Tuesday, July 29, 2014

Interstellar Space Travel - Humanity's Opportunity to Get Real

Space travel!

Astronauts, men on the moon, space stations, spacecraft that have visited all the planets - even asteroids and comets. One spacecraft has even left our solar system. It’s as if science fiction has become science fact. It almost seems that we can do anything in space if we put our minds to it. It seems so easy—I think too easy—to go from appreciating these achievements to dreams of sending explorers to the other planets and beyond.

Artist: WeeYak. More cool images at weeyak.deviantart.com. 
Interstellar space travel!

Not a new term. With hundreds of great sci-fi movies under our belt, we use this phrase as if it’s already a foregone conclusion, even just around the corner. Scientists, engineers and entrepreneurs are now loudly, even boastfully encouraging this perspective.

As for the first big step  - a manned mission to Mars - none of the problems that challenge this project have been solved.

Outer space is deadly. Beyond the protective shielding of Earth’s atmosphere and electromagnetic field, which protect us from solar radiation and cosmic radiation, astronauts will need a way to protect themselves during the flight. Current spacecraft shielding doesn't give enough protection to prevent permanent cell damage.

Human beings evolved to survive and thrive only in the kind gravity, atmospheric pressure, and temperature range found on Earth’s surface. Space suits can compensate for temperature and pressure extremes. But time spent in zero gravity during the months of the journey or working in the low gravity on Mars will have progressively detrimental effects on every part of the body—bones, muscles, lungs, heart and brain. Without a solution, astronauts will be crippled upon return to Earth, if indeed they could handle the trip back.

It’s one thing to spend a couple months aboard the ISS, with the huge sight of planet Earth outside the window. But a flight to Mars would be quite different, where views of Earth would shrink to a pinpoint. There are the unique, untested social and psychological issues related to spending years in space in the cramped cabins of the spacecraft and Mars living quarters.

And did I mention air, water, and food? Solutions for these problems of extended time away from Earth are easier to address, and scientists are working on them.

People in the space industry talk glibly about interstellar space travel being “the destiny of the human race,” as if going to Mars is only the first step. But there are problems that almost never get mentioned.

The Distance Problem – When you look up at the night sky you can see Mars, a pinpoint of light among the stars. It would be natural to think, "If we can go to Mars, we can go to the stars." But that's because you haven't done the math.

Alpha Proxima, the star closest to our solar system, is about 25 trillion miles away. This distance is so vast that the human mind can't understand it. Scientists created the concept of light-years (the distance light travels in a year) to make it easier to comprehend incomprehensible distances.

Speed of Light = 186,000 miles per second
= 670,000,000 miles per hour
= 5,900,000,000 miles per year
1 light-year = 5.9 trillion miles

Current propulsion systems achieve about 50,000 mph - pretty speedy by Earth standards. But at that velocity, it would take more than 50,000 years to arrive at the nearest star. So travel to stars will require much faster spacecraft. But even if a spacecraft could be built to travel 10 million mph, which is about 1.5% the speed of light, the travel times are still absurdly long.

At 10 million mph it would take 67 years, or about 3 generations of human beings to go just 1 light year. A journey to Alpha Proxima, is 4 light-years away – 268 years (12 generations of human beings) traveling at 10 million mph.

A news report about a newly-found exoplanet in a star's habitable zone described it as “only 100 light years away.” Yes, the farthest reaches of our Milky Way galaxy are 1,000 times that distant, so compared to the size of our galaxy, 100 light years is relatively close. But traveling at 10 million mph, it would take 6,700 years (300 generations) to travel "only 100 light-years."

The Impact Energy Problem – Space is far from empty. Asteroids, rocks, ice fragments, dust, gas—there’s lots of stuff in the so-called “void.” And no one knows where all this stuff is. Running into even the tiniest objects while traveling at enormous speeds can create awesome effects at impact.

The faster a spacecraft goes, the higher the probability that it will run into something. And the greater the speed, the greater the kinetic energy that will be produced at impact. Traveling at 10 million mph, even the impact of a single microscopic grain of space dust could destroy a space ship. Unimaginable shielding—something as dense and bulky as a sizeable asteroid—would be needed.

When scientists talk excitedly about exotic propulsion system concepts, they never mention the problem of impacts at very high speeds.

The Propulsion Energy Problem – How much energy would it take to propel a vehicle with that kind of shielding at 10 million mph? Answer: It would take a major portion of all the energy produced everywhere on Earth in one year.

Imagination is a wonderful thing. So is our potential for achievement. But these challenges are more than daunting. When you do the math and consider the realities of the cosmos, interstellar space travel seems pointless and impractical. No, impossible. The problems are insurmountable. It's never going to happen. In the best-case scenario, our glorious species won't even try.

So the biggest challenge isn't shielding or speed. Considering how our minds have been conditioned by science fantasy, our biggest challenge is to get real. The ultimate drama isn't whether human beings will "reach the stars." It's whether we're intelligent and wise enough as a species to get down-to-earth and face facts and focus our ability to stop killing each other and figure out how to preserve Earth's limited resources.

Post by Dennis E. Coates, Ph.D., Copyright 2014. Building Personal Strength .

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