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Quarks to Quasars:The Science of Science Fiction

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The Science in Science Fiction

Written by Ben Bova

I’ve been a fan of Edgar Allan Poe as long as I can remember, but there’s one poem of his that I think is ‘way off the mark.

In Sonnet: To Science, Poe complains that science’s “dull realities” prevent the poet’s heart from “wandering/To seek for treasure in the jeweled skies…”

Dull realities?

There’s nothing dull about the realities that telescopes and spacecraft have discovered about the other worlds of our solar system. Treasure from the jeweled skies, and then some. Anyone who doesn’t thrill at the photos returned from Mars, Jupiter, many-ringed Saturn, et al., doesn’t have a poet’s heart, or any heart whatsoever.

Now, in science fiction the writer has a great deal of latitude to create alien worlds and people them with creatures large and small – and even intelligent. For example, Ray Bradbury could create a Mars of bone-chess cities and fragile, beautiful Martians. We know that Mars isn’t like that. Doesn’t matter. Ray’s stories are still among the most evocative ever written even though we know that the Mars he describes comes from his imagination, not out of reality.

Are Bradbury’s stories science fiction? Technically, no, because they’re not based on known science. But who cares? They’re so damned good!

In this column, however, we’re going to talk about science fiction. That is, stories in which some aspect of future science or technology is so integral to the tale that, if you remove the scientific/technological aspect, the story falls apart.

I’ve found it more interesting, more challenging, and in many ways more rewarding to try to write as realistically as I can about strange worlds where no human has yet set foot. But why try to create a world entirely out of your imagination when NASA is spending billions of your tax dollars to show us what real worlds are like?

And those real worlds are weirder, more intriguing, more exciting than most of the imaginary planets concocted out of whole cloth.

Science fiction, I feel, should have some relationship to the real universe that scientists are exploring for us. Therefore I propose that we follow a rule of thumb that science fiction writers have used for generations:

RULE: The writer is free to invent anything he or she can imagine, as long as nobody can prove it’s wrong.

So let’s look at space travel, and think about human explorers heading for Mars.

First of all, although Mars is one of the nearest planets to us, it never comes closer to Earth than about 35 million miles. Using current rocket technology, it takes at least four months to reach Mars.

Which means that human explorers in transit to Mars are going to get hit by a solar storm. Before they get to their destination they could face a very dramatic, very dangerous situation in transit.

There is weather in space, of a sort. Every now and then the Sun belches out huge clouds of high-energy particles and radiation, called solar flares. A solar flare can release in a few seconds as much energy as the explosion of a hundred million billion tons of TNT. In the shorthand of scientists, that’s 10¹¹ megatons: more energy than the whole world consumes in 50,000 years, but just a minor hiccup in the immense powerhouse that is our Sun.

Here on Earth we’re protected against solar storms by our planet’s magnetic field, which deflects the high-energy particles in the radiation cloud. Our atmosphere also absorbs energetic particles before they can reach the ground. But astronauts venturing beyond Earth’s wrapping of magnetic field are not so protected.

When astronauts went to the Moon during the Apollo days of the 1960s, the trip was short enough so that they avoided solar storms. Even if one had erupted, they were close enough to Earth to come back safely before the radiation cloud could reach them. Probably.

Not so on that months-long journey to Mars. There’s a better-than-even chance that a Mars-bound spacecraft will encounter a solar storm. Or it might get hit on the trip back to Earth.

When the Sun burps out a solar flare, the electromagnetic radiation from the flare – visible light, radio energy, ultraviolet, x- and gamma rays – reaches the Earth with the speed of light, in about eight minutes.[1] This is the warning of danger. In times to come, when human spaceflight through the solar system is routine, the visible flash from a solar flare will trigger alert warnings throughout the spaceways.

Following the visible flare by anywhere from a few minutes to a few hours, the first wave of very energetic protons and electrons comes boiling out from the Sun, traveling at “relativistic” velocities: that is, close to the speed of light.

The energy in these subatomic particles is measured in electron volts (ev). One electron volt is a minuscule bit of energy; it would take five million ev to light a 50-watt bulb. But protons with energies of 20 to 40 milion electron volts (Mev) can easily penetrate a quarter-inch of lead, and particles from solar flares with energies of more than 15,000 billion ev – 15,000 Bev or 15 giga-electron-volts (Gev) – have reached Earth.

The flare has ejected a great puff of very energetic plasma[2] into interplanetary space. It expands as it moves outward from the Sun, growing to dimensions far larger than the Earth. When such a cloud hits the Earth’s magnetic field it rattles the entire geomagnetic field, causing a magnetic storm.

The auroras at both poles flare dramatically and the Northern and Southern Lights are seen far from their usual polar domains. The ionosphere – layers of ionized particles that begin some 50 miles high – runs amok, gaining and losing ionized particles in a wildly unpredictable manner that makes a shambles of the long-distance radio transmissions that are normally reflected off its ionized layers. Even telephone cables buried underground have been affected by powerful magnetic storms.

In a few days the ionosphere settles down. The aurora borealis and aurora australis go back to normal. Until the next solar flare.

But any astronauts caught in deep space unprotected by shielding during a solar storm would be quickly killed by the intense radiation levels of the storm’s energetic protons. Mars-bound explorers will need a reliable storm cellar on their spacecraft.

SIDEBAR: Radiation in Space

The word “radiation” is used in two ways, and it’s important to understand the difference between them.

Light is a form of electromagnetic radiation. Visible light is only a small slice of the broad electromagnetic spectrum, the part that our eyes have adapted to sense. Radio waves are also electromagnetic radiation: “light” that we can’t see. So are microwaves, infrared and ultraviolet light, X-rays and gamma rays.

The kind of radiation that can cause damage to our bodies is called ionizing radiation, because such radiation can ionize atoms within your body, strip electrons off those atoms, which causes harmful physiological effects. X-rays and gamma rays can harm you in that way, so in addition to being forms of electromagnetic radiation they are also dangerous forms of ionizing radiation.

While the electronic systems of a spacecraft can be hardened against ionizing radiation, human beings cannot be. They need protection. So spacecraft will need a storm cellar, a place that’s shielded so that those high-energy protons and other nuclear shrapnel can’t harm the astronauts.

A spacecraft’s storm cellar, then, would be a shielded area where the crew could wait out the high radiation levels that can persist for several days after a flare erupts on the Sun. They will have enough warning time to get into the shelter – a matter of hours or even days between the flare’s sudden outburst and the arrival of the deadly cloud of high radiation.

In fact, the solar storm might miss the spacecraft altogether. That cloud of ionized plasma is guided through space by the kinks and loops of the interplanetary magnetic field. There are no guarantees, either way.

The storm cellar will have to be stocked with enough food to last several days and will need adequate water and air recycling systems, as well as hardened communications so that the crew can talk with Earth.

The most obvious kind of storm cellar is simply some large mass of material between the crew and the potentially lethal radiation. Solid walls of lead would be too massive to be practical on a spacecraft, although the ship’s tanks of propellants might absorb enough of the incoming radiation to consider putting the storm cellar inside the propellant tankage.

A more elegant solution would be to copy nature and put a strong magnetic field around the storm cellar. After all, it is the Earth’s magnetic field that protects us from deadly solar-flare radiation. Superconducting magnets, which can produce extremely high field strengths without needing electrical power (once they are charged up) might do the job. To be superconducting, the magnets must be cooled to the temperature of liquid nitrogen or below, but that should not be too big a problem for a spacecraft carrying humans to Mars.

There’s a complication, though. A magnetic field powerful enough to deflect the high-energy protons of a solar storm would be so strong it would warp the magnet itself out of shape. It would need so much structural mass to hold the magnet together that we might as well build a lead-lined shelter and be done with it.

The truly sophisticated solution is to charge the spacecraft to a very high positive potential so that the high-energy protons are deflected by electrostatic forces: like charges repel one another. To keep the negatively-charged electrons in the radiation cloud from reaching the ship and neutralizing its positive charge, a moderate magnetic field is all that’s needed; the electrons have comparatively little energy in them, so a weaker magnetic field can deflect them well enough.

I worked at a laboratory in the 1960s where just such a storm cellar was tested, in miniature. It worked fine, in the lab.

Whether it’s a metal bubble inside a propellant tank or a shielded shelter wrapped in a cocoon of magnetic force, the storm cellar can make a good scene for high-tension drama as the astronauts head for their distant destination. I used such a possibility in my 1992 novel Mars.

Einstein said, “Imagination is more important than knowledge.” But knowledge is vital. Use the known facts to stir your imagination. You can produce good, taut fiction that takes place even before your characters set foot on Mars – or any other world.

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Ben Bova is the author of nearly 120 books of science fiction and science fact, and is a multiple Hugo winner as Best Editor.