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Universe ?

  1. Mar 9, 2010 #1
    Universe ??

    So in books and pics online, you see the solar system in a single plane, if you want to travel great distances you use other planets gravity to swing you out there. What if we wanted to travel in ANY OTHER direction, could it be done? I heard that its not practical to send manned missions to anywhere really because of the long duration, radiation would kill you. Why not go faster? No gravity so build larger spacecraft, more fuel, burn longer? Am I missing something here? (disregard the cost to travel) Im sure its not cost effective but regardless, even for sats and other probes why not make them go faster to get more info sooner? Who wants to wait 20 years to get some pics of something with technology that is at garage sale for $1.00?
  2. jcsd
  3. Mar 9, 2010 #2
    Re: Universe ??

    If you fly close to speed of light:
    1. even tiny rock in space can destroy your whole spaceship.
    2. but before it happens the front of the spaceship will be burnt by plasma (interstellar gas. even density is low, it is high enough to vaporize you)
    So start of “Enterprise” is not expected soon :)
  4. Mar 10, 2010 #3


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    Re: Universe ??

    The trouble with fuel is that it is heavy. The more fuel you add, the more fuel to you have burn getting your spacecraft + fuel up to the speed you want. If you look at a space shuttle launch, you see that most of the launch weight is in fuel, and most of that fuel is used just to move the rest of the fuel. Adding more fuel to a ship has diminishing returns past a certain point.

    The probes sent into distant space are sent with the highest speed achievable with the technology available at the time. The Solar System is just really really big, so it takes a long time to get anywhere.

    Any remotely feasible suggestions for future high speed space travel involve new fuel sources that can deliver much greater thrust per unit weight than conventional rocket fuel, things like anti-matter engines. Such things are a long way off though.
  5. Mar 10, 2010 #4
    Re: Universe ??

    What about someway of refueling once out of the atmosphere? How fast are you talking when you say they are sent at the best speed for the time, 20000, 30000 mph... more? what about 250000 far less than the speed of light but very fast?
  6. Mar 10, 2010 #5


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    Re: Universe ??

    The problem with re-fueling is two-fold. The first is that rocket fuel needs to be highly processed and refined, so it's not just lying around in space. The second is that if you are moving at speed, and then run into a fuel source that is stationary, you will lose a bunch of your speed as momentum is transferred to that fuel. The net result is that you may as well have carried that additional fuel with you to start with.

    I don't know how fast probes like Voyager move (you couldn't probably find it on Google/Wiki without much trouble) but it is much much less than the speed of light.
  7. Mar 11, 2010 #6
    Re: Universe ??

    The Voyager & Pioneer satellites are traveling at roughly 40,000 mph. Another technology which is under some research is using solar sails to trap the solar winds from our sun, but even then it will only get you to near current velocities but without the huge amount of required fuel. But this technology is a bit out of reach for right now. As for your question to traveling in an opposite direction to those we currently send space craft, the gravitational sling shot would work the same way. On the other hand since all the planets are on a plain perperdicular to your trajectory you will only have one planet from which to sling shot yourself. I am pretty sure thats why we send them along the plain of orbits as well as because thats where the interesting stuff is.

  8. Mar 12, 2010 #7


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    Re: Universe ??

    Interstellar space is so incredibly empty, it is hopeless as a fuel source. A handful of atoms per cubic meter is not going to be helpful.
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