sh1pman

Maybe we will see a radical price reduction from SpaceX when NG starts flying. Until then, no reason for SpaceX to leave money on the table. So, turns out, you need TWO rocket companies with reusable rockets to see the actual reduction in space access cost.

How much fuel does it need to reserve for landing? If it’s 25t or so, then a Mars-bound Starship can probably lift up to 175t and then refill both main and header tanks.

With fully reusable AND refuel-able LV 200t to LEO equals to 200t to anywhere. 200t seems like a lot, maybe 100-150t is enough?

200t to the Moon or to LEO?

I had 2 different bosses. The first is the Buddhist-type that you wouldn’t even know he’s there until someone calls him by a phone. Extremely busy, 12-14 hours at work every day, talks only to other professors and never to us mere mortals. Didn’t even attend lab seminars or other events like birthday parties. That’s why there was his «lieutenant» or second-in-command, senior researcher who organized the work and events. The second was (and is) the polar opposite. Very involved, remembers your deadlines better than you, very nervous about every project, paper, and grant in the lab. Backbone of the group, basically. Has lunch with students every day. Arguments between the Boss and the person who has rage issues get so loud and unbearable that I sometimes have to leave the room to keep my sanity.

Oh yes, this is 100% true IRL. One has huge temper and self-control issues, another always tells bad jokes and stupid pranks, another possesses a Buddhist virtue of infinite patience and lack of concern for material world, and then there’s the Boss...

Well, from my experience in chemistry research, 75% of time it’s just sitting in front of a monitor or a laptop. Another 15% is sitting around the table, discussing things with colleagues and students with tea and snacks. Only 10% of time is actually spent working in white lab coats with glassware and plasticware. So a realistic depiction of scientists at work would probably be quite boring.

Is it NASA's decision if the contract should be cost-plus or fixed?

So just like Orion then.

No, because oceanic uptake is a very slow process, and equilibrium with atmospheric CO2 is reached over thousands of years. Not useful for us now.

According to my calculations, there are ~180 gigatons of excess carbon in the atmosphere. All plant life on Earth weighs ~450 gigatons. We'll need a LOT more plants to trap all that carbon. If an average tree weighs, let’s say, a ton, we need to plant 180 billion new trees and keep them growing, replanting dead ones. Monstrous task.

All of those things are included in the price of synthetic methane made at a nuclear plant. It won't be as cheap as natural gas. Let's say you pay 100$ for every MW*h of nuclear energy. That MW*h will be reduced to 0.25MW*h after all of the chemical conversions, just because of thermodynamics. Meaning that now you have to pay 400$ for the same MW*h. On one hand, it removes the need to build a reactor, but in the long run it's better to have your own. You can also avoid such huge energy losses with just a regular high-voltage power line from a nearby country that has nuclear power plants (unless you're on an island or something). And this: How? Plants are 100% carbon-neutral. When they die, they release all the carbon they collected back into the atmosphere. Well, unless they get buried deep underground, and after millions of years of heat and high pressure get turned into coal.

Well, it's either having your own plant or paying 4x more for the energy (in the form of gas synthesized with someone else's reactor). Im not worried about heating the planet, just that you lose 75% of nuclear energy in the process. Yea. Even if we stop producing CO2 right now, we still need to remove the extra CO2 in the atmosphere produced since the industrial revolution, just to stop the warming. Your plan won't help with this because captured carbon will need to be stored or buried somewhere forever. If it's burned or somehow escapes, well, it's back in the atmosphere again. We need a more permanent solution for that.

Maybe Starlink is a prototype for Dyson Swarm.

You need hydrogen to turn CO2 into CH4, and the best total efficiency of electrolysis + Sabatier is around 50%. Meaning that 50% of energy is released as waste heat. Then, you need to burn that methane again to generate electricity at a natural gas power plant, and their efficiency is at best 40-60%. So by going through this conversion cycle you lose about 3/4 of your initial electrical energy. Better to just buy a nuclear power plant from Russia. They don’t require enriched uranium.

Therefore, all trees are scammers!

Most likely, but Skylon might also work. If they get that engine done. True. You mean Soyuz? There are new versions coming up, some with reusable first stage even. Maybe Roscosmos will see the benefit of full reuse eventually (hopefully). But not with the current director, for sure.

First you said it was impossible, now you're saying it's impractical. Which one is it? Well, the answer for your first question (was it even a question?) is in that equation. You can have a SSTO rocket with a delta-V of 9500+m/s. With chemical engines. Nothing impossible about it, just impractical.

Can't help you if you don't want to learn. If you look at the equation, you'll understand where you are wrong. Because you are wrong, and single stage to orbit designs with chemical engines are possible. Falcon 9 first stage can almost reach orbit. But not DC-X. It was a prototype to study launch and powered landing. Actual SSTO would have enough delta-V to reach orbit and return. Two-stage reusable designs are possible and one of them is being developed right now. Also, what is this "dear"? I'm not your pal.

Exhaust velocity and delta-V are not the same thing. Why do you think DC-X was ever intended to reach orbit? You actually need about 9.5 km/s to reach LEO, because of gravity and atmospheric drag. Again, you're mixing up delta-V and exhaust velocity. Because it's impractical. Multi-stage brings more payload to orbit. I suggest you study Tsiolkovsky rocket equation: https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation

Prob modded with Tundra Exploration, Reusability Expansion and MKS. Duna colonized and industrialized.

Not that much, as it turns out. Around 6-8t with a VacRaptor-powered single stage rocket, or up to 15 with two stage design. Less than F9. However, that single stage design can be a reusable spaceplane, which will shear another ton or two from usable payload, but will cut the cost greatly.

It really needs to switch to some other rocket to be competitive.