Solar Flares Shield Astronauts from Cosmic Rays

It doesn't come easy writes "Considering all of the research into better shielding for astronauts, it's interesting to note that solar flares can help shield space travelers from dangerous cosmic rays. From the article: "The crew of the ISS absorbed about 30% fewer cosmic rays than usual [during this last month of high solar activity]," says Frank Cucinotta, NASA's chief radiation health officer at the Johnson Space Center. "The storms actually improved the radiation environment inside the station." Scientists have long known about this phenomenon. It's called a "Forbush decrease," after American physicist Scott E. Forbush, who studied cosmic rays in the 1930s and 40s. So, I guess it would be safer to plan a manned Mars mission to coincide with peak sunspot activity?"

Comments

Shields up

[cy_a253]

So, I guess it would be safer to plan a manned Mars mission to coincide with peak sunspot activity?"

How about having the spacecraft generate its own external magnetic field? How effective would that be?

Re:Shields up

[Anonymous Coward]

A better shield would be composed of something that is rich in hydrogen, as high velocity charges particles like those in cosmic rays will lose their energy as they intereact with the protons in the hydrogen atoms.

Eventually, when we get to the point where we're building ships in orbit (where mass will be less of an issue than it is when you're launching it all up from Earth), you'd likey be building a vehicle out of more durable materials (mmm, cermets), with a good layer of the previously mentioned hydrogen rich material, most likely a plastic of some sort.

Magnetic fields would add to this protection for lower energy particle radiation, but sometimes they can make such hazards worse by accellerating the particles further. However, done correctly, they could provide a little extra protection, while at the same time giving you a nifty propulsion system in the form of a magnetic sail.

Re:Shields up

[shokk]

You mean like a hot hydrogen plasma confined in a toroid shaped magnetic field similar to what they use for fusion research? Maybe it doesn't need to be quite that hot to protect the astronauts, but keeping it moving around the outside of the craft may produce the same benefit.

that's about once every 11 years...

[HarveyTheWonderBug]

Not very pratical for commuting ...

Magnetize the hull?

[aussie_a]

If I'm understanding this right, the magnetic properties of the solar flare cause the decrease in CME's? If so, couldn't ships magnetize their hull to shield the people inside? It obviously won't stop all the CME's, but it will decrease it.

Might turn out Enterprise's "ionize the hull" isn't as much sci-fi nonesense as it first sounds.

Re:The fantastic four

[grogdamighty]

Jean Gray was one of the X-Men, not the Fantastic Four...

when to have space missions

[ScottSCY]

"So, I guess it would be safer to plan a manned Mars mission to coincide with peak sunspot activity?"
No, the real answer is to have space missions start on Sun-days. har har har har.

Re:when to have space missions

[aussie_a]

No, the real answer is to have space missions start on Sun-days. har har har har.

In space no-one can hear your terrible puns.

Mars trip during solar storm

[Bananatree3]

"So, I guess it would be safer to plan a manned Mars mission to coincide with peak sunspot activity?"

Well, that could be a logical conclusion from the article. BUT, what also occurs during major sunspot activity?. Mondo solar flares! Yes, they may help suppress the Cosmic Radiation. But, I sure wouldn't want to be stuck somewheres in the vast space between Mars and Earth with one of these monsters heading for me. The spaceship would be hit like a rowboat in a hurricane, in terms of solar radiation.

Re:Mars trip during solar storm

[saskboy]

You're correct. The submitter didn't realize that cosmic radiation and solar radiation are not the same thing, since solar radiation is the stuff that comes from our sun, and cosmic radiation comes from sources outside of our solar system like other stars, black holes, pulsars, nova, and other big bad radiation machines out there.

There may be a decrease in radiation coming from elsewhere, but the ship would still be hammered by high speed Coronal Mass Ejection particles. Radiation sheilding is essential; Bring your polyethylene, in other words.

Re:Mars trip during solar storm

[necro81]

An excellent point, and one that probably will mean that it is, in fact, safer to try and avoid spaceflight during high solar activity (when possible). On the other hand, the danger is only there if the CME is directed in your general vicinity. Sure, the Earth gets hit with a solar flare (or its remnants, actually) from time to time, but it does not get hit with every solar flare the Sun produces.

Re:The fantastic four

[Anonymous Coward]

buuuuuuuuurn

(get it, it's a pun)

ISS is inside the van allens/earh's magnetic field

[Pottsynz]

Hence its hardly a perfect testbed for radiation effects regarding long-term space flights. You have to wonder if the factored in the change solar activity makes to the earth's magnetic field when putting this all together.

No protection from death rays!

[uncoveror]

Solar flares may protect astronouts from cosmic rays, but will provide no defense against death rays or destructo-rays!

Re:hmmm, matter absorbing energy?

[ccarson]

Apparently, the Earth magnetic field has decreased by 10% in the last 10 years. I'm an electrical engineer and during my studies in sub-atomic physics, I learned that a particles velocity can be effected by magnetic fields. I keep hearing about the increased activity of our Sun and I believe it's possible that more of the Sun's radiation is penetrating the Earth's magnetic field due to it being weaker. If more radiation hits the Earth and the Sun is spewing out more heat, shouldn't that also increase the overall temperature of the Earth and can global warming be attributed to this? I've been bouncing this idea in my head for a while now and I can't see why this MAY not be true.

NASA source

[saskboy]

NASA Science News for October 7, 2005

Another source:

Strange, but true: Solar flares can be good for astronauts.

Re:NASA source

[Jeff DeMaagd]

True, sadly, Slashdot is reposting yubanet's repost of NASA's story of last week. Even worse, Slashdot will repost this story within 24 hours.

1/r^2 kills this

[G4from128k]

The Sun's magnetic field may be very weak (about 5 Gauss at the surface, about 0.00005 Gauss in solar wind), but it's very big. Creating a field with a compact object (say 100 meters in diameter -- quite a large space craft!) that creates a 0.00005 Gauss field at a distance of 160 million kilometers would require a field strength on the order of about 1.28 x 10^18 Gauss. This is NOT compatible with living things. Fields stronger than 100,000 Gauss can levitate living things. I suspect that the needed deflector field would strip the electrons off the spacecraft's atoms (even a 200,000 gauss magnets have a tendency to explode).

Even if I'm off by many orders of magnitude (IANAP), the required field strength will be unattainably high.

Re:1/r^2 kills this

[mattjb0010]

Fields stronger than 100,000 Gauss can levitate living things.

I've stuck the movie of the levitating frog up here

Re:1/r^2 kills this

[barawn]

Nope.

The fact that the Sun's magnetic field is large isn't what protects us from cosmic rays. The Sun's magnetic field encourages particles to orbit the Sun. That doesn't help us. What helps is when a dipole field gets closer to you - like when the Sun sloughs off a bunch of plasma that drifts near you. Hence a Forbush decrease. What protects us on Earth is the Earth's magnetic field, and the atmosphere.

Anyway, it's relatively easy to craft magnetic fields to any shape you want. So high magnetic field on the outside, zero magnetic field on the inside. We're really good at that. And 5 tesla (50,000 gauss) should be about enough. It has been studied.

The reason it's not ideal is because cosmic rays aren't all charged. Gamma rays make up a component of solar cosmic rays, and okay, there may (should) be a few neutrons from the Sun as well (though that part is really new and not well studied).

But magnetic shielding is very actively being looked at. It's just not an easy problem - we don't have very much experience with superconducting magnets in space, for instance.

Interestingly, one of the best things about this is that you don't really have to worry about the highest energy particles which will get through. Not only is the flux far, far lower, but they deposit less energy than lower energy particles which stop in your body. So it's pretty easy to figure out how high a magnetic field you need.

And smartass comment: magnetic fields don't drop like 1/r^2. Electric fields do. For a simple magnetic dipole, the field strength drops like 1/r^3. Different configurations drop differently, as well.

Re:1/r^2 kills this

[Anonymous Coward]

Relativistic effects also alter the apparent half-life of free neutrons. Neutrons traveling at relativistic speeds will have significantly longer lives relative to us. Particle accelerators rely on this effect to work with short-lived particles.

Re:Danger Level

[Biff Stu]

I once had a chat with a NASA biomedical researcher who told me that astronauts in space occasionally see flashes of light. These flashes coincide with cosmic rays destroying cones and/or rods in their retina. Not a pleasant thought if you ask me.

Of course, these same cosmic rays will also destroy cells in the brain and fragment DNA, potentially generating damage which could either lead to cancer or lead to genetic problems which could be passed on to future generations.

Although I can't quantify the risk associated with the latter phenomena, knowing that every time I see a little flash I have suffered a small but permanent loss of vision would make space travel less appealing.

Except that...

[Anonymous Coward]

The reason for this decrease in galactic cosmic rays is that the solar flares and coronal mass ejections themselves emit relativistic electrons and solar cosmic rays (mostly protons) which are responsible for pushing the galactic particles back. The number of solar energetic particles emitted during flares is much larger than the galactic source. In addition to the energetic particles, the sun also emits copious amount of hard and soft X-rays during solar flares.

I don't think that it matters much to an astronaut whether the ionizing radiation is galactic or solar in origin. As for solar flares improving the radiation environment inside the space station, I find that statement very curious. With experts such as this, maybe that's why they announced the closing of the Space Environment Effects division at NASA last week.

Re:Except that...

[Anonymous Coward]

"Solar flares dump huge amounts of energy into the Earth's magnetic field. The more engergy, the further south the Aurora Borealis appears, as the magnetic field pulls particles from the solar wind to larger circles further away from the poles."

Not exactly. What happens is that with the increased solar wind pressure the magnetosphere becomes distorted, the auroral oval expands equatorwards, and electric currents start flowing. "Magnetic reconnection" events in the magnetotail energize magnetospheric (not solar wind) particles and inject them into the auroral zones resulting in the visible aurora.

Whether or not astronauts are exposed to auroral zone radiation depends on the location of the auroral oval (it expands equatorwards during high geomagnetic activity induced by solar disturbances) and the inclination of the spacecraft orbit. I have satellite (X-ray) images of the auroral oval as far south as Washington DC during one large storm.

For a view of the current "space weather" conditions, see:

http://sohowww.nascom.nasa.gov/spaceweather/

The ACE satellite sits upstream of earth in the solar wind and monitors the solar wind ram pressure and the interplanetary magnetic field Bz component. The NOAA/POES satellite shows images of the current auroral oval (now in its quiet phase).

An excellent article on galactic and solar cosmic rays is here:

http://www.research.ibm.com/journal/rd/421/ziegler .html

If you're wondering why companies like IBM are interested in this, it's because cosmic rays penetrate semiconductor chips and cause "single event upsets" in computers. Or they can knock out an entire satellite. Computer chips need to be "hardened" against radiation before they are space-qualified.

In case you're wondering, I have a PhD in space science lying around here somewhere .....

Great, but... bone loss still a problem

[justsomecomputerguy]

Not saying the bone loss problem can't be solved, but ever since hearing about the bone loss problem I've felt that radiation would be easier to solve than bone loss.

A simplistic source, (http://www.factmonster.com/ipka/A0778174.html) has this easy to digest quote
"... And because the gravity on Mars is only 38% of Earth's, ways to counteract any damaging effects of the weak gravity on their bodies, such as progressive bone loss and muscle atrophy, will have to be found. Currently, there is no fully effective treatment for microgravity-induced bone loss, and counter measures against bone loss are a top space science priority."

For deeper reading try:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd= Retrieve&db=PubMed&list_uids=15852539&dopt=Citatio n

Re:Forbush decrease?

[SwedeGeek]

Well, at least your karma didn't spanked for it like mine did... :(
</whine>

A solar physicist speaks...

[Dr. Zowie]

The problem with going at solar minimum is that more galactic cosmic rays make it inward to the inner solar system, increasing radiation dose. The problem with going at solar maximum is occasional sudden death from energetic proton streams. Solar flares cause three main hazards: gamma rays from the flare itself (a problem but not a lethal one for most events); energetic protons that are accelerated by the flare and any post-flare coronal mass ejection; and bulk clouds of material that are thrown off by the Sun and that entrain magnetic fields.

The energetic protons are a real problem for man and machine. They arrive minutes to hours after the flare itself is seen. They have a high "quality factor", meaning they do a lot more biological damage than an equivalent ionizing dose of X-rays or gamma rays; and they tend to embed themselves in insulators, developing a humongous static charge that screws with electronic circuits and can burn out components. The clouds are more of a problem for planet-sized bodies (like the Earth) than for astronauts, but they do have some potential health consequences. They travel at "only" 1-4 million miles per hour, arriving at Earth about 1-4 days after the solar event.

Over the last three years we've had six or seven large flares that could have caused radiation sickness or death for Apollo astronauts (or Mars-bound astronauts with similar amounts of shielding to a mere Apollo capsule). That's enough that you'd have to expect at least one such event during a Hohmann transfer orbit to Mars, if you travelled at this phase of the solar cycle (declining).

The space station is largely shielded from the energetic protons, because it stays in low Earth orbit, underneath the Van Allen radiation belts -- Earth's magnetosphere diverts the protons away from the station. But the high energy galactic cosmic rays have no trouble passing through and hitting the station. So station astronauts are (probably somewhat) safer during solar maximum, but interplanetary astronauts are (probably) safer during solar minimum. Either way the radiation dose is a problem that has to be designed around.

Incidentally, the largest effect of solar activity on the space station is orbital decay! During solar maximum, the increased far-ultraviolet brightness of the Sun heats the outer layers of the atmosphere (the "thermosphere"), making them expand significantly -- that increases orbital drag a LOT. It's one reason (the other being delays in the Shuttle program) that Skylab re-entered the atmosphere before the Shuttle came on-line to provide additional boost. Skylab was launched during solar minimum in the mid 1970s, and the orbital decay projections were based on solar minimum conditions. It re-entered several years earlier than initially expected, because the atmosphere (and hence orbital drag) got larger in the solar maximum period of the late 1970s. The space station has similar orbital-decay issues; if you Google for the altitude-versus-time plots, you'll see that at its chosen altitude, the ISS needs to be boosted every six months or so, or it will spiral in and re-enter the atmosphere.

Re:hmmm, matter absorbing energy?

[SteveAyre]

Ok, didn't check that bit - it was from memory.

Looking on Google again I found what I'd been think of. It's the Geodynamo if anyone want to look for it.

"Currents flowing in giant loops through the earth's core."
You're pretty much correct there on how they think it happens.

Basically the guy noticed that the direction the molton core convects is different in some places than others. And it changes the way the magnetic flux acts.

When the convects in one direction, the flux goings in one direction; when it convects in the other the flux reverses the direction (which is what I was thinking of when I said about the North/South poles).

Lots of pretty pictures on a few sites talking about the Geodynamo, I'm sure there'd be more stuff around if anyone wants to look for it.

http://www.psc.edu/science/Glatzmaier/glatzmaier.h tml
http://www.psc.edu/research/graphics/gallery/geody namo.html

The first two animations on that page show fairly when what's happening.
The core of the Earth is rather chaotic in terms of which direction the convection is happening in and therefore which direction the magnetic flux is in (this is what I'd been thinking of).
These bits change over time and move around to different points under the Earth's surface (think hotspots which move and cause chains of volanos which are all dormant apart from the ones at the end).
Which direction the flux moves in overall is essentially a complex summation of where these lines of flux are moving.
During the reversal lots of areas of convection change direction and change the direction of their flux. As they do so the overall lines of flux move and weaken, until they swap around.

This is quite an informative page on magnetic field reversals, and it talks about the Geodynamo at the end.
http://www.geomag.bgs.ac.uk/reversals.html

Obligatory Wikipedia links:
http://en.wikipedia.org/wiki/Magnetic_polarity_rev ersal
http://en.wikipedia.org/wiki/Geomagnetic_reversal
http://en.wikipedia.org/wiki/Geodynamo
http://en.wikipedia.org/wiki/Dynamo_theory

Speaking of astronauts.....

[Scott7477]

The Association of Space Explorers is holding their 19th Planetary Congress here in Salt Lake City this week. The theme of the conference is "Our Destiny in Space: Worlds without Borders". I took my son downtown and we got to meet Don Lind, one of the space shuttle astronauts. I thought it was pretty awesome. Thanks, Don. I'm curious to know how many folks have actually met an astronaut...

Some of the things they are talking about(from the official program):

The Genesis of Cooperation in Space: The Apollo-Soyuz Program
Tom Stafford

Panel Discussion (ASE Founders)
Loren Acton, Bertalan Farkas, Georgi Ivanov, Alexei Leonov, Vladimir Lyakhov, Dorin Prunariu, Rusty Schweickart, Vitaly Sevastyonov

Technical Session: International Space Programs Review
Chairs: Chris Hadfield, Leroy Chiao

        NASA Headquarters Update: The ISS Program and Future Issues
        Bill Readdy, NASA

        Life on Station
        Leroy Chiao, NASA

        Report on the Canadian Space Program
        Chris Hadfield, CSA

        Report on the Russian Space Program
        Yuri Usachev, RSC Energia

Technical Session: Crew Safety & Technical Issues
Chairs: Sergei Avdeev, Charlie Precourt

        Shuttle Derived Vehicles
        Mike Conn, ATK Thiokol

        Maintaining On-Orbit Crew Proficiency
        Chris Hadfield, CSA

        Electromagnetic Radiation and Crew Health
        Alexander Serebrov

Technical Session: Future Programs
Chairs: Michel Tognini, Yuri Usachev

        Beyond the Moon: The Asteroid Option
        Tom Jones

        Kliper
        Yuri Usachev, RSC Energia

        Russia's Future in Space
        Georgi Grechko

        The Aurora Program
        Piero Messina, ESA

There's some pretty big names in there, also note that they are talking about astronaut safety with regard to electromagnetic radiation.

I submitted this to /. and got rejected, so take that, CmdrTaco!