[Spaceships] [High-Tech] [Action] Cydonia Or Bust, TL8

[Trachmyr]

First thing I'd consider is if there are any plot-convienient NEOs around... one could imagine a modified shuttle reaching orbit-crossing Comet with a NERVA Rocket in it's hold, some mining equipment and inflatible fuel tanks.

Better yet, the Rocket and other gear launched into LEO by Chemical Rockets, collected and dlivered to the Comet Staging area.

Also, I assume the launch would occur when Earth & Mars are closest.

[Polydamas]

Originally Posted by Langy

You don't. The 5-10 years was if this was a flat-out emergency using a large portion of the entire nation's effort put into it, including bypassing political and environmental consequences of using nukes and being willing to risk losing significant numbers of astronauts to failures.

Then why did you suggest concealing it in post #4? It sounds like you meant your "5-10 year emergency" plans and your "disguise it as a normal mission" plan to be separate, but that wasn't clear in that post.

The problem is that with plausible near-future tech, you are stuck with Hohmann orbits and months of travel time in microgravity, in which the assault team can't train properly because they are stuck in a space the size of a bus. If they have a telescope, the enemy knows you are coming, and has a good idea of your mass and propulsion type and therefore numbers. They will also be able to spot your test flights, even if you keep them near earth. The assault team will be badly affected by the switch from microgravity to Mars surface gravity, and probably won't have much time to acclimatize when they arrive. So the OP sounds like a basically cinematic idea, and worrying about how to make it realistic is probably less useful than worrying about what would make the tunnel fight on Mars really cool.

It seems odd that you can't nuke the site from orbit, but you can win by destroying the control room, whether or not any of the assault team survives.

[Anthony]

Originally Posted by Polydamas

The problem is that with plausible near-future tech, you are stuck with Hohmann orbits and months of travel time in microgravity

Original post did allow anything in Spaceships up to TL 8. Either 'ion' drives or Orion drives will allow a mission delta-V exceeding 60 km/sec with a 50% fuel fraction, which is plenty to get to Mars and back significantly faster than Hohmann transfer, though it's still going to involve months.

Originally Posted by Polydamas

So the OP sounds like a basically cinematic idea, and worrying about how to make it realistic is probably less useful than worrying about what would make the tunnel fight on Mars really cool.

I have to agree. I'd just use the X-Com solution of captured alien equipment.

[Fred Brackin]

Originally Posted by Anthony

Original post did allow anything in Spaceships up to TL 8. Either 'ion' drives or Orion drives will allow a mission delta-V exceeding 60 km/sec with a 50% fuel fraction, which is plenty to get to Mars and back significantly faster than Hohmann transfer, though it's still going to involve months.

I have to agree. I'd just use the X-Com solution of captured alien equipment.

Some Orion or Ion drive of your own calculation might allow 60mps with 50% fuel but those numbers are twice as good as the ones in Spaceships. It's 3 mps per fuel tank for either.

[Fred Brackin]

Originally Posted by Trachmyr

First thing I'd consider is if there are any plot-convienient NEOs around... one could imagine a modified shuttle reaching orbit-crossing Comet with a NERVA Rocket in it's hold, some mining equipment and inflatible fuel tanks.

One's imagiantion may be rather more forgiving than real world facts.

A Shuttle's cargo bay is 40,000 lbs to c.200 miles high and no more. Getting a satelite from that position to even geosynch uses up.....oh at least 3/4s of that payload so your net weight at geosych is no roe than 10,000 lbs.

Beyond Earth orbit, even to a NEO takes more than that and getting the 200,000 Shuttle there and then sending its' payload farther just isn't going to happen.

[Langy]

Originally Posted by Fred Brackin

Some Orion or Ion drive of your own calculation might allow 60mps with 50% fuel but those numbers are twice as good as the ones in Spaceships. It's 3 mps per fuel tank for either.

He said km/s, not mps.

[Fred Brackin]

Originally Posted by Langy

He said km/s, not mps.

He's still 25% higher than the Spaceships numbers.

[Anthony]

Originally Posted by Fred Brackin

Some Orion or Ion drive of your own calculation might allow 60mps with 50% fuel but those numbers are twice as good as the ones in Spaceships. It's 3 mps per fuel tank for either.

Which means an exhaust velocity of 60 mps or 96 kps; applying the rocket equation, we multiply 96 by -ln(0.5) and get 67 km/sec.

Incidentally, those stats are pretty insane; realistic would be more like 0.00005G and 1 mps/tank.

[Langy]

Originally Posted by Fred Brackin

He's still 25% higher than the Spaceships numbers.

You forgot to account for the number of fuel tanks increasing the amount of delta-V each tank adds. That's an x1.4 increase for 10 tanks, or 42mps or 67 kps.

[samd6]

There is one parameter that's bugging me.
Does the team need to return?
If not, that cuts down on fuel and other consumables needed.