New ideas might make active shielding viable


The primary alternative—using active shields that deflect charged particles just like the Earth’s magnetic field does—was first proposed in the 1960s.
They’re nasty when you have no shelter but are relatively easy to shield against since solar protons are mostly low energy.
When high-energy cosmic ray particles hit thin shields, they produce many lower-energy particles—you’d be better off with no shield at all.
What keeps us safe at homeThe reason nearly none of this radiation can reach us is that Earth has a natural, multi-stage shielding system.
It begins with its magnetic field, which deflects most of the incoming particles toward the poles.
A charged particle in a magnetic field follows a curve—the stronger the field, the tighter the curve.
Earth’s magnetic field is very weak and barely bends incoming particles, but it is huge, extending thousands of kilometers into space.
Anything that makes it through the magnetic field runs into the atmosphere, which, when it comes to shielding, is the equivalent of an aluminum wall that’s 3 meters thick.
So solving radiation with passive mass won’t cut it for longer missions, even using the best shielding materials like polyethylene or water.
This is why making a miniaturized, portable version of the Earth’s magnetic field was on the table from the first days of space exploration.

A massive X13 class solar flare that occurred on October 19, 1989, at 12:29 UT set off a geomagnetic storm that was so powerful that the next day, auroras could be seen in Germany, America, Australia, and Japan. It is highly likely that you would have died within a month or so if you had been flying around the Moon at that time and had absorbed well over 6 Sieverts of radiation.

This is the reason why the Orion spacecraft, which is scheduled to carry out a lunar fly-by mission this year, has equipped its crew with a heavily shielded storm shelter. Such shelters, however, are insufficient for a trip to Mars because Orion’s shield is only intended to last 30 days.

It is just not feasible to transport hundreds of tons of material into orbit in order to achieve protection equivalent to that which we have on Earth. The main substitute was first put forth in the 1960s and involves the use of active shields, which deflect charged particles in the same way as the Earth’s magnetic field does. We’re getting close to pulling it off today.

deep-space radiation.

Distinct types of space radiation exist. Protons are the most common charged particle fluxes that can be produced by solar events like flares and coronal mass ejections. Since solar protons are primarily low energy, they are difficult to protect against in the absence of shelter, but they are still unpleasant when you do. Orion-like shelters could be able to stop most solar particle events, which have fluxes between 30 and 100 megaelectron volts.

Secondly, there are galactic cosmic rays, which are extrasolar particles propelled by distant neutron stars or supernovae. Although they are comparatively uncommon, they constantly approach you from all sides. Additionally, they have very high energies—200 MeV to several GeVs—which makes them incredibly permeable. There isn’t much protection against them from thick masses. You would be better off without any shield at all because high-energy cosmic ray particles produce a lot of lower-energy particles when they strike thin shields.

Promoting something.

Ninety-five percent of the radiation dose astronauts receive in space is caused by particles with energies between 70 and 500 MeV. Solar storms are the main concern on short flights because they can be very violent and quickly cause a lot of damage. But, GCRs become more problematic the longer you fly because they build up over time and are resistant to almost everything we try to do.

what safeguards our safety at home.

We are largely shielded from this radiation by the Earth’s natural multi-stage shielding system. It starts with its magnetic field, which directs the majority of incoming particles in the direction of the poles. The tighter the curve, the more strongly a charged particle follows it in a magnetic field. Though it is enormous, reaching thousands of kilometers into space, Earth’s magnetic field is incredibly weak, hardly bending incoming particles.

Anything that escapes the magnetic field enters the atmosphere, which provides shielding comparable to a three-meter-thick wall of aluminum. Lastly, there is the planet itself, which essentially reduces radiation by half because there is always 6.5 trillion tons of rock to shield you from the subsurface.

To put that into context, the crew of the Apollo crew module was shielded from radiation by an average of 5 grams of mass per square centimeter. That is doubled, to roughly 10 g/cm2, in an average ISS module. It weighs thirty-six tons and has a density of 35–45 g/cm2, depending on your exact position. Compared to our best shielded spaceships, the atmosphere alone on Earth provides 810 g/cm2, or about 20 times more.

The two choices are to reduce the mission’s duration, which isn’t always feasible, or add more mass, which adds up quickly. Consequently, even with the best shielding materials, such as water or polyethylene, solving radiation with passive mass will not be sufficient for longer missions. That’s the reason why the idea of creating a portable, miniature version of Earth’s magnetic field was raised from the outset of space travel. We regret to inform you that this was much easier said than done.

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