What else can you do with an Interplanetary Transport System?
antipope.org
antipope.org
I didn't watch all of Elon's presentation and I don't know if he mentioned this. However, I would think that a space elevator of some sort or a massive lunar manufacturing facility would be required to efficiently create all the components of an Interplanetary Transport System.. Upwards of 80% of the mass of going into space is just propellant to escape gravity. Even if the rockets are reusable, we won't truly be an interplanetary civilization until most of the components needed for space travel are actually manufactured in space or in extremely low gravity situations
I guess the downside of constructing or assembling anything anywhere but earth today is that it's going to be a lot more expensive and complicated. Perhaps once Mars has some critical mass the construction can shift to there as the gravity is lower.
The moon is farther away than orbit and also doesn't really have a lot in the way of accessible natural resources. Elon touched briefly on the topic of a moon settlement...
Despite all the talk of a space elevator I think it's still science fiction. Elon's plan is all based on existing technology...
The lack of resources on the Moon could be solved by finding an appropriate near-earth asteroid to mine. The ideal 1st candidate based on potential mineral wealth ($87 billion, but I don't believe those numbers are very accurate) and proximity to earth (a measly .1au, or 9 million miles during its solar periohelion :) is Anteru I believe.
Here we are, on the precipice of colonizing Mars in possibly my 80 yr old father's lifetime, witnessing perhaps mankind's greatest and boldest feat yet and I'm getting greedy and thinking "Yawn, who cares. Let me know when the Interplanetary TRADE System is profitable and indefinitely self-sustaining."
I'd try to visit Mars at least once . When it reaches a level of infrastructure and economic development of early 18th century British or other Euro colonies is when it's looking likely I would consider making a one way trip there.
When you're working on one of these stations, you're not a seasonal worker like an offshore oil driller. It takes ~5 years to travel to Jupiter, so travelling there is most likely a very long term work commitment. At that point, it makes a lot of sense to have some sort of permanent port instead of a work camp between Mars and Jupiter to stretch your space legs,, rest, refuel, resupply, seek entertainment and the company of others, buy whatever black market items are banned on Earth or other colonies, etc. Prostitution would likely make its way there to as it does with mining towns here on earth. These circumstances would be a very attractive economic incentive for some enterprising folks. In fact, if we ever settle anywhere beyond the asteroid belt, this would become inevitable. People with unbearable and untreatable joint pain may find zero gravity to be a panacea for other reasons why someone might opt for this.I'm just spitballing though and came up with this scenario in 5 minutes, so take what I say with a grain of salt :) I just think that if we become truly a spacefaring civilization, permanent habitation in space becomes inevitable for a litany of reasons.
Space travel is going to be possibly the most disruptive development in human history. I'm going out on a llimb here, but I think that new religions will spring up and instead of a pilgrimmage to Mecca, the destination may be to observe the rings of Saturn. Or some people may just fall in love with the calming white noise of a warp drive generator. A 5 hr loop of Star Trek's engine noise is my go-to deep work soundtrack :)
A lot of towns in the United States and globally started out as rest and refueling stops between major centers of trade. Why would this be any different? I think there are enough people here on Earth out of a population of billions who might actually prefer to live in that environment or just don't mind it in the face of striking it rich.
If you had a partial Dyson swarm right now, what would you actually use it for?
We would also probably want to live long healthy lives maybe even transfer our minds into other bodies or devices.
We aren't even a Type I civilization yet so there is lots of planning and inventing to do.
As a wild-and-crazy concept, doing the lunar space elevator thing that Stross mentions in his blog post would allow you to build a manufacturing facility on the moon that turned regolith into a sunshade and then ship them up the lunar space elevator and drop them off into Earth orbit at a moderately reasonable cost.
If you aren't too concerned about the mass of a sunshade, there are lots of ways to constitute them, so this seems like it would be one of the easier manufacturing jobs you might imagine locating on the Moon.
I'll let someone else do the math.
π * 6371^2 ≈1.28e8 km^2 = 1.28e11 m^2 = 1.28e10 oz of gold
So, you would need 800 million pounds of gold, which would cost (at current spot price of 1324.80/oz) almost 18 trillion dollars.
Gold is probably not the best material for this
The total amount of gold we have mined so far is somewhere around 170,000 metric tons.
So if you used all the gold in the world, you'd only have about half of what you need.
At the same time, I was surprised that it is even in the same ballpark.
That's looks like the size to cover the entire planet and completely remove all sunlight. But to counteract global warming, we'd need a much smaller area. If it's 1%, we're down to a mere $180B.
I'm sure you're right that other materials would be far more economical. My gut says Aluminum.
Which just illustrates how terrible global warning really is, I suppose.
At 40 grams per square meter of reflector and 1366 watts per square meter that's an upper bound of 34.15 watts per gram or 34.15 megawatts per tonne of avoided insolation. With one expendable launch of 500 tonnes to LEO that's an upper bound of 17,075 megawatts of avoided insolation per launch. In 2007 the IPCC estimated the net anthropogenic component of radiative forcing for the Earth system at ~1.5 watts/m^2, or 765,108,000 megawatts altogether (1.5 * 510072000 * 10^6 watts). Using the assumptions previously given, one maximum-payload launch could mitigate about 0.002% of anthropogenic radiative forcing. Adjust the achievable mitigation upward proportionately if you think that the shield system can be implemented with less mass and adjust it downward if you want to replace my optimistic upper bounds assumptions with more realistic (lower) ones.
Seriously, doesn't the recent news about higher mortality among lunar astronauts throw all this talk about colonization into doubt?
I think we would all be better off if we didn't develop even more effective ways of killing each other...
b) There is a reason we don't use Trident D-5 SLBMs (or the Russian equivalent) for precision conventional explosive strikes on targets which otherwise require long range bombers with intricate in-flight refuelling arrangements to hit: something about not scaring the other folks with strategic nukes into thinking we've initiated a first strike and hitting the big red end of the world button.
TLDR: even the big guys don't mess with space-based or sub-orbital weaponry. The risk of a misunderstanding is non-trivial and the perceived costs are far too high.
It's probably most cost efficient to de-orbit the entire satellite, and include a rocket that fires upwards when it reaches a certain low height, to make it exceed its natural terminal velocity.
I expect an arms race in this area.
There are also plenty of rocks on the Moon, but I don't have a good feel for how practical weaponizing them would be.
Also it's not clear to me that an Orion taking off from a very-near-Earth orbit is a good idea, either. I'm not sure how to reconcile apocalyptic-sounding fears about EM pulses from nuclear explosions with an Orion departing from LEO.