Now you take the rocket in low earth orbit, and slow it down while firing the rocket at an angle to retain its altitude. You drop a big, many miles long bungee cord down with something on the end of the cord that can maneuver and hook up to the payload. Then you accelerate the rocket back to orbital speed or even back to the moon, while reeling in the payload.
Not possible. Rockets are not helicopters. Can't "slow it down while firing the rocket at an angle to retain its altitude."This is just nonsense
Yes of course it takes the same energy to accelerate the payload into orbit, but you don't have to burn 95% of your propellant to get the rocket off the Earth if you start from the Moon.As I said, the Space Bungee rocket would not be in free fall orbit. It could be travelling any speed you want. You don't have to hook up at 7 km per second. You could be going 50 miles an hour if you want.
Since we now know there is subsurface water all over the Moon, not just fossil water in shaded craters at the poles, water is not a scarce item.
You might even get the government to give the company a small tax credit for supplying you with the methane.
Quote from: bradjensen3 on 08/09/2017 05:59 amNow you take the rocket in low earth orbit, and slow it down while firing the rocket at an angle to retain its altitude. You drop a big, many miles long bungee cord down with something on the end of the cord that can maneuver and hook up to the payload. Then you accelerate the rocket back to orbital speed or even back to the moon, while reeling in the payload. Not possible. Rockets are not helicopters. Can't "slow it down while firing the rocket at an angle to retain its altitude."This is just nonsense
Let's see how gently and patiently we can debunk it, though
There is nothing dodgy about heating water and using it as reaction mass.Yes of course it takes the same energy to accelerate the payload into orbit, but you don't have to burn 95% of your propellant to get the rocket off the Earth if you start from the Moon.As I said, the Space Bungee rocket would not be in free fall orbit. It could be travelling any speed you want. You don't have to hook up at 7 km per second. You could be going 50 miles an hour if you want. I'm not talking about shooting a rocket to the Moon, filling up with reaction mass, then doing the space bungee thing. The Space Bungee rocket would start from the Moon, and return to the Moon for reaction mass refills. If those guys are right about the millions of microcomets impacting the Earth, it might be possible to refill from then. But the safe bet is to use water from the Moon.For that matter, if the payload had a nuclear rocket engine, you could use the Space Bungee rocket as a tanker and deliver a water reaction mass to the payload. Since we now know there is subsurface water all over the Moon, not just fossil water in shaded craters at the poles, water is not a scarce item.
There is nothing dodgy about heating water and using it as reaction mass.
Trying to stay in "orbit" going 50 mph would run you out of propellant very quickly. You'd need way more propellant than just launching normally from Earth.
Quote from: meberbs on 08/09/2017 08:37 pmTrying to stay in "orbit" going 50 mph would run you out of propellant very quickly. You'd need way more propellant than just launching normally from Earth.I am not suggesting that the rocket hover, or go 50 miles an hour for any period of time, if at all. My point is that the rocket doesn't need to be in free fall. The interaction between the Space Bungee rocket and the payload doesn't have to be at 7 km/second. Once again, the underlying notion is to raise a payload using a balloon into the upper atmosphere. Then use a rocket coming form the Moon into low Earth orbit to basically swoop in and grab the payload, and accelerate it into orbit using fuel from the Moon.
I am sorry I got off into side discussions with people who think rockets can't hover and can only go one speed.
It seems to me that there are two factors that lead to expense in putting a payload in orbit. The first is atmospheric drag, and the second is gravity.
The amount of work it takes to accelerate that mass is the same, but it is much cheaper to do that work using a rocket fuelled on the Moon, than using rocket fuel hauled from the Earth's surface.
Thanks for the suggestion to look at the skyhook stuff. Sounds like a fantasy to me.
Well I guess that explains all the Harrier crashes...
Of course a rocket can hover. It isn't what you would normally do.
If you think it is nonsense that a rocket can hover, we aren't speaking from the same physical framework.
Once again, the underlying notion is to raise a payload using a balloon into the upper atmosphere. Then use a rocket coming form the Moon into low Earth orbit to basically swoop in and grab the payload, and accelerate it into orbit using fuel from the Moon.
A harrier is not rocket and does not hover above 5000ft
A rocket basically can not hover at orbital altitudes
That is correct. You don't understand the basic physical framework and orbital mechanism There is no stopping in space without massive thrust and propellant quantities many times our capabilities.
Now we move from the Moon's surface to low earth orbit. For efficiency sake we have a smaller stage, a skimmer, that decelerates in the upper atmosphere, hooks the payload and accelerates it back to orbital speed. The skimmer then connects back to the Moon rocket, perhaps to repeat its process several times. It does not matter if the total work done is more than the work done by blasting the payload off the Earth's surface into orbit, because the fuel is far cheaper, the rocket is reusable, and the effort of getting the rocket and reaction mass into orbit from the Moon is a tiny fraction of what it would be from the Earth's surface.With abundant water on the Moon, the economics of space travel will change.