Ballistic Delivery of Supplies to Mars: Lithobraking

Mars_B4_Moon · 2023-03-03 08:50:27

Germany was probably 'first' to space

To Nuke something is Too extreme

A manhole cover launched into space with a nuclear test is the fastest human-made object. A scientist on Operation Plumbbob told us the unbelievable story.
https://www.yahoo.com/news/manhole-cove … 58106.html

Since it was going so fast, Brownlee said he thinks the cap likely didn't get caught in the Earth's orbit as a satellite like Sputnik and instead shot off into outer space.
Some people have doubted the incredible manhole cover story over the years. But Brownlee, with first-hand knowledge of the test, said he knows the truth.

Could US Navy's Railgun Help Tap Moon's Resources?
https://www.space.com/navy-railgun-test … ation.html

Last edited by Mars_B4_Moon (2023-03-03 08:50:57)

SpaceNut · 2023-03-03 21:02:14

I went back to post 273 to see if there has been any word and silence is all that has occurred for what would seem to be part of not relying on a parachute or large amounts of fuel to make a landing successful.

Mars_B4_Moon · 2023-03-06 17:39:30

The Planet 'Venus' has not been mentioned much in this thread

'Design of a rapid transit to Mars mission using laser-thermal propulsion'
https://arxiv.org/pdf/2201.00244.pdf

but a Space-Tug with no goal of true guided braking and chutes and Aerocapture

I guess this idea also has influence on the overall Launch Windows or Martian Transfer Window topic.

So here is one idea you could have some sort of Space-Train or Railgun blast stuff from The Moon of Earth but first in the direction of Venus first, it could need some extra adjustment or guidance on the 'Product'. The goal is to deliver as much product as possible to Mars, part of your ballistic train or truck is expendable, maybe a disposable ion-drive engine you are willing to let get damaged or burn up. Product is made first on the Lunar surface, the Moon site would first be made to manufacture low tech product that does not damage then shot in the direct of Mars, then on the way to Mars it instead could launch when Mars is far away and swing by Venus first. The typical conjunction mission is ignored, you chose the longer route in which a delivered product or delivery of hard supplies not easily damaged and normally a spacecraft flies between the two planets when they start to align in their orbits. An opposition mission instead gives a stop en route to Mars or on a return trip you can go direct Mars to Earth-Moon system — a Low Tech ballistic delivered product or hardened craft would slingshot past Venus, using the planet's gravity assist to alter course.

A Paper on the Subject

https://web.archive.org/web/20201101032 … .04900.pdf

These flybys provide opportunities to practice deep space human operations, and
offer numerous safe-return-to-Earth options, before committing to longer and lower-
cadence Mars-only flights
• Venus flybys, as part of dedicated missions to Mars, also enable “human in the loop”
scientific study of the second planet
• The time to begin coordinating such Earth-to-Mars-via-Venus missions is now

The NASA Administrator’s IAC speech in 2019 indicated NASA is considering opposition-class human missions to Mars—where Mars and Earth are close to each other in their orbits at launch —that would include a Venus fly by as part of an overall two-year mission

We therefore propose that the planetary science community and the decadal planning process take into consideration and support the science planning of efforts that take advantage of human proximity to Venus for expanded scientific discovery

Spacecraft Mass. A crewed mission to beyond near-Earth space, much less Mars, is no small affair. Between fuel, habitation, protection, power, communication, and human-rated safety requirements, any deep Solar-System-capable mission will require sending many tonnes of
material on interplanetary trajectories. Although “every kilogram counts” on such missions, when the baseline mission is massive, the mass cost of marginal science packages and probes for Venus is comparatively small.

Venus is a place that offers its route more frequently

Mars and Earth's orbits come together every 26 months while in contrast, you could theoretically launch an opposition mission every 19 months.

and if you use the Moon as a manufacture base to deliver hardened products, can sling shot past Venus a gravity assist to Mars you can also perhaps use Mercury to launch built material railgun use Mercury as a manufacturing base. A delivery of Low tech hard products launched from Mercury could perhaps deliver to Mars using using Solar Sails.

Samples 'Solar sail return?'
https://mobile.twitter.com/redtwitdown/ … 7076000768

Mercury Sample Return using Solar Sails
https://ntrs.nasa.gov/citations/20070002800
A conventional Mercury sample return mission requires significant launch mass due to the large deltav required for the outbound and return trips, and the large mass of a planetary lander and ascent vehicle. Solar sailing can be used to reduce lander mass allocation by delivering the lander to a low, thermally safe orbit close to the terminator. Propellant mass is not an issue for solar sails so a sample can be returned relatively easily, without resorting to lengthy, multiple gravity assists. The initial Mercury sample return studies reported here were conducted under ESA contract ESTEC/16534/02/NL/NR, PI Colin McInnes, Technical Officer Peter Falkner. Updated solar sail capabilities were developed under the Ground System Demonstration program, funded by the NASA's In-Space Propulsion Technology (ISPT) Program.

Mercury PDF

Mercury has surface features indicating past explosive volcanism, consistent with the presence of magmatic volatiles in its interior . The surface of Mercury is also enriched in moderately volatile elements such as K, Na, S, and Cl. However, enrichments in moderately
volatile elements are not typically a good indicator of the abundances of more volatile components, such as H2O. In fact, the highly reducing conditions of Mercury’s interior may limit the abundance of H2O, given the effect of fO2 on the fugacity ratio of H2O/H2 via the reaction H2 + ½O2 <- - > H2O

https://ntrs.nasa.gov/api/citations/202 … leenE1.pdf

Mercury sample return to revolutionize our understanding of the solar system

What is the mineralogy of the largest volcanic plains unit on the planet, Borealis Planitia? mineralogical analyses What is the composition of the low-reflectance material on the planet, hypothesized to be the primary crust?

geochemical, mineralogical,
isotopic analyses, age dating,
coordinated analyses at the nano-
scale

What is the composition of the hollows, and how did they form?

We do not know what Mercury is truly made of but with a 'Mercury Sample Return' we would understand what Robots Living and Working or a Machine on Mercy could one day manufacture

Product could once again be shot from Mercury but maybe also with a Solar Sail that unfolds

The Solar-Sail Truck product or Solar Sail Train delivery could be Expendable and only the final hardened Product arrives as a Ballistic Delivered Supply from planet Mercury to planet Mars.

MESSENGER a NASA robotic space probe that orbited the planet Mercury between 2011 and 2015, studying Mercury's chemical composition, geology, and magnetic field.
Among the discoveries presented were the unexpectedly high concentrations of magnesium and calcium found on Mercury's nightside.
BepiColombo is a joint mission of the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) to the planet Mercury. In October 2021, it had its First Mercury flyby it Passed 199 kilometres (124 mi) from Mercury's surface. Occurred on what would have been the 101st birthday of Giuseppe Colombo.
http://messenger.jhuapl.edu/
,
http://www.nasa.gov/mission_pages/messenger/main/
,
http://sci.esa.int/bepicolombo/
,
https://global.jaxa.jp/projects/sas/bepi
,
http://www.isas.jaxa.jp/en/missions/spa … g/mmo.html

old Solar Sail discussion

'Japan launches Solar Sail - at last someone did it!'
https://newmars.com/forums/viewtopic.php?id=2438

Lithobraking Article from 2014

A New Way to Reach Mars Safely, Anytime and on the Cheap
https://www.scientificamerican.com/arti … the-cheap/
Ballistic capture, a low-energy method that has coasted spacecraft into lunar orbit, could help humanity visit the Red Planet much more often

Expanding our Martian horizons
Ballistic capture is not the only fuel-saving technique for entering orbit. In another approach, called aerocapture, an arriving spacecraft dives into the Martian atmosphere and lets friction eat away at some of its excess velocity, rather than relying solely on a big fuel burn to do the trick. That method, however, requires a heavy heat shield, which adds extra mass and thus costs to liftoff, offsetting the penny-pinching on fuel for a Hohmann transfer burn on arrival. Ballistic capture, Topputo says, is "slower and gentler."

Last edited by Mars_B4_Moon (2023-03-15 12:07:55)

tahanson43206 · 2023-09-12 18:04:57

In another topic, Void came up with a suggestion that may be new to the forum.

http://newmars.com/forums/viewtopic.php … 16#p213516

In this post, Void adds detail to his vision of using an incline to help to slow a landing vessel.

Many months ago, Void offered a vision of a way of landing material on Mars that eventually became this topic. The topic itself arrived at the conclusion that "lithobraking" is a reasonable idea if the arriving package bleeds off sufficient energy in the atmosphere so that it will survive encounter with sand on Mars.

Void's latest idea (of using an incline to assist with slowing) seems to me to lend itself nicely to the lithobraking concept worked out earlier.

The original idea for lithobraking was to direct the arriving package vertically at the target area, which itself would be selected to perform the very rapid braking required for this to work. Materials intended for delivery using this method would be solid, high value materials, such as stainless steel of very high purity. The payload would be enclosed in material that would participate in lithobraking, so that at the end of deceleration the payload would be nicely exposed for retrieval.

Void's latest idea for use of an incline to help with lithobraking by extending the period of deceleration seems worth exploring.

A trough might be filled with sand, which is in ample supply on Mars. The arriving payload package would accelerate the sand in the trough to travel sideways away from the trough, and eventually the energy transferred from the payload package to the sand would result in the payload package running out of energy.

Something like this was done with a trough filled with water.

Here is a snippet Google found:

About 26,800 results (0.38 seconds)
John P. Stapp - New Mexico Museum of Space History
At Holloman John Paul Stapp made history aboard the Sonic Wind I rocket sled on December 10, 1954, when he set a land speed record of 632 mph in five seconds, subjecting him to 20 Gs of force during acceleration.
John P. Stapp - New Mexico Museum of Space History
New Mexico Museum of Space History
https://www.nmspacemuseum.org › Inductees
About featured snippets
•

Water is in short supply on Mars, but the supply of sand is effectively unlimited.

An arriving payload would cause sand to enter the airspace around the landing trough at high velocity, but as it happens, sand is a common component of the Mars atmosphere, so it's presence should not be considered out of the ordinary.

It should be possible for someone to put numbers together, to show whether or not this idea of Void's is worth pursuing.

NASA has expressed an interest in landing 40 tons on Mars. A trough large enough to permit gradual lithobraking of a 40 ton payload would (probably) extend for several kilometers, and I would imagine it would need to be a respectable number of meters wide and deep.

(th)

SpaceNut · 2023-09-13 18:07:58

The shape of the surface that touches the regolith or any other media will sort of plow up and build up as the mass and speed decreases along the slope. It will sort of have the appearance of a wake similar to those you would see behind a boat on water.

tahanson43206 · 2023-09-14 14:27:20

For SpaceNut re #280

Thanks for picking up on this idea of Void's .... I think his idea is the missing piece for a complete lithographic ballistic delivery system.

Please continue developing your ideas for what the landing plow might look like... It needs to be light because it will be travelling all the way from Earth, and it needs to be strong, because it will be interacting with sand at speeds on the order of 1000 kph (or more, depending on how effective the atmosphere braking is). Magnetic guidance for the landing track might be helpful.

The energy of the arriving package might be collected, as the inverse of the rail guns that Calliban has been discussing recently.

(th)

Calliban · 2023-09-14 14:48:19

Rail guns in high orbit about the Earth, could be used to fire the projectiles onto a Mars intercepting trajectory.

For relatively small payloads, I wonder if we could slow them down at destination using some sort of inflatable heat shield, that is inflated using a stored gas. The shield could be triggered by rising temperature, as the projectile hits the ionosphere. From the discussion up to now, it is clear that we need to slow the projectiles to a surface intercept speed not exceeding about 1km/s for the projectile to stand a chance of surviving intact. That will impose limits on the maximum practical size of a projectile.

One option that I considered a while back was for a bus containing hundreds of projectiles that are all released from tubes by compressed gas moments before hitting the upper atmosphere. The problem with this idea is that even small variations in entry angle would disperse the projectiles over a very wide area of Martian terrain. Trying to hunt them down using a surface vehicle would then take a lot of EVA time. But as soon as you include a guidance system and trajectory control, you build complexity into the projectiles in a way that defeats the point. Maybe we could string them altogether using a polymer net that burns up at a predefined altitude. That would limit the effective dispersion when they reach ground.

Last edited by Calliban (2023-09-14 14:52:44)

tahanson43206 · 2023-09-14 15:27:37

For Calliban re #282 and renewed interest in this topic ...

It is good to see your ideas back in view!

One observation I would offer is that your point about the cost of guidance mechanisms is well taken if the packages are destroyed upon impact. However, the attractive aspect of Void's latest brainstorm is that the guidance mechanism need NOT be lost, if the slowing mechanism can be made to work. This problem is going to require some sophisticated 3D modelling, but fortunately there are now systems more than capable of dealing with the physics of the situation.

The video of testing of the US Navy rail gun, in another topic, showed plates being penetrated by the projectile after departure from the rail gun. It crossed my mind that those plates are fulfilling the role of slowing the projectile, while at the same time putting on quite a visual show for the audience.

A sand deceleration system might (somehow) involve interaction with ? walls ? of sand set in place before arrival of the projectile.

(th)

Calliban · 2023-09-14 17:39:31

I havn't read Void's proposal. I will track it down.

The ballistic impactors could be delivered to the top of the atmosphere by a reusable spacecraft on a free return trajectory. This would allow the projectiles to be delivered to an approximate area of Mars, without the spacecraft doing the delivery actually hitting the atmosphere. It wouod return to Earth without stopping. The terminal velocity in the Martian atmosphere is a function of frontal area density. So in theory, multiple projectiles could share a single large heat shield. This would slow the projectiles to ~1km/s. They would seperate when the heat shield hits the ground and is pulverised on impact.

tahanson43206 · 2023-09-14 17:57:58

For Calliban... to save you time, here is a quote from an earlier post in this topic:

In another topic, Void came up with a suggestion that may be new to the forum.

http://newmars.com/forums/viewtopic.php … 16#p213516

In this post, Void adds detail to his vision of using an incline to help to slow a landing vessel.

Many months ago, Void offered a vision of a way of landing material on Mars that eventually became this topic. The topic itself arrived at the conclusion that "lithobraking" is a reasonable idea if the arriving package bleeds off sufficient energy in the atmosphere so that it will survive encounter with sand on Mars.

Void's latest idea (of using an incline to assist with slowing) seems to me to lend itself nicely to the lithobraking concept worked out earlier.

(th)

tahanson43206 · 2023-10-02 11:55:36

Once again, Void has gifted the forum with an interesting idea that deserves further development.

In the general category of lithobraking, he has offered the suggestion that carbon and hydrogen might be delivered to the surface of Mars without a lot of energy expended to provide a slow, gentle, rocket assisted landing.

Void's idea was to package the hydrogen and carbon in the form of a chain, which would be released from a vessel on approach to the surface. Void's idea (as I understand it) was to lighten the load on the landing vessel, by ridding itself of payload that could withstand the fall from some height.

I am interested in extending that idea all the way to orbit. It may be possible to package the chain in such a way as to enable it to withstand the heating it will experience as it encounters the CO2 molecules in the atmosphere of Mars.

It should be possible to discover the practicality of Void's original idea and my extension of the concept, using CFD software with runtime parameters set to the gravity and atmosphere of Mars. If the chain survives the flight to the surface intact, and without losing mass on the way, then it would provide an easy-to-retrieve bundle of refined product ready to feed into a fuel manufacturing plant on the surface. The output of the plant would be whatever hydrocarbon suits your preference, starting with methane, which was Dr. Zubrin's preferred fuel for a flight from the surface of Mars back to orbit.

We have no one in the active membership who has access to CFD software, let alone the ability to use it, so I'll take this opportunity to remind our non-member readers that there is no charge for membership in this forum. See the Recruiting topic for precedure. We have thousands of recovered User ID's ready to go back into service with ** real ** people in the driver's seat.

(th)

Void · 2023-10-02 20:42:42

I will offer some notions, (th), which you are quite entitled to ignore if it suits you.

Backshells show some level of survival after striking the Mars surface. Quite broken, but the materials if valuable might be retrieved. https://mars.nasa.gov/resources/26694/r … m-the-air/ Image Quote:

I don't know what the terminal velocity was for this object, or if it reached it after being ejected at a high altitude.

Terminal Velocity is discussed a bit here: https://space.stackexchange.com/questio … x-starship Quote:

9
I have been looking for the same thing. The only mention I found was on a blog post (https://www.neowin.net/forum/topic/1402 … st-flight/) which stated 66-68 m/s for SN8. If true, that would imply ± 320 m/s on Mars.
Despite Mars' lower value for g (3.72), the much lower atmospheric density of 0.02 versus 1.2 kg/m3 results in a much higher Vt. This of course assumes that everything else remains constant (mass, area, Cd).

So, mass makes the speed greater, surface area may make it less.

My suggesting is for what you want you want a strange, shaped disc.

I can't find an example. Let me suggest that you might rely on a Starship to deliver these discs through the atmospheric heat of entry. Since you want plastic, the material is going to be somewhat sensitive.

Let's put a bunch of them like a stack of plates into a metal cylinder on the back of the Starship. On the leeward side. Somehow, you are going to let those plates drop out of the canister at some high altitude. These might be a bit like a Frisbee.

Maybe you would have a Pez dispenser to shoot them out one after another.

Sot the weight vs. surface area will matter for each disc.

When they hit the ground if they shattered a bit, you might not care.

Other possibilities are a onetime cylinder capsule with an ablative heat shield that does the same thing dumps the disks out into the atmosphere at a rather high level. It does not need to be too high as at high altitudes, the air braking will not matter much.

And then you would have a robot go collect the scrap.

This may not fill you bill, but in time perhaps better replacements can show up.

I am trying to assist you.

Done.

Last edited by Void (2023-10-02 21:09:15)

tahanson43206 · 2023-10-03 06:29:32

For Void re #287

Your suggestion (as I read it) is to harvest the heat shield, which will be partially consumed by irritated CO2 molecules that object to being forced out of their comfort zone, but everything else will survive until impact.

May I offer a suggestion for your consideration?

Can you fashion an entire shipment of plastic (ie, Carbon and Hydrogen) into a single lifting body form, with the ability to steer itself to a precise landing site?

This method would (or at least could) deliver the entire quantity of hydrogen and carbon needed to make a return flight for a landing craft.

The oxygen will still need to be pulled from the air, but the critical element needed for the fuel is the hydrogen, and the carbon can be saved if it is not needed for this particular batch of propellant.

All in all, I think this Ballistic Delivery topic is coming along nicely.

We have several options to consider for study, and the lifting body design has distinct advantages.

It is even possible to imagine delivery of oxygen in some chemically bound solid form.

If I can persuade you to give your fertile imagination a workout, please see if you can add that to your vision for a plastic lifting body.

Your goal (if you were to accept it) would be to plan to deliver everything that Dr. Zubrin needs for his return flight, in a single package that lands precisely where he wants to land, and which contains every atom he needs to make propellant for his return flght. The package can be landed before the human landing ship leaves orbit, so the stash of atoms to make propellant can be assured.

All that would be needed to make propellant for the return flight is energy, and that can come from solar power and nuclear power, in some combination.

(th)

Void · 2023-10-03 07:25:59

Well, I think you have a form of what I suggested and yours is not without merit. I think you singular lifting body, needs to be a pancake of sorts, to provide lots of surface area for the amount of Mass. I was not yet entertaining an atmospheric entry, but supposed that the Starship would assist it though the heat.

I recall reading articles a time back of paper thin objects to send to Mars. There the idea was lots of surface area, relative to mass.

But, in truth I need to caution you that the reason I went for plastic for the Moon is that both Carbon and Hydrogen are in short supply, (So Far).

Mars has plentiful Carbon and Oxygen, and the Hydrogen mass of plastic is rather a small part of the total mass of the plastic.

And Mars does have better Hydrogen resources than the Moon as well, of course.

Perhaps in time a new substance can be found, but I don't know what that would be.

Done

tahanson43206 · 2023-10-03 07:34:29

For Void ... re #289

It is good to have your creative thinking at work on behalf of our future Mars adventurers.

It is highly likely that even more innovative mass delivery ideas will occur to you in days ahead.

If you have a friend who is a chemist, that person might be able to add to the value of the topic, by showing precisely what ingredients are needed to make methane, as compared to the ingredients in plastic. I assume the correlation is not one to one, but I expect it will not be far off. The idea that hydrogen is readily available on Mars seems a bit surprising, since Dr. Zubrin was planning to bring a supply for lack of it.

If you ask your chemist friend what package of materials would be most convenient to have in order to make propellant for a return trip from Mars, I'd be surprised if that person suggested pulling atoms from the atmosphere over having them delivered in a compact bundle that just needs to be scooped up and fed into machinery.

(th)

tahanson43206 · 2023-10-03 07:37:58

This topic is available for a chemist to contribute. The question at hand, based upon innovative thinking by Void, is what combination of atoms in solid form would be most advantageously delivered to the surface of Mars using a combination of atmospheric braking and lithobraking, so that a clever expedition member could make propellant for the return trip without having to bother with processing the atmosphere.

All that would be needed in this scenario is energy, and storage tanks for the product.

Since it appears our resident chemists have taken some time off, it might be time to remind our readers that membership in this forum is free. See Recruiting Topic for procedures.

(th)

tahanson43206 · 2023-10-03 10:18:43

For Void ... Just FYI .... carbohydrates contain everything Dr. Zubrin would need to make propellant after landing on Mars.

Carbohydrates are composed of carbon, hydrogen, and oxygen and have a general formula that approximates CH2O. They are polyhydroxy aldehydes or ketones or form polyhydroxy aldehydes or ketones when hydrolyzed. Carbohydrates occur as monosaccharides, disaccharides, oligosaccharides, and polysaccharides.
Carbohydrates - an overview | ScienceDirect Topics
www.sciencedirect.com › topics › neuroscience › carbohydrates
About Featured Snippets

a shipment to Mars might be packaged in a plastic lifting body with a plastic leading ablative surface and filled with suitable carbohydrates in solid form.

Whatever is left over after making propellant could be blended into fuel for humans.

(th)

tahanson43206 · 2023-10-03 12:13:23

For Void re packaging carbohydrates for shipment to Mars, for Dr. Zubrin to use to make propellant.

It appears that glucose can be prepared in solid form (dextrose hydrate), and that it can be separated into it's components, to make methane and oxygen.

It appears that one ton of glucose can make one ton of propellant. I am not a chemist, and I am unsure of the accuracy of this prediction.

If a chemist is available, please confirm the accuracy of the analysis.

Since we have no active chemists among our resident chemists, I invite anyone who is interested in helping the Ballistic Delivery topic to see the Recruiting topic for procedure.

(th)

SpaceNut · 2023-10-03 18:39:37

Ballistic delivery must retain the contents without it breaking as the cargo is them not really worth much in the early stages of buildup of mars.

Also, we must plan the equipment required to build up the soft-landing sights loose regolith so that we can make use of it.

GW Johnson · 2023-10-04 09:18:34

If you put your cargo atop some sort of heat shield, and do direct-entry aerobraking right off the interplanetary trajectory at a shallow angle, then with a large ballistic coefficient you will come out of hypersonics at local Mach 3 at very low altitude on Mars. Your velocity will be close to 0.7 km/s, and your altitude in the 1-10 km range, for objects from about a ton to around 10 tons, including the heat shield. You path angle will have drooped to crudely 45 degrees. You are a single handful of seconds from impact.

The heat shield will be utterly destroyed upon impact, as this thing creates a rather significant crater. A significant portion of your cargo is likely to vaporize, a notion based on observations of what happen with aircraft and missiles that crash at supersonic speeds. In any event, the impact is violent enough to shatter any conceivable material, and scatter the pieces quite widely. Some of it will be buried under the crater floor after the event is over. Most of the rest gets far-flung outside the crater along with the displaced regolith. It's quite thinly spread. That is just not very "recoverable".

If you don't want to deal with vaporization and shatter/scatter effects for the majority of your cargo, then you need to decelerate it below about local Mach 1 on Mars, which would be around 0.22-0.23 km/s speed. You will not be able to use a chute to do this, there isn't time to deploy one, much less have it do any significant deceleration. Besides, we have no chute designs that survive opening at Mach 3; even the ringsail we use on Mars opens at or below Mach 2.5, and even then its survival at a full Mach 2.5 is "iffy". (Ask the guys at JPL if you don't believe me.) Ordinary ribbon chutes have a max speed limitation in the Mach 1.5 to 2 range.

Those physics pretty much leave you with two, and only two, options for crashing cargo onto Mars with any practical hope of recovery. (1) reduce the ballistic coefficient below about 100 kg/sq.m, which limits your entry mass (cargo plus heat shield) to a mere fraction of a ton. (2) add some retropropulsion to it, to reduce its speed below Mach 1 before you hit. That can be quite difficult to do with the heat shield in the way, with only a single handful of seconds to impact if you fail.

I'm sorry, I see no other practical ways to do this "lithobraking" thing. If you hit supersonic, there will be little or nothing left that is recoverable. You simply have to hit subsonic! And there is no time to use a chute if your ballistic coefficient exceeds about only 100-200 kg/sq.m. Multi-ton objects will have ballistic coefficients in the 300-1000 kg/sq.m range. That is the EDL quandary that all the landers ever sent to Mars have had to face.

GW

Last edited by GW Johnson (2023-10-04 09:31:37)

tahanson43206 · 2023-10-04 12:09:38

This is for kbd512 re GW's observation that the default behavior for a blob of atoms encountering the surface of a planet is to splatter. That is what we see on Earth at impact craters that survive, and it is what we see preserved on the Moon and Mars and countless other places.

However, I want to deliver glucose to Mars without parachutes or paraphenalia of any kind, and I want to do it without the default spatter that GW correctly describes.

By any chance, do you have knowledge of how to set up a shaped charge?

I'm wondering of a combination of shaping the material inside the delivery canister, and making the canister of a material that can contain the glucose will help.

(th)

tahanson43206 · 2023-10-04 12:17:45

For all ... the challenge and opportunity of this topic is to design a system for delivery of material to Mars without parachutes or retro rockets or other paraphenalia.

The items to be delivered are elastic balls which cannot be injured or damaged in any way by a change of direction caused by collision with a mass as large as a planet. The elastic forces at work follow very predictable paths. In the absence of any containing forces, the little elsastic balls collide with each other until there is no room to continue the path they were on, at which point they rebound in random directions.

It might be possible to ship product like glucose in a cylindrical container with a balloon at the stern. the idea I have in mind is to use the cylinder to contain the bouncing atoms in the horizontal direction just long enough to cause them to explore the stern as an option, at which point they would inflate the balloon. If everything has been designed correctly, the balloon should allow the momentum of the elastic balls to be dissipated over a period of time, so that eventually the entire collection shrinks back down to it's original size, under the influence of the cold on Mars.

(th)

GW Johnson · 2023-10-04 13:43:35

Somewhere, and I don't know where, I once had a photo taken of the crash site of an F-8 Crusader in Ohio, I think it was. The plane struck near-vertical at around Mach 2 (which on Earth would be around 2000 ft/sec, or around 700 m/sec), and blew a crater in the ground, including bedrock, with the volume of a large house or a small barn. There were no recognizable bits of aircraft anywhere in the vicinity after the crash. That's about a 16 or 17 ton item (US tons).

That should tell you what you are really looking at, and it is for speeds well below those that define planetary entry! Stuff moving that fast (entry speeds) just makes far bigger craters and vaporizes far more rock. All materials, without exception, briefly become essentially fluids composed of individual atoms or molecules at such conditions. That is still true at "only-supersonic" impact speeds, there is just a lot less vaporization. But there are no solids as we understand them, at such conditions. If it ain't solid, it contains nothing.

GW

Last edited by GW Johnson (2023-10-04 13:45:03)

Calliban · 2023-10-05 08:51:10

GW Johnson wrote:

Those physics pretty much leave you with two, and only two, options for crashing cargo onto Mars with any practical hope of recovery. (1) reduce the ballistic coefficient below about 100 kg/sq.m, which limits your entry mass (cargo plus heat shield) to a mere fraction of a ton. (2) add some retropropulsion to it, to reduce its speed below Mach 1 before you hit. That can be quite difficult to do with the heat shield in the way, with only a single handful of seconds to impact if you fail.
GW

The value of the lithobraking idea rests upon its ability to deliver low value commodity products (things like industrial metals, oatmeal, powdered milk, etc) without the need for any active propulsion, guidance or landing systems, except for a dumb heat shield. We send a ship on a free return trajectory and release the cargo a few days before closest approach. The ship would return to Earth, the cargo would hit the Martian atmosphere. I think a ballistic coefficient of 100kg/m2 is acceptable. The materials delivered would be packed into steel shells representing about half of total projectile mass. The heat shield would be a sphere that would inflate around the shell. We might even use water as the inflating agent, allowing it to boil into steam from the heat flux of entry. A total payload of 100 tonnes, could be divided between a couple of thousand spherical projectiles.

The main difficulty I can see is retrieving these payloads from the surface. There are electronics that can be built into shells that would allow individual payloads to be tracked. But if we release a cluster of payloads at the top of the atmosphere, they could disperse over an area of hundreds of square miles by the time they hit the surface. A lot of EVA activity would be needed to collect them up on the surface of Mars. The best option I can see is to divide payloads into small units and hit the atmosphere dead on rather than at an angle. Individual spherical packages would be wired together, so that they make it some way into the atmosphere before atmospheric friction destroys the wires. If we time the deliveries to consistently impact the same area on Mars, we can establish a small base whose dedicated function is to go around collecting the projectiles. Likely we want to pick an area close to the equator, with deep accumulations of loose sand.

Last edited by Calliban (2023-10-05 08:55:25)

tahanson43206 · 2023-10-05 09:26:40

For Calliban re #299

Thank you for coming back to the rescue of Lithobraking topic ...

I thought we had pretty well confirmed that Void's idea could be made to work, but obviously it needs to be shorted up from time to time.

the latest wrinkle is that I have confirmed (within the margin of error) that a shipment of glucose to Mars would provide ALL the atoms Dr. Zubrin needs to make methane and oxygen for his return trip. The trick is to deliver that cargo safely to the surface, and in such a way that it does not turn into liquid as GW Johnson has predicted.

The solution seems to be (as nearly as I can tell) to use aerobraking just enough to insure the survival of the delivery package.

We can also use prepared receptacle sockets for the deliveries. These would be holes dug into the regolith, or found if they are naturally available.

If the cargo turns to liquid as Dr. Johnson predicts, that would be acceptable, if they are all still inside the socket after the dust settles.

***I logged on just now to ask for your assistance with the rotary propulsion initiatives.

(th)

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Re: Ballistic Delivery of Supplies to Mars: Lithobraking

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