Rubble Pile Asteroids - How to work with Them

tahanson43206 · 2024-03-10 08:48:20

This topic is dedicated to the subject of Rubble Pile asteroids.

It is intended to serve as a convenient resource for anyone planning to harvest or otherwise interact with such an asteroid.

Loosely defined, a Rubble Pile asteroid consists of small chunks of material that are bound together only by an extremely weak gravitational force.

In space, suction is not available as a means of collection of such material.

Gravity is available as a tool. Gravity works on any material in the asteroid, but has the disadvantage of weakness.

Electrostatic force is a potential agent for collecting material.

Electromagnetism is another candidate agent, but it depends upon the magnetic susceptibility of the material to be harvested.

Other forces may be available.

Chemically bound agents are a possibility. For example, claws may be able to enclose a clump of material. A set of hemispheres may be moved to enclose a clump of material. A net might be cast to enclose a volume of material.

A volume of material might be enclosed in a cocoon such as an insect larvae might wrap around itself.

(th)

tahanson43206 · 2024-03-10 08:49:17

This post is reserved for an index to posts that may be contributed by NewMars members over time.

(th)

tahanson43206 · 2024-03-10 09:08:26

ChatGPT4 was willing to think about an educational experience for students, to attempt to help them understand the challenges of working with a Rubble Pile asteroid:

Hands-on Activity: Simulating Rubble Pile Asteroid Material Collection
This educational activity is designed to simulate the experience of collecting materials from a rubble pile asteroid, such as Apophis, using simple tools and items found in a home or classroom. It aims to provide a practical understanding of the challenges faced in microgravity environments and the nature of asteroid material.
Objective
The objective of this exercise is to illustrate the complexities of collecting samples from an asteroid composed of loosely bound material, simulating the conditions of microgravity.
Materials Needed
- A large bowl or basin - Represents the asteroid's surface.
- Water - Simulates the microgravity environment.
- Ping pong balls - Represents the asteroid's rubble.
- Collection tools - Spoons, forks, chopsticks, small nets, or tweezers.
Instructions
1. Setup: Fill the bowl halfway with water and place the ping pong balls in it. The floating balls mimic the rubble on an asteroid's surface in a microgravity environment.
2. Task: Participants use the provided tools to remove ping pong balls from the water, simulating material collection on an asteroid.
3. Rules and Challenges: Introduce various challenges to mimic real asteroid collection scenarios, such as collecting specific colors or within a time limit.
Discussion Points
- Which tools were most effective and why?
- How do the challenges in this activity relate to real asteroid mining missions?
- What tool modifications could make the task easier?
Extension Ideas
To further explore asteroid composition and collection challenges, consider adding obstacles in the bowl or using materials that mimic the fragile nature of some asteroid materials.
Educational Value
This hands-on activity not only introduces participants to space exploration challenges but also fosters problem-solving, critical thinking, and an understanding of microgravity's impact on material collection.
By engaging in this simple yet effective simulation, learners of all ages can gain a deeper appreciation for the complexities of space missions and the innovative solutions required to advance our understanding and utilization of space resources.

(th)

tahanson43206 · 2024-03-10 10:49:37

Here are two DALL-E images to show the learning exercise to show how Rubble Piles might be harvested:

In this one, DALL-E decided to put the asteroid in the bowl with the ping pong balls.

Now we have the asteroid up on the wall, but we're missing the tools to retrieve the ping pong balls.

A crucial difference between a ** real ** rubble pile and the kitchen table experiment is that the globs of asteroid material may not have the strength to hold together if grasped.

(th)

tahanson43206 · 2024-03-11 11:57:27

Here is an idea ....

In one of his posts recently, Void mentioned spears ...

In the fishing industry, a number of spears have been developed to catch a wide variety of creatures using spring loaded catching systems.

Google came up with a long list of gadgets.

A rubble pile asteroid's characteristics were described in detail, in one of Calliban's recent posts.

An umbrella is often designed to spring open when the operator pushes a release button...

What I'm thinking about in the context of a rubble pile asteroid, is that an umbrella-like device might be inserted very gently into the midst of all the loosely conglomerated objects. When the tool is fully inserted, the operator can release the spring loaded feature, so that an umbrella will unfold as the operator gently pulls the shaft back. The umbrella should provide a gentle force to nudge the free flying clumps in the direction the operator is inviting them to go.

At the surface of the asteroid, a cylinder can collect the material brought forward by the umbrella, which will then provide a seal for the collection tube. The entire tube might then be shipped to Earth using a solar sail.

Here is a link to a Mary Poppins image created by DALL-E as instructed by ChatGPT4.
https://imgur.com/a/dz3wvQX

Here is a link to the image saved in imgur.com:

(th)

tahanson43206 · 2024-03-11 17:59:12

I asked ChatGPT4 to ask DALL-E to try creating a serious image showing an umbrella material gathering tool. The resulting image is different from what I had it mind, but I'm hoping NewMars members and forum readers will find the image intriguing. I'll set up the link to the image shortly, but in the mean time, here is CH4's request:

Create a three-panel cartoon strip that depicts a serious and realistic scenario of collecting material from a rubble pile asteroid, such as Apophis, as it might unfold during its close pass by Earth in 2029. Panel 1: Shows a scientifically accurate depiction of a spear-like tool gently being pushed into the rubble pile asteroid, representing the initial step of inserting the collection mechanism. Panel 2: Illustrates the moment the spear's mechanism allows an umbrella-like fabric to open within the asteroid, ready to collect material. Panel 3: Captures the retrieval phase, with the bell of the umbrella filled with asteroid material, being carefully pulled out of the asteroid. This strip aims to visually explain a potential method for asteroid material collection in a realistic and scientifically grounded manner.

Link to image is to go here: https://imgur.com/a/IiVDgAe

The live link goes here:

DALL-E is a bit confused about the physical process, but the artwork is so good I thought our members and readers might like seeing it.

(th)

tahanson43206 · 2024-10-10 11:51:32

For Calliban and anyone else who may be interested in creating a business around harvesting asteroid material....

This topic is one of a number created with "asteroid" in the title....

In light of recent discussion of asteroid mining that arose in a topic about planetary defense, I thought this might be a good time to return asteroid mining to the current posts category at least for a day or two.

I remember discussion of an icycle rubble pile harvesting method, and hope that someone in the active membership may be able to find that series and give it another airing.

(th)

Calliban · 2024-10-10 16:32:03

The first asteroids we harvest will be part of the NEA population. We cannot know for sure, but most of this group are not expected to have subsurface ice. Like GW says, we are talking hydrated minerals which are 1% water or hydroxyl by mass. About as wet as desert sand here on Earth. So water isn't going to be part of the mining process because we won't have much to spare. We will have to develop ways of harvesting meagre asteroid water resources because we frankly won't have a choice. The paucity of the resource suggests to me that we should avoid the need for chemical propulsion for NEA trips. An electric engine based on a mass driver may be a good idea. Such an engine can use raw rock as reaction mass.

My original idea for mining was to surround the whole rubble pile asteroid with some kind of flexible bag, made from woven polymer fibres. Mechanical shovels on the end of manipulator arms would be mounted on some kind of frame and would take bites out of the asteroid. The reaction force from the shovels will be balanced by the force resulting when the centre of mass of the frame and the centre of gravity of the asteroid are pushed away from each other. The shovels would drop the material down chutes that sit just above the geostationary point. Centrifugal force results in the material dropping (slowly) down the chute. Rotating wire brushes could give the material an extra push. At the bottom of each chute, the material fills a bag which is fastened when full. Further processing of the material will take place in a facility with gravity.

The assembly should avoid the need to exert forces on the surface of the asteroid. Recent experience suggest that rubble piles behave like liquids when pushed against. I will make a diagram at some point, probably tomorrow.

Last edited by Calliban (2024-10-10 16:51:32)

tahanson43206 · 2024-10-10 17:27:56

For Calliban re #8

Thanks for giving the icicle idea a review!

The idea of trying to find water in the rubble pile Asteroid is one that had not occurred to me, and it is certainly interesting.

The most practical way (that I can think of) to glue rubble pile components to the sticky pole is to bring sufficient water in the mining robot so that the water can ooze out of the perforated pole into the mass of the rubble pile.

The water can indeed be recovered at the processing center. There is no reason for any to be lost, unless there might be sublimation in the deep space environment.

The idea of trying to enclose material from a rubble pile asteroid has indeed received focus in the NewMars archives.

My recollection is that discussion around that idea was quite lively, and it would probably be fun to read it again.

For simplicity and reliability, I have seen nothing superior to the icicle sticky pole method, but we have plenty of room in the forum database for new ideas along alternative lines.

(th)

Calliban · 2024-10-11 05:52:30

My original concept for mining rubble pile asteroids is shown in this image.

This shows the asteroid as a sphere. In reality, few asteroids are spheres. I don't think that makes a great deal of practical difference to how this works.

The whole asteroid is enclosed in a thin polymer bag, with chutes for receiving material around its equator. The bag rotates at the same rate as the asteroid, but outside of its stationary orbit point. This means that at the mouth of each chute, there is a weak centrifugal force pulling material down the chute into bags at the end. The bag is tapered, being wider at the equator than at the poles. This means that any material settling onto the interior surface of the bag, will gradually roll towards the equator, falling into the chutes.

Inside the bag structure there is a ballasted ring, which orbits the asteroid in a stationary orbit, just outside its stationary orbit point. This puts the ring under mild tension. Manipulator arms are mounted on the ring. These have enclosing shovels at their ends, allowing them to grab pieces of the surface and then drop it down the chutes. The shovels are the only part of the structure that physically touches the asteroid. When the asteroid is disturbed, it will resonate like a liquid droplet. Friction will eventually dampen these ripples and resonances. But the speed of operations will be limited by the need to keep surface disruption to a minimum.

The orbit of the ring lines its centre of mass up with the centre of gravity of the asteroid. As the manipulators grab the surface, they will exert a weak reaction force on the ring. This will displace its centre of mass from the centre of gravity. The gravity of the asteroid will exert a restoring force on the ring, pulling its centre of mass back towards the centre of gravity. Provided the ring is properly balanced, its centre of mass will always line up with the centre of gravity.

Material displaced from the surface during grabbing operations, will bounce between the surface and the interior of the polymer bag. Eventually, friction will result in it either falling back to the surface of the asteroid or settling on the inside of the bag and rolling into the chute.

Material accumulates in bags at the ends of the chutes. These are in weak centrifugal gravity. When the bags are full, they are sealed, detatched and replaced. The full bags are taken to a facility in distant orbit around the asteroid. This facility rotates, producing spin gravity needed for ores processing operations.

Last edited by Calliban (2024-10-11 06:07:48)

tahanson43206 · 2024-10-11 06:36:22

For Calliban re #10

Thanks for bringing the original ring jaws design sketch back into view.

We now have the two major competing designs back in play.

Both are valid concepts in need of detail development.

The enclosure method has the distinct advantage of control of the environment. If a part of the rubble pile is dislodged by a jaw movement, it will drift out until it is corralled by the bag.

On the other hand, the enclosure method requires a much greater investment to put all the needed machinery in place.

The icicle method can be implemented on a much smaller scale, but it has the disadvantage of no live tests in space to authenticate the idea.

As I thought about the problem of inserting the perforated rod into a rubble pile, it occurred to me that an even simpler approach is to simply squirt water from ports in a flat plate that is positioned near a section of the rubble pile surface. How far the water would penetrate before it freezes is to be determined.

An expedition to perform a live test should include both concepts, and plenty of onboard intelligence to try to find the best site on the surface for the experiment.

***
The gigantic ring/jaws/bag operation will be sized for the target.

It might travel to the target as a set of distinct vehicles with specific functions to perform at the job site.

This would be a project undertaken by a major corporation or perhaps even a National government.

Much of the functionality could be tested on Earth, by creating a mound of sand or rocks and setting up the ring components on the flat land outside the mound. The ability of components to position themselves automatically, and then to secure themselves to each other could be tested until all the hardware and software works correctly.

This would be a major project that only a bold entity would undertake.

All the components would need to be launched separately and assembled into an expedition in LEO.

The flight to the target appears to be to be possible with existing knowledge and skills, with the caveat that that knowledge and those skills are currently present ONLY in national organizations. The entity that is going to perform management of this operation may be able to hire retirees from the national programs.

An excellent reference for planning navigation is "Planetary Space Navigation" by James Miller. The book includes a full discussion of the physics and mathematics of the field, and then provides detailed explanations of the procedures that put a number of probes at the desired destinations. The procedures often required multiple passes by planets to achieve the velocity and direction needed to reach each destination.

The expedition could be designed to travel as a single entity or as a cluster of smaller ones. In the case of a cluster, only one element needs to be "in charge" of navigation. All the other elements can simply follow the lead element.

The ability to draw upon the resources of one of the National deep space networks would be essential.

(th)

Calliban · 2024-10-15 02:39:42

This video discusses metal production and seperation from lunar regolith.
https://youtu.be/xH4Ki6TxRTs?si=TnEn9ER04HanhaZ_

The same process could work with the various silicates present in stony asteroids. One major advancement that the video discusses is the use of iron-chromium alloy electrodes for magma electrolysis. As both iron and chromium are relatively abundant on the moon, this removes a potential bottleneck from magma electrolysis. Previously, carbon based electrodes were expected to be used.

There is more discussion on the use of calcium as a reducing agent. Calcium oxide bonds with silica, yielding calcium silicate which floats on top of the melt. Calcium can also be used to remove different metals. By adding selective quantities of calcium metal, different metals in the mix can be selectively reduced and seperated. The electrolysis cell can then focus on reducing calcium oxide back to metal.

Melting the various oxides is energy intensive. The author expects this can be achieved by solar concentrators, which will reduce the amount of electricity needed to produce metals. If metal reduction is accomplished using calcium, then calcium oxide electrolysis is the only part of the process that needs electricity. Everything else is done using concentrated solar heat. In free space, this gives us a significant advantage. Concentrating solar heat is cheap and easy and requires focusing a concave mirror at the sun. Electricity will be more expensive, as we need either photovoltaics or turbomachinery.

Last edited by Calliban (2024-10-15 02:56:05)

Void · 2024-10-15 19:24:27

I would say that the game is changing. Most of the materials of a stony asteroid can be propellant mass in a way that does not create a Kesler syndrome. You can expel Oxygen and fine dust with a Mass Driver.

You can apparently use Iron, Aluminum, and Copper in Magdrive.
You can use almost anything in Neumann Drive.

It may be possible that after you have extracted all the materials you want for constructing things, and if you can get rid of the non-conductive materials also, then whatever conductive alloy may remain may work as propulsion mass for Neuman Drive and maybe for Magdrive. Even if that alloy is otherwise useless.

Another thing about Iron in space is probably simple alloys of steel will do in most cases you would not need Stainless or other exotic forms of Steel for most things.

Ending Pending

Last edited by Void (2024-10-15 19:27:20)

Void · 2024-10-15 19:56:56

Perhaps you can tolerate this Calliban.

The Moon is a large stony object and most asteroids we can more easily reach are also stony.

The video has interesting ideas: https://www.bing.com/videos/riverview/r … &FORM=VIRE Quote:

Lunar & Orbital Infrastructure ALL PARTS
YouTube
AnthroFuturism
28.5K views
2 months ago

I myself currently would specify much more in robotics than in humans on the Moon.

Also, I am interested in considering skyhooks with rocket thrusters and pully systems on their ends. I would like to see them used to hook buckets of Oxides of Iron into orbit. They might also be able to drop something as well.

Manufactured Magnetite could be considered or red iron oxides.

In the case of Magnetic Iron manufactured Magnetite, you may be able to swing a powerful magnet to near the surface and somehow squirt dust of Magnetite to the magnet, in hopes of capture. Then the magnet could swing by at a safe distance from the surface.

I know I am deviating from rubble pile asteroids but please be tolerant.

Once we have propellant mass in orbit of the Moon from the Moon, we may have a method to move mass Earth Orbit<>Moon Orbit, and then with similar methods from small world to small world.

https://en.wikipedia.org/wiki/Magnetite
Fe2+Fe3+2O4

And we may attach other molecules to the magnetite dust.

So if we can have a matter projector that could shoot such dust at a passing magnet on a rotavator, we may bring mass from the Moon to Moon orbit.

The Magnetite processed could yield Iron and Oxygen if no other molecules are attached to the dust.

Both Oxygen and Magnetite dust could be expelled from a mass driver to propel a spacecraft. Oxygen is the one which presents less danger as it will sublimate from ice to gas if you are expelling a cold dust of Oxygen, but dust that is fine might be acceptable in some situations.

But if we extract the Iron from the Magnetite, then we have a propellant that can work for both Magdrive and Neumann Drive.

So, with this we might restore the orbital energy of the skyhook. But it might also be possible to drop materials from the skyhook to elevate the orbit of the skyhook.

I suggest wood, if you could get it. But wood would have to be grown in orbital habitats if a source of organic chemicals existed.

Venus, Earth, and the Outer asteroid belt may be a source for that.

Ending Pending

A little more tolerance, I request.

The skyhook magnet could be a scoop/basket. Iron filings on a magnet make a sort of spongy shock absorber.

So, the magnetite dust tossed up say some small distance might be scooped into a hood with a very strong magnet.

Then on the top of the circle described by the rotavator somehow the magnetite dust would be removed to another structure. I don't have that figured out yet.

Ending Pending

Magnetic Shock absorber which can aquire even more magnetic dust: https://www.dreamstime.com/dust-reactio … e243423069 Image Quote: reaction-iron-dust-to-magnetic-field-strong-neodymium-magnet-black-background-282098544.jpg?w=360

Ending Pending

Last edited by Void (2024-10-15 20:22:58)

tahanson43206 · 2024-10-15 21:12:27

For Void re #14

In the case of Magnetic Iron manufactured Magnetite, you may be able to swing a powerful magnet to near the surface and somehow squirt dust of Magnetite to the magnet, in hopes of capture. Then the magnet could swing by at a safe distance from the surface.
I know I am deviating from rubble pile asteroids but please be tolerant.

Your vision(s) in post #14 can fit in a great many topics. This topic is honored to have your creative thinking to help to address the very significant problem the topic is set up to solve.

The ideas floated so far include (but are not limited to)...
1) A giant net
2) A cocoon made by a spider-like robot
3) A giant ring around an entire asteroid to collect jaws full of loose material
4) An icicle making probe to inject water to freeze to collect loose material
5) Others I've forgotten...

and ** NOW ** we have the idea of flowing magnetic material onto the surface of an asteroid.

I'd like to pick up that idea and see if it has potential....

Let us imagine a Void-inspired asteroid magnetic mining expedition ....

We are NOT concerned with the nature of the material inside the asteroid... we have reason to believe (from previous probes) that the target is a rubble pile, and someone (or a group) with resources to invest has ordered the collection of this particular asteroid.

The Void-inspired Magnetic Mining expedition wins the competitive bid, and has arrived on site after a lengthy voyage that includes several swings by major planets to gain momentum to reach the asteroid of interest.

The supply cannister is filled with iron filings chosen for their ability to function in deep space. The robot delivery mechanism spreads these filings evenly over the surface of the asteroid.

After the filings have been distributed, and after they have gently settled onto the surface of the rubble pile, the expedition divides into two parts equipped with magnetic coils designed to turn the entire asteroid into a gigantic bar magnet.

The magnets are energized, and the iron filings form a constrictive envelope around the asteroid. When the magnetic field is in place, a thruster at one end of the asteroid begins to apply force to move the asteroid in a desired direction, taking care to keep force below the limits provided by the magnetic sheath around the asteroid.

Once thrust is applied, magnetic force around the asteroid can be relaxed in order to save energy.

When thrust is needed for course correction, the magnetic field can be reapplied.

(th)

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#1 2024-03-10 08:48:20

Rubble Pile Asteroids - How to work with Them

#2 2024-03-10 08:49:17

Re: Rubble Pile Asteroids - How to work with Them

#3 2024-03-10 09:08:26

Re: Rubble Pile Asteroids - How to work with Them

Hands-on Activity: Simulating Rubble Pile Asteroid Material Collection

Objective

Materials Needed

Instructions

Discussion Points

Extension Ideas

Educational Value

#4 2024-03-10 10:49:37

Re: Rubble Pile Asteroids - How to work with Them

#5 2024-03-11 11:57:27

Re: Rubble Pile Asteroids - How to work with Them

#6 2024-03-11 17:59:12

Re: Rubble Pile Asteroids - How to work with Them

#7 2024-10-10 11:51:32

Re: Rubble Pile Asteroids - How to work with Them

#8 2024-10-10 16:32:03

Re: Rubble Pile Asteroids - How to work with Them

#9 2024-10-10 17:27:56

Re: Rubble Pile Asteroids - How to work with Them

#10 2024-10-11 05:52:30

Re: Rubble Pile Asteroids - How to work with Them

#11 2024-10-11 06:36:22

Re: Rubble Pile Asteroids - How to work with Them

#12 2024-10-15 02:39:42

Re: Rubble Pile Asteroids - How to work with Them

#13 2024-10-15 19:24:27

Re: Rubble Pile Asteroids - How to work with Them

#14 2024-10-15 19:56:56

Re: Rubble Pile Asteroids - How to work with Them

#15 2024-10-15 21:12:27

Re: Rubble Pile Asteroids - How to work with Them

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