The article says that since the thrust is always away from the Sun, it can't be used for inward journeys. But if I'm thinking correctly, this isn't necessarily true.
If you're in a circular orbit, and run this for a while (short compared to orbital period), then turn it off, I think you'll be in an elliptical orbit with perihelion lower than your initial orbit. If when you reach perihelion there happens to be a convenient planet with an atmosphere, you could aerobrake and either land or maybe continue in a circular orbit closer to the sun than your original orbit.
Claim 5 is a bit puzzling to me :
A key feature of the plasma magnet is that the diameter of the magnetosphere increases as the density of the solar wind decreases as it expands away from the sun. The resulting expansion exactly matches the decrease in density, ensuring constant thrust. Therefore the plasma magnet has a constant acceleration irrespective of its position in the solar system.
I'm not 100% sure about the science here, but the "exactly" looks a bit magical to me. If I understand the concept correctly, when the sail is closer to the sun, the particles "pressure" on the sail will "compress" and reduce its effective area.
Formatting problems are making it start out pretty much unreadable for me on Firefox on Mac . Whatever is laying out the text and sidebar is using a width that is much larger than the width of the white area, so part of the text and all of the sidebar end up out in the black right margin. Since the text is black, this doesn't work well.
Workaround: narrow the width of the white area. As soon as the window shrinks to that width, it changes to a format that appears to be designed for narrow devices.
The narrow layout correctly matches the width of the text display to the width of the white area.
For more history on this, see the magnetic sail proposed by Dana Andrews and Robert Zubrin in 1988:
They found that it wasn't very efficient for acceleration but could be used for braking (for example by a light craft propelled by laser to another solar system).
Also tacking works by angling the force to increase or decrease orbital velocity. This assumes that plasma drives can be used for acceleration, and I think that they probably can with the right geometry/technique and were abandoned prematurely. And they obviously can when used with something like nuclear power where avoiding the need to carry propellant is more important than efficiency.
Not changing your angular momentum around the Sun limits the usefulness of this drive by a lot. Sure, you can change the shape of the ellipse that you travel. But anything that you encounter far away from the Sun will be going very fast compared to you, and you'll go very fast compared to anything that you encounter near the Sun, making actual visits very unwise.
The CSS is badly broken for me.
Might regenerative braking at the destination star be possible? If so, nearly all of the stored energy could be depleted in acceleration, leaving just enough to bootstrap deceleration.
From a different source...
(One possible barrier is a magnetic field of 50nT at or beyond 4 km. To create such a field using an electromagnet requires very large-scale engineering, for example a circular electromagnet 300m in radius carrying 10^5 amp-turns. While such an electromagnet is not impossible, it would likely be so massive that the relatively modest thrust coupled from the solar wind would provide accelera tion too slow to be of interest.
So we just need some novel superconductors, a portable fusion plant, and then we’re set! /s
Edit: Corrected formatting errors. Thanks for the heads up!
Shouldn’t they be able to tack “upwind” to go towards the sun?
I've heard about solar sails for decades. Why have we never created one? Is there something limiting its development besides money?
The US doesn't even produce any plutonium anymore and NASA has to buy fuel from Russia and then deal with protestors when they try and test power plants that would be able to last long enough and be durable enough to get us to Mars. Activists have halted much of the worlds energy research.