What propulsion system should we use for Mars exploration?

[PB666]

So I have done somemore homework on this problem, I think I have your Earth to Mars transporter here

What is special about this ship is that it has 12 @ 10m x 100m solar panels. I have up the efficiency so that they produce 450kW per panel (as opposed to the perfect 1300kW that is delivered by the sun)

The 80 @ 1 N thrusters produce use 5.6 Mw of electricity; the panels produce 5400 Mw and are non-tracking, the 20000 units of battery deliver about 4 sec of power, at this power consumption batteries are not useful. There is enough Xenon 50,000 deltaV.

This setup delivers while sunfacing 2.5 milimeters, to break earth orbit you need approximately 3000 dV from which means a perfectly lit ship can do this in 1.2 Msec or 13 days. However because it cannot store power, it can only thrush from behind the earth at considerable distance and close to earth along the sunfacing radials. This effectively cuts that time to about 3 fold higher or 39 days.

The Mars dV is ~900 m/s since the ship is almost perfectly sunfacing when it begins its acceleration off of earths SOI (although behind the earth is almost a million miles away) it can achieve this in 900/0.0025 seconds or 360000 (~4 days). Since the 39 day trip it would have to be accelerating for half the trip or 19 days the most (however we have lost 6.5) so basically we on have 12.5 days to accelerate which roughly means we can only choose a transfer that permits a dV up to 2700 this severly limits the options to much greater than 39 days.

 

 

[Emperor of the Titan Squid]

If we have NERVA in time(which we will) ,go with that.If not go chemical.If we get VASIMR and it works well, use it.If doing cargo missions,use SEP.When we get fusion,that will be perfect.

[shynung]

17 hours ago, Emperor of the Titan Squid said:

When we get fusion,

It's still a really long time before we have space-grade fusion reactors or rockets. We don't even have build-ready space-grade fission reactors by now.

[magnemoe]

12 minutes ago, shynung said:

It's still a really long time before we have space-grade fusion reactors or rockets. We don't even have build-ready space-grade fission reactors by now.

An fusion rocket is easier than an fusion reactor as you don't need to go break even, the fusion just increase the ISP far past that you get from an pure electrical drive like vasmir while giving more trust / w of power.
Yes the engine is more complex than vasmir, most ideas goes for an pulsed design, think orion but with the benefit that the pulses is more like the power of an large diesel engine than an nuclear bomb. 

[shynung]

1 hour ago, magnemoe said:

An fusion rocket is easier than an fusion reactor as you don't need to go break even, the fusion just increase the ISP far past that you get from an pure electrical drive like vasmir while giving more trust / w of power.
Yes the engine is more complex than vasmir, most ideas goes for an pulsed design, think orion but with the benefit that the pulses is more like the power of an large diesel engine than an nuclear bomb. 

So a fusion rocket still needs some power source to ignite and sustain the fusion reaction. That brings another can of worms - where do we get that power?

[fredinno]

1 hour ago, shynung said:

So a fusion rocket still needs some power source to ignite and sustain the fusion reaction. That brings another can of worms - where do we get that power?

WHich also makes a fusion drive made today useless.