Gravity Tractor and Magnetic Enhanced Gravity Tractor

tahanson43206 · 2024-03-06 20:05:17

Calliban reminded us of the Gravity Tractor concept for Asteroid deflection.

Void recently ( March of 2024) proposed an electromagnetic system to pull on ferromagnetic material in an asteroid that has some.

This topic is available for any NewMars member who might like to post links or text about either concept.

(th)

tahanson43206 · 2024-03-06 20:05:56

This post is reserved for an index to any posts that members might contribute over time.

(th)

tahanson43206 · 2024-03-06 20:10:15

This post is reserved for a report on a study of Void's concept for an electromagnet to pull on ferromagnetic material in an asteroid or comet.

The result of the study is a confirmation that a magnetic pull on a suitable rubble pile could be superior in performance to a simple gravity tractor, but the majority of the work of transmitting force to the rubble pile elements would still be done via gravitational force, because the inverse cube law insures that no magnet that humans can create can influence more than the region immediately in the vicinity of the electromagnet.

(th)

tahanson43206 · 2024-03-07 08:04:45

In a long session with ChatGPT4 yesterday, including a shorter visit with Gemini, I learned/re-learned quite a bit about design of electromagnets for various purposes. For an asteroid tractor, it appears to be most practical to use ordinary copper wire (with insulation) to build up a field. Superconductivity is sufficiently difficult that the resources required to achieve it are presently best deployed on Earth.

A magnet that is to be transported to an asteroid to be deflected would seem best designed for simplicity and reliability, so ordinary copper wire around a soft iron core seems more suitable than more powerful but more complex alternatives.

My plan for this topic is to attempt to investigate (to the extent possible with limited resources) the design of a bar magnet 40 meters long, that might be inserted into 2007 UN12, to apply gentle force to change it's path away from a collision with Earth, if that ever becomes likely.

The factors at work include heating of the copper wire. Location of the magnet in deep space, inside a rubble pile that is close to absolute zero implies (to me at least) that there is an opportunity to apply more current than might be possible on Earth. I'm interested in discovering how strong a magnetic field might be created under these circumstances. The stronger the field the better (of course) because the intensity of a magnetic field falls off so dramatically.

In yesterday's study, I learned that to have a field of 1 Tesla at 40 meters, it is necessary to create one of 65,000+ Tesla at the center.

For comparison, here is a snippet about a 45 Tesla magnet created on Earth:

For comparison, Earth's magnetic field ranges between 30-65 millionths of a tesla. The two-story 45 tesla hybrid provides researchers the strongest continuous magnetic field on the planet and is one of only a handful of hybrid magnets.Feb 23, 2023
MagLab makes magic with magnets | NSF
National Science Foundation (.gov)
https://new.nsf.gov › Science Matters

It just occurred to me that wire might be located some distance from the core of such a magnet, such as at the periphery of the object to be moved. I'll try to remember to investigate that possibility.

(th)

Calliban · 2024-03-07 08:30:30

TH, instead of trying to embed magnets in the object, why not just use gravity as the tractor force? On a body with 1E-4g gravity, a 100,000kg space craft will weigh 10kg. But the same 10kg-force is pulling the asteroid towards the spacecraft. But provided the craft has ion propulsion for station keeping, it can gradually drag the asteroid onto a different orbit. But this method requires patience. A 100te spacecraft will alter the velocity of a 1 billion tonne asteroid by 3m/s per year. Maybe enough to avoid a dangerous collision with Earth, if that is what we are trying to achieve. You could ballast the spacecraft to provide more drag force, but that would also require a higher thrust propulsion system. Either way, the spacecraft needs the same thrust and propellant regardless of whether the coupling is provided by gravity or magnetism.

A third option would be some kind of net or lasso. This would spread the force, allowing higher acceleration. But again, it would place a heavier demand on propulsion. Provided that we don't care which direction we shove the asteroid, a solar sail could provive propellantless propulsion. We would ballast and trim the sail such that sunlight pressure balances gravitational attraction throughout the orbit. Or using a net or lasso, we don't need to do that, as the sail will remain in place so long as the connecting cable is under tension. A few thoughts for you to consider.

Last edited by Calliban (2024-03-07 08:40:23)

tahanson43206 · 2024-03-07 08:50:14

For Calliban re #5

Thank you for your further development of the traditional gravity tug idea, and for your addition of mechanical options such as a net.

As I recall, one of the first studies you published in this forum was about capturing an entire asteroid in a large bag. That topic remains available in the forum for anyone to read. If there is anyone who would like to see that earlier work, a search for:
author: Calliban
Subject: bag and asteroid
Location: body of post

That topic included discussion of wrapping such an asteroid in a cocoon of fine line, spun by multiple small robot devices swinging around the asteroid. It would take a while, but the resulting wrapping would permit application of direct force to the rubble pile in order to move it to a desired location.

If you have time, please continue developing your promising ideas, either here or in your original topic.

Our readers should find plenty of interesting ideas as we go along. One of them may even be the entrepreneur who takes one of these ideas and turns it into an expedition.

(th)

tahanson43206 · 2024-03-07 08:53:57

This post is about Void's original idea of using magnetic force to pull on material in an asteroid. While the initial investigation of Void's idea hit the brick wall of the Inverse Cube Law, there remains a slim possibility that we might be able to use part of the basic idea.

In the report below, ChatGPT4 lays out possible pathways forward:

Exploring Electromagnet Design for Asteroid Manipulation: A Preliminary Discussion
In anticipation of our deep dive into the innovative concept of using an electromagnet for asteroid manipulation, here's a brief overview of the foundational aspects and considerations that will guide our exploration. Authored by ChatGPT, this summary aims to set the stage for a fascinating journey into space engineering and magnetic field applications.
Material Selection and Design Considerations:
- The core of the electromagnet would ideally be made from soft iron, chosen for its high magnetic permeability, paired with copper wire windings for efficient electrical conduction.
- Considering the extreme thermal conditions of space, materials and designs must ensure operational efficiency without succumbing to the vacuum, cold, or heat of the solar radiation.
- The power supply challenge in space necessitates reliance on robust sources like solar panels or nuclear power, especially for deep-space missions.
- Structural integrity is paramount, ensuring the electromagnet withstands launch stresses and the space environment's unique conditions.
Innovative Coil Placement:
The idea of moving the coil windings to the periphery of the asteroid introduces an intriguing twist. This approach could potentially:
- Provide a more even distribution of magnetic force across the asteroid's surface, aiding in manipulation.
- Pose challenges related to magnetic field interaction and structural security of the coils on an irregular asteroid surface.
- Offer benefits in flexibility for adjusting the magnetic field characteristics by varying current through different coil sections.
Resources for Design and Simulation:
- Software tools like Finite Element Method Magnetics (FEMM), ANSYS Maxwell, and COMSOL Multiphysics could be invaluable in modeling and optimizing the electromagnet design for this unique application.
As we stand on the brink of this exciting investigation, these preliminary considerations aim to engage and prepare our community for the detailed exploration to come. The potential of a magnetic tug for asteroid manipulation opens up a world of possibilities in planetary defense and space exploration, promising an insightful journey into the application of magnetic forces in the vastness of space.
Stay tuned as we delve deeper into this topic, exploring the intricacies of electromagnet design and its potential impact on future space missions.

(th)

Void · 2024-03-07 09:35:24

With the desire to be friendly and try to be helpful:

We seem to have trouble communicating often (th). Quote:

This post is about Void's original idea of using magnetic force to move an asteroid.

I was actually trying to find a way to use magnetics and electrostatics to mine an asteroid. Moving it over a long period of time might be possible, and I still say it may be possible.

But I will confess, I am in a bind as I think that there were flaws in my thinking for that. The flaws would be the effectiveness of it and also if there is a better way to do it.

So, I am pondering the matter further. I confess, I think I have misunderstood magnetic sails to some extent.

Here is a method which could move large orbital objects around over long periods of time. Things like cyclers made of asteroids: https://www.centauri-dreams.org/2017/12 … nd-beyond/
Quote:

2. Moving Asteroids for Planetary Defense
The propellantless nature of the plasma magnet drive makes it very suitable for pushing asteroids for planetary defense. Once turned on, the drive provides steady thrust to the asteroid, propelling it away from the sun and raising its orbit. Because the drive does not need to be facing any particular direction, it can be attached to a tumbling asteroid without any impact on the thrust direction.

This particular drive is only good for pushing a payload away from the sun though.

Bennu: https://en.wikipedia.org/wiki/101955_Bennu
Quote:

Aphelion 1.3559 au (202.84 Gm)
Perihelion 0.89689 au (134.173 Gm)

But because the Perihelion is inside of the Earths solar orbit, not being able to push a load towards the sun may not matter. The desire could be to cause the cycler to eventually have a resonant orbit with the Earth.
But materials extracted, would have the same Perihelion, so a magnetic field might be used to raise that perihelion and the timing of the asteroid's conjunction with the Earth so that such payloads might be air braked in the Earth's atmosphere, or with thrusters perhaps delivered directly to the Moon.

Orbital Resonance: https://en.wikipedia.org/wiki/Orbital_resonance

I want to make sure that we can agree that this is a potential desire, but it may not be attainable with practical efforts.

As for getting mined materials from Bennu to the Earth/Moon subsystem:

Quote:

4. Asteroid mining
The plasma magnet thruster might be a very useful part of a hybrid solution for automated mining craft. The hybrid propulsion would ally the plasma magnet thruster with a propellant system, such as a chemical or ion engine. The outward bound trip would use the plasma magnet thruster to reach the target asteroid. The propellant tanks would be empty saving mass and therefore improving performance. The propellant tanks would be filled with the appropriate resource, e.g. water for an electrothermal engine, or for a L2/O2 chemical engine. This engine would be turned on for the return trip towards the inner system. The reverse would be used for outward bound trips to the inner system

For now, at least I am satisfied that I mostly agree with that notion.

Now as for mining an asteroid like Bennu, I confess, I am back at the drawing board, seeking a better plan. Callibans ring has some strong merit, but I also still am thinking of magnetic and electrostatic processes with it.

My modification of Callibans ring could involve a tether to tighten around Bennu, to give anchorage, and indeed from that an arm that may reach about. But I am not locked into that just yet.

I realize that this topic is not about mining Bennu and processing its "Ore", but I needed to update you on my intentions and inform you of one type of magnetic sail that could indeed tow an asteroid.

Done

Last edited by Void (2024-03-07 09:58:40)

tahanson43206 · 2024-03-07 12:33:01

For Void re #8

Thank you for the correction ... I have applied it to the post added today. I reviewed the previous posts and found that they appear to have been worded correctly.

Please consider starting a topic dedicated to your towing ideas, if they are sufficiently different from this topic.

The issue at hand is how to pull a rubble pile asteroid. There are a great many technologies that could be used to tow an asteroid after you have a way to pull it.

Calliban reminded us of the gravity tractor. That works on every atom in the asteroid to be towed, and that is good. What is a drawback to that method is that the force of gravity is weak in this situation.

Calliban joined this forum with an opening topic about enclosing an asteroid in a bag. That topic is worth re-reading from the top, and I hope Calliban keeps it going.

Your creative thinking is a major benefit of your participation this forum, and other members are constantly providing problems to be solved in the Mars project, and related space enterprise.

In this particular topic, we don't need help with the tow. What we are working on is how to most efficiently and most effectively cause a rubble pile asteroid to obediently go where we want it to go.

Calliban's gravity tractor would most certainly accomplish that. Our quest in this topic is to try to find an alternative way of herding the particles in a rubble pile that is faster and equally effective and at comparable cost if possible.

(th)

tahanson43206 · 2024-03-07 12:53:16

The members of this forum arrive from a great variety of backgrounds.

While the collective knowledge level is high, individual members may have less knowledge about particular subjects than others.

Because this topic is inspired by a discussion of electromagnetism, I thought that it might be interesting to see if a 1 Tesla (10,000 Gauss) magnet is commercially available. It turns out (much to my surprise) that the answer is *** Yes! ***

AOMAG® Extremely Powerful Rare Earth Dia 1 x 8" Neodymium Magnet Bar Cylinder, One Count
Visit the AOMAG Store
5.0 5.0 out of 5 stars 4 ratings | Search this page
$86.99$86.99
FREE Returns
Material Stainless Steel
Brand AOMAG
Product Dimensions 1"L x 1"W x 8"Th
Shape Cylindrical
Number of Pieces 1
About this item
Surface Gauss Value:10000 Gauss, Great performance, Wholesale Price.
These are very strong magnets with high pulling force, even the size is not so "big". The magnets may cause hurt when two magnets come together. These are NOT toy magnets, please keep them away from children.
Quantity: 1 magnet Dia 25 * 200mm (Tolerance: +/- 1mm)per package
Please note that it is not a pure neodymium mangets. it is 304 stainless steel installed.

A person who invests in one of these magnets will be able to verify the Inverse Cube Law home quickly and easily.

The strength of the magnet decreases as the test article (a soft metal washer or magnet keeper plate) is moved away from one of the poles of the magnet. ChatGPT4 computed estimates for the strength of the magnet at various distances from the magnet. At one meter, a 2.5 cm diameter washer should be pulled at a rate of between 1 and 5 grams. If a NewMars member carefully plots distance vs pull, the Inverse Cube Law should become apparent.

Here is a link to the table: http://newmars.com/forums/viewtopic.php … 12#p220112

If anyone in NewMars makes the investment in this 1 Tesla bar magnet, please report back on your observations.

(th)

kbd512 · 2024-03-07 13:56:01

Can this be done in a more simplistic manner using a simple weight attached to a suitably long tether?

For example, can you set a stake in the asteroid, attach a tether to the stake, and then add a heavy weight at the end of the tether to "tug on" the asteroid?

This is not an exact analogy, but a bolo with unequal weights is an analog to illustrate how the direction of the object will be altered.

This asteroid is going around the Sun, just like any other orbiting body, so if you attach a long tether with a massive counterweight on the opposite end of the tether, then it will alter the orbit of the asteroid. This is a straight "gravity tractor" that requires no magnetics, electromagnetics, or energy input beyond what's required to get the weight secured to the asteroid. The tether can be kevlar and the weight can be Iron.

Calliban · 2024-03-07 15:25:37

You could extend a tether beyond the stationary orbit point of the asteroid and use the rotational energy of the asteroid to shoot material into space. Energy is always conserved, so the energy gained by the expelled package will be balanced by an equal change in kinetic and rotational energy of the asteroid. Rotational energy is converted into linear motion, with some going to the package and some changing the velocity of the asteroid. Yes, it would work. But the total propulsive energy available is equal to the initial rotational energy of the asteroid.

The gravity tractor: Two bodies seperated in space, will experience gravitational attraction to each other. A pebble released over an asteroid, will fall onto its surface. But conversely, the entire asteroid is also pulled towards the pebble and falls onto the pebble, albeit very slowly. In fact, both bodies gain the same momentum by falling in each other gravitational fields. When they collide, net momentum is reduced to zero, so the orbit does not change. The smaller pebble gains more kinetic energy, which is ultimately dissipated as heat. Now imagine two bodies, seperated by a distance, but the smaller body is held at a constant distance from the larger using propulsion. Both bodies experience an equal and opposite force due the gravity of the other. But because the smaller body is prevented from falling to the surface, the momentum gained by the larger body is not cancelled by impact. The smaller body can effectively drag the larger one. But nothing is free. The combined momentum change of the gravity tractor and asteroid, are equal to the momentum of the tractor propulsion exhaust. The gravity tractor works best with low thrust, high-ISP propulsion. Acceleration is miniscule and cannot be greater than the acceleration due to gravity of the tractor in the asteroid gravity well. This will typically be measured in micro-g. So it takes a very long time to meaningfully change the velocity of an asteroid. We are talking many decades to substantially change an orbit in the inner solar system.

Last edited by Calliban (2024-03-07 15:46:24)

SpaceNut · 2024-03-07 18:40:56

Artificial Magnetosphere - Electromagnetic Induction

GW Johnson · 2024-03-08 10:40:57

My poster paper at the 2009 asteroid defense conference in Granada had to do with an electrostatic-augmented gravity tractor.

GW

Void · 2024-03-08 10:57:30

I'm very interested in that Dr. Johnson.
Done

SpaceNut · 2024-03-09 08:45:29

We have force and mass but not the energy to generate the pull or push to make movement.

tahanson43206 · 2024-03-09 10:12:08

For SpaceNut re #16

Please solve the problem you have posed ... we are working on how to move an asteroid. You have identified energy as a point on the critical path to success. It is your opportunity to address the problem by solving it.

It is not helpful to identify problems without solving them. We do not have enough members for any of us to look to others to solve the problems we identify.

In this case, you have correctly identified a need for energy to move an asteroid. Please post recommendations to solve the problem.

(th)

GW Johnson · 2024-03-09 11:19:25

The gravity tractor is something we could do today. It just needs to be tested and revised per those tests.

The spacecraft is propelled by electric propulsion. Those streams have to be canted so they miss the asteroid, as the spacecraft adjusts thrust level to hover at a fixed distance. There is a mutual force of gravity between them, very weak indeed, but not zero. Since the spacecraft is thrusting to maintain fixed hover distance, the asteroid follows it, the force of mutual gravity being the "invisible nonmaterial tow cable".

The resulting acceleration of the asteroid is vanishingly minute, but not zero. If you start years in advance, the effect builds up over those years, altering the trajectory of the asteroid about the sun. That can, if done correctly, convert a strike into a miss. But it is entirely unsuitable for anything but "years in advance". No "last ditch defense" there!

Last ditch defense requires either a series of impactors or a nuke. The problem is the force being applied by the impact or the thermal radiation-induced spalling from the adjacent detonation. If that force is too big, any rubble-pile asteroid (and most are) is disrupted. And if "last ditch", that just made the problem worse by converting the bullet strike into a shotgun blast. There is as yet no accepted solution to that problem.

GW

SpaceNut · 2024-03-09 11:40:32

To little energy TH then you cannot apply enough force. Too much mass means more energy is required... It's an equation to do the work.

In space energy is not mass and there is the problem in making stuff move.

What GW is proposing is attaching the rocket propulsion to the object to move.

tahanson43206 · 2024-03-09 12:04:32

For SpaceNut .... thanks for clarifying that GW Johnson has offered a solution to the problem of how to move the asteroid.

The problem you posed is how to provide the energy for whatever method is proposed.

Instead of just saying there is a need for energy, please help out by suggesting sources of energy suitable for this specific topic.

To identify a problem is good, if that effort is accompanied by a solution.

If a member of this forum shows a problem and does not offer a solution, then someone else has to deal with the problem.

We don't have enough members for that luxury.

You identified the problem, so you have the opportunity to suggest a solution.

In this case, GW Johnson suggested an ion drive. That device would require a supply of energy over many years, in addition to the raw material to be ejected.

Your opportunity is to define the energy source for GW's ion rocket.

No one else is likely to step forward to bail you out.
You ** can ** do it!

(th)

SpaceNut · 2024-03-09 12:43:26

The ion drive propulsion is from electrical power that can come from chemical. solar and nuclear this is not a mystery. It makes use of a fuel to be used as the mass that makes it move when ejected out the nozzle of the drive engine.

The use of magnetics is being used in the engine to keep the flow constricted toa maximize the force of the ejected fuel.

Any magnetic attraction is to not make a direct contact but to use a lesser force to do the work rather than a direct connection.

tahanson43206 · 2024-03-09 13:48:35

For SpaceNut re #21 ...

Good start. Please keep going! I'd like this topic to contain solutions, defined in detail for future readers to print out and execute.

You've indicated directions you might look, and they do look promising.

Please add detail so that a future reader can build the system you are thinking about.

Your reference to using magnetic force inside GW's ion engine is interesting but it has nothing to do with Void's original proposal, which is to use magnetic force to attract material inside a rubble pile asteroid.

This topic is about pulling material that is inside a rubble pile asteroid.

It is not about design of ion engines. We have topics for that, or if we don't we can create one.

Let's stay on the path of converting this forum from talk that goes nowhere to planning documents and guidance documents that are a resource for the young people alive today who will actually perform the Solar System exploration that lies ahead.

If you have information to support Void's initiative, or GW's gravity tractor concept, this topic is a good place for it.

(th)

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#1 2024-03-06 20:05:17

Gravity Tractor and Magnetic Enhanced Gravity Tractor

#2 2024-03-06 20:05:56

Re: Gravity Tractor and Magnetic Enhanced Gravity Tractor

#3 2024-03-06 20:10:15

Re: Gravity Tractor and Magnetic Enhanced Gravity Tractor

#4 2024-03-07 08:04:45

Re: Gravity Tractor and Magnetic Enhanced Gravity Tractor

#5 2024-03-07 08:30:30

Re: Gravity Tractor and Magnetic Enhanced Gravity Tractor

#6 2024-03-07 08:50:14

Re: Gravity Tractor and Magnetic Enhanced Gravity Tractor

#7 2024-03-07 08:53:57

Re: Gravity Tractor and Magnetic Enhanced Gravity Tractor

Exploring Electromagnet Design for Asteroid Manipulation: A Preliminary Discussion

#8 2024-03-07 09:35:24

Re: Gravity Tractor and Magnetic Enhanced Gravity Tractor

#9 2024-03-07 12:33:01

Re: Gravity Tractor and Magnetic Enhanced Gravity Tractor

#10 2024-03-07 12:53:16

Re: Gravity Tractor and Magnetic Enhanced Gravity Tractor

#11 2024-03-07 13:56:01

Re: Gravity Tractor and Magnetic Enhanced Gravity Tractor

#12 2024-03-07 15:25:37

Re: Gravity Tractor and Magnetic Enhanced Gravity Tractor

#13 2024-03-07 18:40:56

Re: Gravity Tractor and Magnetic Enhanced Gravity Tractor

#14 2024-03-08 10:40:57

Re: Gravity Tractor and Magnetic Enhanced Gravity Tractor

#15 2024-03-08 10:57:30

Re: Gravity Tractor and Magnetic Enhanced Gravity Tractor

#16 2024-03-09 08:45:29

Re: Gravity Tractor and Magnetic Enhanced Gravity Tractor

#17 2024-03-09 10:12:08

Re: Gravity Tractor and Magnetic Enhanced Gravity Tractor

#18 2024-03-09 11:19:25

Re: Gravity Tractor and Magnetic Enhanced Gravity Tractor

#19 2024-03-09 11:40:32

Re: Gravity Tractor and Magnetic Enhanced Gravity Tractor

#20 2024-03-09 12:04:32

Re: Gravity Tractor and Magnetic Enhanced Gravity Tractor

#21 2024-03-09 12:43:26

Re: Gravity Tractor and Magnetic Enhanced Gravity Tractor

#22 2024-03-09 13:48:35

Re: Gravity Tractor and Magnetic Enhanced Gravity Tractor

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