# Interstellar Travel Tables

1. Oct 7, 2011

### Jon0815

Using information and calculators I found online, I have put together a series of tables illustrating the energy, fuel mass, and time requirements (both Earth and ship time, at 1 g acceleration) for a spacecraft to reach various percentages of light speed.

I don't have a physics background myself, so I'd appreciate it if anyone who does could look it over and see if they spot any errors.

2. Oct 7, 2011

### Nabeshin

I'm not going to check all of the numbers, but all of the nonaccelerated numbers look reasonable.

What is meant by, "Acceleration time at 1 gravity"? Also, these types of calculations (fuel mass, energy requirements, etc.) are particularly enlightening (and more difficult) in the case of the accelerating starship. I see you've worked out timetables, but it's also interesting to see the absurd amount of fuel necessary to maintain these accelerations :)

3. Oct 7, 2011

### Jon0815

The time it takes to reach to reach the speed at 1 gravity acceleration. I'll change that to make it more clear.

4. Oct 7, 2011

### Astronuc

Staff Emeritus
I'm sorry, but this does not make sense.

g = 9.81 m/s2 is a measure of acceleration, and speed (or magnitude of velocity) is found by integrating the acceleration over time. If one accelerates at a constant acceleration of g, the v = gt + vo.

One also needs the specific impulse in order to determine the propellant mass flow rate to acheive a given thrust, and mass flow rate integrated over time will give the total propellant to be stored. If there is a huge mass of propellant, one will require a substantial thrust to get 1 g of acceleration, and one will need substantial mass in which to store the propellant.

Ideally, one has a high Isp, which means a lot of energy per unit mass of propellant. However, high Isp systems usually have low mass flow rates.

5. Oct 7, 2011

### Nabeshin

Well, acceleration might be constant in the frame of the rocket, but will not be in the static Earth frame. But I think it's now clear what was meant.