A Force Field for Astronauts?

[C1ay]

Opposite charges attract. Like charges repel. It's the first lesson of electromagnetism and, someday, it could save the lives of astronauts.

 

lefthttp://hypography.com/gallery/files/9/9/8/crab_nebula_thumb.jpg[/img]NASA's Vision for Space Exploration calls for a return to the Moon as preparation for even longer journeys to Mars and beyond. But there's a potential showstopper: radiation.

 

Space beyond low-Earth orbit is awash with intense radiation from the Sun and from deep galactic sources such as supernovas. Astronauts en route to the Moon and Mars are going to be exposed to this radiation, increasing their risk of getting cancer and other maladies. Finding a good shield is important.

 

The most common way to deal with radiation is simply to physically block it, as the thick concrete around a nuclear reactor does. But making spaceships from concrete is not an option. (Interestingly, it might be possible to build a moonbase from a concrete mixture of moondust and water, if water can be found on the Moon, but that's another story.) NASA scientists are investigating many radiation-blocking materials such as aluminum, advanced plastics and liquid hydrogen. Each has its own advantages and disadvantages.

 

Those are all physical solutions. There is another possibility, one with no physical substance but plenty of shielding power: a force field.

 

Most of the dangerous radiation in space consists of electrically charged particles: high-speed electrons and protons from the Sun, and massive, positively charged atomic nuclei from distant supernovas.

 

Like charges repel. So why not protect astronauts by surrounding them with a powerful electric field that has the same charge as the incoming radiation, thus deflecting the radiation away?

 

Many experts are skeptical that electric fields can be made to protect astronauts. But Charles Buhler and John Lane, both scientists with ASRC Aerospace Corporation at NASA's Kennedy Space Center, believe it can be done. They've received support from the NASA Institute for Advanced Concepts, whose job is to fund studies of far-out ideas, to investigate the possibility of electric shields for lunar bases.

 

Above: Artist’s concept of an electrostatic radiation shield, consisting of positively charged inner spheres and negatively charged outer spheres. The screen net is connected to ground. Image courtesy ASRC Aerospace.

 

"Using electric fields to repel radiation was one of the first ideas back in the 1950s, when scientists started to look at the problem of protecting astronauts from radiation," Buhler says. "They quickly dropped the idea, though, because it seemed like the high voltages needed and the awkward designs that they thought would be necessary (for example, putting the astronauts inside two concentric metal spheres) would make such an electric shield impractical."

 

Buhler and Lane's approach is different. In their concept, a lunar base would have a half dozen or so inflatable, conductive spheres about 5 meters across mounted above the base. The spheres would then be charged up to a very high static-electrical potential: 100 megavolts or more. This voltage is very large but because there would be very little current flowing (the charge would sit statically on the spheres), not much power would be needed to maintain the charge.

 

The spheres would be made of a thin, strong fabric (such as Vectran, which was used for the landing balloons that cushioned the impact for the Mars Exploration Rovers) and coated with a very thin layer of a conductor such as gold. The fabric spheres could be folded up for transport and then inflated by simply loading them with an electric charge; the like charges of the electrons in the gold layer repel each other and force the sphere to expand outward.

 

righthttp://hypography.com/gallery/files/9/9/8/voltage_thumb.jpg[/img]Right: How the voltage would vary above a lunar base for the sphere configuration shown above. You can learn more about this and other configurations in the report Analysis of a Lunar Base Electrostatic Radiation Shield Concept.

 

Placing the spheres far overhead would reduce the danger of astronauts touching them. By carefully choosing the arrangement of the spheres, scientists can maximize their effectiveness at repelling radiation while minimizing their impact on astronauts and equipment at the ground. In some designs, in fact, the net electric field at ground level is zero, thus alleviating any potential health risks from these strong electric fields.

 

Buhler and Lane are still searching for the best arrangement: Part of the challenge is that radiation comes as both positively and negatively charged particles. The spheres must be arranged so that the electric field is, say, negative far above the base (to repel negative particles) and positive closer to the ground (to repel the positive particles). "We've already simulated three geometries that might work," says Buhler.

 

Portable designs might even be mounted onto "moon buggy" lunar rovers to offer protection for astronauts as they explore the surface, Buhler imagines.

 

It sounds wonderful, but there are many scientific and engineering problems yet to be solved. For example, skeptics note that an electrostatic shield on the Moon is susceptible to being short circuited by floating moondust, which is itself charged by solar ultraviolet radiation. Solar wind blowing across the shield can cause problems, too. Electrons and protons in the wind could become trapped by the maze of forces that make up the shield, leading to strong and unintended electrical currents right above the heads of the astronauts.

 

The research is still preliminary, Buhler stresses. Moondust, solar wind and other problems are still being investigated. It may be that a different kind of shield would work better, for instance, a superconducting magnetic field. These wild ideas have yet to sort themselves out.

 

But, who knows, perhaps one day astronauts on the Moon and Mars will work safely, protected by a simple principle of electromagnetism even a child can understand.

 

Source: Science@NASA

[UncleAl]

Not A Space Agency

 

This same sort of hornswoggle was originally proposed as a multiple tesla magnetic field using a supercon solenoid. Push come to shove, anybody doing any serious traveling in the solar system (or cooling his heels in ISS FUBAR) will get cooked by radiation (solar fast protons; cosmic rays) . It is much worse when you leave the protection of the Earth's magnetic field, though ISS FUBAR ***-tronaughts routinely get radiation cataracts.

 

The intense magnetic field was not clever at all, but it was doable. Charging 50 million volts on a human-bearing vehicle is frank stooopidity. Working on a 50 kV power line is quite dangerous, but procedure will protect a lineworker. Working an a 250+ kV power line requires intensive training, special armored clothing, and a lot of luck. A 50 MV environment (gee - there is no electric field inside a closed conductor!) is utterly insane.

 

The magnetic field would be a giant iron dust collector. The electric field would simply blow off into space as field emission into vacuum. Any little boo-boo will fry the entire craft and its occupants - snap, crackle, pop!

[CraigD]

I recall that most designs for long-journey manned spacecraft take advantage of the efficacy of ordinary water as a shielding material by surrounding part of the crew compartment with a fairly thin (10-15 cm) layer of water. Since an extreme solar event can be safely detected before the massive particle flux reaches dangerous levels, all that’s required is a small compartment for the crew to crowd into for the duration of the event.

 

Water shielding wasn’t practical for the Apollo missions, because the spacecraft had to keep their mass as low as possible to make it possible for even the most powerful rocket system available to boost them to the moon. It’s probably not practical for first-generation moon dwellings, because water appears to be extremely rare on the moon.

 

Long-journey manned spacecraft, such as those being considered for a mars mission, are typically much more massive than the Apollo vehicles, involving many launches and assembly in earth orbit, so these factors don’t make water shielding impractical. Even if strong static charged conductive surfaces like those suggested by ASRC Aerospace Corp’s Buhler and Lane can be made to work I don’t believe they would be chosen over water shielding for such spacecraft.

 

They might be effective for shielding exposed moon vehicles and dwellings, where sufficient quantities of water are unavailable at a reasonable cost, and the available, hydrogen-poor lunar material a poor choice for reasonably low-mass shielding. I’m very skeptical that such a system can be made to work, both for the reasons UncleAl raises, and because the scattering caused by a thin conductor, even if aswarm with charge, might not deflect enough dangerous particles. They’d certainly have no effect on the dangerously more numerous high-energy photons that accompany these massive particles during an extreme solar event.

 

Even on the moon, I expect very small water shield “umbrellas” is a more practical solution.

[Turtle]

Now comes the idea of a plasma shield to protect astronauts! I don't know enough physics to judge the suitability, but I see they plan to use superconductors & maybe Uncle Al's new superconducting material he proposed has a potential use.;)

Here's a quote & link to article:

 

http://www.newscientistspace.com/article/dn9567-plasma-bubble-could-protect-astronauts-on-mars-trip.html

 

The wire mesh would need to be made of superconducting material and it would need to be able to operate at relatively high temperatures, since it would be heated by sunlight. This sort of superconducting wire is available commercially, Slough says.

:hihi:

[Mercedes Benzene]

This is an interesting topic, but I do not believe that NASA will go through with any of these ideas.

I mean: really! NASA wants to get back to the moon and then eventually to mars...

They want to do all of this, and with a continually cut budget...

The least of their concerns is a radiation shield. They'll find a way to make do with current blocking technology.

 

Nonetheless, a wonderful article.

[Turtle]

This is an interesting topic, but I do not believe that NASA will go through with any of these ideas.

I mean: really! NASA wants to get back to the moon and then eventually to mars...

They want to do all of this, and with a continually cut budget...

The least of their concerns is a radiation shield. They'll find a way to make do with current blocking technology.

 

Nonetheless, a wonderful article.

 

No human can survive a trip to Mars without shielding; it has to have a workable solution before we go. I remember Uncle Al saying it takes 3 feet of lead to provide the same protection as Earth's atmosphere.

[Mercedes Benzene]

No human can survive a trip to Mars without shielding; it has to have a workable solution before we go. I remember Uncle Al saying it takes 3 feet of lead to provide the same protection as Earth's atmosphere.

 

Yes, but the technology that we have available now is sufficient enough...

Humans will be exposed to radiation no matter what. It is just to what degree that seems to be the problem here.

Astronauts easily go over the reccomended annual dose of background radiation in a 3-week stay on the international space station.

I don't think that NASA will work to develop protection that is any more adequate than what they use now.

[Turtle]

Yes, but the technology that we have available now is sufficient enough...

Humans will be exposed to radiation no matter what. It is just to what degree that seems to be the problem here.

Astronauts easily go over the reccomended annual dose of background radiation in a 3-week stay on the international space station.

I don't think that NASA will work to develop protection that is any more adequate than what they use now.

 

No no no! You misunderstand. The low Earth orbit craft are inside Earth's magnetic field with provides enough shielding to prevent death. That is not the case on a trip to Mars. If NASA (or anyone) is going to Mars with people the shielding problem has to have a workable solution.

[Mercedes Benzene]

:lol:

No no no! You misunderstand. The low Earth orbit craft are inside Earth's magnetic field with provides enough shielding to prevent death. That is not the case on a trip to Mars. If NASA (or anyone) is going to Mars with people the shielding problem has to have a workable solution.

 

Oh okay. Thanks Turtle. ;)

I still have questions about the trips that we have made to the moon though.