials. I would be surprised if there is anything we might propose for Mars that has not been extensively studied.

(th)

RobertDyck · 2021-02-03 19:04:05

SpaceNut wrote:

On set of topic was no parachutes, no adapt or hiad or heatshield, retro propulsion ect... only brute force landings permitted to the surface bunker buster style landing

SpaceNut · 2021-02-03 19:16:46

Reference point For SpaceNut ... this topic is about delivery of cargo in the same manner as an artillery shell is delivered to a target. There is no parachute involved. There is no heat shield involved (although intercontinental ballistic missiles apparently do have heat shields).

GW Johnson · 2021-02-03 20:16:39

I think what you will find is that some sort of minimal ablative heat shield coating is required, as even from Hohmann transfer, the entry interface speed is about 5.5 km/s. From faster trajectories, it can easily approach 7.5 km/s.

For comparison, entry from low Earth orbit has an entry interface speed of 7.9-8.0 km/s. This heat shield does not have to be anything particularly expensive or technological. The warhead heat shields from 1955-forward certainly have not.

If your payload material is not heat sensitive, you can do without a backshell. If it is sensitive, you must protect it from hot wake plasma, which will have an effective temperature near 6000 K at a speed of 6 km/s. 7000 K at 7 km/s. 5000 K at 5 km/s. Etc. Physics!

I also think you will have to experience significant entry deceleration to speeds that won't vaporize your payload at impact from the conversion of its kinetic energy to heat. That means you have to slow below about Mach 3-4 at impact. Anything faster and your payload is vapor, not anything you might possibly recover. Damned pesky physics again. Been there and seen that with nonexplosive penetrator "warheads" at Mach 4+ speeds. The effect is quite real. And the vapor expands supersonically, like any detonating high explosive.

And that doesn't even consider the strength-of-materials aspect of shattering into tiny fragments upon impact. If you expect to "defeat" that, you must slow down to nearer Mach 1 at impact, at the very most. Nominal speed of sound on Mars is 230-240 m/s. It can be almost 300 m/s on a warmer day. It's more variable on Mars than it is here.

Everyone is subject to physics. It's an equal-opportunity concept debunker, ain't it?

I stick by my suggestion that you divide the incoming payload item into quarter-ton portions, each with its own minimal heat shield, parachute, and airbag. Plus a transmitter-locator, and something more sophisticated than a timer for sequencing the use of those items.

And there is no doubt, NONE WHATSOEVER, that your incoming item will require fine trajectory control. The window for a survivable entry trajectory is actually quite narrow, and quite limited in extent. Damned inconvenient physics again!

You ain't gonna be successful sending some "dumb artillery shell" to Mars as a feasible means of payload delivery, not even for a solid steel ingot.

It ain't me saying that, it's physics. Which all concepts must obey, or else fail.

GW

tahanson43206 · 2021-02-03 22:01:43

For GW Johnson re #61

Thank you for adding more detail to the topic!

Your statement here is what I am hoping you might be willing to develop a bit more ...

Been there and seen that with nonexplosive penetrator "warheads" at Mach 4+ speeds.

Earlier in this topic I noted the work of the US (and other nation's) military to explore the capability of non-explosive ordnance.

Until now however, I'd missed your earlier mention of having experience in this area.

Atoms of material are not lost, even if the structure of which they are a part is vaporized.

Did you get a chance to study the impact zone after the dust had settled from those tests?

In an earlier post, I reported on thousands of pounds of metals recovered from a Navy test range that was turned over for non-military use.

The metal of all those rounds went into the earth at the test site, and was recovered later.

However, it is likely the artillery fired at the naval range was NOT traveling at the speed you witnessed.

I'm curious to know what form the material takes as it experiences the intense heating you've described.

Diamonds are made artificially by subjecting carbon to great pressure which is accompanied by temperature rise.

I presume that something similar happens when objects collide at the velocities we are discussing in this topic.

Edit#1: For GW Johnson re topic about gasoline prices ... kbd512 just brought this topic back into view, so I took a look at it.

The sequence where I started (more or less at random) was in 2012, when you were having an interesting (to me for sure) discussion with a couple other members of the forum. Each of you seemed (as I read the flow) to be trying to work with facts (to the extent they can be determined). I appreciated your analysis of the changes in price of oil as various events occurred, and particularly the influence of local sensibilities to US activities.

At the time (2012) I get the impression you did not foresee the dramatic increase in US production of oil. I am amazed that so much has happened along that line in just a few years! The situation seems to have changed.

Other changes are occurring ... The Australians are (apparently) seeking to branch out from sales of coal to China to take advantage of their abundant sunshine to make salable products for the foreign market.

Wind investments are (apparently) paying off with acceptable returns, so that investors are encouraged.

GM just announced plans to discontinue manufacture of fossil fuel consuming vehicles by a (relatively) near term date.

However, all this is a digression from Ballistic Delivery of Supplies to Mars.

On ** that ** subject, I am hoping you will share your observations from the 4 km/s impact experiments you witnessed. Your observations are of ** great ** interest (to me for sure), because the atoms delivered to the surface of Mars aren't going anywhere, and the kinetic energy will diffuse into the regolith over some period of time.

I'm curious to know if all that kinetic energy might be used to create compounds that are useful in some way.

(th)

tahanson43206 · 2021-02-04 10:52:43

For Calliban re topic ...

This topic could be expanded into a set of three designed to develop the three categories of cargo delivery you suggested.

In order for them to become viable businesses, people are going to need to specialize in the knowledge and skills required for each category.

The soft landing category is the province of all the existing organizations engaged in this activity. The field is wide open (at present) for a provider of delivery services that specializes in one or more of the ballistic landing categories.

GW Johnson has shown ways a moderate ballistic landing could be achieved, using a combination of trajectory through the atmosphere, suitable heat shield design, suitable case design, and (in some cases) supplemental slowing mechanisms.

I am most interested in the 7 km/s category. The payload will become embedded with the regolith, so the customer service will include collecting the delivered atoms and separating them from their cushion material.

In this category, I'm interested in the shape of the receiving tunnel on Mars (or any destination body).

Computational Fluid Dynamics programs could provide insight for development of this category. There are both commercial and free/open source versions of CFD software.

For GW Johnson re Physics ... Every successful business that ever was or ever will be is based on Physics.

Even the ethereal businesses built around thought arise from clever implementation of physics by Nature in the complex atomic structures that allow thought to flourish.

It is the ** mastery ** of physics that differentiates the successful business from those that fall by the wayside.

NASA and ESA, Russia and China, India and Japan (and lately other nations) have demonstrated the ability (a) to deliver ballistic payloads to other bodies in the Solar system, and (b) in a minority of cases, to deliver payloads gently to the surfaces of other bodies.

This topic is dedicated to the fullest possible exploitation of physics to maximize return to shareholders for the pure ballistic approach.

There are some who (apparently) see ballistic delivery of valuable atoms to the surfaces of other worlds as a failure. Elon Musk is currently demonstrating a variety of interesting ways to accomplish that, and from what I can gather, he does NOT regard these experiments as failures.

I am quite sure that ** very ** atom thus delivered is recovered, with the possible exception of those that are wafted off into the Gulf of Mexico on the wind.

I am hoping to enlist your interest in the set of problems (and opportunities) that arise from a focus on pure ballistic delivery.

For Calliban ... some posts back you (or it might have been kbd512) introduced the suggestion of using a magnetic field to slow arriving ballistic packages.

I tried to offer encouragement for this line of thought, and offered examples of others who have thought (tentatively) along those lines.

I tried to offer a suggestion of an aspect of physics that might be helpful.

Please continue developing your ideas along these lines.

(th)

GW Johnson · 2021-02-04 12:39:53

Decades ago I worked as support to a small project to develop a carbon fiber composite solid motor case and propellant for a small anti-tank rocket. These cases were hydrotested to 4000 psi, and would see max motor pressure near 2000 psi if soaked out hot (145 F). We used no external insulation, just letting the outer layers ablate.

By project's end, we were test-flying missiles at a DOD test range. The missile averaged Mach 5 to target, meaning its flight time to a tank 1 mile away was 1 second. That's right at "only" 1.6 km/s.

The "warhead" was a solid tungsten penetrator dart. We evaluated its impact on two different targets. One was steel tank armor 9 inches thick. The other was a reinforced concrete bunker wall 5 feet thick. The penetrator dart was about 3 inches max diameter, and about 15-18 inches long.

Against the steel armor plate, the dart left about a 4 inch diameter entry wound and a 9 inch diameter exit wound, with a big conical cavity blown out of the armor plate. There was a huge red fireball explosion at impact. We never found any fragments of the penetrator, and only part of the fragments of the steel, meaning they were not just shattered, but vaporized. Those steel fragments we did find destroyed all the structures behind the armor plate.

It was similar against the reinforced concrete, except the big conical cavity was much larger. The entry wound was a few inches diameter, and the exit wound was about 5 feet diameter. Again, we found no fragments of the penetrator, and only part of the spalled concrete fragments, so a lot of the material was just explosively vaporized. The structures behind the wall target were destroyed by the spalled fragments we did find.

GW

tahanson43206 · 2021-02-04 13:16:34

For GW Johnson re #84

Thank you very much!

SearchTerm:Ballistics testing military munitions tank concrete GW Johnson see post #84

The intention of military investigators was to pass through defenses to inflict damage on whatever is being protected.

The intention of this topic is to deliver high value atoms to destination in the most cost effective way possible.

There would appear to be a nearly infinite number of approaches to this problem.

They range from zero slowing with no target proparation (asteroids in nature, for example) to total slowing (many examples)

Every solution to this problem has expense at the front end and expense at the back end.

I am interested in any insight you may have, as you look back at the experiments of which you were a part, if the materials comprising the impactor had been so valuable the funders wanted to retrieve them at any cost.

The concept of vaporizing the impactor (and much of the target) is interesting but not helpful.

The atoms went somewhere.

No one at the time was interested (as near as I can tell from your description) in where the impactor atoms went, other than as they had an effect on the target, which makes perfect sense, in context.

In contrast, I am ** very ** interested in recovery of the entire payload.

My expectation is that Physics will come to the rescue, by showing that all the atoms survived, and where they went.

Thank you (again) for your substantial contribution to progress of this topic!

(th)

tahanson43206 · 2021-02-04 13:20:31

For Calliban re topic ...

I'm not sure how helpful this is, but I remembered that many asteroid fragments (or perhaps meteor remnants) have been found in the Arctic ice.

Upon arrival at the surface of the ice, they would have been white hot, and surrounded by hot atmospheric gases.

Upon entry into the snow pack, they would have been slowed and cooled and subsequently preserved until they were found.

(th)

Calliban · 2021-02-04 16:25:24

An impact speed of 1km/s is about the speed of an assault rifle bullet. These are used at firing ranges. Behind targets are Earth berms to absorb bullets that pass through. Full metal jacket bullets are often a requirement at firing ranges, because they are less likely to break up and therefore do not result in so much lead contamination. They certainly don't vaporise, although pure lead bullets at that speed can.

An impact speed of 450m/s (1000mph) would be less than half the speed of a 5.56mm assault rifle bullet. Only 20% as much kinetic energy as a bullet from an SA80 and only 7.9% of the energy per unit mass as GWs 1.6km/s tungsten impactor. Of course, survivability will depend upon what it hits. I used classical Newtonian simplification to estimate the pressures on a 1te (mostly steel) projectile penetrating Martian regolith at 450m/s. For a 1m long projectile with penetrative depth of 2.5m, it came to about 50MPa. That is a lot, but is only about 10% the yield strength of carbon steel. Of course that does assume that it impacts fairly loose regolith. If it were to hit a solid rock in its path the conclusions may be different.

The penetrative depth of a projectile is a function of the relative density of the projectile and media and its length. The energy dissipated is basically force x distance. So the pressure on a projectile will scale with the square of impact speed. For impact speeds of 1km/s the impact pressure would approach the yield strength of carbon steel. So from this admittedly simplistic approximation, there would appear to be a good change that steel projectiles will survive impact at 450m/s. The prospects at 1000m/s are poor, dropping rapidly to zero at still greater speeds.

Last edited by Calliban (2021-02-04 16:32:52)

tahanson43206 · 2021-02-05 06:47:39

For Calliban re #87 (and topic)

Thanks for staying with this topic! I am encouraged to think that there is a combination of factors that can yield a competitive price over a wide range of velocities, materials and techniques.

GW Johnson has personal experience with collisions on the order of the ones in discussion here. The experiments he witnessed were designed to demonstrate destructive capability, and thus were only indirectly useful for designing packages to survive collision.

In your post #87, you've added to points you've made earlier, about the nature of the receiving field.

The ideal receiving field would be composed of a substance that is highly compressible, and which is able to absorb the shock of the passage of a glowing hot mass of a cargo pod without spraying material all over the place.

Even water is not ideal, because it is not (particularly if at all) compressible.

I'd like to see if the vertical descent at 7 km/s problem can be solved with known materials and techniques.

If not, so be it, but that achievement would be noteworthy, and it would set the stage for delivery options at lower velocities and different cargo components.

Edit#1: In another topic, development of a paste to hold Hydrogen for use in a fuel cell vehicle was reported. In thinking about the landing problem in this topic, I am wondering if there is a substance that is (a) highly compressible and (b) extremely viscous and (c) undaunted by heat and (d) possible to make on Mars.

It is clear from the posts of GW Johnson (and others) that an atmosphere (such as that at Mars) is compressible, able to deal with hot glowing objects, and available on Mars. However, the density of the atmosphere of Mars is so low that an object travelling at 7 km/s needs a very long track to slow to gentle landing velocity.

***
The magnetic field deceleration idea has been introduced to this topic but not yet explored (as I recall at this point).

A hot glowing object may have an electric charge. If it does, then it would (presumably) interact with a magnetic field.

Edit #2: At the other end of the scale, NASA might be a candidate customer for fuel for sample return flights. I'm thinking here of simple tanks of compressed gas. The gas would have to be refrigerated before it is loaded into a vehicle for a return flight from Mars, but a stash of tanks of gas would be a lot easier to prepare for use as propellant than be the case without them.

Somewhere on the scale, from Zero slowing Vertical descent to Zero velocity NASA style landing there is a sweet spot for tanks of gas.

GW Johnson may have pointed the way with his description of a long (intelligently guided) flight through the atmosphere of Mars.

There is no reason (that I can see) why the flight through the atmosphere has to be linear. It could curve around the planet to maximize the benefits of aerobraking to arrive at a velocity where impact into a suitable soft landing site would be practical.

Edit#3: The tanks themselves would be useful far into the future, to hold output from onsite manufacturing facilities, prior to liquefaction of the gases.

(th)

tahanson43206 · 2021-02-05 11:24:02

For Calliban re topic ...

A while back, either your kbd512 (or perhaps both?) introduced the idea of using magnetic force to slow a moving object.

While the context here is an object moving in a linear fashion (a ballistic cargo package), there is an Earthly application to consider:

The hysteresis disk is attached to the brake shaft. A magnetic drag on the hysteresis disk allows for a constant drag, or eventual stoppage of the output shaft. When electricity is removed from the brake, the hysteresis disk is free to turn, and no relative force is transmitted between either member.
Electromagnetic brake - Wikipedia
en.wikipedia.org › wiki › Electromagnetic_brake
About Featured Snippets

I note the line about "electricity removed from the brake".

That implies to me the hysteresis plate is a passive element of the package.

Is it possible to design the cargo container so that it has the properties of a hysteresis plate as used in the example?

Then (I'm assuming) application of an electric current to a properly designed magnet would (presumably) allow for slowing of an object moving in a linear fashion.

I note at this point that magnetic repulsion is a feature of one of two designs for Earthly magnetic trains.

It would seem reasonable (to me at least, and at this point) to suppose that a flying object could be sustained in elevation by a repelling magnetic field while it is experiencing slowing as it's kinetic energy is transferred to a suitably designed magnet.

Thus, I am imagining a hybrid of GW Johnson's vision of a vehicle slowed by passage through a compressible substance (gas/atmosphere) "flying" itself into alignment with a magnetic track capable of slowing forward progress by pulling kinetic energy out of the vehicle and storing it in capacitors or other similar storage devices capable of accepting large amounts of current in a short period of time.

Edit#1: The hysteresis plate in the example sited above presumably heats up. A vehicle designed to interact with a magnetic slowing track would be expected to experience heating as well, and ** that ** would be on top of the atmospheric heating already experienced.

However, the cargo carrier might be designed to handle the two kinds of heating in different parts of the structure.

A rapid quenching operation might be a welcome addition to the design of the cargo receiving facility.

Liquid CO2 might handle that responsibility admirably.

(th)

SpaceNut · 2021-02-05 16:36:07

Magnetic repulsion would be reaction to the same field facing towards each other and that would be an inverse square function with regards to distance between each other. The fields at orbit are very weak and even if you did get the polarity of the field correct that ships field needs to be even larger than the one from the planet at that distance to do anything and would need to increase as it approaches.
Co2 and even air are non magnetic and just allows the lines of flux to pass through them and there are no conducting loops to create the field with.
A track on the ground would work but we do not have one and would need to be flat as well as have wheels on the landing items to use it to slow down.

Calliban · 2021-02-05 17:17:51

Will look into the magnetic braking idea later. It would be an interesting idea to explore of the moon, where there is no atmosphere and propellants are expensive. Orbital velocity close to the surface is ~1.5km/s.

On the topic of ballistic delivery of materials to Mars. I have just finished producing a spreadsheet model, that allows deceleration of objects in the atmosphere to be modelled. It is only valid at supersonic speeds. I will provide more details later. Indications are that in order to prevent heat shield mass from dominating the mass of payload, the projectiles should mass no more than a few hundred kg.

Calliban · 2021-02-12 09:38:07

One for Gary: would you be able to check these results against your spreadsheet?

I have completed work on a spreadsheet that is designed to calculate velocity, peak temperature and deceleration for a projectile entering the Martian atmosphere. At the moment there is no vector analysis and the assumption is that the trajectory is vertical, i.e 90 degrees to the horizontal plane of the surface. The spreadsheet is only valid for supersonic speeds - speed of sound ~230m/s on Mars.

Some details of how the spreadsheet works.

Atmosphere: The Martian atmosphere is taken to be 100km thick. Pressure is calculated as a function of scale height in the atmosphere, which is assumed constant at 11.1km. P=P0e^-(x/11.100), where x is height above standard surface (km). P0 is 610Pa. The density of the atmosphere at height 'x' is calculated using the ideal gas equation: density = PxMM/RT. The molar mass, MM, is the molar mass of CO2, 0.044kg.mol-1. The temperature of the atmosphere is modelled as a linear increase from 210K at Mars equivalent sea level, to 100K at the top of the Martian atmosphere. On this basis, density is calculated based upon the constant scale height equivalent pressure and the temperature at height 'x'.

The change in velocity of the projectile is computed as it passes through each 0.01km finite element of the Martian atmosphere. As the projectile is moving at supersonic speeds, the Martian atmosphere is assumed to be incompressible. Hence the rate of change of velocity can be calculated based on momentum conservation. The atmospheric mass that the projectile encounters across each finite element of depth, is equal to cross-sectional area x local density x depth of element. This mass of atmosphere is accelerated to the same speed as the projectile. Hence, across each element, the change in velocity can be computed: dV = V0 x (Mp/(Mp + Ma))+g x dt
Where dt is the amount of time it takes for the projectile to cross the previous element, and g is Martian gravity.

Acceleration is calculated as being the change of velocity across the finite element, divided by the time it takes to cross it. This is calculated as the velocity at the end of the element, minus the velocity in the previous element, divided by the time taken to cross the previous element.

Total radiation heating is calculated by assuming that all KE lost by the projectile across each element, is absorbed by atmospheric gas ahead of the projectile and radiated as black body radiation. This forms a blackbody radiator. Some 50% of heat is radiated towards the projectile and some 50% is radiated in a forward direction. Radiation temperature at the surface of the projectile is calculated using the Stefan-Boltzmann equation.

Incoming projectiles are assumed to be protected by spherical heat shields. The projectile is positioned at the bottom of the spherical heat shield, such that the centre of mass of the sphere is skewed away from its centre. This ensures that the projectile aligns with the ground as deceleration commences. The thermal protection of each sphere is tapered, with more protection on the leading point favoured by the skewed centre of gravity.

Principle pass/fail criterion: at a height of 5km, the speed of the projectile must not exceed 1000mph (450m/s). This was previously calculated as the maximum impact speed at which a carbon steel projectile would have a good chance of survival (compressive forces <yield strength at all time during impact deceleration).

First run scenario: Entry speed at the top of the atmosphere = 7km/s. For a heat shield diameter of 1.6m, the total mass of the heat shield and the projectile it protects, must not exceed 85kg in order for velocity to be <450m/s @5km height above datum sea level.
Peak deceleration = 761.1m/s2 (77.6g) at a height of 22.49km above the Martian surface. Peak radiation temperature occurs at the nose of the sphere and is 1297.8K (1025°C) at a height of 25.49km and radiation temperatureexceeds 1000K for 9.4 seconds. Total descent time from the top of the atmosphere to a height of 5km = 25.4 seconds. The projectile loses half its initial velocity and 75% of KE in the first 12.6 seconds, at which point height is 21.57km.

These results, assuming that they are accurate, allow the heat shield design requirements to be specified. Assuming that the heat shield makes up no more than one third of the total combined mass of the heat shield and projectile payload; it must weigh no more than 28kg. It must have sufficient strength to withstand acceleration of 78g, with a point reactive force of 43.36KN enacted by the payload at the nose and pressure forces averaging 32.35KPa across the frontal area of the spherical shell. Finite element thermal conduction modelling should be applied to determine the optimum thickness of ablative ceramic at each point in the shell. If steel if used for the inner surface of heat shield, temperature behind the ceramic must not rise above 400C. If aluminium alloys are used, temperature <200C. An inflatable heat shield would be the ideal design solution, as it would allow reentry projectiles to be stored in a more compact arrangement prior to deployment. But for this to be workable, the heat shield must be flexible. Maybe that could be done by making it out of some sort of ceramic fibre with a plastic inner membrane.

Ballistic projectiles that are designed for a vertical impact with the Martian atmosphere, should experience a more gradual deceleration if the they hit the atmosphere at any other angle. So anything designed to enter to survive entry at an angle perpendicular to the surface, should be able to survive entry at any other angle. Any thoughts?

Last edited by Calliban (2021-02-12 10:03:46)

SpaceNut · 2021-02-12 10:14:49

Deceleration of the vehicle is also a function of the diameter of the face being slowed by the increasing air density...same a wind blowing windmill blade...

tahanson43206 · 2021-02-12 13:35:44

For Calliban re #92

Awesome! Thanks for keeping this topic going!

I recognize that your work so far in this specialized area needs to be checked and perhaps double checked by others, but at this point, I'm noting the results you've presented: 450 m/sec impact velocity for a package that leaves Earth at [85kg ] of mass, of which 2/3 is case, navigation and payload.

Taking your suggested proportions as a guide, I would imagine a payload allocation of 1/3, or about 28 Kg.

That is actually quite a useful payload, assuming it is something that can survive the 450 m/sec impact, and ** that ** can be eased by preparation of the impact field, as has been discussed earlier in this topic.

In addition, since NONE of the atoms of the package are lost (assuming the field is prepared properly) ALL of the atoms of the package are recoverable.

SearchTerm:Spreadsheet of calculations for ballistic 90 degree package 85 kg to deliver 28 kg.

SearchTerm:Ballistic package 90 degree from 7 km/sec to Mars at 450 m/sec 85 kb deliver 28 kg

http://newmars.com/forums/viewtopic.php … 89#p176689 Calliban

***
For SpaceNut ... here's another spreadsheet that we might be able to store in a repository!

That is, if Calliban is willing to make it available, and ** if ** we succeed in arriving at a successful conclusion of the current Dropbox inquiry.

Edit#1: For Calliban ... this forum has a recruiting campaign underway ... we're off to a slow start, but we ** are ** under way ...

What kind of person would you like to recruit to help you develop the Ballistic Delivery business concept? I understand (from your previous comments) that you are currently fully engaged with your present full time occupation (and numerous other responsibilities and interests) but I'm hoping you might be willing to provide an occasional bit of guidance to a (presumably younger) person who is inspired by Void's idea to see how far it can go.

***
More for SpaceNut ... if we decide to set up a DropBox repository for NewMarsMember, we could set up a permanent "Help Wanted" file.

DropBox doesn't lend itself to web pages ... it is more of a document repository (as I experience it now) but it could certainly hold a list of current volunteer openings for the forum.

(th)

Calliban · 2021-02-13 03:23:29

I don't know at present what the mass division between the heat shield and projectile payload will be within the 85kg mass budget. I estimated 1/3 heat shield, 2/3 payload. But the the real mass of the heat shield will not be known without a design effort, which would necessarily include heat transfer modelling. It may turn out that it isn't plausible to build a satisfactory heat shield within the mass budget. Or maybe it is an even smaller part of the budget than I have assumed. It is unknown at present. Ideally, we would want the heat shield to comprise as little mass as possible.

The fact that radiation temperature of the heat shield barely exceeds 1000°C is good news. It opens up the possibility of using basalt fibre in an inflatable heat shield. This is extremely strong. So my initial thoughts are densely woven basalt fibre, with an inner polymer layer to contain internal pressure. I would need to carry out heat transfer modelling to determine the viability of this design. This link suggests room temperature thermal conductivity of 0.025W/m.K - an exceptionally low value.
http://nopr.niscair.res.in/bitstream/12 … 056-64.pdf

We can expect the basalt fibre to survive the impact. We would probably spray the upper surface of the heat shield a bright colour so that we could identify impact sites from air. A satellite could then map their exact position. A rover crew would then pick them up. A possible use for shredded heat shield would be a fibre reinforcement. If the shell of the projectile is made from steel, copper or nickel alloy, then there are a range of possible uses for these materials for a Mars colony.

I am happy to share the spreadsheet. I doubt very much that we would get to pick and choose exactly who decides to dedicate their free time to helping this forum. But the best fit is probably a mechanical engineer.

Last edited by Calliban (2021-02-13 03:52:53)

tahanson43206 · 2021-02-13 08:29:50

For Calliban re #95

First, thanks for continued development of this topic, and specifically for exploration of the basalt fiber heat shield idea!

Second, thanks for offering to share your spreadsheet! SpaceNut has initiated an inquiry with Society management regarding permanent storage.

Third ... because the cost of modern electronics is so low, I recommend you plan to include a tracking circuit board in your package design. The package would then deliver precise location information to the moment of impact. If that is combined with highly efficient, highly effective flight path control, the location of the delivery should be knowable.

Fourth ... your closing paragraph .... it is to be expected that a member such as yourself would not be keeping track of the back room activities of this forum, let alone the Society itself. Thus, it would seem you have missed recent developments.

This forum no longer admits spammers. The registration procedure which you used is no longer available. Instead, we have moved to a 100% by-invitation-only mode of admission. We are actively recruiting persons who will contribute to the various projects under consideration or active development in this forum.

If you become aware of someone you think would be a valuable contributor to the forum, please invite that person to apply at NewMarsMember * gmail.com.

We (SpaceNut, kbd512 and I) have set up and tested a simple vetting procedure. The applicant is requested to write two short essays ... SpaceNut requested that the applicant write a short paragraph about how they learned about the forum. kbd512 asked for a bit longer essay, stating how the member would like to contribute to the forum. I am very specifically looking for volunteers to help with projects of various kinds.

Taking a larger view, there are thousands of young people alive on Earth today who will participate in developing the infrastructure for Mars settlement, or actually moving to Mars to take part in development of the infrastructure there. It is perfectly feasible for the Mars Society to become a gathering point, and a source of information for this cohort. This forum has the potential to play a role in serving that population.

Thanks for the suggestion of someone to help with the Ballistic Delivery topic. I am increasingly confident this technology will become the organizing principle for multiple companies from multiple nations.

(th)

SpaceNut · 2021-02-13 09:48:48

Ballistic entry delivery to the surface ends the moment we add heat shields, parachutes, retro rockets, air bag cushions and this topic was purposely narrowed to not include any of these to slow and protect cargo delivery to the surface as being intact for use without any cleanup separating processing required.

These things are part of the Void's Mars Starship Belly Flop Cargo Drop where it was recognized that an unprepared surface could not support a starship in its current landing pad geometry filled with cargo but it was much closer with it made lighter by sending it towards the surface once in the glide profile.

It was also thought that once its out of that glide dispensing that a question was poised to whether or not a starship could return to orbit? This is a GW question for sure....

repost

Calliban wrote:

I agree with Void: much of the work carried out for construction of a lunar base can be done using teleoperated robots. The Earth-Moon distance is 1.28 seconds. Bulk materials can be launched from the moon using an electromagnetically accelerated sledge mounted on steel rails. In low lunar orbit, typical orbital speed is 1.5km/s. An ion propelled vehicle in a slightly higher orbit could capture an electromagnetically launched payload using a skyhook type cable.
Mars would be a useful source of all elements that the moon cannot provide: argon propellant, carbon, nitrogen, hydrogen, etc.

Bulk materials are free already in the universe and they rain down on all planetoids and planets alike as comets, asteroids, meteors and throwing's more stuff into the pathways become a risk and not even valid if it does not make it to the objective location that we launch it towards let alone evaporates in the ballistic incoming slide to burn up or implodes on impact with the surface...Short of the materials needing to be supplied are gasses to an atmosphere.

Besides we need processed goods that are refined to sheet stock, shapes and materials made into actual items to be the transport trade. The big ship that cycles from place to place will need those goods as much as the location that they are going to as well...

tahanson43206 · 2021-02-13 10:41:05

For SpaceNut re #97

Thanks for your continuing close attention to and support of this (to me very promising) topic!

To clarify a point ... As I read Calliban's proposal, it can be interpreted as entirely ballistic delivery of valuable materials to the surface of Mars.

As I read his recent post, the heat shield ** itself ** is expected to be directly useful to the settlers, so it can be considered part of the payload, and thus qualifies as "pure" ballistic delivery.

Calliban's design does ** not ** call for parachutes, retro-rockets or any other traditional paraphernalia!

Thus, it ** does ** qualify as a pure ballistics delivery method.

I particularly like the fact that Calliban has accepted the worst case premise of 7 km/sec arrival at the top of the atmosphere, and 90 degree angle of attack.

As GW Johnson has confirmed on multiple occasions, and as Calliban mentions, planning delivery trajectory at angles smaller than 90 degrees will permit increased size/mass of the delivery package.

Even if the primary payload is only 1/3 of 85 kg, ** that ** is a significant mass of high value material to be delivered to Mars settlers.The remaining 2/3 of 85 kg is available for recovery and re-use by Mars settlers, but that part of the delivery will (most likely) require some post-arrival processing.

Edit#1: The names "Beagle" and "Bombardier" are potentially available for an enterprise specializing in Ballistic Delivery of supplies to Mars, if the organizations involved are based in England or Canada respectively.

(th)

Calliban · 2021-02-13 11:17:22

SpaceNut wrote:

Ballistic entry delivery to the surface ends the moment we add heat shields, parachutes, retro rockets, air bag cushions and this topic was purposely narrowed to not include any of these to slow and protect cargo delivery to the surface as being intact for use without any cleanup separating processing required.

We established quite quickly that ballistic delivery isn't really possible without taking some advantage of the atmosphere for deceleration. This is because no impactor can survive intact at impact velocity greater than 1km/s (due to mechanical forces) and the heat resulting from depositing so much KE at the impact site would melt the projectile. Note that an incoming projectile moving at 7kms has about 100 times as much KE as it would take to obliterate a solid steel impactor on impact. So one way or another, the projectile has to lose 99% of its incoming KE in order to survive impact.

At impact speed of 450m/s, most solid metals would survive unless they hit solid rock and many mechanical components and electronics would survive as well if properly encapsulated. So decelerating to that that speed can be thought of as a minimum design requirement for delivering anything intact to the surface of Mars.

Meeting the minimum design requirement does not require parachutes, airbags or propulsive landing. But it does place hard limits on the mass per unit surface area of whatever we wish to deliver, if we expect any part of it to survive intact on impact. That comes out as a constant of about 10kg/m2 for a spherical impactor. And it will experience shock heating exceeding 1000°C for about a dozen seconds for an entry speed of 7kms at a 90° angle of attack. The problem is that nothing with a density that low will have sufficient mechanical strength to survive impact. So if we want the concept to work at all, we must divided our design into two parts: (1) One part that is designed to reduce impact speed to 450m/s, which is the heat shield / drag balloon that we have described here; (2) Another part that is designed to survive the impact at these reduced speeds. There is no way around splitting the design in this way, unless you are prepared to make the impactor impractically small.

On the basis of the limit of 10kg/m2, a pure spherical projectile with a density of 5000kg/m3, would be limited to a diameter of 1.2cm (0.5") to be moving slowly enough to survive impact. With a density similar to water (1000kg/m3), maximum diameter would be 6cm. But then it would be too weak to survive impact. So sticking to the purist version of Void's original proposal, the impact cannot be bigger than a musket ball to survive impact.

These type of discussions allow us to establish what is possible within the limits that nature has prescribed. So I don't think modifying Void's original idea to include a crude heat shield/ drag device is really wasting anyone's time.

Last edited by Calliban (2021-02-13 11:41:23)

SpaceNut · 2021-02-13 11:48:45

That makes the heatshield a crumple zone for impact since its carried all the way to the surface and it needs to be heavier since its required to take the blow of impact as a car does in a collision.

I agree that voids original start was not to use these other aids to land as disposable items but to try and bring them all the way down to the surface but they are still no good, to any one if they can not be reused intact once delivered but must be reclaimed and remanufactured for renewed use.

I think the angle of attack for planet atmospheric entry is 70' due to bouncing off from the thicker atmospher at the higher velocity that one risks since we are not firing engines to cause a planetary turn once we get to the right angle point to force the item to land.

There is a simulator for this which I will locate.
User name RG Clark was the poster for some of the EDL concepts in spaceplanes for lift/drag

http://exoscientist.blogspot.com/ is RG Clark's website where the simulator is located but have not found the link as of yet. The website is heavy with content simular to the one GW Johnson has

New Mars Forums

Announcement

#76 2021-02-03 18:41:32

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#77 2021-02-03 18:46:34

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#78 2021-02-03 18:53:02

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#79 2021-02-03 19:04:05

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#80 2021-02-03 19:16:46

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#81 2021-02-03 20:16:39

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#82 2021-02-03 22:01:43

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#83 2021-02-04 10:52:43

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#84 2021-02-04 12:39:53

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#85 2021-02-04 13:16:34

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#86 2021-02-04 13:20:31

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#87 2021-02-04 16:25:24

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#88 2021-02-05 06:47:39

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#89 2021-02-05 11:24:02

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#90 2021-02-05 16:36:07

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#91 2021-02-05 17:17:51

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#92 2021-02-12 09:38:07

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#93 2021-02-12 10:14:49

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#94 2021-02-12 13:35:44

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#95 2021-02-13 03:23:29

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#96 2021-02-13 08:29:50

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#97 2021-02-13 09:48:48

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#98 2021-02-13 10:41:05

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#99 2021-02-13 11:17:22

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#100 2021-02-13 11:48:45

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

Board footer