# Talk:Magnetic sail

Dmcdysan (talk) 02:54, 23 June 2022 (UTC)

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## superconducting ?

A magnetic sail or magsail ... a large loop of superconducting wire

Does it have to be superconducting ?

Given the low field strenghts needed, I guess not, but then it constantly drains energy from its onboard electric power source, dissipating it in loop by Ohm's law, shortening the total time of acceleration (and thus limiting maximal velocity) of spacecraft. Besides, wire would have to be thicker and therefore heavier.

## is "magnetic sail in magnetic field" illustration correct ?

A magnetic sail in magnetic field (represented by magenta arrows). The sail generates its own magnetic field, represented a small bar magnet. The ambient magnetic field pulls on the magnetic sail like any other magnet. The force on the sail is to the left.

I'm almost certain this is incorrect. A constant (over the volume enclosing loop) magnetic field exerts no net linear force on a current loop. However, it *does* exert a torque on that current loop. The torque tends to "line up" the loop with the field. Once it is "lined up", there is no net torque on the loop (only a force on each small segment of the loop pulling it out from the center of the loop). By "lined up", I mean that the loop's "dipole vector" (at right angles to the plane of the loop) is anti-parallel to the magnetic field vector. The magnetic field produced by the loop tends to cancel out the ambient magnetic field.

On the other hand, if the magnetic field is diverging (stronger in some place than others), there *can* be a net linear force on a current loop. I don't think any magnetic sails designs make use of this property.

(EditHint: move this to a physics page ?)

-- DavidCary 07:24, 11 Jul 2004 (UTC)

I could create a less mspaint-ish illustration, once I know what it should actually depict (I'm not too good at physics, damn me). So, if you have any exact ideas, please tell me. Until then, I'll do the other illustration. Frank Miller 22:45, 2 December 2006 (UTC)

## Deleted illustration

I deleted the illustration Magnetic sail in a magnetic field. It was not terribly informative, and (as discussed above) did not accurately illustrate where the force comes from. The force on a magnet in a magnetic field comes from the gradient of the field, not from the field itself. In the illustration as shown, there would be a restoring torque on the sail if it is rotated, but no net force. The actual physics are much more difficult to show in a simple illustration. Geoffrey.landis 17:13, 28 February 2007 (UTC)

## Merge From Mini-magnetospheric Plasma Propulsion

I merged Mini-magnetospheric Plasma Propulsion into this page. There was a fair bit of shared material, and the concept of M2P2 can only really be understood once you understand the magnetic sail. --Dashpool (talk) 16:26, 1 June 2008 (UTC)

See Talk:Mini-magnetospheric plasma propulsion. --Dashpool (talk) 06:58, 3 June 2008 (UTC)

Steering magnetic sails: [[1]] --Dashpool (talk) 08:10, 3 June 2008 (UTC)

## moved unformated text from article

7. Bolonkin A.A., Theory of Space Magnetic Sail. Some Common Mistakes and Electrostatic MagSail. Presented as paper AIAA-2006-8148 to 14th AIAA/ANI Space Planes and Hypersonoc Systems and Technologies Conference, 6-9 November 2006, National Conference Center, Canberra, Australia. See also paper AIAA-2006-7709. In work is shown that the most magnetic sail researchers made a common mistake: not include the opposed magnetic field created the rotated solar wind around magnetic ring. This opposed magnetic field significantly decreases efficiency the magnetic sail.
8. Bolonkin A.A., Non-Rocket Space Launch and Flight, Elsevier, 2006, 488 pgs. Chapter 13: Electrostatic solar wind propulsion, pp. 245-270. Author offered the new electroctatic magnetic sail where the solid superconductivity gigantic ring is changed by electronic ring rotated abound positive charged ball.
9. Bolonkin A.A., New Concepts, Ideas, Innovations in Aerospace, Technology and Human Science, NOVA, 2008, 400 pgs. Chapter 4: Theory of Space Magnetic Sail. Some common Mistakes and Electrostatic MagSail. Author shows that the most magnetic sail researchers made a common mistake: not include the opposed magnetic field created the rotated solar wind around magnetic ring. This opposed magnetic field significantly decreases efficiency the magnetic sail.

Patents:
[1] Bolonkin, A.A., Space Propulsion Using Solar Wind and Installation for It, Russian patent application #3635955/23 126453, 19 August, 1983 (in Russian), Russian PTO.
[2] Bolonkin, A.A., Getting of Electric Energy from Space and Installation for It, Russian patent application #3638699/25 126303, 19 August, 1983 (in Russian), Russian PTO.
[3] Bolonkin, A. A., Transformation of Energy of Rarefaction Plasma in Electric Current and Installation for it. Russian patent application #3663911/25 159775, 23 November 1983 (in Russian), Russian PTO.
Ö

User BKruglyak added a large chunk of text criticizing the magnetic sail concept. Although the criticism itself may be notable, it does not merit the emphasis given by allocating a large section of text here. Was also poorly formatted and contained personal attacks on integrity of various researchers. It probably merits a couple of sentences in the main body of the text: something like "most analyses of magnetic sails have neglected the magnetic field generated by the solar wind itself as it interacts with the sail. These dynamically generated fields could overwhelm than those generated by the coil, and significantly reduce the efficiency of the device." (and an appropriate citation). --Dashpool (talk) 07:23, 8 July 2008 (UTC)
Without the above references, the text is unreferenced, so I've moved it here. Whether it is correct or not, the tone, style and formatting is inappropriate. If anybody wants to fix it up with the references and re-add to the article, please do so.- (User) WolfKeeper (Talk) 15:39, 8 July 2008 (UTC)
I recently proposed reorganizing this article in the "Theory in the limit of small plasma densities" talks section to include a section on critiques, similar to the unsigned talk post suggesting a section on "Critism." I recommend that the Bolonkin 2006 article "Theory of Space Magnetic Sail. Some Common Mistakes and Electrostatic MagSail" be cited and briefly summarized in such a section. A rebuttal by Vulpetti at https://centauri-dreams.org/wp-content/Bolonkin%20Refutation_edited.pdf should also be cited and summarized. There are several critiques on the M2P2 approach, some of which also apply to the plasma magnet (e.g., 1/r magnetic field falloff rate vs classical 1/r^3. Dmcdysan (talk) 19:15, 23 June 2022 (UTC)

Criticism:

```  The simplest computation shows a profound mistake in the most known works about MagSail. Some of them (40) are presented in [7].
Take the typical MagSail ring: radius of ring is R = 50 km, electric current I =104 A. The intensity H1 of magnetic field in center of ring is
```
``` H1=I/2R=104/105=0.1   N/m,	(1)
```

This intensity is approximately same of the ring as well as near it.
We assume in our subsequent computation that H1 = constant.

``` Take the typical solar wind flows into ring at distance from Sun 1 AU (the Earth’s orbit about its primary star) with average wind speed V = 400 km/s, and density N = 107 1/m3. The solar wind contains electrons and protons. Within the ring magnetic field they rotate under Lawrence force and produce their own magnetic field that is OPPOSED to the ring magnetic field, decreases it (diamagnetic property), and pumps the ring magnetic energy into energy of its own magnetic field (summary energy is constant). This magnetic field from the rotated electrons (we here neglect the additional magnetic field from the rotated protons) can be estimated by equations (we consider only electrons into the ring):
```

H2=i/2r, r=V/(q/me)/B, i=3.14R2qNV, B=muoH1 , (2)

where H2 is magnetic intensity from rotated solar wind electrons, A/m; r is
electron gyro-radius, m; i is electric currency of solar wind electrons,
A; V = 400 km/s is average solar wind speed, B is magnetic intensity,
T; mu0 = 12.56x10-7 is magnetic constant.

```  Substituting our values, we received r = 18.2 m; i = 5024 A; H2 = 276 A/m. The last magnitude shows that the magnetic intensity of solar wind electrons is in 2760 times greater (H2 >> H1) than the ring magnetic intensity of MagSail! It is correct fo any charged beam that interacts with the MagSail.< That means all research and computation (without an influence the solar wind or charged beam into MagSail) is wrong and basically worthless for all practical space exploration and exploitation applications.
```
```  How can it happen that hundreds of researchers, professors at famous universities, audiences of specialists, members of scientific Conferences and Congresses, editors of scientific journals: "Journal of Propulsion and Power", (Editor V. Yang); Journal "Spacecraft and Rockets", (Editor V. Zoby), paid so little attention to student-level mistakes in many scientific publications and public presentations to scientific conferences? More over, the director NASA Institute for Advanced Concepts (NIAC)
```

Mr. R. Cassanova awarded (totaling more than \$1 million dollars!) to his close
associate, professor R.M. Winglee (University of Washington) for pseudo-scientific work

It is still happening because popular textbook authors continue to consider the
interaction between the strong magnetic field of particle accelerators and small amount
of charged particles where we can neglect the influence of charged particles in
magnetic field of the accelerator. With MagSail’s, we have the opposed situation: the
weak ring magnetic field and strong magnetic field of solar sail or charged beam.

7. Bolonkin A.A., Theory of Space Magnetic Sail. Some Common Mistakes and Electrostatic MagSail. Paper AIAA-2006-8148 presented to 14th AIAA/AHI Space Planes and Hypersonic System and Technologies Conference, 6-9 November 2006, National Conference Center, Canberra, Australia. See also AIAA-2006-7709 or BolonkinA.A., New Concepts, Ideas, Innovations in Aerospace, Technology and Human Science, NOVA, 2008, 400 pgs. Part A, Chapter 4.
8. Bolonkin A.A., Non-Rocket Space Launch and Flight, Elsevier, 2006, 488 pgs., Ch.13, pp.245-270.

## Who is Zubrin?

Changes are needed in the "Principles of origin and design" section to clarify who Zubrin is and assert the notability of his mention in this article. Specifically, I'd like to see a link over to Robert_Zubrin and a mention of his name before "Zubrin's proposed magnetic sail design would ...", which leaves readers scrolling back up to see if they missed prior mention of him. Failing that, perhaps rewording to "The original design..." ◗●◖ falkreon (talk) 00:25, 30 March 2009 (UTC)

## Can Such devices be used to leave the earths gravitational field?

For sufficiently (nuclear powered?) devices - would the generation of a magnetic field/associated electric field enable escape from the earths own gravitational pull (in theory, of course).

ConcernedScientist (talk) 22:08, 22 April 2009 (UTC)

No, unfortunately things like the ionosphere and high winds etc would mess with your influence too much. Plus the size of your device would be gigantic... But they can travel around orbital levels, which might be useful for satellites. There are plenty of other ways to get up there. 99.236.221.124 (talk) 22:12, 5 May 2010 (UTC)

## Magnetic bacteria as natural magnetic sails

With the discovery of magnetite crystals in the famous martian meteorite and their resemblance to the magnetite crystals made here on earth by magnetic bacteria I would love to hear a discussion on possible panspermia mechanisms involving the physics of the magnetic sail on magnetic bacteria. TSpencerGrow (talk) 09:20, 27 September 2010 (UTC)

## Critism

It would be nice if there was a section with views from detractors or just explaining the problems with this system. The Solar Sail as well as the ramjet article could use the same. —Preceding unsigned comment added by 98.232.220.23 (talk) 14:12, 21 September 2010 (UTC)

## Speed

"A common misconception is that a magnetic sail cannot exceed the speed of the plasma pushing it."

I can understand how you can do that with a normal sailboat. By slowing down the air and speeding up the water, you extract energy and preserve momentum. You then use that energy to speed up the boat and slow down the air and water.

With a magnetic sail, there's just the plasma, right? From the point of reference that the plasma is still, how can the sail accelerate? — DanielLC 01:37, 11 May 2011 (UTC)

## It should be capable of repelling from a planet far from the poles if aligned to field lines, no?

If the craft (or just the sail itself) is aligned with the field lines of the planet's magnetosphere, shouldn't it be capable of repelling from (or attracting to) the planet even when away from the poles? --TiagoTiago (talk) 17:17, 6 November 2011 (UTC)

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## Methods of Operation: Sailing against the Plasma Wind

Dmcdysan (talk) 20:17, 11 June 2022 (UTC)This section needs citation(s), and could be written more clearly. I will begin working on this and submit some proposed citations and likely revised text.

I have read quite a bit about magnetic sails, but have never seen anything like the following:

"A common misconception is that a magnetic sail cannot exceed the speed of the plasma pushing it. As the speed of a magnetic sail increases, its acceleration becomes more dependent on its ability to tack efficiently. At high speeds, the plasma wind's direction will seem to come increasingly from the front of the spacecraft. Advanced sailing spacecraft might deploy field coils as "keels", so the spacecraft could use the difference in vector between the solar magnetic field and the solar wind, much as sailing yachts do."

It appears to make an analogy with sailboats that may not be valid.

I recommend deletion unless someone can cite a reference. Dmcdysan (talk) 20:17, 11 June 2022 (UTC)

## Theory in the limit of small plasma densities

"A bow shock can be neglected in the limit of small plasma densities."

This is not what the C. Gros 2017 citation states in Figure 4 and Appendix B. It does state that the effective reflection area A(v) approaches zero as v/c approaches 1 (see Figure 4). Propose removing the above sentence and summarizing Figure 4 and Appendix B in the Effective reflection area subsection.

I looked at citations for the C. Gros 2017 citation and found several papers that cite the results but do not confirm the method. This result is at odds with other predictions, for example the Freeland 2015 "Mathematics of Magsails" and the 1988 Zubrin paper.

A better organization for this article could be to summarize each of the major magnetic sail approaches and cite the major results and conclusions with reference to another section that contains the mathematical details. Another section could be that for critiques and that is where the material from "Theory in the limit of small plasma densities" would go with a changed title since the analysis is independent of plasma density and dependent only on ship's speed. Another section could compare results from the proposals and the critiques.

Thoughts, anyone? Dmcdysan (talk) 19:04, 23 June 2022 (UTC)

## Inside a planetary magnetosphere

Did some searching and added a citation to a Zubrin 1991 paper. Appears that text is a high-level summary of that paper.

Marked statement for "similar to electrodynamic tether" as needing citation since it is unclear.

Looked for references that cited the Zubrin 1991 paper and there are many, but did not find any that appear proposing to advance/refine this work. Didn't find any that refuted it either. More recent, relevant citations are still needed, otherwise this should be a historical note.

Figure in this section was not helpful in explaining this to me. It is not from the Zubrin 1991 paper. Recommend deletion. Dmcdysan (talk) 21:20, 23 June 2022 (UTC)

## In a plasma wind

Edited text in this subsection and provided citations and links to other Wikipedia pages that have citations.

Figure is not useful. Better covered in Wikipedia page 'Lorentz force" since this the Figure attempts to depict F = v x B inaccurately. All other paragraphs are marked citation needed. Cut and pasted them and the Figure here in case someone wants to add citations or discuss resurrecting the Figure.

A magnetic sail in a wind of charged particles. The sail generates a magnetic field, represented by red arrows, which deflects the particles to the left. The force on the sail is opposite.

Just as with solar sails, magnetic sails can "tack". If a magnetic sail orients at an angle relative to the solar wind, charged particles are deflected preferentially to one side and the magnetic sail is pushed laterally. This means that magnetic sails could maneuver to most orbits.[citation needed]

Solar weather also has major effects on the sail. It is possible that the plasma eruption from a severe solar flare could damage an efficient, fragile sail..[citation needed]

A common misconception is that a magnetic sail cannot exceed the speed of the plasma pushing it. As the speed of a magnetic sail increases, its acceleration becomes more dependent on its ability to tack efficiently. At high speeds, the plasma wind's direction will seem to come increasingly from the front of the spacecraft. Advanced sailing spacecraft might deploy field coils as "keels", so the spacecraft could use the difference in vector between the solar magnetic field and the solar wind, much as sailing yachts do.[citation needed]

Removed

since citations have been added and old text cut and pasted here in case discussion needed.Dmcdysan (talk) 22:15, 25 June 2022 (UTC)