[Pen and Paper Design] SLS and Falcon-Heavy Launched 570 day Mars Mission

[Rune]

Okay, some more propulsion-related calculations:

Each vehicle has a 130mT nuclear propulsion stage using an NTR similar to the NERVA. the NERVA had a mass of 10mT, and the tank/docking/RCS systems will probably add another 10mT. This means our vehicles will each have 110mT of liquid hydrogen propellant, and tank dimensions of 10m wide and 19.767m long. According to the Dv map I posted, a transfer from LEO to low mars orbit requires 2440 + 680 + 90 + 390 + 670 + 340 + 400 + 700 = 5710 m/s of Dv. With 110mT of propellant and an isp of 825s, this means I should be able to calculate how much payload the mission can allow. I have been looking for a rocket equation calculator which uses propellant mass and Dv to find the dry mass, but all the calculators I find only use the wet/dry masses and not the propellant/dry masses. Can anybody help?

Propellant mass plus dry mass equals wet mass, or in scientific terms (Pm)+(Dm)=(Wm). That's what's stopping you? If we do some basic, basic algebra: Wm/Dm=(Pm+Dm)/Dm=(Pm/Dm)+(Dm/Dm)=(Pm/Dm)+1.

Rune. Don't forget to add the tank and engine weight to the dry weight. A good first order approximation for tankage is 10% of wet mass.

[fredinno]

Here are the new versions for this spacecraft.

http://imgbox.com/fogrsNI2 (Mission Timeline)

http://imgbox.com/0BFr2yy6

http://imgbox.com/3klRnw7I

NOW WITH HiPEP ION DRIVES!!!

I'm still completely open to suggestions for improvement guys (though I kind of hope this is the final version)!

I'm currently planning on making a NASA-ESA Manned Mars Moon Mission or a Venus HAVOC-style mission next. What would be the best idea guys?

[ChrisSpace]

I... oh my god... this is beautiful... Just a few questions/suggestions:

- liquid xenon has a density of 3.1mT/m3, so have the LXe tanks been sized correctly?

- the diagrams seem too cluttered up with all the labels and descriptions. is there a way to make it neater?

- the landing engines don't use methane-oxygen (methalox) combustion, so ISRU will be more difficult.

- are you sure the ion engines produce enough thrust for the spacecraft they are on? as a general rule of thumb, no interplanetary burn should take more than 12 hours.

[fredinno]

I... oh my god... this is beautiful... Just a few questions/suggestions:

- liquid xenon has a density of 3.1mT/m3, so have the LXe tanks been sized correctly?

- the diagrams seem too cluttered up with all the labels and descriptions. is there a way to make it neater?

- the landing engines don't use methane-oxygen (methalox) combustion, so ISRU will be more difficult.

- are you sure the ion engines produce enough thrust for the spacecraft they are on? as a general rule of thumb, no interplanetary burn should take more than 12 hours.

Thanks for your help again.

- I've made sure the xenon is sized correctly, so yes.

- Regarding the clutter, I'll probably make a 2nd version getting rid of it soon.

- The landing engines do use methalox combustion. LNG (aka liquid nat. gas) is methane. I should probably change that abbreviation. I think it's confusing.

- Pretty sure regarding the thrust, but I'm going to have to calculate the thrust. The only ion drive more powerful than HiPEP is VASMIR, and I'm going to have to use Argon instead of Xenon for that. Thanks for mentioning that.

BTW, I highly encourage others to review my design.

BTW, ChrisSpace, should I make a Manned Mars Moon Mission or a Venus HAVOC-style mission next?

[ChrisSpace]

As for the LNG/methalox thing - oops.

For your next mission design, is say you go for a HAVOC-style venus mission. Bonus points if there is a manned surface mission and surface EVA, like in the film 'space odyssey: voyage to the planets'. I might be able to help with that part.

[fredinno]

HAVOC? Well, I guess we're on the same page. I thought the original mission could use a little bit of tweaking, and being a concept, it didn't really go into too much detail.

Manned surface mission and EVA? Not really tdying to offend you, but you just thew realism out the window there with that one. Could you provide elaboration on how in the world we would send humans o the real-life incarnation of hell, keep them alive, and send them back? Thanks.

Edited May 20, 2015 by fredinno

[fredinno]

Can people please review my new Mars Mission Version please (possibly also find ways to improve it)? It's really quiet here...

[Findthepin1]

electrolyze the ice in the ground to get hydrogen and oxygen. now you have rocket fuel. also you can use the oxygen from the ice to breathe, or get oxygen from the air. you can melt ice to get water. chances are if you are landing in the northern hemisphere, there will be ice. chances are also you'll land in the northern hemisphere.

you only need to carry enough fuel on the descent to land. you can make more.

[fredinno]

electrolyze the ice in the ground to get hydrogen and oxygen. now you have rocket fuel. also you can use the oxygen from the ice to breathe, or get oxygen from the air. you can melt ice to get water. chances are if you are landing in the northern hemisphere, there will be ice. chances are also you'll land in the northern hemisphere.

you only need to carry enough fuel on the descent to land. you can make more.

That would either limit me to landing on the poles, or force me to extract water from the permafrost-like underground (which would mean removing the corrosive perchlorate salt from it too.) I'm carrying mined hydrogen from water ice on Phobos (which would be proven with a precursor mission) to generate Methane-LOX fuel from CO2 in Mars' atmosphere.

aka: 2H2+ CO2 -> CH4+ O2

This was a method popularized by Zubrin's Mars Direct, and the Hydrogen fuel that I would need to carry is approx. 5% of the total mass of the produced Rocket fuel.

I also stated this on my plans, BTW.