Lubin explains that the proposed system would require about the same amount of energy as the upcoming Space Launch System to get to "relativistic speeds." Which is to say speeds matching a significant percentage of the speed of light. In this case, 30 percent in about 10 minutes.
Someone misunderstood something.
To start with - the same energy as the SLS? Is that once it is in orbit, or is that from the ground? Because I would like to see the laser that can get something into orbit.
On seconds thoughts, I really wouldn't
like to see it.
Additionally, 0.3c in ten minutes involves quite a lot of acceleration:Warning: Spoiler! (Click to show)
c = 299,792,458 m/s
0.3c = 89,937,737 m/s
10 minutes = 600 seconds
a = dV/t
a = 89,937,737/600 = 149,896 m/s²
OK, this is ignoring relativity because I can't remember the equations off the top of my head, and I can't be bothered to look them up.
I don't know that we have anything
that could survive fifteen thousand G's.
Edit: I was wrong, it turns out that 15,000G is the rating of electronics in artillery shells. So we could probably build something useful that could survive that acceleration. /Edit
Originally Posted by KonaJoe
The acceleration/deceleration forces to reach mars within 1 month would mean roughly constant +5g forces the whole way.
I can see what you are saying, but it's actually not that bad - you'd be seeing accelerations of somewhere around 0.0137G.
The fastest way to get a ship between two planets is to accelerate halfway there, and then decelerate for the other half. You could make use of aerobraking in Mars' atmosphere, meaning you could accelerate for a little over half way there and ditch the remaining speed when you get there, but that then means that you have to add in extra heat shielding and design your orbital vessel for wind resistance.
If we ignore aerobraking (and the relative motion of the planets, and orbital velocity, and a whole bunch of other things), we can quite easily work out the required accelerations.
Earth - Mars distance is between 54.6 and 401 million kilometers depending on their relative positions in orbit. We probably won't be travelling to Mars when it is 401m km away, partly because it would take longer and partly because the sun would be in the way.
So let's assume an average - 225m km.Warning: Spoiler! (Click to show)
1 month is 2,592,000 seconds.
We need to get half way in half the time, so 112,500,000,000m in 1,296,000s
Equations of motion give us s=ut+1/2at²
Since we are starting out from "rest", u=0
So s = 1/2at²
Rearranging gives a = 2s/t²
a = (2 * 112,500,000,000)/1,296,000²
a = 0.134m/s
We can easily survive that, after all we survive 73 times that every day, although it might just be enough to make some tasks annoying.
Incidentally, on the way you would also pass about 170km/s, becoming the fastest man made object by far (currently held by the Helios 2 probe, at 70km/s, despite what Fox news says)Edited by GingerJohn - 2/23/16 at 5:26am