Ballistic Delivery of Supplies to Mars: Lithobraking

tahanson43206 · 2021-04-25 10:29:00

For GW Johnson re Post #225

This post is reserved for SearchTerms, after I have time to re-read and absorb (to the extent I can) the lessons contained in #225.

Thank you (very much) for this comprehensive contribution to the topic.

(th)

SpaceNut · 2021-05-04 20:55:19

Precussor mission equipment delivery is going to be a real issue to prepare teh landing site for starships first mission in the mars 17 design.
Things that we need will need to be delivered long before man can even think of going in a starship to mars.
We need robotic commanded from earth equipment that can work from the daily tasks but how complex can we get with teh automation AI part of what we need the machines to do.

https://en.wikipedia.org/wiki/Mars_Exploration_Rover

The Mars Exploration Rover was designed to be stowed atop a Delta II rocket. Each spacecraft consists of several components:
Rover: 185 kg (408 lb)
Lander: 348 kg (767 lb)
Backshell / Parachute: 209 kg (461 lb)
Heat Shield: 78 kg (172 lb)
Cruise Stage: 193 kg (425 lb)
Propellant: 50 kg (110 lb)
Instruments: 5 kg (11 lb)[49]
Total mass is 1,063 kg (2,344 lb).

https://en.wikipedia.org/wiki/Mars_rover

https://en.wikipedia.org/wiki/Mars_Science_Laboratory

The spacecraft flight system had a mass at launch of 3,893 kg (8,583 lb), consisting of an Earth-Mars fueled cruise stage (539 kg (1,188 lb)), the entry-descent-landing (EDL) system (2,401 kg (5,293 lb) including 390 kg (860 lb) of landing propellant), and a 899 kg (1,982 lb) mobile rover with an integrated instrument package

The question is for the increase of mass what is the penalties for the other things which must also scale to make what we need on the surface deliverable....we sort of have hint with Red Dragon in that we could get quite a bit but this is the GW realm of rocketry that I am still learning...

tahanson43206 · 2021-05-04 22:20:03

For SpaceNut ....

I think that a ship full of engineers and teleoperations specialists is the ** best ** bet for the first human visit to Mars.
RobertDyck's Large Ship (with suitable adjustments) would seem (to me at least) well worth considering as the accommodation for the work crew.

We've already established (within a reasonable set of bounds) that the ballistic delivery method is practical for a class of supplies that would be needed to make a sturdy landing platform, and soft landing can be attempted for machinery.

I think that trying to scrimp on mass makes very little sense .... simply size your expedition to meet your needs, and plan to lift the mass to orbit.

At this point, there is no need to worry about mass, because we have absolutely ** no ** idea how motivated a Nation State might be to fund an expedition.

We already ** know ** that Russia, the US, China, Japan, India and the Emirates have felt motivated to make the investments to send mass to orbit and beyond.

I recommend that planners ** plan ** and let fund raisers attend to their specialty.

(th)

SpaceNut · 2021-05-05 18:24:48

Thats only if we get a ship of Roberts ever built as we still have not done so for other than the ISS and thats a design not even close to what we need and the gateway is following in the same direction which is wrong.

The max mass of a deliverable cargo for hard kinetic impact is?
https://www.ajdesigner.com/phpenergyken … n_mass.php

At the top of Mars’ atmosphere, roughly 83 miles above the planet’s surface, the spacecraft was traveling about 12,000 mph. This means the spacecraft had a kinetic energy of 44 gigajoules and a potential energy of 1.2 gigajoules

What's the loss of payload to harden the shell so as to keep it intact?
https://www.lockheedmartin.com/en-us/ca … space.html

These are not reinforced for impact landings so there is a need to determine what it will take in mass to make it so that it stays together when it hits.

Since we have never not delivered a complete back shell and heat shield we still do not have a payload number let alone know how tough it is.

we assume that if its still together that we will slow

What's the safety keep out zone for the kinetic impact area size?

https://www.noao.edu/jagi/sepo/educatio … fiiia.html

The total amount of energy, K, required to form a crater is proportional to the volume, V, of material excavated in the impact.
Since a crater is basically a hemisphere (half a sphere), its volume, V, is proportional to the diameter, D, of the crater. (V = 2/3 [pi] (D/2)3 )
So the energy, K, needed is proportional to the diameter cubed, D3.
The energy of an impact is the kinetic energy, as defined above: K = 1/2 m v2.
Since the energy K, is proportional to D3, we can predict D3 is proportional to 1/2 m v2

What ship did we use to launch if from earth that exists today?

What's the max payload of the soft landed stuff and does it scale up or is there a limitation?

tahanson43206 · 2021-05-05 19:43:00

For SpaceNut re #229

Many of the questions asked in this post have been answered previously. It is the water-under-the-bridge nature of this forum that requires us to keep asking and answering the same questions over and over again.

I recognize that at the present time we have no alternative. What an alternative would provide is a place where a person could go, once or a hundred times, and find the same answer to the same question.

An example is RobertDyck's recommendation for a Half-Bar atmosphere for Mars habitat, Space craft and land vehicles on Mars. It should be possible to direct a person to a repository where that recommendation is always available, 24*7, 365*50, free to all.

Over the weekend I heard from an engineer friend who works for a nuclear power plant. He's approaching retirement, and is back thinking about space. He informed me that he is thinking about 5 psi for a Mars habitat.

I wonder how many millions of others are ** out there ** on Earth, busy re-inventing the wheel, over and over again.

Calliban posted his analysis of the velocity that ballistic payloads could be expected to survive.

The amount of mass that can be slowed to that velocity by an aeroshell was posted.

The amount of mass that is payload vs aeroshell was estimated.

The ship that performs the launch is completely independent of the payload package. Whatever ship is available at an affordable price is the one the shipper will select.

This topic is not about soft landings, so I hope someone in the appropriate topic takes up the question.

(th)

tahanson43206 · 2021-05-06 06:28:39

For SpaceNut re problem of endless repeating questions ...

It came to me overnight that we ** do ** have a way of storing FAQ (Frequently Asked Questions) in this (somewhat lean) data structure! The first post of a topic can be designated as the repository for FAQ (and answers)

The answers would be links to the posts where the questions are answered the first time. The "owner" of a topic would be responsible for maintaining the FAQ section in Post #1, except that in the absence of the owner, a Moderator or Administrator could fill in for the original author.

Since I launched this topic (inspired by a vision of Void) I will attempt to improve the FAQ section in Post #1.

The questions you asked recently are a good starting point for an FAQ section.

(th)

Calliban · 2021-05-06 17:23:40

This topic is an exploration of minimum cost design. Obviously, using powered landing, even the most fragile items can be delivered to the surface of Mars. But that is expensive in terms of total mass budget. So the question becomes, can we shave money off of delivery costs by having simpler delivery options, that avoid the overheads associated with soft landing? I think the answer is yes. But the benefits probably disappear if the ballistic payloads end up being scattered over thousands of square km and a full time EVA crew must be employed to retrieve them. The alternative to this is to equip each vehicle with a guidance system. This could be controlled from the ground on Mars, using radar to track each projectile. Active trajectory control would begin when the projectile exits hypersonic and the plasma density in the shock wave is low enough to allow radio communication. Guidance means having aerodynamic control surfaces. This adds to both cost and weight. Is there payload mass benefit in this approach? I don't know.

SpaceNut · 2021-05-06 19:07:54

Since he questions have to do with those that make the aero shell back and heat shield we would need to contact to get the idea looked at from a technical area.
https://www.lockheedmartin.com/en-us/ne … tacts.html Commercial Space Chris Pettigrew
I think this would be the one to discuss the concept of an intact unit with the same mass of the normal stuff removed all but for a stripped down guidance and navigation for the unit slamming into the planet. The payload launch from earth still needs the cruise section but it can lose the ability to parachute, and retro rocket....

tahanson43206 · 2021-05-06 20:15:35

For Calliban and SpaceNut .... thank you both for (a) support for the topic and (b) a concrete suggestion (pun intended) to follow ... I'll pursue it tomorrow if there is time, but soon for sure.

(th)

SpaceNut · 2021-05-06 21:30:15

Landing was a close one as GW indicates so if a starship does ever get launched its going to need the "concrete Pad" for sure as it almost did not have enough solid footing to keep it upright.

https://dartslab.jpl.nasa.gov/Reference … alaram.pdf
MARS SMART LANDER SIMULATIONS FOR ENTRY, DESCENT, AND LANDING
https://www.colorado.edu/event/ippw2018 … id1000.pdf

https://dartslab.jpl.nasa.gov/index.php

https://www.mathworks.com/company/newsl … -mars.html

https://spaceflight-simulator.fandom.com/wiki/Mars

Calliban · 2021-11-15 08:45:24

I have forgotten where we got to on this topic. But the thought occured to me that with so much dry ice on the Martian surface, there is the possibility of slowing down ballistic projectiles by directing them into pits filled with subliming CO2. The dense gas would slow the projectiles considerably, which would then embed themselves into the dry ice at the base of the pit. We would do this by injecting liquid CO2 into the pit above a layer of dry ice. The liquid CO2 would phase change into a mixture of gaseous CO2 with particles of CO2 ice within the gas stream. It would explode upward along the pressure gradient, but would be partially chocked by friction with the walls of the pit. The result would be a pressure gradient, with stable dry ice at the bottom, with pressure and gas density declining between the bottom and top of the pit.

tahanson43206 · 2021-11-15 09:53:29

For Calliban re #236

Thank you for bringing this (to my mind important) topic back into view, and for adding an interesting refinement

For first time readers: This topic was inspired by a vision of Void, who imagined throwing objects out of Starships before landing, to reduce mass to be decelerated by thrusters.

For Calliban ... the topic left off in what I thought was excellent condition.... thanks to collaboration between you and GW Johnson, we arrived at a modest confidence level that solid mass could be delivered to the surface of Mars using ballistic delivery if the package is slowed sufficiently by existing/proven aeroshells. We are (or at least ** I ** am) looking for a major corporate organization to pick up the idea and to deliver large quantities of raw or refined material to the surface of Mars, without incurring the expense of chemical retropropulsion.

Experiments are needed to confirm the practicality of the work done to this point.

As a reminder, work done during the Cold War to develop solid metal "bullets" to knock down incoming Soviet warheads was carried to a significant level, at Lawrence Livermore Labs. The details are documented earlier in this forum. The gent who carried out / led the research delivered solid projectiles into sand banks at near orbital velocities. He is still alive, and might be willing to report on the condition of the projectiles after they came to a stop.

As has been discussed earlier in the forum, this (ballistic delivery) is a likely multi-billion dollar business.

(th)

GW Johnson · 2021-11-16 15:45:28

Ballistic delivery as envisaged here works, if you aerobrake to about local Mach 2.5 to 3. If the ballistic coefficient is high, you will be under 5 km altitude and seconds from impact at this point.

You will smack the surface of Mars at about 0.6 to 0.7 km/s, which is more than fast enough to convert KE into a really hot, shock-wave-driven fireball. Your payload will be fragmented into shrapnel, and part of it will be vaporized. Unless you add a solid braking rocket to reduce velocity down around 100-200 mph.

If your ballistic coefficient is low, you come out of aerobraking higher up, hopefully above 10 km. A supersonic chute could hold you at or near Mach 1 at impact, maybe a minute later. That would be something near 250 m/s, or in the vicinity of 500 or 600 mph. You don't get the shock fireball. You still get a bunch of fragmentation, but not any noticeable vaporization.

Solid raw materials like steel ingots could be delivered that way, but not finished steel shapes (which would be destroyed upon impact).

The difference between Earth and Mars entry is one of altitude. You come out of the hypersonics on Earth at around 45-50 km up, and at Mach 3 with a higher sound speed in the warmer air, which corresponds to about 1 km/s velocity. You have a long way to fall from there, and the last 6-ish km are in rather dense air so that terminal velocities are far lower, for almost any object shape and density.

On Mars, you come out of the hypersonics at the same Mach 3, but in colder air with a lower sound speed, at about 0.7 km/s. The problem is the altitude: nominally near the 5-10 km range, depending upon ballistic coefficient. You come out headed downward somewhere between 45 and 90 degrees down, so there are only a mere single handful of seconds to impact. And even if you come out higher than 10 km, where a chute barely has time to deploy and inflate, the air is so thin that terminal velocity WITH A CHUTE is still just at or above Mach 1. There's not time for the chute to decelerate anything very much, and the air is just too thin for it to be very effective.

So, either you smack the surface really, really hard, or else you add some last-second rocket braking. There really are no other choices that are known to work.

GW

kbd512 · 2021-11-17 08:44:03

GW,

We don't need to deliver finished goods. The "value added" part of the manufacturing should be done on Mars. Trying to plan to infinite detail or to accurately predict the needs of a growing colony, months to years ahead of time, is a waste of time and money. It's better to supply the electrical power, the raw materials, and the production machinery, then let "the market" decide which products need to be produced most urgently. Anything produced on Earth that later becomes kerf / waste / spoilage on Mars will quickly become unsustainably expensive. For example, a shipment of bolts that don't fit are nearly worthless without local machinery to transform them into something useful.

Steel, concrete, and glass are the foundational materials that modern human civilization was built upon. I expect the concrete and glass to be locally sourced without undue collection effort. Steel is a bit harder to come by, despite all the Iron oxide present and Nickel-Iron asteroid fragments. If there was an inexpensive way to deliver refined steel balls from orbit, protected from the heat of reentry by a Carbon ablator, then local production machinery could begin with a supply of refined steel to produce the mining and construction equipment ultimately required to locally source Iron for steel. The machinery required to locally produce plate / sheet / tubing / bar stock could feasibly be delivered via Starships and assembled onsite. I don't think it's practical to deliver a "factory in a box", but individual machines and components are a different matter.

tahanson43206 · 2021-11-17 09:01:32

Thanks to GW Johnson and kbd512 for continuing to refine and develop this topic.

We need some real live tests to confirm the hypothesis that ballistic delivery is practical for the Mars situation. The addition of rockets to the package is an option, but that defeats the purpose, which is to deliver needed supplies without a lot of paraphernalia.

The suggestion of kbd512 in post 239 to use Carbon based leading edge material for the descent has the advantage that any charred material that remains after the package comes to rest is useful.

Computer modeling should be able to predict with reasonable accuracy the nature of the delivery method, and the design of the heat shield that will allow the package to be delivered in the optimum condition at the optimum price.

However, live testing can be done next September, when the landing site probes are launched, if all the cards fall as needed.

(th)

Calliban · 2021-11-17 09:59:12

Some interesting points. I intend to do more work on this topic at some point. Two firm conclusions that were revealed by previous analysis on this topic: (1) The forces acting on an impactor scale with the square of impact velocity; (2) At 500m/s, the frontal pressure exceeds the tensile strength of all feasible construction materials (Pressure is in GPa). Even a dumb impactor made from solid metal, would be torn apart at impact speeds greater than this. For robust manufactured components, impact speed is limited to no more than a few hundred metres per second.

The value of this topic is to simplify delivery and reduce landing related costs for hardy components and bulk materials. However, this advantage only holds if payloads can be delivered accurately enough to negate the need for surface scouting teams in retrieving the payloads. This rules out the possibility of releasing a number of non-guided impactor at the edge of the atmosphere. A few degrees variance due to changes in atmospheric density or wind, could result in packages being scattered over hundreds of square miles. Another option would be to use a guided bus, which deploys individual payloads at lower altitude, blowing them out of tubes using compressed air.

I like the idea of guiding individual payloads into a funnel on the surface of Mars. As the payload approaches, cold CO2 gas is blown through the funnel at 200m/s, providing rapid braking of the payload to sub-Mach speeds. The problem is that if one is going to pay for guidance systems that are accurate enough, is there any cost advantage over a rocket assisted landing?

Last edited by Calliban (2021-11-17 10:08:52)

tahanson43206 · 2021-11-17 10:18:43

For Calliban re topic

it is good to see your renewed interest in this topic!

Your post #241 shows the upper limit of what might occur, if the regolith were a solid mass with an infinite tensile strength.

However, the regolith is ** not ** a solid mass of infinite tensile strength.

There exists actual impact data from the Star Wars research program in the United States. I don't know where that data is stored, but I do know the principle investigator is still living and potentially might be willing to offer some real world perspective on the issue.

My recollection is that solid metal projectiles were fired into sand banks at velocities approaching orbital.

What I do not recall is whether the PI reported on the condition of the projectiles after they were dug out of the sand banks, but I would imagine they were, because that was a scientific experiment and not a military one. The US (and I'm sure all) military has fired ordnance into sand banks for centuries.

Even GW Johnson has reported on military experiments along those lines, but since that ** was ** a military experiment, the actual location of the atoms of the impactor were not investigated.

The purpose of this exercise is to find the least cost best delivery solution for durable goods delivered to Mars.

Centimeter scale accuracy of delivery is a baseline requirement for any system to be designed for this application. The idea of uncontrolled solid objects flying into the atmosphere of Mars is not going to be accepted by any human being living there.

The "air defense" systems for Mars are going to be a great deal more robust than the non-existent defense systems we have on Earth today.

Space traffic approaching Mars is going to be highly regulated.

The "Wild West" days will continue for a few years, but they will inevitably come to an end.

(th)

kbd512 · 2021-11-17 13:24:11

Calliban,

You really should visit a gun range some time. Your assertion about a 500m/s impact velocity exceeding the tensile strength of all known materials does not correlate well with anything I've actually observed by firing steel / Copper / Lead bullets into steel plate and sand trap targets. All deformation is not catastrophic, either. 500m/s is 1,641fps. That's muzzle velocity for a 9mm +P round coming out of a carbine length barrel. Lead soft enough to indent with my fingernail is badly deformed but survives largely intact after smacking into a steel plate a few meters down range, but especially into sand. If the bullet is a solid slug of metal not specifically designed to deform or fragment upon impact, then it's typically mangled by steel plate or slightly deformed from sand or water.

Every mild steel core 7.62mmx39mm AK cartridge I've ever fired at a piece of steel ends up on the ground somewhere, badly deformed but most of the cores completely intact. If you fire them at sand, then apart from stripping a dead soft steel or Copper jacket, many of them could be re-inserted into a new jacket and fired again. That happens with boring regularity. At 100m, 100% of the bullets fired from ARs and AKs are well above Mach 2. All those little bullet-shaped slugs of metal you see in the berm behind the target are steel cores. Don't take my word for it, though, just visit your local range with a shovel and take note of how much intact metal is buried mere inches into the ground.

I'm talking about dropping large PICA-insulated cannon balls at a sand trap target, from orbit. All of them will be intact and probably still stackable after the ordeal. The heat of reentry is a problem if the metal is not protected. If it's thermally protected and shaped like a cannon ball, then it will survive both reentry and a Mars terminal velocity impact, either completely intact or slightly deformed. Either way, the valuable refined metal is delivered to the surface in bulk quantities for minimal cost. The first order of business after retrieval is remelting it into liquid metal, so even if it's badly mangled, it's going straight into an arc furnace anyway.

kbd512 · 2021-11-17 13:34:43

tahanson43206,

Apart from de-orbiting a cannon ball at minimum cost, we don't need to conduct any experiments. I've already conducted a more extreme version of the experiment many thousands of times. Fire a high-powered rifle at a sand berm 100m away. Note that the muzzle velocity is well above Mach 2, and nearer to Mach 3 for the AR-15. Note that the bullets are retrievable after a little digging. You don't need any more evidence. It clearly works. If it didn't, then the ballistics tests portion of all those gun magazines wouldn't have pictures of so many bullets that they dug out of a target or sand trap. A slug of Iron / Copper / Lead will survive a Mach 2 impact with a sand trap. No idea about Aluminum / Magnesium / Zinc / other metals. Given the fact that Lead will be A-OK, I suspect any other thermally protected metal will do just fine.

tahanson43206 · 2021-11-17 13:51:23

For kbd512 ... thanks for your robust support of the proposal...

While your experience gives me confidence we are on the right path here, it seems to me that it will take live tests at Mars to convince the Boards of Directors of UPS, FedEx and similar global shipping companies to put their reputations on the line.

GW Johnson is showing the way for members of this small group to have a potential impact, by reaching out to key decision makers.

Please consider writing up a proposal for major players to tag along on the Landing Probe flight next September.

The experiment would be along the lines of the "cannon ball" you described, covered with suitable protective material.

The key for success is the guidance package. I'm interested in offering centimetre accuracy for deliveries from deep space trajectories.

The Linux I'm using likes British spelling.

(th)

Calliban · 2021-11-17 17:48:05

Kbd512, that's interesting. I get the feeling that the models I am using may be overly simplistic. I am using Newtonian approximations, and from what you have said, I begin to wonder how well they approximate real life. If we assume that soil has density 2500kg/m3 and steel about 3x that, then bullets should penetrate the dirt to a depth about 3x their length, regardless of velocity. For a 7.62mm shell, I would expect stopping distance in soil to be a few inches. Does this accord with your observations?

Last edited by Calliban (2021-11-17 17:51:01)

kbd512 · 2021-11-18 00:47:29

Calliban,

Penetration is mostly a function of velocity and the sectional density of the projectile involved. The stopping distance of the bullets I've observed in sandy and clay-rich soils at the local ranges is somewhat variable, but not by that much. The water content and compaction of the soil, therefore the density of a given part of the berm, as well as bullet impact angle, also play minor roles in how deeply a slug of high velocity metal will penetrate. Again, it's not a wild difference. Ricochets are a different matter. Tumbling seems to cause the projectile to come to a stop faster. If a bullet is specifically designed to fragment or expand upon impact, then it will likewise stop considerably faster. That is where you will observe metal coming apart and subsequently being hard to collect. All of this stuff is plainly observable.

If you visit Houston, I'll take you out so you can see it for yourself. It's all good fun, so long as everyone follows the rules. I'll provide instruction prior to the range visit, but then I expect the rules to be followed. I'll provide a few reminders, so long as you continue to follow instructions. If you successfully violate the rules even once, we're done. I've had far too many people flag me with loaded firearms over the years and simply won't tolerate it anymore. As simple as the rules are, I expect people to follow them.

At the range I'm firing at either a paper target or steel plate in front of the berm. If you fire at steel, you want FMJ or soft point and you need to keep your distance, especially when firing high velocity stuff. On that note, I expect the PICA heat shield to be completely stripped upon impact, much like a bullet jacket after hitting just about any solid target, and that's exactly what we want. After the cannon balls land, we want clean bare metal after a quick "dust off". Given the lower sectional density and low relative velocity of cannon balls "dropped" / de-orbited on Mars, I expect very little digging to recover the metal. From there, it's off to the smelter.

Watch the video below where a guy fires a .50 BMG into sandbags from point blank range. The steel core is completely stopped inside of the second sandbag. Note how the Copper jacket is completely stripped off the steel core. This is what I routinely observe at the range from steel core 7.62x39 / 7.62x51 / 7.62x54R / M855 5.56x45 fired into the berm and especially steel plate. M193 is plain old lead-core FMJ, the Colonel's original recipe, such as it were, and does not behave like M855 ("green tip") at all. At or near muzzle velocity, it quickly yaws and fragments at the cannelure- usually 2 to 3 large pieces and a bunch of very small Lead and Copper fragments. Contrary to what you'd think would happen, simple drywall takes a lot of the energy out of those zippy (Mach 3) little M193 bullets, whereas 9mm FMJ punches right through drywall and pine like it's not there. 9mm FMJ is more than double the weight and less than half the sectional density of 5.56mm M193.

how many sand bags does it take to stop a 50 cal rifle?

The differences in sectional density and momentum is why baseballs bounce off of sand bags, arrows sail right through sandbags (like 9mm penetration of drywall where much faster 5.56mm is already coming apart), and most small arms ammo is completely stopped by a single sand bag. The .50BMG, the largest of what I consider small arms ammo, only requires 2 sandbags to stop it.

Calliban · 2021-11-18 04:05:00

That sounds like a lot of fun. I have no idea when I will next be able to get over to the states though. My wife and I have friends in Boston. At some point, we plan to hire a car and drive from coast to coast or down the east coast. I will need to either save a lot of leave or be between contracts to do that one. Texas is a place I have always wanted to visit.

I should point out that the only weapons I have fired are smooth bore antiques, 5.56 rim fire rifle and homemade replicas. Both quite a lot of years ago. I have made a few replicas from seemless steel tubes that I was able to turn on the lathe. The UK has a lot of laws that make shooting difficult here. The government don't like citizens to own guns, I suspect because they fear armed insurrection. A school shooting in the 90s allowed them to push through a lot of very restrictive laws on handguns. Too bad. In my experience, nut cases always manage to find guns because they don't care whether its legal or not. The only people that care about laws are responsible people. Who don't tend to shoot other people. But the situation is what it is.

From what you describe, a single sand bag will usually stop a 9mm shell. Sand has about twice the density of water. Lead is about 10x and steel about 8x. If a 9mm shell is about 3/4 of an inch long, and is mostly lead, then Newtonian approximation would suggest a penetrative depth of about 3-3/4 inches in loose sand. I am guessing the sand bags are about 1' wide? It does sound to me if the newtonian approximation underestimates how far these things will go before stopping. Which means it over estimates the force acting on the projectile.

Last edited by Calliban (2021-11-18 04:22:07)

tahanson43206 · 2021-11-18 07:50:32

For kbd512 and Calliban ...

Thank you for this helpful exchange!

I'd like to see this discussion advance to a working business.

Taking the cannon ball model as a basis for extrapolation, we need to find a funder who will pay for an experiment to prove kbd512's prediction for the Mars case. I'm not sure what kind of company would like to become the recognized name in Ballistic Delivery to Mars, but there ** must ** be such a company. The competitive nature of Capitalism guarantees (or at least greatly increases chances) that someone will take the lead and others will compete.

For this to happen, we need a customer whose needs will make the effort worth while.

An organization planning to set up a city on Mars is a candidate, and there are at least two and there may be three candidates:

SpaceX, China and possibly the Emirates.

I'd like to invite kbd512 to take the lead in composing correspondence to these three entities, inviting them to consider their needs for refined metal to be delivered at low cost from Earth to Mars by an organization on Earth interested in providing the service.

We have a model in place for how such correspondence can be developed, reviewed, edited and ultimately sent on to prospective readers.

Edit: We also need to know where dunes of fine soft Martian dirt are abundant. This may be another case of needing ground truth.

(th)

SpaceNut · 2021-11-18 15:37:32

So our selected target area must be critiqued for the ability to not hit bedrock or other such not so soft areas to allow for it to get the power of entry dissipated...So hitting a surface rock would be out just as much as hitting one that is hidden.
This is just one of the reasons why we want to send a smaller mission to get a better sense of that area that we want to send ships to...

New Mars Forums

Announcement

#226 2021-04-25 10:29:00

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#227 2021-05-04 20:55:19

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#228 2021-05-04 22:20:03

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#229 2021-05-05 18:24:48

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#230 2021-05-05 19:43:00

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#231 2021-05-06 06:28:39

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#232 2021-05-06 17:23:40

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#233 2021-05-06 19:07:54

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#234 2021-05-06 20:15:35

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#235 2021-05-06 21:30:15

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#236 2021-11-15 08:45:24

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#237 2021-11-15 09:53:29

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#238 2021-11-16 15:45:28

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#239 2021-11-17 08:44:03

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#240 2021-11-17 09:01:32

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#241 2021-11-17 09:59:12

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#242 2021-11-17 10:18:43

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#243 2021-11-17 13:24:11

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#244 2021-11-17 13:34:43

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#245 2021-11-17 13:51:23

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#246 2021-11-17 17:48:05

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#247 2021-11-18 00:47:29

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#248 2021-11-18 04:05:00

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#249 2021-11-18 07:50:32

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

#250 2021-11-18 15:37:32

Re: Ballistic Delivery of Supplies to Mars: Lithobraking

Board footer