Hacker News Reader

Comment by QAPereo | Hacker News Reader

Inasmuch as Mars with our current technology offers no back up for civilization, the same can certainly be said for the moon. I would argue over that the moon actually has some benefits Mars lacks, in addition to proximity it has a much lesser gravitational field and therefore a much lower delta V. Moon colony could realistically jumpstart space and vacuum industries beyond LEO, and frankly it would probably give us a chance to test the many technologies we'd eventually need on Mars without having to actually make the trip to Mars.

Most of all the moon would be an excellent way station for asteroid mining .

View on HN

When the topic of Backup for Civilization comes up, instead of Wall-E, I tend to think of Elysium, i.e. the backup option is only for the wealthy, leaving the rest in a worse state.

https://www.space.com/22287-elysium-space-station-science-na...

> the backup option is only for the wealthy, leaving the rest in a worse state.

Like most technology, it flows from the rich to the poor eventually as it becomes cheaper. The important part you omitted is that it leaves the rest in a worse relative state. Their absolute state is no worse, and likely better.

Arguing against a backup for civilization (or more appropriately, a backup for the species) because it will be used by the rich is like arguing against a cure for cancer because the rich will benefit before anyone else. In the end, a cure existing still drastically increases the chance the poor might be able to make use of it, from zero to some non-zero amount.

This is all also ignoring the fact that when it comes to species level propagation and survival, I would rather Hitler and his closest Nazi associates makes it off world sustainably in the event of a species level disaster than nobody. My commitment to making sure Humanity survives is much more than my commitment to ensuring we are a caring and accepting civilization. We can rediscover valuing life, but once we're gone, the chances we are coming back are essentially nil.

Why is humanity's survival important?

It's important for the exact same reason you're able to ask that question. Without humanity, who asks why? Humanity is, to the best of our knowledge, the best and possibly only chance of increasing understanding of the universe. I care about that, as well as about our species generally in what is likely an evolved and chemically reinforced way. At some point that may be less true, and I would care less (but would still care).

At a meta level, if you truly don't care about the survival of your species (even if only through the survival of your own relatives and loved ones), you're an evolutionary dead end.

It sounds like you value the persistence of understanding in a way that just isn't particularly important to me. The survival of my loved ones -- and that's a category that can go across species -- is absolutely important to me. The survival of evil space Nazis? Eh.

That said, I also don't really think I see being an evolutionary dead end as too huge of a concern. Many of us appreciate things that aren't truly keen from an evolutionary perspective. Consider how many of us will remain happily childless (perhaps not yourself) well into our 30s and beyond. Not amazing for propagating our own personal genes and yet, they're decisions we actively and happily make.

> The survival of my loved ones -- and that's a category that can go across species -- is absolutely important to me. The survival of evil space Nazis? Eh.

The idea is that if it's between all people dead, or all people except evil space Nazis, I'll take evil space Nazis. Just because they are evil space Nazis now doesn't mean they will be hundreds of years from now, but they'll never get that chance if all humans are gone.

Human history is largely a story about bigoted, insular racist violent psychopaths becoming slightly less of each of those things over time. I don't see why that trend won't continue in general even if we hit a local maxima of fascist oppression from time to time (as this would be).

Because I love people, I can understand the concept of loving people in general, and want other people to be able to experience that. Human extinction means that nobody might ever experience that again, and I think that's a shame, and will do what I can to prevent that type of outcome.

> Many of us appreciate things that aren't truly keen from an evolutionary perspective.

There isn't appreciation of that type without people to do the appreciating. Your ability to appreciate it is provided by our current circumstances. I think keeping those circumstances active is worthwhile. Otherwise you are taking more than you are giving to the species as a whole, which is unsustainable if too many people do so. Even if you don't care about how sustainable it is, you would be riding on the hard work the rest of the species is putting into the system to propagate. Don't be taker.

If it's up to me between no humans and evil space Nazis? I'll take no humans every time. We're a stain on the face of existence, we pollute and destroy our environment, we abuse our own species and others as a matter of course, and we're just overall destructive. The only thing that changes that is that sometimes one or two people rise up and decide that they will resist that status quo and do something about it. To allow a group of people who are evil in the conception of a default-destructive species to be the only ones left? Better to let the species die.

I think you are deeply misjudging the complexity of the human experience and being particularly blind to or biased against our collective history. If you spend any amount of time talking to people or even just reading the personal writings left to us by the ages you quickly realize that everyone who has ever lived is no different from yourself, we simply made different choices based on the information available to us, for good or evil. Anyone, given the right conditions, is capable of being a monster or a saint.

Survival of humanity isn't important universally. The universe doesn't care. But it's the most important thing for humans.

> The universe doesn't care.

And that's exactly why it's important.

> Survival of humanity isn't important universally.

Unless there is something there that cares about it, there is little reason for the universe to exist - nothing would know the difference.

Which is why it actually is important universally.

> But it's the most important thing for humans.

No, it's more important for the universe to have humans, than it is for humans to have a universe.

If the universe did not have humans (or another sentients) then it might as well not exist. AKA: Humans super important to the universe.

If humans did not have a universe, then humans would not exist. If humans did not exist then nothing is important to them.

That seems like a circular argument. It's not important for the universe to have a purpose, or to "care"...except to us. Things don't need a reason to exist.

What is the difference between a universe that doesn't exist, and one that no one notices exists? There is no difference.

The difference is itself: one universe exists, one doesn't. Notice doesn't define existence. Measurability doesn't define existence. Meaning doesn't define existence.

Why are you saying that the universe might not exist if it were not for humans. I have a few questions for you.

1. What if humans become extinct in a few hundred years? Should the universe then not exist anymore and make more lifeforms?

2. What if there are billions of other "intelligent" species in the universe? Why should the universe care about one specific species that is actually not that great, and very destructive.

3. What if this universe is just an experiment, a petridish and we are just one out of billions of parameters.

4. What if our kind of intelligence is really not that impressive, what if intelligence of dark matter entities, which we don't know about anything is much more powerful, what if even that is not that impressive?

Again, the universe doesn't care. It is not a person, it doesn't have a plan, it is neutral, unless we met our "gods" one day. Humans are just a blip among much larger things that are happening in the universe.

> Why are you saying that the universe might not exist if it were not for humans.

I didn't say that. I said there is no difference between a universe not existing, and one that has no one who notices that it exists.

Re: 1 and 2 I said "(or another sentients)".

3: I guess you are implying someone made the universe and is running it? In that case, they are the ones aware of it, so that counts.

4: Hu?? What are dark matter entities? We notice the universe and care that it exists. That's enough. The specific level of intelligence, (or aggression for that matter) does not matter.

> Again, the universe doesn't care.

That's the point. WE care, and we are the ones that give the universe a "voice" as you will. We speak for it, we do the "caring" for it. Without us (or other sentients) it might as well not not exist.

> Humans are just a blip among much larger things that are happening in the universe.

Just because someone is big doesn't make it important. Importance comes from meaning. A really big explosion in space, that does noting at all, is completely unimportant. While a tiny little seed that someone wanted to plant matters a lot.

I care and I am part of this universe, like you and every other human on this planet.

So at lest partially universe care about humanity.

"We are the universe experiencing itself"

Because the universe drives towards increased complexity.

Solar fusion creates heavier elements. Gas clouds collapse into stars and planets.

Life, while insignificant on a mass scale, nonetheless represents one of the greatest increases in complexity and diversity the universe has thus far produced.

For that reason alone, it's sacred, and should be cherished.

To date, humanity has been the only species with a demonstrated ability to reliably lift portions of the Earth ecosystem out of the planetary gravity well.

It is therefore essential to creating self-sustaining spores filled with Earth-life.

Humanity must survive if Earth-life is to survive.

As such, humanity also gets to pick the species (or subspecies) that get included in the spores. Autotrophic algae will likely get a guaranteed berth on the ship, whereas elephants are going to have to breed themselves down smaller and smarter if they want off this rock.

It's literally the definition of the word: of great significance or value; likely to have a profound effect on success, survival, or well-being

why would it not be? Life exists to create more of itself. We inherently want there to be more of us.

Pipe down, Skynet.

Elysium isn't about space stations, it's about wealthy enclaves. Those already exist, and our society is becoming more stratified every year. There's no need for the very rich to leave the planet for that.

Backing up the species is about keeping a strong diverse stock of human genetics and knowledge somewhere safe from whatever harm might befall the earth.

Under those terms, I for one do not care whether it's rich people or poor people. I doubt I'll be in the 0.00001% of the population who are part of it regardless.

At this point, no amount of money will save you, we need Earth for food at the very least. That may change, but not soon.

For another take on backing on human civilization, check out Neal Stephenson's novel Seveneves. Humanity evacuates 1500 people to orbit as moon debris decimates all remaining life on the earth's surface. As a story, it's pretty dry, but as a thought experiment, it's very interesting.

https://en.wikipedia.org/wiki/Seveneves

I wouldn't call it dry. I thought the writing style was a little juvenile, but the ideas are generally interesting as you said, the descriptions of technology are fairly detailed and I thought of it as a rollicking adventure by the end.

Dry implies flat and drab to me. If anything, I think Stephenson's flaw as a writer is that he comes across as an excited boy who just wants to tell you everything he's been researching, rather than show you naturally with a well-written story.

I was totally engaged by Seveneves, right up until the time jump, at which point I completely lost interest. The hard rain stuff at the beginning is totally fascinating.

Same experience. It was like it was written by two different authors (one fantastic and one awful).

You can also rotate the crew on the moon. Can send things to the moon you didn't anticipate. Can send replacement/repair parts.

Can't do that for Mars.

Of course you can, it just takes a few orders of magnitude longer.

If the one specialist in your mission dies and it takes 8 years to send a new one, that's not called an effective replacement.

It doesn't take 8 years to get to mars unless you are waiting for the most efficient orbits with chemical rockets. NERVA was built and successfully tested 50 years ago, and it will get you to mars in a few months.

Just send the information and teach a new specialist onlune.

(And don't forget to take an ebook-reader with you in the spaceship with an extensive e-books library).

Has it ever taken 8 years to send something to the moon?

At least in the US, if we urgently needed to send something to the moon in 8 years, we would not be able to do it. Between politically making it happen, deciding who spends the money on it, choosing a contractor that represents the right disadvantaged special interest group, years of contract negotiation, town hall discussions, environmental impact studies, project management failures, budget overruns, pork barrel carve-outs and jobs programs for various congresspeople's districts, etc. it would take way more than 8 years.

Depending on how you count, e.g. May 1961 (Freedom 7 flight) to July 1969 (Apollo 11 flight), yes.

By then you'll be dead if you actually needed those replacement parts.

Mars has atmosphere for aerobraking and ISRU possibilities that the moon does not. In many ways, it is much more practical from a spaceflight standpoint. That's not to say that there aren't possibilities for both, but Mars is seen as the preferred choice for a variety of sound reasons.

The Martian atmosphere is next to worthless for aerobraking human-scale infrastructure.

One of the most significant points in the Moon's favor is the (relative) ease with which a space elevator could be built. It doesn't need unobtainium, current structural materials are strong enough.

SpaceX have run the simulations and while Red Dragon is possible, there's no way they can adapt Dragon to land on the Moon without adding an extra stage. That difference is entirely down to Aerobraking. Even the thin atmosphere of Mars makes a huge difference.

Anyone who plays KSP can confirm this for you, especially using the Real Solar System mod, though the same lessson is apparent even in the stock game.

We can also look at delta-V charts. Earth to the Moon is like 16.4km/s, Earth to Mars is like 14.3km/s using every available aerobraking opportunity (6.4km/s saved) and assuming 500m/s for the final powered landing. (The Red Dragon plan called for aerobraking from 6km/s to 540m/s and then switching to thrusters.)

Is that 2.1km/s really a whole extra stage? Or can it be met by reducing cargo capacity somewhat?

Two interesting points about Red Dragon - it wasn't feasible to put parachutes on it so its aerobraking would have been greatly limited. It wouldn't have much surface to use for deceleration in that case. I'm curious just how long it would have spent aerobraking, SpaceX's docs don't seem to mention that. And it was cancelled a few months ago with the intent of designing a "vastly" heavier lander, for which aerobraking will be that much less practical.

edit: But I can do a back of the envelope calculation. Decelerating 6500kg from 6km/s to 540m/s is 116G joules. The diameter is 3.6 meters so a molecule of air in from of the Dragon would be displaced (on average) 0.53 meters. Let's assume the atmosphere is a constant density (0.020 kg/m^3). Assume a drag coefficient of 0.05 (and ignoring the lifting body effect) that is around 200kN of force, tapering down to 1.5kN. That is like 3000 km of aerobraking at maximum atmospheric density and should take around 2300 seconds. But that depends a lot on the deorbit profile. I'm going to need a bigger simulation...

For Red Dragon they were going to add an asymmetrical 'sled' under the capsule that alters its geometry to form a lifting body, so it could spend significantly more time up in the atmosphere braking than most custom designed landers would. The sled would be jettisoned immediately before the propulsive landing.

It's not an ideal design, but this way they would only have had to make minor changes to the capsule, mainly to add more fuel for the landing than the regular design.

Okay, I concede it is totally possible. After including Nasa's atmosphere model and some drag coefficients from super-sonic bullets, it looks like Red Dragon's aerobraking maneuver would take 1600 seconds, cover 4800km and leave them with 3600 meters of altitude. (Those supersonic drag coefs were what really made the difference since they are around 0.3 at hypersonic and rise to 0.6 as it slows.)

If your plans for an extraterrestial base require building something as expensive as a space elevator, you'll never get the funding. Any plan for human settlement must be splittable into reasonable annual budgets. Being to ambitions is what killed many previous missions.

The same can be said of a space elevator around Mars too, of course. (Though not the earth).

"Mars' atmosphere is in the perfect goldilocks zone of being a total headache" - https://www.youtube.com/watch?v=h2nqgKL2JQU

Thank you, i couldn't remember where I had heard this before.

Okay, I'm basing this mostly on playing Kerbal Space Program, but hear me out here...

I believe the extra delta-V you need to get to Mars is less than the delta-V you need to slow down to land on the Moon.

Reply on news.ycombinator.com