Design of a rapid transit to Mars mission using laser-thermal propulsion • Hacker News Board

Re: Design of a rapid transit to Mars mission using laser-thermal propulsion

#61

Post by jmyeet » Thu, Feb 17, 2022, 4:46 PM UTC

politician wrote: post #40

jmyeet wrote: post #23

Earlier quoted context omitted.

Let's accept this premise (which amounts to essentially "we don't know what we don't know") and I'll ask a natural follow up question: what is the difference between colonizing the Moon and colonizing Mars in terms of problems we'd need to solve and thus technology we'd likely gain?

The ISRU profiles of both bodies are significantly different and Mars has much higher gravity. The Moon is, first and foremost, a weapons platform, and any every competent military sees it as such. There will never be a functioning colony on the Moon until the Earth is unified under a single government. Mars is far enough away that colonization is possible, and the technology needs are so dramatic that we’ll have to…

> The Moon is, first and foremost, a weapons platform

This just isn't true. To quote Isaac Arthur, "there is no such thing as an unarmed spaceship". Kinetic energy is all the weapon you need.

Any colony on the Moon or Mars would need to be essentially self-sufficient from day one because the cost of getting payloads to eitehr are so vast to be uneconomical.

Re: Design of a rapid transit to Mars mission using laser-thermal propulsion

#62

Post by tiborsaas » Thu, Feb 17, 2022, 4:46 PM UTC

jmyeet wrote: post #2

Sure let's continue unmanned exploration of Mars but manned exploration let alone colonization makes absolutely zero sense. mars is nothing more than a further, more annoying version of the Moon. Similar gravity, less sunlight (ie further from the Sun), communication latency (~10 minutes vs 1.5 seconds), no magnetosphere (just like the Moon so you'll probably need to live underground) and just enough atmosphere to pr…

With this mindset we won't get very far as a species. It was probably already a mistake to climb down from the trees, right? But seriously, what else we should do as humans? I just can't imagine we will sit on our asses because that's a reasonable thing to do.

If the benefits of going to Mars only results in a new generation of humans to fall in love with space, that's already good enough.

Also don't forget all the cool technology that will spin off from this endeavour.

Being able to afford human space exploration is a really good sign since that indicates that we don't have any limiting factors to hold us back. The reverse scenario is way more depressing.

Re: Design of a rapid transit to Mars mission using laser-thermal propulsion

#63

Post by m4rtink » Thu, Feb 17, 2022, 4:49 PM UTC

jeffreygoesto wrote: post #38

ben_w wrote: post #11

Earlier quoted context omitted.

Disaster recovery, the penultimate in off-site backups of humanity itself.

With a "humanity" like this, maybe a bad idea... Maybe fix some of the bugs first with that money? Mars does not run away, you know...

Mars might not, but the technological/resource window of our civilization could. And we should not risk it.

Re: Design of a rapid transit to Mars mission using laser-thermal propulsion

#64

Post by jmyeet » Thu, Feb 17, 2022, 4:53 PM UTC

tiborsaas wrote: post #62

jmyeet wrote: post #2

Sure let's continue unmanned exploration of Mars but manned exploration let alone colonization makes absolutely zero sense. mars is nothing more than a further, more annoying version of the Moon. Similar gravity, less sunlight (ie further from the Sun), communication latency (~10 minutes vs 1.5 seconds), no magnetosphere (just like the Moon so you'll probably need to live underground) and just enough atmosphere to pr…

With this mindset we won't get very far as a species. It was probably already a mistake to climb down from the trees, right? But seriously, what else we should do as humans? I just can't imagine we will sit on our asses because that's a reasonable thing to do. If the benefits of going to Mars only results in a new generation of humans to fall in love with space, that's already good enough. Also don't forget all the c…

> With this mindset we won't get very far as a species.

I assume you're saying this in good faith but it's really a straw man argument because it's a false dichotomy. For one there's the obvious: I'm not saying "go nowhere". I'm saying "the Moon makes more sense to colonize than Mars". Also, that doesn't preclude ever colonizing Mars. A Moon-first policy just makes way more sense.

Another flaw: why do we even need to colonize a planet? It actually doesn't make much sense if you really think about it. I'm firmly in the camp that thinks humanity's future is in a cloud of orbitals aka an eventual Dyson Swarm.

It's way more efficient in terms of living area pre unit mass. It requires no energy tech more sophisticated than solar power. It requires no material that we don't already have. You don't have all the problems with getting into and out of large gravity wells. Gravity (ie spin gravity) can be exactly Earth normal.

Re: Design of a rapid transit to Mars mission using laser-thermal propulsion

#65

Post by jmyeet » Thu, Feb 17, 2022, 4:57 PM UTC

gambiting wrote: post #14

ben_w wrote: post #11

Earlier quoted context omitted.

Disaster recovery, the penultimate in off-site backups of humanity itself.

If that really is your goal then build a colony at the bottom of the ocean or deep under ground here on Earth - at sufficient depth there is literally nothing that could endanger such colony, it's functionally equivalent to being on mars without the idiotic travel cost.

Wouldn't earthquakes and even volcanoes still be an issue? I also imagine being at the bottom of the Gulf of Mexico was of no help when the dinosaur-killing asteroid hit.

Plus where does your energy come from? You don't have solar. You need to make your own light to grow food. Geothermal is possible I guess but the ocean is terrible for corrosion and building. The high pressure at the bottom of the ocean makes everything worse.

Re: Design of a rapid transit to Mars mission using laser-thermal propulsion

#66

Post by bryanlarsen » Thu, Feb 17, 2022, 4:57 PM UTC

jmyeet wrote: post #2

Sure let's continue unmanned exploration of Mars but manned exploration let alone colonization makes absolutely zero sense. mars is nothing more than a further, more annoying version of the Moon. Similar gravity, less sunlight (ie further from the Sun), communication latency (~10 minutes vs 1.5 seconds), no magnetosphere (just like the Moon so you'll probably need to live underground) and just enough atmosphere to pr…

In terms of fuel requirements, Mars and the Moon are about the same distance away, since Mars can utilize aerobraking and the moon has to use fuel to slow down.

Re: Design of a rapid transit to Mars mission using laser-thermal propulsion

#67

Post by maxerickson » Thu, Feb 17, 2022, 4:58 PM UTC

ceejayoz wrote: post #57

maxerickson wrote: post #48

Earlier quoted context omitted.

Like if you could build something awesome on Mars it would pretty much universally be easier to build it in North Dakota.

Sure. It's easier to build in North Dakota than it is in the Swiss Alps, too, but people do that in part because they like the Alps. There are going to be people for whom the idea of a frontier life in a place of natural, untouched beauty appeals. We've always had those folks. Some of them find life is harder than they expected; some thrive.

There has always been new opportunity at frontiers.

Mars is just harsher than anywhere on earth. There's less of everything other than space and harmful radiation (and you sort of have to make the space that you want/need when you get there...)

Re: Design of a rapid transit to Mars mission using laser-thermal propulsion

#68

Post by jmyeet » Thu, Feb 17, 2022, 4:58 PM UTC

Retric wrote: post #54

sevenf0ur wrote: post #16

Earlier quoted context omitted.

Agreed, if an extinction level event happened on Earth, we'd be better off riding it out underground, than moving off planet.

I agree going to Mars is never going to be a useful for evacuation, but it could help if we where already there. Most plausibility the long duration space flight should prevent the common cold from making the trip which would also prevent many hypothetical super plagues from doing so as well. In theory you could do the same on earth, but it’s unlikely for a self sustaining underground colony to consistently maintain…

To be clear, off-planet colonization isn't an evacuation strategy. It's a continuation strategy in the event that humanity is wiped off the Earth.

Re: Design of a rapid transit to Mars mission using laser-thermal propulsion

#69

Post by bostonsre » Thu, Feb 17, 2022, 4:59 PM UTC

gambiting wrote: post #49

ericmay wrote: post #29

Earlier quoted context omitted.

Why do anything?

This is a very flippant comment, but I will try to respond anyway - we simply haven't achieved a post scarcity society yet. Maybe we will at some point, but we just aren't there yet. So right now our time, money and natural resources are quite simply limited. So maybe it's not that we shouldn't have a base on Mars - it's just that maybe that shouldn't be the first step in human habitation in space.

What about motivating humans to strive for greatness? Being curmudgeon underground mole people sounds a lot less likely to inspire the next generation to strive to excel at STEM education. I think even just trying to colonize mars could inspire tens of millions of the next generation when they look up at the sky. A large majority of those won't go into the space colonization field and most will instead contribute to improving our lot and maybe even attempting to get to a post scarcity society.

Re: Design of a rapid transit to Mars mission using laser-thermal propulsion

#70

Post by bryanlarsen » Thu, Feb 17, 2022, 5:01 PM UTC

revicon wrote: post #18

bbojan wrote: post #5

Earlier quoted context omitted.

The Moon has very little hydrogen, carbon and nitrogen, which Mars has in abundance. These are very important elements both for biology and chemistry. E.g. if you want to have a self-sufficient colony outside Earth, you could do it on Mars but not on the Moon. Mars could be terraformed (in theory); the Moon never could.

With no magnetosphere would there even be a point to terraforming?

Maintaining an atmosphere is a lot easier than creating it in the first place, and can use the same process and machines. In other words just live with the slow loss and replace the loss gradually.