How so many educated, intelligent people seem to think that we (as a species, or even as Americans) are so resource-poor that “space exploration” and “improving the earth” yield an either/or decision absolutely mystifies me.
You want to free up resources for either one? Start with global military spending and the financial sector. Both have their place and both have grown far beyond it.
Look at the numbers. SpaceX is doing it’s thing for a few billion a year. That’s chump change compared to the money being spent on, let’s say professional basketball. Not picking on basketball it’s my favorite spectator sport. But saying, if you want to find something less worthy than “improving the earth”, you have about a hundred better targets than space exploration.
> SpaceX is doing it’s thing for a few billion a year
One can project from SpaceX's launch history that as the commercialization of space intensifies, this figure is going to continue to grow exponentially
Malthusians exist. They think we're running out of oil, soil and arable land, fresh water, and... just about everything. The logic is that since population growth is exponential, we really could run out of resources. And... that's both totally correct and totally wrong. Totally correct: because yeah, duh, if we had 1 trillion people... Totally wrong: because in fact the arc of evolution of fertility rates, population pyramids, and total population is bent and bending more and we will in fact be facing a shrinking world population soon.
Meanwhile we have more oil and gas reserves now than ever. We're not running out of anything, not really. But the malthusians want to reduce population by 16x. They really do. It's crazy.
Now, to answer your question... Substitute any topic into "how is it that so many educated, intelligent people seem to think that we...". The answer is pretty simple: we each don't know everything, in fact we know very little (and about many many things nothing really), and we are very (extremely!) susceptible to peer pressure, and we like to go with the flow, and we accept authority blindly where we know little, and so on.
It's a real problem. We just don't teach people how to think about what they know little about. Epistemology is hard enough, but we need people to do more than reason about what they know and how they know it and what they might not know and all that. We need people to have an idea of how to think about the stuff they know little about that they don't even want to know about -- stuff that -no matter how little they care for the details of- is super topical and where getting the answers collectively wrong could be disastrous.
Climate change also exists. So do resource limits.
Something that doesn't exist is the science of living outside of an existing planetary ecosystem.
Do some research on how much is understood about creating a stable ecosystem out of sand, metal ore, and water. You'll find it's a good approximation to zero.
Flag wavers think it's all about building giant rockets, planting a flag - and boom. Colony! Asteroid mining! Etc!
The reality couldn't be more different. Giant rockets are barely the loading screen. Feeding humans, dealing with waste products without choking on them, growing or synthesising essential nutrients, building systems that do all of this in a stable self-sustaining way - these are all beyond hard.
And that's not even getting into psychology and politics.
So until that changes, running your own planet - the one you got for free, and which was working fine already - as if you're trying to test it to destruction to find out just how stable it really is, is an unbelievably dumb thing to do.
Not a Malthusian, but I’m very worried about the amount of resources we are using. We already lack the carbon budget and farming capacity for the world’s population to live to the standard of an average US citizen. There might be enough space and enough atoms, but we don’t yet have the capability to direct it into sustainable quality of life for all.
On the environment and fauna, animals are going extinct (like the white rhino) so yes, we are running out of stuff.
Trees—like Dominican mahogany grow really slowly and now there are so few of them we have basically run out. I can name several other examples—most notably Guayacan.
There is a bunch of scarcity and destruction. I’m pretty sure we can fix them—but for the trees and the animals it’s unlikely that I get to experience them as was so in previous lifetimes.
It’s a shame we couldn’t manage them sustainably previously.
As long as the population increases, Malthus is right. There is going to be some ultimate carrying capacity at some point. Ultimate amount of energy we can harness. It's just a question when. Certainly before our energy consumption is enough to literally boil the oceans.
Plug in different growth rates and the answer could range from tens of years to hundreds of millions of years!
If there were fewer people on Earth, then presumably there would be less deforestation, overfishing, greenhouse emissions, etc. I strongly reject the idea that the Earth can support the current human population at the current levels of consumption and pollution.
> But the malthusians want to reduce population by 16x
This seems pretty extreme, but thank you for bringing the concept of Malthusianism ( https://en.wikipedia.org/wiki/Malthusianism ) to my attention. While i'm not convinced that it's likely to be the end of humanity (but rather the results of thousands of compounding factors), the irresponsibility in regards to unrestrained consumerism is something that i see every day, and there is certainly some merit to those arguments in my eyes because of this.
> The answer is pretty simple: we each don't know everything, in fact we know very little (and about many many things nothing really), and we are very (extremely!) susceptible to peer pressure, and we like to go with the flow, and we accept authority blindly where we know little, and so on.
This, however, i'm not entirely sure about. Short of militant disregard for climate change or even the idea that human actions are capable of changing it in the first place, the viewpoints that i've personally seen expressed are more in the direction of feeling powerless and somewhat depressed about the state of things. Instead of outright ignorance, most of the people that i've talked with believe that the governments have largely failed them and the mechanisms of representation that should be in place are only so as far as looks are concerned. For example, lobbying and corporate interests are prioritized, as well as industry development is prioritized over sustainability. In the end, it feels like maximizing profit margins takes precedence over sustainable progress and long term advancement.
Edit: Climate change and all that is just one example, but the fact that many feel powerless even if they aware of what's going on stands for other things as well.
And most of those people that i've talked with have felt like there's little to nothing that they can individually do, seeing as a significant portion of the society is more than happy to live a hedonistic lifestyle that's rooted in consumption. That doesn't mean that we need to live in some dystopian nightmare either, but i'd argue that it's definitely a worthy goal to make the environment thrive first and to focus on a more utilitarian way of life - meat dishes as something to enjoy rather than to have with every meal, a new phone every 5 years instead of every single year, energy efficient hardware (like Athlon 200GEs) for homelabs instead of the latest Threadripper CPUs (unless absolutely necessary), a used but dependable car instead of a new one and so on. And, of course, supporting local and small businesses, as well as trying your own hand at some of that stuff - going out to hunt game, drag it back home, skin it and cook it (if nothing else, that really makes you appreciate the meat you're eating), or even just simpler things like growing your own tomatoes and cucumbers (which are absolutely delicious), where possible.
If everyone lived at least a bit more like that, we'd have even more breathing room in regards to the environment, in regards to resource usage etc., which feels like a good thing no matter how you look at it. Of course, that's probably also unrealistic as far as expectations go.
Using these resources to improve chemical flamethrowers is sub-optimal. A dead end. Nuclear fusion is a more likely answer to spaceflight and Earth's clean energy problem. It likely should be the priority.
>Nuclear fusion is a more likely answer to spaceflight and Earth's clean energy problem.
Considering we don't even have fission rockets or airplanes in normal use, making a fusion powerplant that is light enough to get off the ground seems very far fetched.
Even if we eventually use fusion for travel beyond earth orbit, I'd bet chemical rockets would still be in use.
Don't we already have thrusters that are useful in space, but completely unable to support themselves against 1G and so they can't lift off from the ground?
I feel like I've read something that said fusion power would fall in the same category.
Even if we pretended that it's rational to hedge all your bets on not only having a working fusion reacter in the near term future but having the capability to miniturise it to a degree where it could be used as an engine for a launch vehicle, you would still be dead wrong.
Fusion still shares the same fundumental problem that chemical rockets or even more advanced options like blackhole or antimatter drives face - the rocket equation. We need to use near term reusable launch vehicles like the Starship to help set up the required launch assist structures that would make genuine mass transit of people and cargo into orbit possible.
Things like skyhooks, lofstroom loops, and eventually orbital rings that would allow people to ride trains or cable cars from an earth city straight into orbit for the same price range as intercity travel today. Needless to say, that is not going to happen until there is enough of an industry up there to justify the large upfront costs of such megaprojects (especially the orbital ring) so the Starship is our best near term hope of getting us up to that point.
Note that none of these projects require advanced materials or new technologies (as opposed to the space elevator that is likely to remain science fiction when it comes to dealing with a body with the gravity well of earth anyway), they're just massive engineering projects.
nuclear engines, even just the fission, are the future for the space. The thing is you'd never be able to launch them on Earth. So, the first thing is to get enough stuff into space and establish an assembly/test platform there, Moon probably. With Starship the Moon becomes just a 3 day trip for 100ton cargo while burning less than $10M of fuel.
>Using these resources to improve chemical flamethrowers is sub-optimal. A dead end.
Earth launch future is large rail gun (somewhere like Bolivia) as a first stage booster. Requires a bit of political will, international cooperation and a few billions. Unfortunately the 1st and 2nd aren't coming soon, so the "chemical flamethrowers" for now.
In 2019, Elon tweeted[0] that the price of one Raptor engine is under $1M with the goal going under 250K for the next version. Any recent info where there are now?
I'm still surprised they moved to this orbital fly so quickly without doing more tests. Going from 3 engines to almost 30 is crazy. Also, If I understand it right, both booster and starship will end up in the ocean. I hope they will be able to reuse at least a few engines.
A whole industry bootstrapping itself to make semi-conductors doubling every 18 months, going from exotic, mission critical hardware to commodity; SpaceX is doing the same thing with flight hardware. Contrast that with previous generation engines (the RS-25 comes to mind) with a sticker price of 125 millions... per engine! [0]
> A whole industry bootstrapping itself to make semi-conductors doubling every 18 months, going from exotic, mission critical hardware to commodity;
Silicon Valley did not bootstrap itself. It received untold billions of dollars from the US government during the Cold War (and lots of stuff happened during the WW2 economy, when the US was the Allies' armorer). Do you think it a coïncidence that most spy satellites are launched from Vandenberg? Or that Skunk Works, located in California, developed so many secret aircraft?
Do a search for "The secret history of Silicon Valley":
The fact that the US was, post-WW2, the largest economy in the world, and the main developed nation that didn't see mass destruction, certainly didn't hurt.
The fact that the US government throws a lot of money around certainly helps private industry:
This also does not diminish the entrepreneurs that, once the baton is handed to them, charge forward. My main argument is that there's not as much "bootstrapping" as many people believe.
IIRC, the recent doublings have been happening in Taiwan. That's why people make such a big deal about TMSC. America (i.e. Intel) actually has some catching up to do.
SpaceX has quite a few engineers that learned the practical details of rocketry on the government’s dime. Be it at NASA or Boeing or an aerospace department at a university that gets government funding. I don’t mean to detract from SpaceX’s accomplishment, but they “bootstrapped” themselves the way a rich kid starts a company using the resources and connections put in place by his “family”.
bootstrapping itself by extending tech designed decades ago? that doesn't sound right. Until today, the biggest rocket design was still the soviet N1 from the 60s. It's good to celebrate space achievement but rewriting history is annoying
Something kinda similar happened in Japan after the second world war - from cities burned to the ground in 1945 to first japanese nuclear power plant and bullet trains by the 1964 Olympics. Pretty remarkable IMHO.
This is hardly beyond standard practice in the industry.
The SLS is going to orbital flight with no flight testing. Heck the Falcon Heavy launched a car past Mars' orbit on it's first flight. I think SpaceX's main goal was to refine their manufacturing process and make sure they can achieve a certain level of consistency in building these things. The fact that they installed all these Raptors before even doing a pressure test tells you they are far more confident in their processes than they were even 6 months ago.
> hardly beyond standard practice in the industry. The SLS is
Perhaps explaining GP's surprise: I've heard SpaceX's testing philosophy contrasted against this sort of thing. That none of their tests are "too big to fail". On the other hand, according to this narrative they also stress iteration speed over success rate, and ramping up fast works to that end too.
Maybe they were getting diminishing returns (in terms of lessons learnt) in small scale tests though. No doubt there are phenomena you only see in larger tests, and (as you say) their confidence in getting the smaller stuff right might be quite high.
"I'm still surprised they moved to this orbital fly so quickly without doing more tests."
I'll bet they're going to remove all 29 of these engines and re-attach them again later. I would expect they want much more testing than they've done to date (for example, pressure testing the tanks -- they have not done that with this booster, BN4, according to Reddit).
> Also, If I understand it right, both booster and starship will end up in the ocean.
You mean for the first test flight? Do you have a source?
Long term plan is definitely land landing, but I haven't seen anything about the first test flight.
I assumed that they would try and land it from the start, they've already landed starship a few times, and it seems like that's where a lot of the unknowns still are (e.g. they're apparently adjusting wing size down after the last landing)?
Basically both vechicles (the massive booster and the starship itself (2nd stage) are going to "land" on the water, which means a hover and then sinking into the water.
Booster - Boost and separate, boostback burn and splashdown off the coast.
Starship - 90 min orbit at about 120km, reentry and spashdown near Hawaii
It's fairly quite likely that both would crater on this first flight - for instance this is the first booster flight and also the first reentry for the starship itself.
The Falcon 9 booster also had similar flight plans until it could successfully fly a controlled trajectory to the surface of the ocean before they risked a drone ship too.
The plan for the first test flight is to aim for a controlled water landing, but the odds of that being completely successful aren't high enough to risk a land landing. The new drone ships are still under construction: https://spaceexplored.com/2021/07/07/update-on-spacexs-gulf-...
Elon appears to be building a large ground-locked monument to demonstrate his argument in this tweet:
Unlike its aircraft division, which is fine, the FAA space division has a fundamentally broken regulatory structure.
Their rules are meant for a handful of expendable launches per year from a few government facilities. Under those rules, humanity will never get to Mars. -- https://twitter.com/elonmusk/status/1354862567680847876
The single most important job humanity has is to get our eggs into more than one basket. The FAA is standing athwart the most effective effort to move in that direction, yelling Stop. The more fragile our environment is, the more protection it needs, the more important it is for them to get out of the way of projects like this.
The single most important job for humanity right now is to save this one planet we have from destruction. There is enough time to think about colonizing the stars after that. I'm as much into spaceships as the next nerd, but people need to get real. The world isn't going to end because his next launch is a month late due to pesky safety regulations or whatever else. This effort is going to play out over many generations and centuries. Meanwhile our entire species stands no chance against one slight more deadly virus released tomorrow.
Criticizing regulators is Elon's MO, whether it is the SEC for his Tweets, various transportation departments for self driving software safety, labor departments for covid restrictions for worker safety, FAA for rocket launches... You'd think there is some national conspiracy against him at this point.
Instead of parroting what you read on social media, how about doing a bit of critical thinking on this. What about all the resources going into video games, sports, movies, music, amusements parks, television, weapons systems, desserts, travel and vacations, etc? They dwarf everything put into space exploration, and are arguably less useful. Do you make the same tired comments when those industries are brought up?
And that's not even getting into the fact that multiple things can be done by humanity at once.
edit: apologies for the first sentence here which was unnecessary to make my point.
I think the best way to save the planet is to move heavy industry into space. Move our power generation into space and beam it down. Make advanced technologies in space which benefit those on Earth. Move people into real orbital habitats.
Make Earth proper a gigantic park / nature reserve.
We can't "wait" for anything, or the window during which we can develop space travel will close. 10 or 100 years from now we might no longer have the motivation or the means to fund and build new vechicles like these.
He's not claiming there is a national conspiracy against him. He is claiming that between regulatory capture and regulators trying to justify their existence, government agencies are not acting in humanity's interest.
No, you’re wrong. Every little bit of friction counts. Funding, regulation and public support all contribute to the end result. It’s already super hard, the only way any progress has been made is because we rolled one in a trillion with an super genius who is immune to stress and is interested in space. The amount of stress, the relentless pressure of doing all this and doing it in the public eye and suffering the cosmic level of irony of being publicly maligned for it… it would crumple you. It would crumple ten of you.
If it were at all easy or probable then there would be other players in the space. There aren’t. If you contribute to the friction that opposes spacexs forward progress then you bear the responsibility for working against the things that you claim to love as a self proclaimed nerd.
There were people who put on demonstrations against wealthy people spending their money on being patrons for scientists and early biologists. It was very unpopular for rich people to sponsor nonsense, the collection of random fluids and samples. All of which is the basis for modern biology and medicine. So which side of history are you going to be on? The idiotic mob or the people making things better?
> > The single most important job humanity has is to get our eggs into more than one basket.
> The single most important job for humanity right now is to save this one planet we have from destruction.
Aren't these two sides of the same coin? If we colonise Mars, but leave Earth a smoking ruin, then we've made things worse by trading a planet with a function biosphere for one without. If we wait till Earth is in perfect state before colonising another planet, we'll never leave, and be subject to many of the same risks.
We can fix the Earth's ecology from the damage of the last century and expand into space at the same time - these are not mutually exclusive. There can be enough people and funding to do both. And even better - the technology developed from the latter can assist for the former.
Consider the fact, that the publicly richest citizen on Earth, as well as one of the people behind one of the largest financial transaction sites, may have genuinely already concluded that, as the history of politics among other things have shown, that the Earth/humanity may simply be unsavable, for whatever reasons they find.
He has a lot of talent at his disposable, and presumably information to a decent bit of otherwise locked away studies/reports. Do I think he is correct? Perhaps not, but my nor your opinion really matters.
If he's made the decision shits truly FUBAR, ala Foundation, then leave him alone while he works on what he may genuinely believe to be a shot at surviving the FUBAR long-term.
> The single most important job humanity has is to get our eggs into more than one basket.
We are very far from a self sustaining society and economy on Mars. Easily a century or more. I'm cheering on SpaceX, but find this talking point of Elon's very tiresome. It's little more than sci-fi fantacism. As just a simple example: no one knows what childhood development is going to be like at 40% of earth's gravity. And that's just one issue among millions.
For better or worse we need to fix the planet we have. And we don't need to invent new technology to do it, though we certainly should pursue new technologies that might help or accelerate the process. What we lack fundamentally right now is political will/unity.
We can arrest climate change. We can end famine. We can extend modern medical care to the entire world. All of these are directly possible, today, with no new invention.
But we have to, to paraphrase Sagan, become a species more prudent than we are today.
There are a couple of major reasons the FAA is involved:
1. Fuel-air explosions at ground level can injure people or destroy property (even kilometers away)
2. Rockets on unplanned trajectories can ruin people's day
3. Lots of fuel is toxic, we need to mitigate this.
Basically someone has to walk through all the worst case scenarios and ensure that everyone (and nature) remains safe or as safe as it is possible to be.
Toxicity and polluting aspects of Rockets is of a negligible concern, Everyday Astronaut (Youtube fame) gets this so often that he did an entire hour long video on this: https://www.youtube.com/watch?v=C4VHfmiwuv4
> Rockets on unplanned trajectories can ruin people's day
The single most important job humanity has is to get our eggs into more than one basket.
Perhaps that's true, but space launches are important enough that going "slowly"[1] is a good idea. One catastrophic accident with the destruction of a spacecraft leaving a large amount of orbital debris would make space launches much, much harder until we clean up. Rushing to space could slow us down a lot.
[1] The space race has only been going for 70 years, and less than 25 years commercially. The idea that anything is happening "too slowly" is quite baffling really.
From Musk's perspective, any timeline which does not establish a permanent presence on Mars within his lifetime is too slow. It looked like that would be impossible before the Starship program, now it merely looks unlikely.
> The single most important job humanity has is to get our eggs into more than one basket.
This is a defensible opinion, as are the others saying that the most important job of humanity is to fix our current basket.
While neither agreeing or disagreeing, I will note another very important thing SpaceX is doing:
"The value of beauty and inspiration is very much underrated, no question. But I want to be clear: I'm not trying to be anyone's savior. I'm just trying to think about the future and not be sad."
A lot of what SpaceX is doing is extremely inspirational, and I think the world could use more things to look forward to in the future.
> This is a defensible opinion, as are the others saying that the most important job of humanity is to fix our current basket.
It's always presented as a false dichotomy, though. We can have both.
People insist we should be spending our money fixing the planet, but we already are, including Musk who just sponsored the largest XPrize in history for a carbon sequestration method.
First we must overcome the political hurdles to get people to even recognize that climate change is a problem. Obviously money is only barely starting to trickle in to carbon sequestration tech.
I have a feeling Musk and the FAA have very different standards around public safety. He has his differences with the SEC and NTSB too, but I feel the FAA hews far closer to the public safety end of the spectrum, and not the "move fast and break things(bones)" end.
There are a couple of points where I disagree with you, but one in particular I hear very often and should be debunked.
A colony on mars, even of significant size and population, is 100% condemned to certain death if separated from Earth. It would be, for all intents and purposes, in the same "basket".
Google "how to make a pen from scratch" for a quick primer into why, but the tl;dr version is that it takes having a huge industrial base already existing in order to keep, let alone advance, our current technological level. And Mars is not friendly enough to support us with lower tech.
Our intuitions go the way of "we can put 1000 smart people there, that's enough to survive and thrive". Well, we as a species can't move our microprocessor factories from Taiwan in less than a decade, and you expect them to be rebuilt on Mars from scratch?
> A colony on mars, even of significant size and population, is 100% condemned to certain death if separated from Earth
It would be in the near future, true. In fact, the key milestone for humanity being truly multi-planetary is that each planet must be independently self-sufficient.
There's no laws of physics that would prevent human life on Mars or Venus from eventually becoming self-sufficient.
The time-frames to get to that point are large (mid-hundreds to low-thousands of years by my random guess). A thousand years isn't that long in terms of the evolution of the species, though, and are the time scales we should be thinking of multiplanetary life on.
Watch 'Mars Industrialization Roadmap' by Casey Handmer. That is exactly what he is addressing. He literally mentions the 'I, Pencil'. And btw a million people is the goal, not 1000.
To be honest, I can't tell you what kind of future innovation is going to result from cheaper spaceflight. But there is serious scientific and engineering potential to be unlocked. What SpaceX is doing seems environmentally unfriendly, and I know no-one wants to hear "but xyz is worse". But we really do need to keep such things in mind, because SpaceX's footprint here is completely dwarfed by domestic carbon creation. The Apollo Project lead to all sorts of spinoff technologies that we use today. It wouldn't be unreasonable to expect some of the future technological advancements to reduce pollution or carbon emissions.
It could. That's pretty much the entire argument in favor of exploration actually.
We are going to need far more advanced technology than we have today if we are going to reverse the effects of climate change. If we move heavy industry to space that can dramatically reduce our carbon emissions here on Earth. The technology to do that may also lead to breakthroughs in other areas like energy generation or storage.
I run thousands of hours of batch data processing jobs a day. They aren't particularly time sensitive, as long as they finish in a day I am happy. There's no reason the computers doing that need to be on Earth consuming precious water and electricity resources.
Musk is very good at getting public support on his side. Please, we’ve already lost the public support for so many important institutions in the US. I get they are slow, and this is frustrating but I don’t want the FAA to be on the chopping block because someone didn’t plan ahead. If the FDA gets in the way of vaccine development you bet musk would tweet against it.
It should be remembered that the unspoken rule of any agency or institution is to justify its own continued existence. For be bureaucracy that is the FAA, all the onerous requirements they place on spaceflight is a feature, not a bug.
The bureaucracy at the FAA has protected millions of airline passengers over the course of decades. Just look at how one minor discrepancy in an aircraft can lead to a total loss of the jet and hundreds of lives lost. Now combine that with a rocket loaded with a hundred thousand gallons of fuel and it's understandable that we should be careful. I don't want our space-faring expeditions to look like China's, where they're okay dumping hydrazine on local villages [1].
Sorry, this is such an absolutely absurd argument.
What are minimal capital and time requirements to do this eggs in more than one basket thing? Not talking about an orbiting space whatever but a real, sustainable ecology on another planet.
The depth of our ignorance even about whole classes of basic science there, notwithstanding the number and scale of engineering problems to solve....
Is there any reality where this isn't minimum a century and thousands to millions of $T?
For someone who believes this is the most urgent problem on which to spend capital and time, the most efficient target of advocacy energy has to be the US military which spends $700B a year, not the effing FAA and the relatively small scale projects of this one company- no matter how exciting and advanced they happen to be.
Even making the case for this program, when one considers what could be done with even a fraction of that scale of capital deployed on this planet....Fusion energy itself is probably a $10T investment, orders of magnitude less in money and time.
Space is cool but not for one femtosecond should anyone entertain any of this eggs in more than one basket nonsense.
Almost as if he's thought about the thing he's devoted a good chunk of his life and wealth towards, here's Musk:
“The point at which one says the goal is to make life multi-planetary, it means that we need to have a self-sustaining city on Mars,” Musk said. “That city has to survive if the resupply ships stop coming from Earth for any reason whatsoever. Doesn’t matter why. If those resupply ships stop coming, does the city die out or not? In order to make something self-sustaining, you can’t be missing anything. You must have all the ingredients. It can’t be like, well this thing is self-sustaining except for this one little thing that we don’t have. It can’t be. That’d be like saying, ‘Well, we went on this long sea voyage, and we had everything except vitamin C.’ OK, great. Now you’re going to get scurvy and die—and painfully, by the way. It’s going to suck. You’re going to die slowly and painfully for lack of vitamin C. So we’ve got to make sure we’ve got the vitamin C there on Mars. Then it’s like, OK, rough order of magnitude, what kind of tonnage do you need to make it self-sustaining? It’s probably not less than a million tons.”
That’s not a precise number, of course. It’s a rough estimate. But Mars settlers will need vast quantities of stuff. The settlers will need to build an entire industrial base to mine the Red Planet, and there are many steps in mining. To make consumer products requires a huge infrastructure base to refine and shape materials.
“I’ll probably be long dead before Mars becomes self-sustaining, but I’d like to at least be around to see a bunch of ships land on Mars,” Musk said.
This is a tiring argument of opportunity cost for Space Exploration. It has been discussed ad-nauseum on HN. It is not a zero sum game - we can explore space and simulatenously do the things that are immediately in need and urgent.
I think a lot of people are just pissed off seeing someone succeed so much at something that wasn't supposed to be possible (resuable rockets). Makes them feel worse about their own mediocre lives.
This wouldn't have been a problem in the past. You'd just shrug off the crazy explorers and write them off as soon to be dead. Now, evidence of their success and relentless progress is shoved in our face every day.
I guess you haven't been reading the room lately. In the modern retelling, the explorers that found the "New World" produced only net negatives and we'd have been all much better off had they stayed in western europe.
I find these 'what-ifs' to be only thought-exercises. You'll never truly know if the world is in fact a better place because there's no A/B test, no re-do.
In the end humans are naturally curious, expansionist, greedy (to varying degrees). We've always been this way and so it's only natural for us to continue.
We've been described as a virus before, feels relatively accurate esp if we start planet and system hopping.
Very few make or believe that argument. There's absolutely nothing wrong with wishing that things had gone a little better than they did at the time. We can still believe in a more humane world while still greatly appreciating the benefits that modern society has given us.
This is nonsense. I am sympathetic to even the most obnoxiously leftist descriptions of the exploration of the New World, but even then, acknowledging that the large scale conquest of the Americas involved multiple genocides is not in conflict with acknowledging that some of the explorers that found new lands (not only the Americas) were brave visionaries.
Why is it so difficult to just accept that a single person can have both inspiration qualities that we should try to emulate and also grave moral failings we should learn from? No one is perfect and hardly anyone is purely evil either.
You can explore and discover new worlds without raping, killing and exploiting the new people you find. The problem wasn't the exploration, and there's nothing inherent about exploration that forces you to murder others.
What's the scaling like for rocket engines? How much more efficiency (in various forms) could you get if you made 1 giant engine instead? (Disregarding reliability)
There are a lot of issues you get from scaling an engine up, one of the major issues being combustion instability. The larger the "blob" of fuel and oxidizer mixed together that you're trying to burn, the more you will get things like eddy currents and shockwaves flowing through the material. These disrupt the combustion and make it uneven, possibly leading to feedback cycles where these elements self-reinforce eventually causing vibration or otherwise damage to the engine. The smaller the physical size of your combustion chamber the easier these things are. The largest single engine ever built, the F1 engine that pushed the Saturn V, had massive issues with this that were further made worse because the engines were largely designed without the aid of computers.
I'm not a rocket scientist, but my understanding is that efficiency is derived from the exit velocity of matter from the engine. So the faster it can fire matter in the opposite direction the more efficient it is. There are some other factors as well like bell shape, which are generally designed to provide better efficiencies at different atmospheric pressures (ranging from sea level to vacuum of space). The main consideration after these factors is the mass of the engines. If multiple engines and one giant engine had all of these same factors equal, then I don't think there would be much difference in the efficiency of the rocket. Likely though, there are differences and other advantages to multiple small engines. The easiest one for me to think of is modularity. If you want a specific thrust for a payload it's much easier to add more small engines together than to try and throttle down the large engine to the correct amount, if that is possible at all.
Musk has actually talked about that before, during the early stages of Raptor development. He said they were downsizing Raptor from the originally planned size, because their analysis showed a smaller size was the sweet spot for maximum thrust/weight ratio.
The short answer to your question is that larger engines have very few advantages and many disadvantages.
Specific impulse is the most obvious parameter of a rocket engine, but it's relatively less important for a first stage where thrust/weight is also a very important concern. Specific impulse depends on the chemistry, combustion cycle, combustion efficiency and nozzle design. There isn't any obvious reason why it would scale either way with engine size.
Thrust/weight is very important for engines on a first stage because of gravity losses. Imagine if the rocket sitting on the pad had a thrust/weight of just 1.1; that would mean that at liftoff 91% of the thrust would be wasted just countering gravity. You both want a high thrust/weight at liftoff and a small dry mass to give the second stage the most momentum possible at stage separation. High thrust also helps for reuse in making the burn time of the first stage shorter (for fixed specific impulse and propellant load), which means that at stage separation the first stage isn't too far downrange and is easier to return to the launch site.
Note that there's both the thrust/weight of the rocket as a whole, and of the engines themselves. The engines comprise a significant proportion of the first stage's weight, though, so looking at engine weight (and thrust to weight) is also useful. Consider the RS-25, Merlin 1D, and Raptor. Their specific impulses are 366s, 282s, and 330s (at sea level), so the RS-25 looks pretty good. But their thrust/weight ratios are roughly 60, 185, and 200 (target). The Merlin 1D was, I believe, the highest thrust-weight ratio liquid-fueled engine ever. This is one of the primary reasons, in addition to cost, it is considered so good, despite having such anemic specific impulse.
You can optimize thrust/weight several ways. Firstly, you can try to cram more thrust out of an engine of a fixed size. This is done by driving up chamber pressures as high as you can, which might be easier with a smaller engine due to square-cube scaling. Secondly, you can make the engine smaller, without changing its thrust, and try to cram as many of them in as possible. Consider thrust/area as another important metric -- for fixed rocket dimensions, being able to cram more engines into the base is an easy way to get more thrust and improve the total thrust/weight of the stack.
Another consideration, which has all too often been ignored in the rocketry business, is cost. More specifically $/thrust, if we're looking at a first stage. Here, smaller engines have a clear advantage in that your tooling doesn't need to be as large and expensive, and you're going to need more of them so you can start to leverage economies of scale rather than having each engine being an individual, artisan-produced artifact. That obviously has a limit -- there's a point at which more engines would make things more expensive, but judging from the thrust and cost of the Raptor, I would guess it's right around the optimal point.
Finally, it's worth noting that, all other considerations aside, going bigger in rocket engines tends to make the engineering more difficult. The square-cube law makes heat flux in the combustion chamber scale roughly linearly with engine size, which makes cooling more difficult. And the larger the combustion chamber, the more at risk it is of combustion instabilities. Look, for example, at the Russian RD-170 engine. It looks like four engines but is actually one engine with four combustion chambers. They did that because while it looks more complex, it actually makes things easier.
Well, I guess Proton is kind of out of the international heavy lift business now. It has had only 2 launches this decade. The Proton-M could do 2.35M lbs of thrust. The Saturn V could do 7.5M lbs. So this Super Heavy + Raptors must be in the range of 15M lbs.
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You want to free up resources for either one? Start with global military spending and the financial sector. Both have their place and both have grown far beyond it.
One can project from SpaceX's launch history that as the commercialization of space intensifies, this figure is going to continue to grow exponentially
https://www.spacexstats.xyz/#launchhistory-per-year
Meanwhile we have more oil and gas reserves now than ever. We're not running out of anything, not really. But the malthusians want to reduce population by 16x. They really do. It's crazy.
Now, to answer your question... Substitute any topic into "how is it that so many educated, intelligent people seem to think that we...". The answer is pretty simple: we each don't know everything, in fact we know very little (and about many many things nothing really), and we are very (extremely!) susceptible to peer pressure, and we like to go with the flow, and we accept authority blindly where we know little, and so on.
It's a real problem. We just don't teach people how to think about what they know little about. Epistemology is hard enough, but we need people to do more than reason about what they know and how they know it and what they might not know and all that. We need people to have an idea of how to think about the stuff they know little about that they don't even want to know about -- stuff that -no matter how little they care for the details of- is super topical and where getting the answers collectively wrong could be disastrous.
Climate change also exists. So do resource limits.
Something that doesn't exist is the science of living outside of an existing planetary ecosystem.
Do some research on how much is understood about creating a stable ecosystem out of sand, metal ore, and water. You'll find it's a good approximation to zero.
Flag wavers think it's all about building giant rockets, planting a flag - and boom. Colony! Asteroid mining! Etc!
The reality couldn't be more different. Giant rockets are barely the loading screen. Feeding humans, dealing with waste products without choking on them, growing or synthesising essential nutrients, building systems that do all of this in a stable self-sustaining way - these are all beyond hard.
And that's not even getting into psychology and politics.
So until that changes, running your own planet - the one you got for free, and which was working fine already - as if you're trying to test it to destruction to find out just how stable it really is, is an unbelievably dumb thing to do.
Trees—like Dominican mahogany grow really slowly and now there are so few of them we have basically run out. I can name several other examples—most notably Guayacan.
There is a bunch of scarcity and destruction. I’m pretty sure we can fix them—but for the trees and the animals it’s unlikely that I get to experience them as was so in previous lifetimes.
It’s a shame we couldn’t manage them sustainably previously.
As long as the population increases, Malthus is right. There is going to be some ultimate carrying capacity at some point. Ultimate amount of energy we can harness. It's just a question when. Certainly before our energy consumption is enough to literally boil the oceans.
Plug in different growth rates and the answer could range from tens of years to hundreds of millions of years!
This seems pretty extreme, but thank you for bringing the concept of Malthusianism ( https://en.wikipedia.org/wiki/Malthusianism ) to my attention. While i'm not convinced that it's likely to be the end of humanity (but rather the results of thousands of compounding factors), the irresponsibility in regards to unrestrained consumerism is something that i see every day, and there is certainly some merit to those arguments in my eyes because of this.
> The answer is pretty simple: we each don't know everything, in fact we know very little (and about many many things nothing really), and we are very (extremely!) susceptible to peer pressure, and we like to go with the flow, and we accept authority blindly where we know little, and so on.
This, however, i'm not entirely sure about. Short of militant disregard for climate change or even the idea that human actions are capable of changing it in the first place, the viewpoints that i've personally seen expressed are more in the direction of feeling powerless and somewhat depressed about the state of things. Instead of outright ignorance, most of the people that i've talked with believe that the governments have largely failed them and the mechanisms of representation that should be in place are only so as far as looks are concerned. For example, lobbying and corporate interests are prioritized, as well as industry development is prioritized over sustainability. In the end, it feels like maximizing profit margins takes precedence over sustainable progress and long term advancement.
Edit: Climate change and all that is just one example, but the fact that many feel powerless even if they aware of what's going on stands for other things as well.
And most of those people that i've talked with have felt like there's little to nothing that they can individually do, seeing as a significant portion of the society is more than happy to live a hedonistic lifestyle that's rooted in consumption. That doesn't mean that we need to live in some dystopian nightmare either, but i'd argue that it's definitely a worthy goal to make the environment thrive first and to focus on a more utilitarian way of life - meat dishes as something to enjoy rather than to have with every meal, a new phone every 5 years instead of every single year, energy efficient hardware (like Athlon 200GEs) for homelabs instead of the latest Threadripper CPUs (unless absolutely necessary), a used but dependable car instead of a new one and so on. And, of course, supporting local and small businesses, as well as trying your own hand at some of that stuff - going out to hunt game, drag it back home, skin it and cook it (if nothing else, that really makes you appreciate the meat you're eating), or even just simpler things like growing your own tomatoes and cucumbers (which are absolutely delicious), where possible.
If everyone lived at least a bit more like that, we'd have even more breathing room in regards to the environment, in regards to resource usage etc., which feels like a good thing no matter how you look at it. Of course, that's probably also unrealistic as far as expectations go.
Rocket engines, hypersonic vehicles, and orbital rockets have a dual use for missile technology ( both conventional and nuclear )
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Considering we don't even have fission rockets or airplanes in normal use, making a fusion powerplant that is light enough to get off the ground seems very far fetched.
Even if we eventually use fusion for travel beyond earth orbit, I'd bet chemical rockets would still be in use.
Don't we already have thrusters that are useful in space, but completely unable to support themselves against 1G and so they can't lift off from the ground?
I feel like I've read something that said fusion power would fall in the same category.
Fusion still shares the same fundumental problem that chemical rockets or even more advanced options like blackhole or antimatter drives face - the rocket equation. We need to use near term reusable launch vehicles like the Starship to help set up the required launch assist structures that would make genuine mass transit of people and cargo into orbit possible.
Things like skyhooks, lofstroom loops, and eventually orbital rings that would allow people to ride trains or cable cars from an earth city straight into orbit for the same price range as intercity travel today. Needless to say, that is not going to happen until there is enough of an industry up there to justify the large upfront costs of such megaprojects (especially the orbital ring) so the Starship is our best near term hope of getting us up to that point.
Note that none of these projects require advanced materials or new technologies (as opposed to the space elevator that is likely to remain science fiction when it comes to dealing with a body with the gravity well of earth anyway), they're just massive engineering projects.
>Using these resources to improve chemical flamethrowers is sub-optimal. A dead end.
Earth launch future is large rail gun (somewhere like Bolivia) as a first stage booster. Requires a bit of political will, international cooperation and a few billions. Unfortunately the 1st and 2nd aren't coming soon, so the "chemical flamethrowers" for now.
I'm still surprised they moved to this orbital fly so quickly without doing more tests. Going from 3 engines to almost 30 is crazy. Also, If I understand it right, both booster and starship will end up in the ocean. I hope they will be able to reuse at least a few engines.
[0] https://twitter.com/elonmusk/status/1179107539352313856
A whole industry bootstrapping itself to make semi-conductors doubling every 18 months, going from exotic, mission critical hardware to commodity; SpaceX is doing the same thing with flight hardware. Contrast that with previous generation engines (the RS-25 comes to mind) with a sticker price of 125 millions... per engine! [0]
[0] https://spacenews.com/aerojet-rocketdyne-defends-sls-engine-...
> A whole industry bootstrapping itself to make semi-conductors doubling every 18 months, going from exotic, mission critical hardware to commodity;
Silicon Valley did not bootstrap itself. It received untold billions of dollars from the US government during the Cold War (and lots of stuff happened during the WW2 economy, when the US was the Allies' armorer). Do you think it a coïncidence that most spy satellites are launched from Vandenberg? Or that Skunk Works, located in California, developed so many secret aircraft?
Do a search for "The secret history of Silicon Valley":
* https://steveblank.com/secret-history/
> SpaceX is doing the same thing with flight hardware.
Notwithstanding the millions that NASA gave them in their early stages.
* https://www.nasa.gov/exploration/news/COTS_selection.html
The list of spinoff technologies just from NASA is impressive:
* https://en.wikipedia.org/wiki/NASA_spinoff_technologies
The fact that the US was, post-WW2, the largest economy in the world, and the main developed nation that didn't see mass destruction, certainly didn't hurt.
The fact that the US government throws a lot of money around certainly helps private industry:
* https://en.wikipedia.org/wiki/The_Entrepreneurial_State
This also does not diminish the entrepreneurs that, once the baton is handed to them, charge forward. My main argument is that there's not as much "bootstrapping" as many people believe.
> Semi-Conductor doubling every 18 months
IIRC, the recent doublings have been happening in Taiwan. That's why people make such a big deal about TMSC. America (i.e. Intel) actually has some catching up to do.
(Please, I'm not making a political point, I just cannot refrain from punning.)
Perhaps explaining GP's surprise: I've heard SpaceX's testing philosophy contrasted against this sort of thing. That none of their tests are "too big to fail". On the other hand, according to this narrative they also stress iteration speed over success rate, and ramping up fast works to that end too.
Maybe they were getting diminishing returns (in terms of lessons learnt) in small scale tests though. No doubt there are phenomena you only see in larger tests, and (as you say) their confidence in getting the smaller stuff right might be quite high.
I'll bet they're going to remove all 29 of these engines and re-attach them again later. I would expect they want much more testing than they've done to date (for example, pressure testing the tanks -- they have not done that with this booster, BN4, according to Reddit).
You mean for the first test flight? Do you have a source?
Long term plan is definitely land landing, but I haven't seen anything about the first test flight.
I assumed that they would try and land it from the start, they've already landed starship a few times, and it seems like that's where a lot of the unknowns still are (e.g. they're apparently adjusting wing size down after the last landing)?
Article: https://spaceflightnow.com/2021/05/13/spacex-outlines-plans-...
Video (Marcus House): https://youtu.be/9-9k513UIVw?t=298
Basically both vechicles (the massive booster and the starship itself (2nd stage) are going to "land" on the water, which means a hover and then sinking into the water.
Booster - Boost and separate, boostback burn and splashdown off the coast. Starship - 90 min orbit at about 120km, reentry and spashdown near Hawaii
It's fairly quite likely that both would crater on this first flight - for instance this is the first booster flight and also the first reentry for the starship itself.
The Falcon 9 booster also had similar flight plans until it could successfully fly a controlled trajectory to the surface of the ocean before they risked a drone ship too.
https://www.space.com/starship-super-heavy-engine-section-ph...
Criticizing regulators is Elon's MO, whether it is the SEC for his Tweets, various transportation departments for self driving software safety, labor departments for covid restrictions for worker safety, FAA for rocket launches... You'd think there is some national conspiracy against him at this point.
And that's not even getting into the fact that multiple things can be done by humanity at once.
edit: apologies for the first sentence here which was unnecessary to make my point.
Make Earth proper a gigantic park / nature reserve.
We can't "wait" for anything, or the window during which we can develop space travel will close. 10 or 100 years from now we might no longer have the motivation or the means to fund and build new vechicles like these.
If it were at all easy or probable then there would be other players in the space. There aren’t. If you contribute to the friction that opposes spacexs forward progress then you bear the responsibility for working against the things that you claim to love as a self proclaimed nerd.
There were people who put on demonstrations against wealthy people spending their money on being patrons for scientists and early biologists. It was very unpopular for rich people to sponsor nonsense, the collection of random fluids and samples. All of which is the basis for modern biology and medicine. So which side of history are you going to be on? The idiotic mob or the people making things better?
> The single most important job for humanity right now is to save this one planet we have from destruction.
Aren't these two sides of the same coin? If we colonise Mars, but leave Earth a smoking ruin, then we've made things worse by trading a planet with a function biosphere for one without. If we wait till Earth is in perfect state before colonising another planet, we'll never leave, and be subject to many of the same risks.
He has a lot of talent at his disposable, and presumably information to a decent bit of otherwise locked away studies/reports. Do I think he is correct? Perhaps not, but my nor your opinion really matters.
If he's made the decision shits truly FUBAR, ala Foundation, then leave him alone while he works on what he may genuinely believe to be a shot at surviving the FUBAR long-term.
I think you lack some self-awareness here. Space is clearly a mild curiosity to you at most.
We are very far from a self sustaining society and economy on Mars. Easily a century or more. I'm cheering on SpaceX, but find this talking point of Elon's very tiresome. It's little more than sci-fi fantacism. As just a simple example: no one knows what childhood development is going to be like at 40% of earth's gravity. And that's just one issue among millions.
For better or worse we need to fix the planet we have. And we don't need to invent new technology to do it, though we certainly should pursue new technologies that might help or accelerate the process. What we lack fundamentally right now is political will/unity.
We can arrest climate change. We can end famine. We can extend modern medical care to the entire world. All of these are directly possible, today, with no new invention.
But we have to, to paraphrase Sagan, become a species more prudent than we are today.
What do you mean by "modern" medical care?
Do you think that will make a significant difference in life expectancy?
The difference between, say, Rwanda and the USA is less than ten years, I believe. Comparable to the gender gap in some countries like Russia.
What about the gap between countries like the USA and UK versus Japan at the top? Is that important to close?
(My info from https://en.wikipedia.org/wiki/List_of_countries_by_life_expe...)
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1. Fuel-air explosions at ground level can injure people or destroy property (even kilometers away)
2. Rockets on unplanned trajectories can ruin people's day
3. Lots of fuel is toxic, we need to mitigate this.
Basically someone has to walk through all the worst case scenarios and ensure that everyone (and nature) remains safe or as safe as it is possible to be.
Toxicity and polluting aspects of Rockets is of a negligible concern, Everyday Astronaut (Youtube fame) gets this so often that he did an entire hour long video on this: https://www.youtube.com/watch?v=C4VHfmiwuv4
> Rockets on unplanned trajectories can ruin people's day
Well darn.
Perhaps that's true, but space launches are important enough that going "slowly"[1] is a good idea. One catastrophic accident with the destruction of a spacecraft leaving a large amount of orbital debris would make space launches much, much harder until we clean up. Rushing to space could slow us down a lot.
[1] The space race has only been going for 70 years, and less than 25 years commercially. The idea that anything is happening "too slowly" is quite baffling really.
This is a defensible opinion, as are the others saying that the most important job of humanity is to fix our current basket.
While neither agreeing or disagreeing, I will note another very important thing SpaceX is doing:
"The value of beauty and inspiration is very much underrated, no question. But I want to be clear: I'm not trying to be anyone's savior. I'm just trying to think about the future and not be sad."
A lot of what SpaceX is doing is extremely inspirational, and I think the world could use more things to look forward to in the future.
It's always presented as a false dichotomy, though. We can have both.
People insist we should be spending our money fixing the planet, but we already are, including Musk who just sponsored the largest XPrize in history for a carbon sequestration method.
First we must overcome the political hurdles to get people to even recognize that climate change is a problem. Obviously money is only barely starting to trickle in to carbon sequestration tech.
They have really not been slowed down that much FAA.
So everybody should just chill out.
Btw, for people interest, this interview with Ken Davidian FAA's Office of Commercial Space Transportation is interesting:
https://www.interplanetary.org.uk/podcast/episode/90af4411/2...
A colony on mars, even of significant size and population, is 100% condemned to certain death if separated from Earth. It would be, for all intents and purposes, in the same "basket".
Google "how to make a pen from scratch" for a quick primer into why, but the tl;dr version is that it takes having a huge industrial base already existing in order to keep, let alone advance, our current technological level. And Mars is not friendly enough to support us with lower tech.
Our intuitions go the way of "we can put 1000 smart people there, that's enough to survive and thrive". Well, we as a species can't move our microprocessor factories from Taiwan in less than a decade, and you expect them to be rebuilt on Mars from scratch?
It would be in the near future, true. In fact, the key milestone for humanity being truly multi-planetary is that each planet must be independently self-sufficient.
There's no laws of physics that would prevent human life on Mars or Venus from eventually becoming self-sufficient.
The time-frames to get to that point are large (mid-hundreds to low-thousands of years by my random guess). A thousand years isn't that long in terms of the evolution of the species, though, and are the time scales we should be thinking of multiplanetary life on.
See here: https://www.youtube.com/watch?v=11hYo9UTSRM
And the corresponding book:
How To Industrialize Mars: A Strategy For Self-Sufficiency: How To Settle A Lethal Vacuum In 400 Easy Steps
Part of the whole project of Mars is making this very thing possible in the first place. It requires rethinking a lot of how we do things.
We are going to need far more advanced technology than we have today if we are going to reverse the effects of climate change. If we move heavy industry to space that can dramatically reduce our carbon emissions here on Earth. The technology to do that may also lead to breakthroughs in other areas like energy generation or storage.
I run thousands of hours of batch data processing jobs a day. They aren't particularly time sensitive, as long as they finish in a day I am happy. There's no reason the computers doing that need to be on Earth consuming precious water and electricity resources.
That's a non sequitur
1: https://spaceflightnow.com/2015/01/04/photos-long-march-rock...
What are minimal capital and time requirements to do this eggs in more than one basket thing? Not talking about an orbiting space whatever but a real, sustainable ecology on another planet.
The depth of our ignorance even about whole classes of basic science there, notwithstanding the number and scale of engineering problems to solve....
Is there any reality where this isn't minimum a century and thousands to millions of $T?
For someone who believes this is the most urgent problem on which to spend capital and time, the most efficient target of advocacy energy has to be the US military which spends $700B a year, not the effing FAA and the relatively small scale projects of this one company- no matter how exciting and advanced they happen to be.
Even making the case for this program, when one considers what could be done with even a fraction of that scale of capital deployed on this planet....Fusion energy itself is probably a $10T investment, orders of magnitude less in money and time.
Space is cool but not for one femtosecond should anyone entertain any of this eggs in more than one basket nonsense.
“The point at which one says the goal is to make life multi-planetary, it means that we need to have a self-sustaining city on Mars,” Musk said. “That city has to survive if the resupply ships stop coming from Earth for any reason whatsoever. Doesn’t matter why. If those resupply ships stop coming, does the city die out or not? In order to make something self-sustaining, you can’t be missing anything. You must have all the ingredients. It can’t be like, well this thing is self-sustaining except for this one little thing that we don’t have. It can’t be. That’d be like saying, ‘Well, we went on this long sea voyage, and we had everything except vitamin C.’ OK, great. Now you’re going to get scurvy and die—and painfully, by the way. It’s going to suck. You’re going to die slowly and painfully for lack of vitamin C. So we’ve got to make sure we’ve got the vitamin C there on Mars. Then it’s like, OK, rough order of magnitude, what kind of tonnage do you need to make it self-sustaining? It’s probably not less than a million tons.”
That’s not a precise number, of course. It’s a rough estimate. But Mars settlers will need vast quantities of stuff. The settlers will need to build an entire industrial base to mine the Red Planet, and there are many steps in mining. To make consumer products requires a huge infrastructure base to refine and shape materials. “I’ll probably be long dead before Mars becomes self-sustaining, but I’d like to at least be around to see a bunch of ships land on Mars,” Musk said.
[0]: https://arstechnica.com/science/2020/03/inside-elon-musks-pl...
Humans have been exploring forever. Why stop now?
This wouldn't have been a problem in the past. You'd just shrug off the crazy explorers and write them off as soon to be dead. Now, evidence of their success and relentless progress is shoved in our face every day.
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In the end humans are naturally curious, expansionist, greedy (to varying degrees). We've always been this way and so it's only natural for us to continue.
We've been described as a virus before, feels relatively accurate esp if we start planet and system hopping.
Why is it so difficult to just accept that a single person can have both inspiration qualities that we should try to emulate and also grave moral failings we should learn from? No one is perfect and hardly anyone is purely evil either.
Specific impulse is the most obvious parameter of a rocket engine, but it's relatively less important for a first stage where thrust/weight is also a very important concern. Specific impulse depends on the chemistry, combustion cycle, combustion efficiency and nozzle design. There isn't any obvious reason why it would scale either way with engine size.
Thrust/weight is very important for engines on a first stage because of gravity losses. Imagine if the rocket sitting on the pad had a thrust/weight of just 1.1; that would mean that at liftoff 91% of the thrust would be wasted just countering gravity. You both want a high thrust/weight at liftoff and a small dry mass to give the second stage the most momentum possible at stage separation. High thrust also helps for reuse in making the burn time of the first stage shorter (for fixed specific impulse and propellant load), which means that at stage separation the first stage isn't too far downrange and is easier to return to the launch site.
Note that there's both the thrust/weight of the rocket as a whole, and of the engines themselves. The engines comprise a significant proportion of the first stage's weight, though, so looking at engine weight (and thrust to weight) is also useful. Consider the RS-25, Merlin 1D, and Raptor. Their specific impulses are 366s, 282s, and 330s (at sea level), so the RS-25 looks pretty good. But their thrust/weight ratios are roughly 60, 185, and 200 (target). The Merlin 1D was, I believe, the highest thrust-weight ratio liquid-fueled engine ever. This is one of the primary reasons, in addition to cost, it is considered so good, despite having such anemic specific impulse.
You can optimize thrust/weight several ways. Firstly, you can try to cram more thrust out of an engine of a fixed size. This is done by driving up chamber pressures as high as you can, which might be easier with a smaller engine due to square-cube scaling. Secondly, you can make the engine smaller, without changing its thrust, and try to cram as many of them in as possible. Consider thrust/area as another important metric -- for fixed rocket dimensions, being able to cram more engines into the base is an easy way to get more thrust and improve the total thrust/weight of the stack.
Another consideration, which has all too often been ignored in the rocketry business, is cost. More specifically $/thrust, if we're looking at a first stage. Here, smaller engines have a clear advantage in that your tooling doesn't need to be as large and expensive, and you're going to need more of them so you can start to leverage economies of scale rather than having each engine being an individual, artisan-produced artifact. That obviously has a limit -- there's a point at which more engines would make things more expensive, but judging from the thrust and cost of the Raptor, I would guess it's right around the optimal point.
Finally, it's worth noting that, all other considerations aside, going bigger in rocket engines tends to make the engineering more difficult. The square-cube law makes heat flux in the combustion chamber scale roughly linearly with engine size, which makes cooling more difficult. And the larger the combustion chamber, the more at risk it is of combustion instabilities. Look, for example, at the Russian RD-170 engine. It looks like four engines but is actually one engine with four combustion chambers. They did that because while it looks more complex, it actually makes things easier.
https://en.wikipedia.org/wiki/N1_(rocket)