ChrisSpace

Okay, here's my more detailed answer (assuming the goal is to find an ideal engine for a vehicle that can lift off from anywhere and go anywhere else) Chemical propulsion: Horridly low Isp. Solid-Core Nuclear-, Solar- or Antimatter-thermal rocket, LANTR, Vapour-Core or Liquid-Core NTR: Isp is a bit low, but I like the idea. Metallic Hydrogen, Antimatter Gas Core engine, high-TWR He3-D Fusion, Epstein Drive, Inertially confined Proton-Proton Fusion or Antimatter-Catalysed Microfission Hydrogen-Boron Fusion: High-thrust and High-Isp. My personal choices. Gas-core, Plasma-core or detailed Beam-core Antimatter designs, Antimatter "Bottle" engine, Positron Ablative, Laser-thermal, Metastable Helium, Magnetoplasmadynamic, Pulsed Plasmoid, VASIMR, Colloid, Hall Effect, Ion, Arcjet, Microwave Electrothermal, Resistojet, Wakefield E-Beam, most types of Fusion, Closed-Cycle Gas Core NTR, Fission-fragment, Fission Sail, Antimatter-driven Sail, Mini-mag Orion, n-Li6 micro fission, PuFF, most types of Antimatter-Catalysed micro fission or micro fusion, Photon, Magnetic or Electric sail, Mass Driver or Photon Beam engine: TWR too low to lift off Earth, at least not with enough propellant to reach LEO with any payload. Coaxial Gas Core NTR, Open-Cycle Gas Core NTR, NSWR, Nuclear Pulse Propulsion or Medusa: Throws radioactive death everywhere.

You'd need to ruin Earth quite a lot to make offworld colonization more favourable. Possible, but highly unlikely. In a large enough habitat, this isn't really a problem. "About to" is a long way away. And if you have the ability to build a large colony on Mars, you also probably have the ability to push Phobos into a higher orbit. The air may not carry as much coldness, but the ground certainly does. So you can grow potatoes in it, but you can't walk on it?! So, space imperialism. Seems legit. Reaching orbit isn't so much about going up really high as it is about going sideways really fast.

I'm highly doubtful of this. Mars has no native ecosystems that need protecting, and it's overexploitation won't do any harm to Earth. 1620 was 128 years after Columbus. That's a long time for things to slowly build up. Of course a few tens of billions aren't enough for the million-population goal, but a few dozen or even a hundred is certainly doable. This isn't a problem if you have some large-scale orbital infrastructure, like a space elevator or "Orbital Ring". While Mars still has it's benefits, I certainly see your point.

From my research, it appears that the "lower limit" for long-term human survival is somehwere between 0.2 and 0.35g. But I could be wrong. We need more educated people in a lot of industries here on Earth too. But I see your point. Certainly a good point. Raw materials for building and manufacturing things could be aquired from the Belt, so that solves that problem. 1. Probably. 2. Maybe. 3. Venus, the Moon, L-points, the Belt, the Galilean moons, Titan, etc etc. 4. Complicated. Isaac Arthur recently made a video on the topic of colonizing Titan. It's actually a good idea, depending on your definition of "colonization". Unless the temperature, atmospheric pressure, atmospheric composition, radiation levels and so on are all perfect for human nabitation (spoiler alert: they won't be), even the new "Earth" will need to be terraformed. And considering the distances involved, it might just be easier to terraform Venus or Mars.

Definitely the Epst- oh, out of ones that have been built in real life? Probably one of those Cold War NTRs.

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If you want a more supervillain-ey target, redirecting Swift-Tuttle to impact Earth in 2126 with a Dv change in 2060 (roughly half an orbit beforehand) would take 11m/s of Dv, or an energy equivalent to nearly 90 megatons of TNT and over 360MN of thrust for a 6-year burn. If your time limit and energy budget are halfway between these two extremes, redirecting 4179 Toutatis to impact Earth in 2069 with a Dv change 2 years earlier would require a bit over 47m/s of Dv, or an energy equivalent to a bit over 13 megatons of TNT, or over 150MN for a 6-month burn. As for what propulsion system to use for this, unless you can get a working very-high-thrust antimatter or fusion engine, I'd personally recommend either chemical or nuclear-pulse propulsion.

Fun fact: If a spacecraft left Earth and landed on the asteroid Apophis exactly six months before it flies past Earth in 2029, it would only take about 2 meters per second of Dv, or about 122GJ of kinetic energy and 23.2kN of thrust for a 2-month burn, to change the asteroid's path to impact Earth. Redirecting 153814 2001 WN5 with the same time limit would take roughly 15.8m/s of Dv, or about 34-705TJ of energy and 0.82-17MN of thrust for a 2-month burn.

I know. That's how I got the other fusion engines to run. This did not work at all.

I really apologise if this has been asked already, but I'm having problems with the Epst- I mean, the Kerbstein Engine. I've managed to get the D-T VISTA Engine to work, but nothing seems to get the Kerbstein to run. I also couldn't get the massive million-isp fusion engine to produce any thrust, although it did make an exhaust plume.

Is this mod supposed to come with a prebuilt Endurance/Ranger/Lander? I'm getting all the parts, but not the full ships in the VAB or SPH. Sorry if this has been asked before.

Just dropping by to mention that I absolutely love this mod. I don't have any pictures, but let me describe what happened when I tested it: So, my initial test vehicle was really simple: an Orion Drive, a nuke tank (forget what it's actual name is), and a large command pod from another mod. After countless failures with another mod's fusion engines, I wasn't expecting much. A liftoff from Kerbin into suborbital space, at best. So without much thought I hit the spacebar... To quote Solomon Epstein: "Way better than I ever expected. [Isp/thrust] was through the roof. A hundred times better than had even thought possible." By the time I finally decided to cut off the engine, I was going at over fifty kilometres per second and had only used up about a quarter of the nukes in the tank. A few in-game days or weeks later, after having some fun testing other mods, I realised that my test ship had plenty of Dv to do more than simply become an interstellar probe (as I had intended after cutting off the engine). So at 33 million kilometres from Kerbol, I turned the thing's path right around and set course for Jool, specifically Laythe. It wasn't until the atmospheric entry flames had disappeared did I remember that an Orion engine's thrust can't be throttled, and as such landing was problematic, and everything except the command pod exploded. From then on I've used the orion drive as a 3-part booster (decoupler, nuke tank, orion) to get literally anything into orbit. So, thanks for making this mod. It's really helped me out.

Just dropping by to express my support of this mod. Seriously, this stuff is really useful! Oh, wow. I like it! Would it be too much to ask for a centrifuge with a 3.75m or 5m "core" diameter?

Yeah, but doing the stuff specified would require more money and resources than any of those. As the low-hanging fruit of early planetary science dries up, new missions gradually become more expensive (Just look at the progression between the three types of Mars rovers, for example). So, Elysium? This idea is completely ridiculous, but I'll admit it's very interesting. I can certainly see ways colonies could become profitable. Aside from sunlight, Mercury doesn't have anything the Belt doesn't. Or just build an isolated colony in the ocean or Antarctica.

You talk as though SLS and Orion are likely to actually happen. But what would be the point of that? The only strategic value I see in Mercury is it's abundant solar energy, which could be beamed to Earth. In theory, at least. When I asked this I wasn't asking from a scientific/research/exploration perspective, I was talking from the perspective of the people who would actually be the ones funding this. Of course there's tons of exciting reasons to do it, but none of those reasons matter to those whose support is needed. So how does a tortoise's track record in the 100m dash compare to a snail's? They've said "it's going to happen really soon" for years now. Until that thing's on the pad I'm not convinced it will be. Well, if everything goes perfectly right they certainly could get the BFR flying by '26 or even '24, but everything will not go perfectly right. As my sister sometimes says, "Hope for the best, expect the worst". Although I wouldn't call my own predictions "the worst", things could get a lot worse. Again, why and how? 3 Phobos lander probes have been launched so far, all failed. Hopefully this is just a string of random bad luck. If not... If it weren't for the forum rules I'd have a lot to say about this.

I'd say the mid-30s at the earliest. Why would they want to do that? If it can be refilled at the edge of Earth's gravity well (perhaps at a lagrange point), it could go pretty much anywhere. Of course, Venus would still be inaccessible (unless that futuristic hindenburg idea works), as would anything past Saturn due to the outrageous travel time. I find it unlikely that a new space race could start this way, but I can't say about about it because forum rules. "A few million"? Not in this century. 1 million maximum. To me, asking "which has a lower chance of failiure, BFR or SLS?" sounds a bit like "what's more likely to win the 100m dash in the next olympics? A tortise or a snail?" DSG becoming a thing and lunar flyby tourism being practical? You call that pessimistic? Flags and footprints on Mercury? ...wat? What's the point of that? That study was made in 2003 IIRC. As you'd expect, things have gotten worse since then. Historical analogies don't really work here.

I have tons of other stuff to say, but for the aforementioned reasons I can't say much else here. PM me if you want to hear my other ideas.

Finally, proof that my room isn't the messiest place in the universe!

Well, I can't say everything I want to right now, for 2 reasons: 1. It would take me all day to type it all here. 2. The forum rules still have that thing regarding political discussion. Now, I guess I'll start with what I consider to be the most important aspect of any modern or near-future story: MacGuffinite. To simplify, MacGuffinite is whatever is driving and encouraging the exploration, colonization and/or industrialization of space. Atomic Rockets lists a few potential forms of MacGiffinite, and I'll briefly give my opinion of each (but you should read the Atomic Rockets page on the subject first): Reducing transport costs to space*~: Unless the reduction is completely ridiculous this wouldn't be enough in itself. Atomic Rockets lists many interesting ways of reducing launch costs in it's Surface to Orbit page, but none of them are as dirt-cheap as you'd need for a setting involving, say, a large Mars colony. Reducing support costs for space intfastructure*~: Similar-ish opinion to the above. Growing high-value products (eg Chocolate)~: Why not just do that in a controlled environment on Earth? Orbital Propellant/ISRU facilities to reduce Dv requirements*~: You still need a motive to put those there in the first place. Asteroid mining*~: You can just use unmanned vessels, and even if you need humans on-site, we certainly ain't talkin' about a major colony, more a high-tech spaceified oil rig. Then again, once people realize how profitable it could become, so many organizations and factions would try to get themselves a slice of the quadrillion-dollar cake that who knows what could happen. "Mining" natural gas from Titan~: Won't be more profitable than getting it on Earth until there's almost none left. But if it does become profitable, you have some real possibilities here. You'd probably need humans on-site, possibly even on the surface, and for that you'd need to either invest in propulsion technology that opens up the rest of the solar system too, or place propellant facilities in deep space En Route to the distant moon. Phosphorus mining~: Similar opinion to asteroid mining. Helium-3~: Even if you ignore that the only two ways to get it are by either sifting through 150,000 metric tons of regolith for 1 kilogram of the stuff or diving into a gas giant's atmosphere with enough Dv for a grand tour of the solar system, Helium-3 fusion as a power source is still rather experimental, to say the least. "Carribean sugar islands" analogy: If you're just making the stuff artifically, why do it in space at all? Manufacturing/Experimenting with extremely dangerous things*~: No reason to put humans up there, just control everything remotely from the ground. Icy outer planet's moons as heat sinks~: Anything emitting enough waste heat to be put on a separate world probably has to belong to a setting that has already entered a spacefaring stage. Lebensraum/Overpopulation: Once Antarctica, the Sahara and the bottom of the ocean have all been colonized, we can give this some serious discussion. In any case, stabilizing Earth's population would require hundreds of thousands of people to be launched into space every day. Manned space stations filling the role of satelites*: With the advancement of computer technology and undersea cables, that ship sailed decades ago. Repairing satelites damaged by Kessler Syndrome*~: This idea could work, so long as the random nature of damage control stays out of reach of autonomous vessels. Tax Haven*~: No reason to put one in space rather than some isolated fortress in, say, the aforementioned bottom of the ocean. Prolonged lifespan due to lower gravity*~: If you spend too long in an extremely low-gravity environment, returning to Earth becomes extremely dangerous, potentially even impossible. Although there's certainly an overlap between the "prolonged lifespan" zone and the "can still go back" zone, and I stringly suspect Mars' gravity is in that overlap. Species survival~: Unless you're the CEO of Tesla and SpaceX, this really isn't enough of a motive. And anything that could wipe out all human life on Earth would probably either be so rare that we shouldn't bother worrying about it (eg the neutron star collision in Evacuate Earth), or it would be something that would kill everyone on Mars, Titan etc as well (eg the Singularity). "If you build it, they will come": No. Just... no. Political reasons*~: I obviously can't say much ragarding this, so I'll just vaguely state that this might work in some settings but not in others. "Moral equivalent of war": Same answer to "If you build it, they will come". Preserving culture: Same answer as "Tax Haven". In addition to those, I've heard of three more potential forms of MacGuffinite: Tourism*~: I personally can't imagine tourism as being a major driving force behind space industrialization, and in any case, it isn't even realistic as a concept without really cheap orbital launch costs. "Battlestars"*~: This concept was discussed by George Friedman in his book The next 100 years. TLDR, he thinks that primary command and control facilities in military operations will be moved into space specifically geostationary orbit, because reasons. He actually has some convincing points, but even if he's right, that doesn't provide any driving force for colonization or industrialization further into space. Space-based solar power~: Sounds good in theory, probably impractical and exceedingly expensive in practice. So, what do I think would make the best MacGuffinite for your two settings I'm interested in? Well, I personally don't think any single potential motive is enough, rather a range of several may be required for each. If I had to pick, the ideas that could work for the extended space race are marked with a * and the ideas for the mars colony setting are marked with a ~.

I calculated the thrust and thrust power of the ISV Venture Star from Avatar, because I was bored. AND HOLY [REDACTED] THAT THING IS POWERFUL!

I really like this idea. It's a bit like my alternate solar system timeline, but with the "real" solar system. I have tons of ideas for this kind of thing. ...Wat? I have a ton of good ideas for this. Literally, I have 1000 kilograms of good ideas. "Interstellar turck driver"? Doesn't sound very realistic.

Update: When you get a girlfriend who is just as excited about this as you are. Also: When you want to know the Isp and Dv of every fictional spaceship you see.

Nothing about my idea is short-term. Or even realistic. Atomic Rockets has an NTR weighing 5 metric tons that has a thrust of 3500kN. For a full NTR vessel that's 0.45g of acceleration per engine. So this isn't as much of a problem as you might expect. If by "nuclear electric" you mean "Ion/Magnetoplasma/VASMIR powered by a nuclear reactor", like Hermes in The Martian, the main problem there is acceleration. You'd basically need two propulsion systems, one for travel in deep space and one for high-thrust manuvers such as liftoff and landing on Mars.

I suppose in most situations it would be, but I can still see a few advantages: - larger payloads can be delivered to the moon and Mars - travel times to Mars can be shorter, reducing radiation exposure for the passengers - much more of the solar system can be opened up for... something. Surely the moons of the outer planets must have something profitable? - using one type of propellant instead of 2 might make stuff easier, I think - rescue/damage control vehicles can arrive at emergency situations faster - aforementioned stuff about the launch vehicle