Magnetic sail and Ion wind

The researchers suggest using a magnetic field rather than a bulky solar sail for interstellar flights. It will allow to receive an impulse from the ions flying out of the Sun. In addition, scientists expect to use “dynamic soaring” at the boundary of interstellar space.

An eclipse of the Sun in polarized light. The red color is charged particles that can push a magnetic sail. Source: M. Druckmuller/ Habbal et al., ApJL, 2021

Imperfect Solar Sail

Scientists from McGill University in Canada and the Tau Zero Foundation in the USA have proposed an alternative to solar sails. These designs are considered as one of the most promising ways to travel beyond the Solar System. Unlike other carriers, they do not need incredibly high fuel consumption due to the fact that they can simply capture photons emitted by our star.

But in order to accelerate a large enough spacecraft, the size of a solar sail must be measured in kilometers. And the material should be extremely durable and lightweight, with high reflectivity and very effective in removing heat.

Because of the combination of all these parameters, scientists still cannot imagine a solar sail that could accelerate the device to a speed greater than 2 percent of light. And this means that travel to other stars will continue for decades.

Superconductor instead of a sail

Scientists suggest using charged ions rather than neutral photons to accelerate the spacecraft. Our Sun also releases them in large quantities, although much less than particles of light.

But each of them carries much more energy than a photon. Usually, only problems are expected from this, because these particles can transfer their charge to the sail and thereby create a static charge that distorts the structure.

However, if the mirror film of the sail is replaced with a superconductor and a magnetic field is created with its help, then it can capture ions and use them to accelerate the apparatus.

“Dynamic soaring” for a magnetic sail

However, charged particles move in space at a speed of only 700 km/s. Which is only a quarter of a percent of the light. Therefore, at first glance, a magnetic sail does not seem better than a solar one.

But scientists are confident that thanks to the effect known as “dynamic soaring”, more can be achieved. This phenomenon is used by birds, which find it difficult to accelerate solely due to their own muscles. A headwind allows them to accelerate.

Scientists expect to see the same thing on the border of the Solar System with interstellar space. Here, the ions accelerated by the Sun collide with the same ones that came to us from other stars. And, perhaps, this “headwind” will allow the spacecraft to develop at a much higher speed.

According to

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