Interstellar Travel – Part Two

Too Close
See also parts one, three and four.

How will we get to the stars? With extreme difficulty. We have enough trouble getting to Mars and it’s right next door. The time it takes light to get from Earth to Mars is measured in minutes. The closest extrasolar star is over four light years away. A ship with people on board will take months to get to Mars using current technology. At that rate it would take over a hundred thousand years to reach the nearest star. Obviously we’re not going to get there in chemical rockets, even forgetting about the impossibility of carrying enough fuel to do it.

As any engineer worth their salt would say, there must be a better way. And there are a few. We’ll look at some that are theoretically possible using currently known technology.

Nuclear power is more efficient than chemical power. It still only releases about one tenth of one percent of its fuel as energy, though. It could be used to force something, steam maybe, through rocket nozzles to drive the ship in a traditional way. Another option is to detonate a series of atomic bombs behind the ship to push it along. These would require carrying less fuel than chemical rockets, but they’re still pretty bad.

The best method of propulsion that we could use now, with physics that we understand and technology that we can build, is the light sail. Four hundred years ago Johannes Kepler, an astronomer, noticed that something was blowing long tails off comets. He speculated that someday we might be able to use that wind to sail in space. These days Freeman Dyson, the legendary scientist, is saying the same thing. It’s been tried and it works. Light really does push on a reflective surface. One could simply use sunlight, but it gets weaker very rapidly with distance. A better way is to use a powerful laser, whose beam doesn’t scatter too quickly and which can provide plenty of power to the sail as it speeds away. Calculations show that such a ship could reach one tenth of the speed of light, and wouldn’t have to carry all that heavy fuel.

At that speed it would still take about five decades to reach the nearest stars, so it would be best to send robots first. With enough intelligence built in they could explore, set up a base, extract resources to build more robots, look for suitable destinations and prepare the way for us. Fifty years is still too long, though. The original crew would grow old on the way. The current best solution for that is the generation ship, carrying a clan of families to continually replenish the crew. Analyses show that a minimum of eighty people is needed for sufficient genetic diversity, but 150 would be a better number.

Next time we’ll look at methods that aren’t possible now, but could be soon.


About arjaybe

Jim has fought forest fires and controlled traffic in the air and on the sea. Now he writes stories.
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8 Responses to Interstellar Travel – Part Two

  1. mixedupmeme says:

    I have no doubt it will be done. What do I base my statement on?

    Somebody said that it couldn’t be done,
    But, he with a chuckle replied
    That “maybe it couldn’t,” but he would be one
    Who wouldn’t say so till he’d tried.
    So he buckled right in with the trace of a grin
    On his face. If he worried he hid it.
    He started to sing as he tackled the thing
    That couldn’t be done, and he did it.

    Somebody scoffed: “Oh, you’ll never do that;
    At least no one has done it”;
    But he took off his coat and he took off his hat,
    And the first thing we knew he’d begun it.
    With a lift of his chin and a bit of a grin,
    Without any doubting or quiddit,
    He started to sing as he tackled the thing
    That couldn’t be done, and he did it.

    There are thousands to tell you it cannot be done,
    There are thousands to prophesy failure;
    There are thousands to point out to you one by one,
    The dangers that wait to assail you.
    But just buckle it in with a bit of a grin,
    Just take off your coat and go to it;
    Just start to sing as you tackle the thing
    That “couldn’t be done,” and you’ll do it.

    Edgar Albert Guest

  2. mixedupmeme says:

    Missed the copy/paste by a line…….oh well.

  3. mixedupmeme says:

    Thank you! But could you also erase any evidence that I even did such a stupid thing?

  4. mixedupmeme says:

    On second thought….leave it as is. You need the extra comments. LOL

    • arjaybe says:

      Maybe I could figure out a way to do it and end up with more comments, too.-) Hmm. No, I can’t think of anything. Actually, I’m having trouble thinking at all, what with this head cold.


      • mixedupmeme says:

        Sorry to hear that. Nothing worse than a cold. I was just working on a post/song about being cold and maybe it would have helped you. lol

        But since it is beautiful and near 80 F here, you will just have to wait.

        • arjaybe says:

          It’s only about 15C here (~60F). It’s supposed to be sunny tomorrow, so I think I’ll take my bike out for its last ride of the year, then tuck it in for the winter.


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