[Space/Spaceships] Getting the velocity/Delta V I want with the tech I want

Belial666 · 04-08-2014, 06:12 PM

The solution is both low-tech and simple; don't build a ship with engines, powerplant or onboard fuel.

1) Build ships equipped with solar sails.

2) Build space mirror(s). A big one 100 times wider than each ship's sail should do. More smaller ones might also do if you can deal with the destructive interference.

3) Aim sunlight from the mirror to the ship, propelling it with solar radiation pressure. Except you use concentrated sunlight at 10.000/1 concentration, not the pansy acceleration given by normal starlight.

4) Ship accelerates all the way to the halfway point. Assuming mirror array around Earth or similar light intensity, 10.000/1 concentrated sunlight and average mass of ship ~1 kilo per square meter of sail (total mass 1000 tons), you're going to get 0,01 gs or 0,1 meters per second per second. That is 8,6 Km/second per day. After 5 months you'll be halfway there.

5) Spend another 5 months with the array on the other star decelerating you. Because you don't want to smack on the planet at 2000 km/sec which is what you'd do if you accelerated constantly. Of course, if you could survive such impacts you'd make the trip in 7 months total, not 10. You'd also make a big hole on the surface of the planet though. Like, New-York-sized.

04-08-2014, 06:12 PM	#11
Belial666 Join Date: Jan 2011	Re: [Space/Spaceships] Getting the velocity/Delta V I want with the tech I want The solution is both low-tech and simple; don't build a ship with engines, powerplant or onboard fuel. 1) Build ships equipped with solar sails. 2) Build space mirror(s). A big one 100 times wider than each ship's sail should do. More smaller ones might also do if you can deal with the destructive interference. 3) Aim sunlight from the mirror to the ship, propelling it with solar radiation pressure. Except you use concentrated sunlight at 10.000/1 concentration, not the pansy acceleration given by normal starlight. 4) Ship accelerates all the way to the halfway point. Assuming mirror array around Earth or similar light intensity, 10.000/1 concentrated sunlight and average mass of ship ~1 kilo per square meter of sail (total mass 1000 tons), you're going to get 0,01 gs or 0,1 meters per second per second. That is 8,6 Km/second per day. After 5 months you'll be halfway there. 5) Spend another 5 months with the array on the other star decelerating you. Because you don't want to smack on the planet at 2000 km/sec which is what you'd do if you accelerated constantly. Of course, if you could survive such impacts you'd make the trip in 7 months total, not 10. You'd also make a big hole on the surface of the planet though. Like, New-York-sized.