Ballistic Delivery of Supplies to Mars: Lithobraking

Calliban · 2021-01-26 03:28:36

OK, the brine tank idea was a long shot, literally. The speed with which the door would need to close makes the idea impractical, at least for a tank 100m in diameter. The larger the tank has to be, the more it costs. It also requires that shells are delivered with extreme accuracy. If even one of them is out by a few metres, then that is the end of the brine tank.

The crude heat shield idea is only workable at all if the target for the projectiles is the surface of Mars. The idea is to slow them down sufficiently that they survive the impact more of less intact - say impact speed no greater than 1km/s for solid metal projectiles; <500m/s for other stuff like rugged components, cement, grains, etc.

The problem with most of the suggestions that might actually work is that they introduce additional complexity and cost. The whole point of Void's ballistic delivery concept was to provide a cheap or at least cheaper way of delivering certain materials to the surface of Mars, that avoids the sort of design complexity that we saw in the skycrane needed to deliver Opportunity.

None the less, I believe that Void's idea has sparked a useful discussion. There is value in examining minimum cost delivery solutions for materials to the surface of Mars. If we can live with an impact velocity of 500m/s, then a heat shield alone may be a sufficient solution. Maybe an additional drag chute that operates on a timer after hitting the top of the atmosphere. The smaller the projectiles are, the simpler the reentry solution, because aerodynamic drag will be more effective in slowing them down. Just a few thoughts.

tahanson43206 · 2021-01-26 07:27:28

To everyone who contributed to this topic, Bravo! and Thanks!

With Calliban's summary in Post 51, we have a nice cap for this early phase of an examination of Void's idea ...

None the less, I believe that Void's idea has sparked a useful discussion. There is value in examining minimum cost delivery solutions for materials to the surface of Mars. If we can live with an impact velocity of 500m/s, then a heat shield alone may be a sufficient solution. Maybe an additional drag chute that operates on a timer after hitting the top of the atmosphere. The smaller the projectiles are, the simpler the reentry solution, because aerodynamic drag will be more effective in slowing them down.

(th)

SpaceNut · 2021-01-26 19:33:43

One of the ideas I have is to make it with a scissor wing unit to unfold in the thicker atmosphere due to lift created by a wing it will slow down if given the chance to an impactable speed that will allow for survival of more of the kinetic payload being delivered.

Calliban · 2021-01-27 04:19:25

tahanson43206 wrote:

I am looking for a solution that invests energy at departure from Earth sufficient to place the spacecraft right at the surface of Phobos when Phobos is receding from the approaching spacecraft. This would yield an optimum solution to Void's Ballistic Package Delivery concept.
(th)

The thought occurs to me, that I have subconsciously constrained my thinking. If the objective is to deliver projectiles to some sort of receiver in Mars orbit (maybe mounted on Phobos, maybe not) then there is nothing to say that the projectiles need to be the size of artillery shells. We could store bullet sized projectiles in some sort of bus and dispense them maybe 100km prior to impact with some sort of receiver.

That receiver could be an area of Phobos regolith, covered with a quilt of two sheets of woven fibreglass, which are separated by a gap of a few inches. The projectiles would punch holes in both fibreglass sheets rather like a bullet and would then deposit their energy in the trapped regolith beneath the sheets. The fibreglass sheet would capture any regolith ejected beneath and between the two sheets. When enough projectiles have accumulated, we would remove the quilt and pull the projectiles out of the regolith using an electromagnet.

I do wonder however, what benefit such a Phobos delivery system could offer to a Mars colony. Having delivered the material to Phobos, you still need to get it down to Mars surface. Unless that is, Phobos is where you are building whatever it is that you want to build.

For delivery of projectiles to the Martian surface, one way of reducing velocity prior to impact is to make them smaller. Ultimately, we would want a system that allowed heat shield thermal protection to be sprayed, cemented or cast onto them. We could adjust impact velocity for different materials, simply by reducing the density of material packed into a standard steel shell casing. This allows us to tailor the net density of the shell, which would effect its terminal velocity in the lower atmosphere of Mars.

After impact on say an area of several square miles of Martian surface, we could retrieve projectiles by driving a surface vehicle over the regolith which is equipped with an electromagnet on its chassis. This would suck any buried projectiles out of the regolith. To keep the circular error probability of projectile impact point to no more than a few miles from an intended target site, the projectiles would need to be carried within a bus that would expel them using compressed gas immediately prior to impact with the upper Martian atmosphere. If any part of the bus reaches the surface of Mars, we may be able to harvest its fragments as well.

Last edited by Calliban (2021-01-27 07:23:57)

kbd512 · 2021-01-27 10:18:37

SpaceNut,

What you're describing is the Snakeye bomb that we drop at very low altitudes. Snakeye uses steel fins that are deployed upon release to greatly increase drag to give the aircraft that dropped it sufficient time to clear the blast radius. How about we give up on this idea of using a cannon to shoot projectiles to Mars and instead consider a sling-a-tron launching something analogous to Snakeye?

There are too many technical issues to overcome with a cannon that can launch projectiles at escape velocity, even from the surface of the moon. In contrast to a hyper-velocity cannon of some kind with tens of thousands of gees worth of acceleration, a sling-a-tron can bring the velocity of the projectile it releases up to speed slowly enough that an enormous quantity of electrical or chemical energy doesn't have to be released in a fraction of a second. Since a sling-a-tron uses an electric motor to spin the payload up to escape velocity prior to release, no propellant chemicals are required, nor novel forms of energy storage such as super capacitors or flywheels. If the sling-a-tron is located on the surface of the moon, then no atmospheric heating / drag / sonic boom / nuclear attack issues are in play, either.

Here on Earth, the hyper-velocity rail guns can't use Aluminum or Magnesium alloy projectiles because the projectile will deform enough to induce a catastrophic failure in the gun barrel before the projectile melts outside of the barrel in Earth's atmosphere. That tends to limit what kinds of materials are suitable for launching at escape velocity, mostly Iron / Titanium / Tungsten / Copper / Silicon metal alloys or expensive high-strength composites.

Suppose we did sling Snakeyes off the surface of the moon. We'd need a small mid-course guidance correction computer and propulsion unit, perhaps CO2-based cold gas thrusters, the fins and heat shield could be made from Basalt fibers, and the external surfaces could be coated in PICA. The payload could be a sphere of metal. I can't think of a good reason to send water or minerals like Sulfur to Mars, but metals mined from the surface of the moon, where it's much easier to get mining equipment and nuclear reactors to, would be a good candidate for supplying building materials for Mars. We really need to figure out how to make a heat shield fiber using lunar regolith.

The only materials were expending are low-cost Basalt fiber-reinforced composites and a heat shield coating. We'll simply allow the payload to crash into the surface of Mars, rather than trying to work out a sophisticated capture mechanism. That only leaves mining metals from the surface of the moon, building a sling-a-tron, and supplying the input energy to do all of that. Eventually, mining is a necessary step for creating a technologically advanced civilization on Mars as well, but we need to identify the best sources of raw materials first, as well as methods for mining and refining ores on Mars.

tahanson43206 · 2021-01-27 10:20:25

For Calliban re #54

Thanks for keeping this topic going a bit further ... I had thought it might have run out of energy, so am delighted to see your additional insights!

Regarding the use of Phobos as a Port of Entry for Mars ... this is an old idea, thoroughly thrashed out and then allowed to flow under the bridge like everything else in this forum.

The development of a robust taxi service between Phobos and Mars is guaranteed, if the population of Mars imposes border controls, as any sane group of people would do after they've achieved enough to become vulnerable to dangers from outside the planet.

Humans, by there very nature, are absolutely guaranteed to become threats to others. They can't help themselves.

However, to your point about smaller packages for delivery of small quantities of needed bulk materials, such as seeds, refined metals, highly processed pharmaceuticals and a myriad of other substances that an advanced society needs and which I simply am unaware of or have overlooked in composing this endorsement for your idea.

Nature (the Universe) provides countless examples of delivery packages (insects, seeds, virus) that are small enough to waft on the winds of Earth. While the size of these packages would be much less on Mars, the principle still holds ...

Please DO continue to extend your thinking further along these lines!

Finally ... to your interesting suggestion of fiberglas(tm) or similar mats to hold the regolith in when projectiles arrive ... Please DO continue to develop this idea further!

I am off to investigate the possibility of finding a trajectory from Earth that puts packages (of any size) on Phobos with 1 or 2 meters per second of impact velocity, just sufficient to insure they arrive and form a (minimal) bond with the regolith.

***
Off topic ... I have no way of knowing if you like cats, but I know from your occasional comments that you are a family man. I'd like to invite your consideration of the Mars Convention 2020 video #44 featuring NASA scientist Geoffrey Landis. Dr. Landis is married to (Mary A. Turzillo) who is a science fiction writer in her own right, and they have a household featuring several cats. Dr. Landis' talk is likely to be of interest to anyone with a scientific or engineering background, and the charming domestic scene unfolding during the 45 minutes of Video 44 should be of interest to a great part of the population of Earth.

I've been following Dr. Landis' career as a scientist and as a science fiction (and fact) writer for quite some time. I am pleased to have this opportunity to bring this video to a (possibly) wider audience.

(th)

SpaceNut · 2021-01-30 21:09:19

I was remembering that the Orion at one time did have air bags for cushioning the landing and that test trials had been done. Even if these where under the heat shield and opened just before impact the effective cushioning might be enough under some payload numbers.

edit
https://en.wikipedia.org/wiki/Orion_(spacecraft)

To fill in numbers on the orion mass.
https://www.lpi.usra.edu/lunar/constell … tsheet.pdf

Orion will be 5 meters (16.5 feet) in diameter and have a mass of about 22.7 metric tons (25 tons). Inside, it will have more than two-and-a-half times the volume of an Apollo capsule.

https://www.nasa.gov/specials/orionfirstflight/

Water Impact Test. An 18,000-pound Orion mockup was dropped dozens of times into the Hydro Impact Basin at NASA’s Langley Research Center, allowing engineers to better understand the conditions the spacecraft may encounter when landing in the Pacific Ocean

https://www.nbcnews.com/mach/science/na … cna1025631
crashed into the Atlantic at 300 mph (480 kph) as planned, This was the second abort test for Orion, conducted at a speed of more than 800 mph (1,300 kph). The first, in New Mexico in 2010, was lower and slower.

https://ntrs.nasa.gov/archive/nasa/casi … 003410.pdf

tahanson43206 · 2021-01-31 08:06:13

For SpaceNut re #57

Thank you for the reminder of Orion and the air bags idea!

Recently (and before) Calliban has posted ideas for carrying Void's ballistic deliver idea further. One of them (as I vaguely recall it) was to prepare a landing/capture pit ahead of time, to gently decelerate an arriving cargo package.

There is a practical limit to the velocity and mass of the package that could be handled, but it might turn out the upper range of whatever that limit is would be quite attractive for bulk material delivery.

One of Calliban's ideas was a pool of liquid CO2 (that memory just came back)

In any case, I'm glad to see this topic continuing to struggle to achieve viability in the real world/universe.

***
anoither of Calliban's suggestions was a particularly interesting one (to me for sure). He has a record of thinking about magnetic launcher designs (as does kbd512), and recently (perhaps in this topic) he suggested using magnetic deceleration for an arriving cargo payload.

I wrote a reply (as I recall) reporting on a similar idea for a Lunar Transportation Loop to Lunar L1 and back to a magnetic track on the side of the Moon opposite the L1 point.

Capturing energy from a moving object using a magnetic field/track is the inverse of accelerating an object along a track to achieve escape velocity (from the Moon for example).

Energy has to be stored in high speed storage devices. Capacitors would be ideal. if they can be made capacious enough. There's been some progress, but not nearly enough for a ballistic capture operation. Still, it's worth keeping this idea in a ready access compartment for use when appropriate.

(th)

SpaceNut · 2021-01-31 09:54:51

Borrowed from Void's Ice cover lakes....with a twist

One could make dry ice with a covering of regolith to stop sublimation and under that is the liquid co2 pool. Now all we need is a beacon to allow for the targeting of the landing zone to become more accurate for the landing.

We may still need to put a reflective covering on top of it to keep it from warming as well. The walls inside where the liquid is contain could also need cooling refrigerant to keep the co2 in a liquid state as well for the landing.

Of course once the top layers are breeched we will be venting the liquid co2 into mars atmosphere which will require more energy to seal with a new dry ice layer to cap it so we can get it ready for the next landing.

Void · 2021-01-31 13:54:28

You all seem to really be doing something here. I am very glad that I was not here to, direct things because this way there is a whole bunch of good materials, that I would probably not have generated.
An ice covered lake might indeed work for some types of impactors.
Another strange notion would be to impact the side of a mountain or canyon with glancing blows. Of course such an impactor would also have to have special qualities to survive, and to navigate itself accurately. Also the impactor might end up buried too deep under a landslide. So, for this one skills would have to be developed to do it in a worthwhile fashion. This impactor might even have a "Greased skid bottom". Not actual grease, (Maybe tar?), but some coating that will shed. Maybe.
I have something quite different from the above, but I see that it is now becoming acceptable to do atmospheric breaking. Currently, I am thinking Frisbee + Helicopter blades.
I will develop a post about it. If allowed I will place that post as well, but I will not get mad, if you want to put it somewhere else.
Done.

Void · 2021-01-31 14:27:39

Helicopter + Frisbee + Solar Concentrating Mirrors >>> And other things?
https://www.walmart.com/ip/Plastic-Disc/176904523
https://www.walmart.com/ip/Plastic-Disc/176904523
What I want would be something like the following:
1) Can be stacked well in a starship cargo hold to be lifted to LEO.
2) Can be connected into arrays of solar concentrating mirror for space propulsion from LEO to Mars. (Ballistic Capture or Hohmann Capture methods). This would most likely be a electric drive, but I do wonder, since Hydrogen is considered for Nuclear Thermal, why not have a look at solar thermal? Perhaps a solar thermal preheat, and then finish it with microwaves?
3) Upon atmospheric entry and travel at Mars, it should have holes and not helicopter blades to make it spin, and maybe the spin would help stabalize it and maybe possibly have some lift somehow. I think that getting a proper shape for atmospheric stability is going to be a dominant property need.
4) For a heat shield, I prefer just metal, but ablatives might also have been sprayed on the the convex side. So unlike a space capsule, the heated surface would conduct heat to the convex leeward side, and that along with having a large surface area would possibly negate the need for an ablative heat shield, or tiles. I certainly prefer not to waste money and propulsion on a heat shield.
5) In some cases can "Sled down a slope". Might even be icy/snowy. You might need a "Smart" version for this. Less smart ones could impact CO2 Snow/ice or perhaps a sand dune.
6) If it gets dented up, perhaps a rubber mallet could do some good. It would be a bit like a shock absorber spring. You might have delivered a usable solar device to Mars.
https://en.wikipedia.org/wiki/Sledding
7) I would start with stainless steel. It should be possible to test these things to some degree from orbit and down to say a pressure of up to 12 mBar. But it may be possible to have other materials included in it's structure.
Its a start. I promise not to get into a hissy fit if you decide to move this post. Would be very happy to see others inovated on this and all the previous notions that are in this topic. Other things added are not offensive.
Done.

tahanson43206 · 2021-02-01 12:15:11

For Void re recent posts added to this Topic ...

Thank you for your contributions! It is good to see your ID in the flow, because (after all) this topic was inspired by one of your many ideas.

I noted your experience with electric devices of various kinds.

Recently, Calliban (I ** think ** it was Calliban) offered a suggestion for deceleration of rapidly moving cargo pods using electromagnetic technology.

The example he gave (as I recall) was of the electromagnetic launcher that is (for example) implemented (with great difficulty) on a US aircraft carrier.

What I'm hoping to tempt you to think about is how the familiar concept of a solenoid might be enlisted to decelerate a hot, glowing mass arriving from Earth with useful cargo. A solenoid (to the extend I understand them) appears to work if a solid cylinder of metal (chosen for its properties) is exposed to a magnetic field generated by coils in the cylinder into which the solid metal is introduced.

In a meeting of Tesla Coil enthusiasts, a year or so ago, I witnessed a demonstration of magnetic hysteresis (if I am using the right term). The demonstrator dropped a solid cylinder into a hollow cylinder, and it took "forever" for the smaller cylinder to emerge from the bottom. The demonstrator asserted that we had witnessed magnetic hysteresis at work (again, assuming I am using the right word).

To my knowledge, other than an ocean the size of the Pacific on Earth, there is no known way to decelerate a hot, glowing massive object arriving from space. However, this topic is broad enough to include thoughts along those lines.

(th)

Void · 2021-02-01 14:04:46

I can try to think of something. These ideas can be divided into ones requiring unusual precision, and those less precise.

The easiest target I can think of would a crater at high latitude in the winter.

Here is such a crater:

https://en.wikipedia.org/wiki/Korolev_(Martian_crater)

I only mention it here, because this would require a lesser precision. But still a very hard task. The impactor would be directed properly to the slope of the craters wall, presuming a favorable location. And then the impactor would go sledding. A parachute might be included, if the remnants of it we valuable to people on Mars. Perhaps a aircraft carrier type solution included?

That by itself would need a lot of precision, and so that complicates things. But if this could be solved, the solution might point to something for other members to work with.

Done.

Last edited by Void (2021-02-01 14:14:17)

Calliban · 2021-02-01 16:05:08

Void wrote:

I can try to think of something. These ideas can be divided into ones requiring unusual precision, and those less precise.
The easiest target I can think of would a crater at high latitude in the winter.
Here is such a crater:
https://en.wikipedia.org/wiki/Korolev_(Martian_crater)
I only mention it here, because this would require a lesser precision. But still a very hard task. The impactor would be directed properly to the slope of the craters wall, presuming a favorable location. And then the impactor would go sledding. A parachute might be included, if the remnants of it we valuable to people on Mars. Perhaps a aircraft carrier type solution included?
That by itself would need a lot of precision, and so that complicates things. But if this could be solved, the solution might point to something for other members to work with.
Done.

I think the ice covered crater is probably the best impact point in terms of limiting peak deceleration of the projectiles, because ice has a lower density than most of the Martian surface. The only thing that would make Korolev less than ideal would be if (1) It were remote from the location of our base, necessitating long distance transportation of the projectiles back to base; or (2) Our base was within the crater beneath the ice, where impacts would subject it to shock waves.

The problem with attempting to deliver projectiles to a very precise location is that this would mean including a guidance system and some sort of attitude control. That means building complexity and cost into the shells, when the whole idea behind the ballistic delivery concept was that it provides a cheap means of delivery.

SpaceNut · 2021-02-01 17:51:59

The frisbee shape is a heat shield and we know that one is needed to keep from wasting the material we are trying to get to the surface so Pica X is a given for that to work.

Skid plate sled carrier for a drop onto a solid ice surface would slide if its got a shock absorbing suspension to isolate the payload from it.

Korolev Martian crater would be a likely place with less energy being embodied to retrieve but it would only happen with a nuclear power source in winter and summer for a solar powered system.

There must be other such targets to use as well.

Void · 2021-02-01 19:54:03

OK, I guess I will make another run at this.
(th), you can move this post if you like.
Spacenut was trying to get me to look at: https://mars.nasa.gov/mars2020/timeline … MSF0951a18
-Peak heating will be

Peak heating occurs about 80 seconds after atmospheric entry, when the temperature at the external surface of the heat shield reaches about 2,370 degrees Fahrenheit (about 1,300 degrees Celsius). Safe in the aeroshell, however, the rover gets up to only about room temperature.

It does need thrusters, to stay on course, because:

As it begins to descend through the atmosphere, the spacecraft encounters pockets of air that are more or less dense, which can nudge it off course. To compensate, it fires small thrusters on its backshell that adjust its angle and direction of lift. This “guided entry” technique helps the spacecraft stay on the path to its downrange target.

Parachute:

Parachute Deployment
The heat shield slows the spacecraft to under 1,000 miles per hour (1,600 kilometers per hour). At that point, it’s safe to deploy the supersonic parachute. To nail the timing of this critical event, Perseverance uses a new technology – Range Trigger – to calculate its distance to the landing target and open the parachute at the ideal time to hit its mark.

The parachute, which is 70.5 feet (21.5 meters) in diameter, deploys about 240 seconds after entry, at an altitude of about 7 miles (11 kilometers) and a velocity of about 940 mph (1,512 kph).

In the thin Martian atmosphere, the parachute is only able to slow the vehicle to about 200 miles per hour (320 kilometers per hour). To get to its safe touchdown speed, Perseverance must cut itself free of the parachute, and ride the rest of the way down using rockets.

So, not using a parachute or vertical thrust, an impact of about a velocity of about 940 mph (1,512 kph), would be expected. I confess, I would think the impactor would be very mangled if it impacted strait down, and I still have deep reservations about an inclined plain path intercepting a slope covered with CO2. I guess you might still have wreakage to gather. I won't completely dismiss the notion, but am concerned about its value.
A supersonic parachute proportional to the above example, but for a "Backpack" ejected from a Starship, perhaps would yield about 200 miles per hour (320 kilometers per hour). This is more plausable.
For a impact using a parachute, it could be allowed to have a smaller proportional parachute, up to the point where the impact is just to intense to be practicle to deliver salvage of use.
So, this quote suggests that a parachute could slow down more than 1 ton??? I think that if parachutes were to be used it would be because the materials of the parachutes would be valuable.

The Mars 2020 rover, Perseverance, is based on the Mars Science Laboratory's Curiosity rover configuration. It is car-sized, about 10 feet long (not including the arm), 9 feet wide, and 7 feet tall (about 3 meters long, 2.7 meters wide, and 2.2 meters tall). But at 2,260 pounds (1,025 kilograms), it weighs less than a compact car.

I don't think that that weight includes the sky crane or it's propellants, cables, etc. So, maybe the picture could be better.
Still, it would be much less than a Starships capacity for cargo. Which then says either don't care about that, or put a multitude of them on the Starship and eject them all, or build a mini-Starship for a lesser number of them. In other words, the method may not be worthless to think about. And if you forget parachutes at all, you could have one big backpack and a whole lot of scrap.
So, I am not satisfied that this method will be worthwhile. But I am not done with it. Scrap from crashes might not be overlooked so this might have value.
I know that Elon Musk indicates that the Mars settlement(s) must be self sufficient, but a snap of the finger will not make it so. There will be a time interval between first human or robot landing, and self sufficiency. I think it is likely to take a significant period. So, for some materials it might be considered to try the above method(s).
By a backpack on a Starship, I indicate that this device would be on the leward side, above the engines and some way up to the nose or to the nose.
An interesting notion just occured to me, that in this case, you might actually land the Starship with the backpack on, and not save propellants, but possibly have an easy way to release it from the ship to the ground. Then the Starship does not have to lift a cargo hold back to orbit(s). And so then would save propellants, and if it is to be unloaded/scrapped, then it is on the ground fairly intact. Also, I would suggest that for this method, less engine power is needed to land the ship safely. That might matter.
However, a release during the 7 minutes of terror, would reduce the terminal velocity of the Starship, and that would be helpful, if it could be done safely. You would save propellants on landing and on lifting off. However for this Starship you could lift little or no cargo to orbit after than, unless you put a new backpack onto it.
You could simply deliver backpacks to Martian orbit, and send this version up to bring them down one at a time.
Clearly a ~vertical impact will shatter the device, to a degree, less for 200 mph and parachute, and severly at 940 mph and no parachute.
A vertical impact would likely be best done into relatively pure ice such as Korolav Crater, or maybe some created ice body??? Mainly because with a metal detector and means to dig you should be able to retrieve much of it.
My understanding is that the Martian atmosphere is so thin that Meteors will shatter on impact. We this is not about collecting Meteors though.
For the backpack, I have a notion of structure, which might be improved by others or myself, presuming anyone ever uses this method.
I choose to name 3 classes of materials.
1-Delicate (Machinery and humans, animals).
2-Moderate (Strong Machine Parts, and some Foods).
3-Processed Materials. For the moment I choose to view only Stainless Steel, Aluminum, and Copper.
I exclude the class 1 from this proposed hard lander.
I have begun to include some possible members of class 2.
I do, of course include class 3.
So, I have something that was induced in my head by Dr. Robert Zubrin. Stress ratios for atmospheric entry.
Entering Earths atmosphere from LEO ~ 8.0
Entering the Mars atmosphere from interplanetary space, probably a Hohmann Transfer ~ 6.5
Entering the Mars atmosphere from low Martian orbit ~ 4.0
For me this works better than actual speeds. If Starship can survive entering Earths atmosphere, at ~8.0 for stress, then either form of entry to the Martian atmosphere should be easier.
So, then bogus thinking or not, if bare Stainless Steel is good for the Leward Starship for descent from LEO, it should be fine for leward side where the backpack would be, for both Martian entry modes.
Stainless Steel https://en.wikipedia.org/wiki/Stainless_steelless , Steel as a backpack "Shell".
Melting points of Stainless Steel:
https://en.wikipedia.org/wiki/Stainless_steel
That's a nice web site good temperature tables. Remember, that if needed heat shield could be on the backpack.
OK, I came up with this for Copper, I hope it is appropriate: Copper Foam.
https://www.americanelements.com/copper-foam-7440-50-8
So, the backpack can have a lot of Voids, if you want to reduce it's terminal velocity.
Similarly I hope that Aluminum Foam can be made.
https://en.wikipedia.org/wiki/Metal_foam
So, now there is a possible fill for the backpack with possible useful thermal and impact modifying characteristics.
So, those 3 above are what I called class 3 materials.
I am hoping that the nature of this backpack would be that you might include some class 2 items inside.
------
Another thing I have mentioned is precision and accuracy of impact. By having the Starship take the backpack approximately to where it is wanted, part of the problem is solved for impacts. Either a ~vertical impact, or an inclined plain impact on the crater rim of Korolav Crater, or similar places. It may be that the crater rims are large enough that it would usually work to impact an incline rim. And those might be covered with snow.
If you want more precision than that you have to invest in the control devices to allow it, and those would be destroyed on impact.
However maybe you could build a sliding place and go ahead and add navigation and thrust to these impactors. It would be quite alot about what such junk is worth on Mars, relative to the expense of getting it there.
$$$$$
I'm pooped. You realize that I only mentioned the impactors as a passing throught, and now much has been invested. I hope that some type proves to be of use. I have a few more that are different than this one.
No spell checking today. My computer gets bogged down as soon as I linger at NewMars.com
Done.

Spacenut, a couple of points. Nuclear is OK in my book, but the south facing rim of Korolav, would be a good place to frack, so as to store high heat from solar concentrators in the summer also for use in the winter.

As far as the mirrors falling out of the sky, that remains to be seen what heat shield protection they need. It would depend on their surface area and inertia. Also I a hoping that some of the built up heat of the windward side will conduct to the leeward side and be radiated off. Not proven, but the heat shielding if needed should not need to be anything as strong as for the windward side of Starship.
But there is much to learn. The heat stress for entering Martian atmosphere is ~4.0 relative to for LEO into the Earth's atmosphere, ~8.0. So it may be about 1/2 as hard. I was surprised by that. It seems that coming from the Earth to Mars by Hohmann, is ~6.5 in relative stress. These are ratio's that I created based on speed numbers that I have read about. And remember, it is Stainless Steel most likely. Falcon 9 fairings have heat shields, but I believe that they are not Stainless Steel. Honestly, you might catch me wrong to the degree that their must be some heat shield, but I would go ablative, as the mirrors are only going to enter the atmosphere, and will also bang hard on the ground a get scrapped up.

Yes, I think it was said that you could ski on the Moon on just the dust. Don't know how true. But a lesser effect must exist on Mars, where gliding down an incline may be possible.

Done.

Last edited by Void (2021-02-01 20:00:48)

Calliban · 2021-02-02 07:48:23

Assumption: impactor is shaped like a bullet, using friction with regolith to slow down on impact.

Type 1 landing (cheapest): aeroshield deceleration only. Typical impact velocity is 1000mph = 450m/s. Note that impact velocity will be smaller for a smaller projectile, as air resistance will have more effect. We can calculate peak deceleration based upon the penetrative depth of the projectile into its target. For a solid projectile made from solid metal say, density would be ~5000kg/m3. The density of Martian regolith is ~2000kg/m3; density of ice = 1000kg/m3. So a 1m long projectile will penetrate ~2.5m into regolith and 5m into ice. Deceleration = 4100g in regolith 2060g in ice. Deceleration time = 0.1-0.2 seconds. Typical pressures on projectile 1m long and 0.5m wide = 26-51MPa. Yield strength of plain carbon steel ~400MPa (for comparison).

Type 2 landing (intermediate cost): aeroshield and parachute. Typical impact speed ~200mph for an object with the mass of Opportunity. Deceleration on impact = 400-800g. Note: for small payloads impact speed will be less. For deceleration of 800g, typical pressures on 1000kg projectile would be 10MPa.

Type 3 landing (expensive): aeroshield, parachute, rocket deceleration. Deceleration on impact ~0g.

Some figures for tolerance to shock:

Shock capability of mechanical wrist watches: 5000g. This would suggest to me that most solid machine parts would survive a type 1 landing if they were properly packaged. Things like drill bits, rhodium bushes for cast basalt fibres, etc.

Rating of electronics built into military artillery shells = 15,500g. This suggests that we should be able to fit each impactor with a radio location device that allows us to track its landing position. It also suggests that well packaged electronics can survive a Type 1 landing.

Brief human exposure survived in crash = >100g. This suggests that only type 3 landings will be suitable for human beings, although there may be options to consider for very small 1-man capsules.

Complex machines like computers and mechanical equipment, will require either a type 3 landing, or maybe a type 2 landing for some relatively small assembled payloads. We could potentially deliver individual components with a type 1 landing and then assemble them into what we need on Mars. Metals, chemicals, food, etc, could all be delivered using a type 1 landing. A successful type 1 and type 2 landing requires that individual payloads are quite small <1 tonne, as they need to decelerate to speeds <1000mph on impact in the thin Martian atmosphere.

For a type 1 delivery to make financial sense, the entry vehicles should be dumb with no active guidance after atmospheric entry. If the sensible Martian atmosphere is 100km deep, this may mean that payloads end up impacting the surface a few kilometres from the intended impact point. I don't think that is a big deal so long as we know where they have landed, I.e we can track them.

I don't see it making much sense trying to deliver payloads like this on a Starship and ejecting them prior to entry, when the Starship already has its own purpose built rocket driven landing system. A vehicle carrying payloads intended for type 1 or 2 landings does not need to decelerate for Mars orbital injection or landing. It would be an expendible bus that would release its payloads shortly before crashing into the top of the Martian atmosphere. I would anticipate that type 1 delivery would only make sense during the early stages of Mars colonisation, as it is most useful for delivery of food, materials and solid machine parts; things that we would ultimately aim to manufacture on Mars rather than ship from Earth. When Starship travel to and from Mars becomes routine, shipping costs will be reduced to the point where it will no longer be beneficial to risk the sort of damage that could occur in a type 1 landing.

Last edited by Calliban (2021-02-02 07:56:11)

tahanson43206 · 2021-02-02 08:19:07

For Calliban re #67

Thank you for this comprehensive analysis of the potential of ballistic cargo delivery to the surface of Mars!

I think your analysis would/does deserve publication in a physical medium. Years ago the appropriate title would have been L5 News.

However, time has passed and I've lost track of the publications that have achieved lasting success in the Space business.

Void deserves a mention in the byline, for having initiated the discussion that led to the result you have provided.

I think the cost of an electronics tracking package for each Type 1 impactor is justifiable as a trade for the time needed for automated retrieval equipment to find the cargo. Sacks of coffee (and countless other consumer products) are fitted with chips so they can be detected if they walk out of the store without payment. Considering the cost of propellant to carry the payload all the way to Mars, the cost of a small electronic tracker package seems (to me at least) a modest part of the overall cost. These projectiles would be arriving in the thousands, so the electronics would be mass produced.

If an article comes into existence because of your development of Void's idea, it would be a favorable exposure for this forum as part of the Mars Society.

SearchTerm:Ballistic delivery of cargo to Mars - Three levels - See post #67 by Calliban

(th)

SpaceNut · 2021-02-02 09:58:26

Remember, I was told that no items for 2 an 3 protection were allowed in a ballistic payload to the surface as wished from the onset not even a heat shield.

I put all of that in the other topic that generated from the voids starting point of the belly slide in which the impactor is shaped like a bullet is how the starship would glide in....as up until that point we are at a ballistic entry.

For information only....
The space shuttle's tiles were designed to absorb the heat of re-entry, as the 77 tonne orbiter went from 28,000 km/h to zero.

Mars payload insertion to mars with cruise stage is 15mT at orbit where after firing the engines to break inward towards the planet we are delivering under 2 mT to the surface....Curiosity had the largest aeroshell ever sent to Mars, measuring 4.5 meters across. The parachute deployed in a fraction of a second, and when fully inflated, experienced 32,000 kilograms of force. If you were on board at the time, you would experience 3.6 times as much force as crashing into a wall going 100 km/h wearing your seatbelt.

https://aerospace.illinois.edu/news/dev … icles-mars

vehicle entering the Martian atmosphere at hypersonic speeds of up to Mach 30 and then slow down quickly due to air friction. Once they reach Mach 3, they deploy a parachute and fire their retrorockets to slow down further.
The problem with heavier missions, according to Putnam, is that parachute systems do not scale well with increasing vehicle mass.

tahanson43206 · 2021-02-02 10:06:22

This is for SpaceNut .... in his post #67 above, Calliban has made another significant contribution to the forum, and to the topic set up to explore Void's idea in particular. In your role as Senior/Lead Administrator, it would seem appropriate for you to think about the suggestion I am about to offer ...

The main page of the forum displays a teaser for an article that dates back to 2018 ... the article reflected ongoing discussion at the time.

There might be an opportunity to post a new article in that place, while keeping the one that is there now in an archive. That is a common practice on other web sites, and it may be possible on this one.

Here is the text that advertises the article we have now:

ON MARS, AIR AND WATER MIGHT BE THE KEY TO POWER STORAGE
By Josh Friedman on November 19, 2018
Martian air and water might be all that’s needed to store energy on the Red Planet, according to a recent discussion on the NewMars forums. Solar power, perhaps in the form of a Solar Power Tower, is one of the strongest contenders for a system to generate energy for a pioneering Martian settlement. However, solar power systems only generate energy when the Sun is shining. This creates a need to store energy to keep the lights on at night.

Post #67 is not quite suitable for posting as an article, but it has all the elements around which an article worth publication could be constructed.

The article could contain links to posts as part of its content. That would be a departure from the example of the Air and Water article, and quite common practice in modern Internet hyperlink style writing.

We do this already inside the forum, so this would be routine for authors working here, and to readers of the forum.

By doing this, we could change the way we advertise Calliban's work .... instead of offering the entire article to selected trade journals, we could offer a link to the article posted on the front page of the web site.

The goal here would be to connect with a person with deep pockets and massive ambition, who could turn Calliban's outline of a business concept into real hardware delivering real goods to Mars over the next ten years.

We presently have no physical examples of the proposed delivery technique to study ... Calliban has show a way forward ... A test probe would include the impactor and a lander that would observe and survey the results.

NASA has already provided an example worth noting.... They created an impact on the Moon to study debris ejected from the site to try to find water. They deployed an observer probe to send data back to Earth.

The proposed business exploration would send one (or more) impactors and one or more observing probes, and at least one soft lander to evaluate the performance of the delivery method.

(th)

SpaceNut · 2021-02-02 14:19:34

The hot list of topics and post to be created by the Admin is something we have on a waiting list for development for the front page of NewMars. It would function simular to the one on the NasaSpaceFlight home page.

Was thinking about the problem of how to slow the incoming payload down so that the impact would be less violent to what we are trying to protect and aside from expanding the surface area of the shape which we are using there are no other ways to cheat physics.

Calliban · 2021-02-02 16:39:01

SpaceNut wrote:

Mars payload insertion to mars with cruise stage is 15mT at orbit where after firing the engines to break inward towards the planet we are delivering under 2 mT to the surface....Curiosity had the largest aeroshell ever sent to Mars, measuring 4.5 meters across. The parachute deployed in a fraction of a second, and when fully inflated, experienced 32,000 kilograms of force. If you were on board at the time, you would experience 3.6 times as much force as crashing into a wall going 100 km/h wearing your seatbelt.

That is useful to know. From what you are saying, some 15 tonnes of payload had to be launched on trans-Mars trajectory to deliver <2 tonnes to the surface. That would make delivering anything by soft landing quite expensive.

I think ultimately, type 1 projectiles would be delivered by a modified Starship that is launched into Earth orbit. The ship would never actually land on Mars and would not be a manned vehicle. It would carry type 1 projectiles in long tubes. We would fuel the Starship in Earth orbit and put it on a free return trajectory that actually impacts a specific point on Mars. A day before impact, we use compressed gas to expel the projectiles from the tubes. The Starship then carries out a course correction, allowing it to miss the surface of Mars and return to Earth on the free return trajectory. The projectiles remain on course to enter the Martian atmosphere, decelerate using aeroshield and impact the surface. When the empty Starship arrives back at Earth, aerobraking is used to decelerate back into Earth orbit. At this point, the ship is reloaded with new projectiles and fuel. This arrangement ensures that the only fuel needed by the Starship is that required to achieve Earth escape velocity from LEO and trans-Mars injection. Aside from the relatively small adjustment needed to avoid impact, no additional propellant is needed because the Starship itself will not be slowing down at Mars.

I would certainly like to contribute to an article at some point. At the moment, we are working with back of the envelope type calculations, trying to assess whether a concept might be workable. It looks like it could be. We would need a more scientific method before condensing the discussion here into an article. Specifically, we need a way of modelling atmospheric entry and assessing how mass, shape, size and density effect impact speed. For the supersonic phase in which air is incompressible, the Newtonian projectile approximation could be used to model rate of deceleration and heating. Once beneath sonic speeds, more classical fluid mechanics can be used, in which drag forces are roughly proportional to the square of velocity.

Last edited by Calliban (2021-02-02 16:40:25)

SpaceNut · 2021-02-02 16:49:02

GW could answer the free return aero capture with the internal tanks still full for earth orbit resolution.

If our payload is to seed mars atmosphere we could use a transpiring heat shield system of water, liquid nitrogen plus others as the means to place the gasses in the correct location in the atmosphere.

https://en.wikipedia.org/wiki/Mars_landing
https://en.wikipedia.org/wiki/Aerocapture
https://en.wikipedia.org/wiki/Ballistics

https://en.wikipedia.org/wiki/Mars_Science_Laboratory
https://en.wikipedia.org/wiki/Phoenix_(spacecraft)

tahanson43206 · 2021-02-02 18:32:59

For Calliban re #72

SearchTerm:Article prerequisites for: See Calliban #72 above

For SpaceNut re #73

This topic is about Ballistic Delivery of Supplies to Mars

Your branch to seeding the atmosphere is definitely interesting and worth developing, but that needs to happen in another topic.

My goal for this topic is to see a ** real ** business come into being in time to catch the wave that will happen if Elon Musk stays on course.

The need is for supplies of all kinds to be delivered rapidly and efficiently to the surface of Mars, using the most cost effective approaches for each class of cargo.

I think that Calliban has shown that there are at least three categories of cargo for which there will definitely be a market if Elon's vision comes to pass. let alone the visions of the authors of the papers presented during the 2020 Mars Convention for million person city-states on Mars.

A useful test is to send a category 1 cargo to Mars with an accompanying observation probe at a minimum, and a lander to investigate results as a preferred package.

This should be (certainly could be) funded entirely by a company that makes its living shipping cargo on Earth. It seems (to me at least) highly unlikely ** any ** cargo shipping company on Earth is thinking about the much larger space marketplace.

Names that come to mind for a start include: UPS, FedEx, DHL ...

Other registered members of the forum can (hopefully) add other names ... railroads, shipping lines, freight lines, airlines ....

Let's consider moving from endless discussion to the early stages of useful activity.

(th)

GW Johnson · 2021-02-03 17:04:39

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.

Higher ballistic coefficients penetrate deeper into Mars's atmosphere beore they come out of hypersonics (with all the plasma and heating) at about Mach 3 speeds. That's in the neighborhood of 0.7-1 km/s velocity, angled steeply downward. And that's also just physics, although somewhat complicated to calculate. It applies to everyone's concepts that do any sort of atmospheric entry.

If you are half a ton to a ton in total mass, you reach that Mach 3 point fairly high up at 15-25 km altitude on Mars, and there is time to deploy a chute, and enjoy some further deceleration from it. Terminal velocities will be in the neighborhood of half to three quarters of a Mach number on Mars (depending upon the chute canopy loading), which translates to around 150-200 m/s. Very hard payloads might survive that more or less intact, but we are talking big solid chunks of steel, or solid stones, or something else like that.

If you are well over a ton, you come out of hypersonics much lower, near 5-10 km, and there is simply not time to deploy a chute, much less have it actually decelerate you. You will still be over Mach 2 at impact. More likely still about Mach 3. Impact velocity will be 0.7 to 1 km/s, and failing terminal retropropulsion, there is not a thing you can do about that! Again, it's just physics that everyone is subject to.

If the payload is small (quarter-ton sizes) so that a chute can get you down to around half a Mach at impact, and the impact forces can be withstood by real-world fabrics, you can use an airbag to cushion the impact, and thus have shock-hardened electronics survive. We landed two small rovers that way on Mars. Nothing living can survive that, though. Too many gees. Again, physics.

This kind of entry requires really good orbital approach control: you have to come in straight at the limb of the planet. Your trajectory has to be essentially tangential to the ground, and at the correct altitude above it. Mars entry interface is listed as 130 or 140 km by Justus and Braun, I believe. What that really means is that propulsive course correction capability is absolutely required. So says the physics.

My guess would be that if your payload sent that way to Mars is many tons, then after the final course correction, but before (!) entry interface, you separate it into multiple fractional-ton portions, each with its own heat shield and parachute and airbag equipment. You'll need something more sophisticated than a timer to sequence these devices, as Mars's atmosphere is rather variable in density, per Justus and Braun.

These payloads will come down as a shotgun pattern, separated from each other by several 10's of km, at least. You'll need a radio transmitter on each to find them all. The vagaries of aerodynamic drag just do not permit a precise landing point. Damned physics again.

GW

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