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posted by martyb on Tuesday February 21 2017, @09:44AM   Printer-friendly
from the giving-launches-a-lift dept.

The Belfast Telegraph reports on the Spaceflight Bill, proposed legislation that is to be put before Parliament this week.

The government issued a statement on the proposed legislation. According to the statement, Britain could build space-ports on its own territory "by 2020."

Whether the launch facilities would be on the home islands, in the British Overseas Territories (which include islands in the Caribbean such as Montserrat), or both was unclear to the submitter.

[What, if any, advantages are there for launching from Britain vs a location in the Caribbean? -Ed.]


Original Submission

 
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  • (Score: 2, Disagree) by FatPhil on Tuesday February 21 2017, @10:45AM

    by FatPhil (863) <pc-soylentNO@SPAMasdf.fi> on Tuesday February 21 2017, @10:45AM (#469650) Homepage
    That's strange - gravity's less towards the equator, as you're further from the centre of the earth. The first 20km of the launch is for free.
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  • (Score: 3, Informative) by massa on Tuesday February 21 2017, @11:56AM

    by massa (5547) on Tuesday February 21 2017, @11:56AM (#469655)

    s/then/than/

  • (Score: 5, Informative) by subs on Tuesday February 21 2017, @12:13PM

    by subs (4485) on Tuesday February 21 2017, @12:13PM (#469657)

    In order to get into orbit, you don't need to get a set distance from the Earth's center. You need to simply clear the atmosphere (which is approximately equally thick everywhere) and most importantly, you need a heck of a lot of lateral speed - that's the real cost driver. You need to achieve about 8000 m/s of sideways velocity to remain in orbit around Earth. The Earth rotates at approximately 500 m/s at the equator. Any reduction in the total required speed, even by a little bit, translates into huge savings in terms of propellant mass at launch, because the equation that drives the propellant requirements is exponential. The less propellant you need, the more payload you can take and the cheaper the launch (per unit mass) will be.

    • (Score: 0) by Anonymous Coward on Tuesday February 21 2017, @02:34PM

      by Anonymous Coward on Tuesday February 21 2017, @02:34PM (#469679)

      Excellent explanation. And if someone's still not clear on this, get Kerbal Space Program :)

    • (Score: 2) by FatPhil on Tuesday February 21 2017, @03:10PM

      by FatPhil (863) <pc-soylentNO@SPAMasdf.fi> on Tuesday February 21 2017, @03:10PM (#469703) Homepage
      OK, but why doesn't having the whole 500 m/s as a starting lateral speed, rather than just part of it, help you reach 8000 m/s?
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      • (Score: 2) by mrchew1982 on Tuesday February 21 2017, @04:14PM

        by mrchew1982 (3565) on Tuesday February 21 2017, @04:14PM (#469743)

        Launching from the earth is essentially launching from a moving platform (according to the frame of reference from orbit). The earth at the equator is moving at ~500meters per second west to east, most launches are in this same direction to harness that velocity. The closer to the poles that you get the lower that west to east speed is because you get closer to the Earth's center of rotation. As a visual just imaging a spinning record, the closer to the edge that you get the longer the distance traveled per revolution, hence it travels at a faster speed even though it's the same rpm. (This is also the way gears work).

        Now this is all for equatorial launches (travelling around the world west to east or geostationary) usually used for communication satellites. If they're going to be launching spy satellites (which would be my guess because there's no other reason to want complete control of the launch facility, commercial launches are just too cheap to justify the expenses...) chances are they'll launch into a polar orbit (north to south over the poles of the earth) because they get to spy on more places on the earth that way.

        There's some great YouTube videos out there that explain this stuff. Scott Manley has quite a few, he's good at breaking things down into understandable chunks although a bit smug at times.

        • (Score: 2) by FatPhil on Tuesday February 21 2017, @06:01PM

          by FatPhil (863) <pc-soylentNO@SPAMasdf.fi> on Tuesday February 21 2017, @06:01PM (#469794) Homepage
          So you agree with me - equatorial should be more efficient because of the fact you start off with the largest speed for free?
          --
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          • (Score: 1) by butthurt on Tuesday February 21 2017, @06:31PM

            by butthurt (6141) on Tuesday February 21 2017, @06:31PM (#469804) Journal

            As massa tried to point out, what C R Johnson meant in #469634 was probably:

            The downside is that it takes a lot more energy to get to orbit [than] if you launch close to the equator.

      • (Score: 2) by subs on Tuesday February 21 2017, @07:19PM

        by subs (4485) on Tuesday February 21 2017, @07:19PM (#469830)

        I think there might be a misunderstanding here. The more speed you have at the outset, the better. So yes, closer to the equator is better in terms of fuel burn. This is all assuming your target is geostationary orbit (which is at the equator). If you want to go into a polar orbit, proximity to the equator is actually a detriment. It all depends on where you want to go. This is also why e.g. the Russians use Baikonur (which is as south as the USSR could basically get) for launches aimed at equatorial / low-inclinations orbits and Plesetsk (which is almost as far north as practical) for launches aimed at polar / high-inclination orbits.