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Space Travel to mars

  1. Nov 8, 2015 #1
    So off to Mars we go. But really how are we going to get there? The most expensive part of space travel is overcoming atmosphere. So you could say the biggest obstacle of space travel is Earth travel. It takes virtually no energy to cross space but it takes massive amounts to get into space.

    It's kind of like walking to the bus stop. It may take a lot of my energy to get to the stop but once there I have to spend very little energy. So my though is that we build a bus stop in space. We send many rockets from earth to this space bus station and from there a "mothership" departs for Mars. Now this mothership doesn't need much energy to travel as tthere is no resistance in space.

    The primary concern will be life support and artificial Gravity. I suggest using a very simple spiral design that uses a sort of photovoltaic cloth that spirals around the core of the ship. This cloth is also reflective thus creating a solar sail. Due to the spiral shape thi will create a form of both propulsion and Gravity this eliminating two key energy hogs.

    As I mentioned this cloth would also be photovoltaic and create energy "on the fly." The bigger the sails the more energy can be given to thrust and the quicker we can get people to Mars. So that parts easy. The question we really have to focus on is how to overcome atmosphere. Well first why not shorten the distance? Instead of launching at sea level why not launch from a summit?!

    Second, since the trip will only be to a near earth bus station you could forgo all extras needed for a long journey. What do you guys/gals think?
     
    Last edited by a moderator: Nov 8, 2015
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  3. Nov 8, 2015 #2

    Drakkith

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    The most expensive part is accelerating up to the speed necessary to get into orbit or leave Earth completely, not overcoming the atmosphere.

    Choosing the spots for space launch is complicated. One reason that the U.S. has its primary launch facilities in Florida and California is so we can launch our vehicles out over the water. If the launch is a failure the vehicle crashes in the ocean instead of on land where people live. In addition, since most of the launch vehicle's fuel is spent accelerating, we wouldn't gain much from launching from a mountain. Launching from a lower latitude is actually more beneficial (for eastward launches) as we can use more of the Earth's rotational velocity during launch.
     
  4. Nov 8, 2015 #3

    phinds

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    There have been a number of threads here on "going to Mars". I think that the consensus of those threads is correct. It says that the idea of going to Mars and building a colony there any time in the next several decades is just wishful thinking. Some of the flaws in your logic have already been pointed out. You'll see others if you check out some of the other threads with a forum search.
     
  5. Nov 9, 2015 #4

    Janus

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    Friction is not the issue, gravity is. In order to overcome Earth's gravity, you need to burn the equivalent fuel as it would take to get up to ~11 km second. After that, the fuel needed to overcome the Sun's gravity enough to reach Mars is the equivalent of what you would need to add an additional 3 km/sec.
    There's an additional complication. The more massive your ship, the more fuel it takes to get it up to a given speed. But the fuel you carry adds to to the total mass of your ship. Thus you need extra fuel in order to move the fuel you'll be using later.

    So Basically, it works like this: Given the best chemical rockets we have, it takes ~10 kg of fuel for every kg of ship you want to escape from the Earth. Once you escape from the Earth, you still need to add another 3 km/s to reach Mars, The fuel needed to do this has to be included in your total fuel load, Plus the fuel needed to get this fuel away from the Earth. This means that the total fuel needed is ~20 kg per Kg you want to get to Mars, That extra 3 km/sec is going to cost you as much in fuel as it did just to escape Earth's gravity.
     
    Last edited: Nov 16, 2015
  6. Nov 9, 2015 #5
    The amount of fuel necessary for reaching orbit is large (~95% of the launch vehicle mass), but with current rockets, the _cost_ of all this fuel is actually a very small fraction of total cost of the launch - below 1%.

    IOW: the problem we are currently having with space travel is not that we need lots of fuel. The rest of the "system" is too expensive.

    We need to make launches cheaper. Say, making launch vehicles at least partially reusable would help: 1st stage engines are big, complex and costly pieces of turbomachinery, it would help a lot if we would use them more than once. Another improvement is to launch more - as it currently stands, launch pads and launch personnel are seriously underutilized, usually several months pass between launches from any given pad.
     
  7. Nov 16, 2015 #6

    Chronos

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    We must either find much more efficient launch technologies, or launch from a much shallower gravity wells for space travel to become practical and economical.
     
  8. Nov 16, 2015 #7

    Drakkith

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    I don't suppose giant slingshots are effective ways to launch vehicles into orbit, are they? :-p
     
  9. Nov 16, 2015 #8
    Sorry, but this is not true.

    Our current "launch technology" (namely two-stage chemical rockets) is in fact adequate. It is not imperative to find something much better than this to start serious space exploration.

    Current anemic pace of space exploration is caused by high cost of launch, but high cost of launch is *not inherent* in "two-stage chemical rockets" way of doing it. It is technically possible to launch ~20 tons to LEO for only about one or two million dollars.
     
  10. Nov 18, 2015 #9
    Granted, the overwhelming bulk of the energy we use in space travel today is reserved for escaping Earth's gravity. It should also be noted that with very few exceptions (like NASA's Deep Space 1) all our space travel has been coasting through space. We use the gravity of other objects to "assist" in a spacecraft's speed, but we do not use any other means of propulsion for the vast majority of our spacecraft.

    If we could propel a spacecraft at 9.8 meters per second per second while in space, not only could we eliminate the need to artificially create gravity, we could be at Mars in just two days instead of the 6 months it would take coasting. It would only take 3 hours to reach the moon, instead of 3 days. At 1 g continuous acceleration/deceleration every object in the solar system would only be weeks away, instead of years.

    What we really need is a refueling station already in space. So that once the spacecraft escapes Earth's gravity it can be refueled and that fuel used to propel the craft toward its destination while in space. Particularly for manned missions. Coasting from one object to another beyond the orbit of the moon is not really a viable option for manned missions.
     
  11. Nov 18, 2015 #10
    There is a specialized forum to discuss this:

    forum.nasaspaceflight.com

    They had all this covered. Repeatedly.
     
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