> One proposed sunshade would be composed of 16 trillion small disks at the Sun-Earth L1 Lagrangian point, 1.5 million kilometers above Earth. Each disk is proposed to have a 0.6-meter diameter and a thickness of about 5 micrometers. The mass of each disk would be about a gram, adding up to a total of almost 20 million tonnes. Such a group of small sunshades that blocks 2% of the sunlight, deflecting it off into space, would be enough to halt global warming, giving us ample time to cut our emissions back on earth.
Also, how do you imagine that Elon Musk is somehow going to elongate our usage of fossil fuels? Elon Musk has done more for EVs than any single person in human history, and you claim he's going to do something which will extend fossil fuel use?
Your post just doesn't add up, it sounds like you want further warming to occur?
On one axis: beneficial vs. negative consequences.
On the other: immediate vs. eventual apparentness.
We tend to adopt technologies with immediately apparent and beneficial consequences.
This creates two sets of failures:
- Not adopting technologies with eventually-apparent beneficial consequences.
- Failing to reject technologies with eventually-apparent negative net consequences.
- Failing to adopt technlogies with non-apparent net benefits.
(We also do correctly reject technologies with immediately apparent harmful consequences.)
This is confounded by other factors. Technologies aren't single effects but sets (matrices) of effects, and can interact with other technologies.
There's a huge problem in that the non-apparent results, positive or negative, take time to become apparent. For various psychological, sociological, economic, and political reasons, there's also a frequent bias to promoting benefits over harms, at least by parties with an interest in the technology. (Those suspecting they may be disadvantaged will employ the opposite bias.)
When you're looking at planetary-scale actions and behaviours in which there's no ability to opt out (we're either all in or all out), then you've got a problem of assuming a major risk, and there being potential major negative unforseen consequences.
It's the unintended consequences of historical emissions which are the result of precisely that dynamic -- it was not widely seen when widespread use of coal, oil, and gas began, in the 18th, 19th, and 20th centuries, that these could have a relatively immediate (decades-to-centuries) impact on the state of the environment on Earth. Even when proposed mechanisms and cautions were sounded, resistance to those warnings grew -- Cassandra's Curse.
Fixing one problem by going whole-hog in on a new technology, without having the time or opportunity to consider what might happen as a result ... strikes many people as a trifle rash.
We already know about them, for the most part. They're known-knowns or known-unknowns.
A sunshade is a giant cloud of unknown-unknowns, plus whatever we think we might anticipate.
do you really think we should be repeating the exact same approach? Because to me it sounds insane.
Our thoughtless embrace of technology has caused much of our current problems - thoughtless embrace of technology will not magically solve them.
It's not our thoughtless embrace of technology that caused much of our problems - our problems were and are caused by people. In particular, by coordination problems. By our inability to do things together for long-term benefits. Our cherished democracy and free market only exacerbate this problem. So it's a good idea, IMO, to have a backup plan that doesn't require everyone to change their life styles - otherwise, in 50 years we may be wishing we had some prototyping done instead of it just being a theoretical idea.
Now that I've said that explicitly... how reasonable of an assumption does that sound?
I think we should prepare to have this tech ready for use in case things get significantly worse in the next few decades. In the meantime, there are less risky geoengineering approaches also worth investigating and pushing up the TRL ladder.
Collecting and disposing of 16 trillion objects is no small feat, before you consider fuel and energy to get there and back (or there and away).
Now L1 is an unstable point, so eventually the shades will drift out of position, but I imagine that will take a long time.
It had been pointed out that the main reason for warming, advanced level of CO2, leads to bigger agricultural growth, so here we have to opposite trends.
We'd prefer of course to have the shield controllable, and shadow only a small (like, 10%) fraction of solar energy. More, the shield likely won't be ready all at once, so we can have early indication for how it works being partially deployed.
It’s not that climate change isn’t real, or even a question of whether human activity is the root cause. But faced with a solution which doesn’t require massive societal change of a particular sort, the solution is rejected out of hand.
Just because it doesn’t force a specific set of political changes which up until now have been punctuated by the threat of nothing less than Armageddon,... we cannot actually reject a cheap solution that takes Armageddon off the table, just because it may make the other goals harder to accomplish.
It is morally unacceptable to let the Earth burn rather than be left to solve issues of pollution and clean energy independent of the almost unfathomable toll of a 3°C future. That to me is frankly an untenable position when you contemplate the actual number of lives in the balance.
1. The single cheapest and quickest way to make a difference is to - en-masse - moderate our behaviours. But guess what? People are so wedded to their monster-truck-driving, plastic-consumable-disposing, distance-product-shipping, holiday-air-travelling lifestyles that they won’t (on the whole) bear even the slightest personal “burden”. The relatively moderate costs associated with behaviour-modifying policies (eg a carbon price), are vehemently and successfully opposed (or neutered) by governments all over the world. And the reason they are free to do so is because there’s no political cost to doing so. Given all that, why on earth would anyone think it’s going to be politically acceptable to fund even costlier and potentially fraught geo-engineering responses?
2. Shades will do nothing at all for the ongoing acidification of the oceans and the consequent marine species destruction.
The cheapest and only long-term sustainable solution is to massively reduce the global population. Say we manage to massively transform society and half the average person’s ecological footprint. All that effort will be for nothing if we’re doubling our population in a couple of decades anyway. Any effort to modify our behavior will be pointless if we keep outbreeding the gains we make. By contrast, if we simply reduce the birthrate by a factor 10-100 we can drastically reduce our impact on our environment without any other changes.
Any other measure is just a stop-gap until we acknowledge the inconvenient truth: humanity is a plague. We’re breeding like cockroaches and if we don’t stop it we are doomed, regardless of any other measures taken.
I am very much a technology optimist. I believe that technology is the route to providing sustainable solutions across the board in energy, transportation, agriculture, and materials. Even more, I believe that the only solution is for technology advances to make the sustainable solution to be the preferred solution. When going green is also cheaper, faster, better, then everyone goes green by default.
The role of government here is to align incentives and subsidize market-driven R&D efforts which result in technologically superior products that also happen to be sustainable which can win in a competitive marketplace on their own merits. The perfect example of this is EVs. EVs will totally supplant new ICE vehicle sales in the next couple decades because they will ultimately be a better vehicle in every possible metric.
I think we are seeing the same effects in terms of renewable energy that can now compete on cost even without subsidies, and we are in the beginning stages of where we need to go with agriculture (I'm sure actually much progress has been made, but I'm less familiar with that tech).
From a materials science perspective, we need better alternatives for clothing fibers, and better alternatives for plastics in our products and packaging. Cotton is biodegradable but takes far too much water to produce -- possibly something that further genetic modifications to cotton could reduce. Plastic blends in textiles are great for performance, but end up as microplastic in our waterways and oceans. The alternative isn't that everyone is going to switch to hemp. The alternative must be a better material developed that provides superior performance, longevity, texture, carbon footprint, and ultimately clean disposal or recyclability. Government's role is to align incentives for this R&D to occur by taxing externalities or subsidizing new products that present lower externalities.
As to the queston of controlling the effects of increased CO2, one of which is global warming, and another of which is ocean acidification, I think we will come to a point where we need ways to effectively reduce atmospheric CO2 independently of efforts to reduce CO2 emissions, and technology will ultimately afford us that.
I think it's an open question whether the timescale over which atmospheric CO2 may ever be brought back below, e.g. 300ppm, will require engineering a more direct solution to both ocean acidification, and global warming. Even if tomorrow anthropogenic CO2 emissions dropped to zero, how long would that even take? Solar shields and atmospheric CO2 extraction are technologies that warrant future research and discussion.
The real obstacle is the confusion in the public opinion spurred by big oil marketing and lobbying. It's really hard to find quality information online, but it exists since many years and it's pushed down on purpose by interest groups. Here is an example:
Exxon, a big oil corporation, had accurate predictive models of climate change, agreeing with scientific consensus, already in 1982 and confirmed "it will cause dramatic environmental effects before the year 2050".
Shortly after Exxon began to deny global warming and started "greenwashing" marketing campaigns, which today show up directly in the news articles on global warming, e.g., in The New York Times:
We should be skeptical of any ways to address climate change that rely on technology and require very little behavior change.
Burning fossil fuels does more than just warm the planet, so trying to stop the planet from warming through some far out means wouldn’t address these other huge issues. Also, the easiest path to haunting climate change is to literally stop doing the damaging things.
But you're right that The Climate Change Movement™ dismisses these things out of hand. This is because it is only incidentally about combating climate change. It is primarily about giving more power to approved politicians and bureaucracies. This is also why we have made no almost progress on the underlying issues. We were never meant to.
Further, have you thought about how we get off fossil for steel, concrete, plastics, hell even natural gas power plants? Climate change is the most important issue right now and even so, we are undeniably a fossil society. We need everything we can muster, and sunshade should be part of our tool kit to help the transition.
Lots of people are thinking about these questions! Still early research phase, but the chemistry works out.
Concrete - http://news.mit.edu/2019/carbon-dioxide-emissions-free-cemen...
Plastics - no carbon emitted as long as you don't burn your plastics. Could also capture emissions from a plastic incinerator if you really want to burn trash
Natural gas power plants - replace with solar/wind + batteries?
Also, I suspect we'd be better off right now if we'd been land-filling plastic, instead of shipping it overseas to be burned, shredded, littered, dumped, or even discharged at sea. Even official estimates claim minimal percentages are actually being recycled, before accounting for fraud.
We might have significant reduced levels of micro-plastic in the ocean, and a greater amount of carbon sequestered, instead of the high cost and seemingly minimal benefit we've seen "recycling" plastic.
I’m not saying stop drilling fossil fuels, because we need it for almost every part of our society. I’m saying we should be pushing harder down the path of not using fossil fuels as an energy source. If suddenly it becomes way more economical to burn fossil fuels then we’ll stop pursuing any alternatives. That’s just how it works. I wish it wasn’t.
Get down off your high horse and pay attention.
The car is not driverless. You are just backseat.
The greatest risk you run with your current attitude is that you contribute to the "it's a crisis but I have higher priorities" thinking. This is what bends the horseshoe, ideology. If we weren't in a crisis, I'd be more sympathetic.
Not saying it's impossible or impractical, but the political consequences are non-trivial ... imagine being able to shave 10% off a nation's photovoltaic power capacity if they don't knuckle under to trade demands, or to mess with their storm frequency/weather patterns. It's a huge can of worms.
Probably this will be governed by the UN.
There could be some interesting implications if you do have active control -- like "should we cool this area to move this huricane".
"Yeah, but we can't make it turn back over water, but instead of it hitting country A, it could hit country B".
There are other suggestions for placing sunshades in MEO. Each shade there is ~60% less effective than it would be in L1 (because of the time it would spend not shadowing any part of earth), but it is much closer, so putting them up there would be easier and cheaper. Those could in theory be regional.
However, it's been pointed out that sunshades would also necessarily be pretty damned good solar sails, so they might well make their own way to L1.
If station keeping is needed, I would think you would want to make the shades as big as possible.
Is that strictly due to time when it's casting a shadow, or does that take into account the geometry of the shadow cast and the flux density of the sunlight at each point (watts/m2)?
That'd be an interesting calculation to see.
Tesla means a gigafactory’s worth of battery production, and the solar panels charge the batteries, but what are the rockets for? As discussed - a planet sized solar shade, casting the planet into darkness. Or at least into the shady side. Solar panels are mounted on the bright side of the solar shade, charging batteries on the shade. Those batteries get shuttled back to Earth on a rocket, and are replaced when the next rocket ship arrives. Musk becomes the primary provider of energy on Earth, selling energy where previously the Sun just gave the stuff away for free.
Selling energy to all the nations of Earth, just to run LEDs in order to grow plants, proves to be very lucrative, but at that point, Musk has no need for money. All that’s left is for him to use this power to open a rift to the next dimension over to get power over life and death itself, and the SOE’s agents can’t stop him. Or are they? (Last part stolen from parent poster and isn’t the book I’d write. Big fan though!)
While shutting down 90% of the agriculture output and completely messing with local climate.
Unfortunately even recognition of a capability to build such a thing will certainly reduce pressure to rapidly de-carbonize, even the acidification of the oceans is hailed as solvable now by putting vast but affordable quantities of mined olivine them.
Human depredation, mis-consumption and mis-appreciation of natural systems (as well as each other) remain gravely destructive and tragic modern persuasions until the narrative is healed.
Reflectors in on the ground also have the benefit of being controllable.
1) Solar isn't really cooling anything, it's just transferring the heat to the point of use through the grid.
2) There's a lot of square footage of pavement and rooftops before we need to seek out virgin land.
3)Adding any feature to a production of 16 trillion won't be trivial in cost or complexity. Anything besides passive steerage (akin to a solar-windsock) is going to sink the project, IMO. I suspect that once you start adding power, gyros, controls, communication, navigation, etc, it will be more economical/feasable to scale up the size of each deployable shade by 2+ orders of magnitude (4+ by area). Which isn't to say it would be feasible, just more feasible.
Agreed it would be difficult and heavy to add minature gyroscopic and solar cell, comms and control unit to the 16 trillion disks proposal, since they are just 60cms wide. That plan seems basically like throwing confetti into L1, where it might get drifted away by solar ejections, out of stable orbit, in matter of years.
Since each of those disks is 1 gram and about 0.25 square meters, that scheme involves total of 4 trillion square meter shades orientated randomly. If shades are squares for simplicity and 8 meters in diameter, so 64 meters square and similar material would be 256 grams, add some stiffening and a control unit for say an extra 150 grams. Maybe a clever unfolding feature like an insects wing. Its a bit more material to launch but probably less than double at some control/shade ratio, and the tracking shades will block light about 30% more effectively than randomly orientated ones. Works out around 50 billion of the 400gram 8 meter wide shades with mini solar-comms-gyro units to produce. So I'm still overconfident in the practically of this kind of scheme, especially since cost to space has been minaturised since they previously had expert attention.
I have to admit its just one of those hunches Im hawking of late, cheers for following :)
For example, the author does assume 1gram (2ft diam) shields, but also specifies the necessity of precise angular orientation, and relatively modest location control / steering. This is to be accomplished by an unspecified number of "control satellites" using aimable mirrors and passive radiative pressure, which keeps the discs simple and the weight at 1 gram. Required disc area is ~7x the required total shading area, due to indecent angle and required transparency and spacing. A new gps-like network of "navigation beacons" will also be required to maintain spatial reference. He then says that to track individual disk locations/ orientation, that each disc needs a GPS-like nav receiver, 2 cameras, some processing/ communication ability, and a power supply, presumably solar. But he doesn't account for (or even reconsider) that there will be added weight and cost due to this.
He also doesn't consider the cost of inventing, manufacturing, and deploying the control satellites or the new type of nav beacon network, or even estimate how many of each will be needed. (GPS tech won't work, but if he knows that, he doesn't state it.)
There's other questionable assumptions, like a launch cadence of every 5 minutes for 10 years to leo, and that cost of launch will roughly equal cost of fuel due to the scale.
He also estimates the method of transfer from leo to L1 will require delta-v of 1km/s and assumes it will be solar powered / ion propelled, but leaves it at that, also without scope or cost.
It's interesting, but less convincing than I expected, given all the missing details, and also makes me more convinced that risk assessment, management and mitigation haven't thoughtfully been considered. That said, the shading, geometric layout, and required material properties calculations are quite impressive.
+/- 16 trillion self-powered, locally communicating "cellular" elements, each with some minimal sensory and processing capability. Add to that the mobility presumed by the author, and the fact that it is literally designed to block the sun, and you've got everything you need for a matrix rewrite...
The control coordination of trillions of L1 satelites doesnt strike me as a huge challenge to people already working in similar fields. I do some work on simulations and read about related technics. Control units just get individual and group call codes that they can respond to, in timed windows if helpful. A number of manager satellites beam signals to sectors and listen to responses. They could likely often pinpoint individual transmissions themselves with modern radar style tech, although trillion is a large number, sheilds will rarely eclipse one and other because they would be very dispersed and relatively small. They dont have to relay all messages individually through neighbours but perhaps could. The options for implementation are extensive but I believe familiar to network designers. They don't really have AI processing to do, its just a matter of maybe reporting their neighbors numbers so position can be determined and relayed so they know where to 'light-sail' and can receive schedules for when to let light past - if that becomes necessary or is deemed advantageous. Im just rambling but there are loads of possibilities for how to organize them. As a multi-node processor it would be rather slow because of the average latency between nodes being many kilometers, rather than millimeters to meters in a supercomputing cluster.
Personally, I'm terrified by how people here suddenly are so enthusiastic about the sunshade, without even knowing its side effects, when the problem can be solved at its source.
Buying time is always good if it forestalls doom.
Climate change activists who let perfect be the enemy of good will get all of us killed.
Nothing short of catastrophic events will make people give up on their unsustainable lifestyle.
If your primary goal is to force people to do something they don't want to do, on principle, call yourself an activist, a freedom-fighter, or a terrorist, I don't care. It's all the same to me.
If your primary goal is the survival of the human race, you shouldn't moralize.
Enough. This isn't a Parliament and you don't get a liberum veto.
Could you expound on that a bit? The assertion alone doesn't parse.
It makes me wonder about the people doing the moralizing: do they really care to contribute to the solution, or are they grinding their own personal axe about the behavior of others?
On the other hand a fractured/weak Europe means higher gas prices, no medling in russian affairs, less pressure by russian citizens drooling over the fence with their eyes fixed on european stability and wellfare, free hand to do as Russia pleases in ex Soviet states and so on.
* that good black chernozem soul which makes up the Russian breadbasket would turn into desert in south of this region, while in the north the soil is too poor
* mass forest fires would choke the air
* melting permafrost would destroy existing badly maintained infrastructure and cities
If Russia is hoping for positives out of climate change they are in for a surprise
1) Social destabilization driven by collapse of southern agricultural communities and their migration northward. Keep in mind that already the northern communities are being heavily impacted by the thaw of the permafrost that many cities and towns are built on - to establish more infrastructure means building on a growing swamp. To be able to get crops to market, it means building very long roads on a growing swamp as well - remember that Russia suffers from a lack of internal rivers to convey agricultural products throughout it's vast geography.
2) Consequences of disturbances to fish stocks for northern communities - who are dependent on either fish directly, or seals and other species indirectly
3) Limited societal benefit of new hydrocarbon resources given the existing klepto-oligarchy - it's unlikely that new resources will be used to stabilise the broader community or social fabric.
4) Possibility that they cannot exploit said hydrocarbons due to global moratoriums or increased uptake in alternative energy sources
5) Broader geopolitical implications of social collapse of soviet satellites; some of which are currently heavily dependent on current rainfall patterns for cotton, wheat and other grains - Kazakhstan, Turkmenistan, etc - if these countries go to the wall - what does that mean for the Russian state? It's likely that Russia would have to invest aggressively in shoring up the southern borders.
6) China; the eastern regions of Russia could be a tempting acquisition for China looking for new agricultural land or control of northern ports such as vladivostok as ice coverage decreases- further exacerbating pressures on the central Russian government.
1. the alternate proposals won't work (at all, which seems unlikely)
2. the expected case for climate change isn't actually as bad as people are saying it is
3. people don't actually care about climate change as much as they care about using climate change to push their own agendas
Personally, I lean towards #3. But that still doesn't make me very happy with climate activists.
The plan also requires a certain amount of stationkeeping, probably with solar sails, and if you can do that then you can also move the elements out of the way of the sun entirely, with a little time.
2) It sort of misses the point- that might address the known-unknowns of the primary effect (solar radiation hitting Earth). It does nothing to address unknown-unknowns or even secondary or tertiary effects.
The mere presence of the shields might block solar wind, distort Earth's magnetic field, reflect / refocus cosmic radiation, amplify affect of solar flares, interfere with radio or satellite communication...
We just don't know. And the stakes are too big, even compared to worst case global warming.
The bigger the potential impact a project has, the better prepared you should be to undo or mitigate it, before it causes problems worse than the ones it's meant to fix. I don't see that here.
All the "mights" you mention can be easily evaluated by straightforward physics.
You can't possibly think that it's straightforward to model all those physical aspects for 16 trillion objects. We don't even have the 3-body solution solved; just predicting the gravitational behavior is unbelievably complex and chaotic. That many degrees of freedom is simply unsolvable (without quantum computing).
It's hubris to believe we can predict even basic behavior and interference of such a project, let alone intended or unintended side effects, whether known or unknown.
Intentional projects would be an improvement over current state of unintentional changes.
But the money is on the side of renewables - from :
> Not a single coal-fired power plant along the Ohio River will be able to compete on price with new wind and solar power by 2025, according to a new report by energy analysts.
Solar prices are dropping so it'll eventually beat fossil fuels in the market. Sunshades or similar geoengineering projects may require less political will at the right price point and allow us to kick the can down the road long enough for our own greed to save us :)
 - https://insideclimatenews.org/news/25032019/coal-energy-cost...
I honestly don't know or know of any quality modeling of it.
But if we're speculating... with cheap launch capacity and cheap/efficient solar, we could start talking about building solar farms in space.
Also - again speculating - if the shade has limited coverage, there should be a temperature difference on the edge of the shadow. That may cause increased wind, which could benefit windmills.
At the end of the day, we’re a part of nature too, just doing our part to increase entropy via energy dispersion. Can’t stop the second law. Just gotta find ways to do it that kill us off slower.
Most of the energy we have used comes from the sun. Aside from nuclear.
I wonder if we will one day regulate our climate on earth by shading hot areas and pointing mirrors at cold ones. There are all kinds of knock on effects of doing that, but it seems like a human thing to do. Modify the environment instead of adapting to it. That's kind of our thing.
From what I understand, it will help... eventually.
If ambient temperatures come back to normal, then the ocean won't absorb as much CO2.
It would be better if we could come up with a way to neutralize / sequester the co2 already in the ocean.
Basically, artificial green-sand beaches which absorb CO2 as they weather.
Carbon pricing sounds like a cheaper and a more direct solution addressing the cause of the problem (more greenhouse gases in the atmosphere) instead of its effect (temperature rise). What could go wrong?
If feasible at all, make a part of those shades photovoltaic panels, and beam the energy back using microwaves, as that would provide an extra incentive to launch that (GEO might be more useful for that kind of setup, I have no idea what deltav it would take to transfer to/from both, but you could use ion thrusters since you have on-board power).
Better to send up 10,000X dumb shades with random orientation and spin. Not only are the dumb ones much lighter, they're proportionally much cheaper too, since they're basically just structured aluminum foil rather than needing thrusters, reaction wheels, computers, etc.
Would be interesting to keep inflow the same and reduce outflow, but I have no idea what I am talking about.
You don't really make the atmosphere thinner by removing CO2 or methane...they are trace gasses relative to N2 and O2, CO2 is less than a .05% of the atmosphere, IIRC. So, you mostly want to prevent heat from hitting the Earth, or decrease the absorption (increase albedo), or you want to remove the heat-trapping gasses that will continue a warming cycle by trapping the heat we do get.
I think space sunshade's a decent idea, but we still need very aggressive decarbonization, as CO2 is very bad for the ocean, nevermind the heat trapping.
Infrared radiation only comes from things that have been heated (mostly) by that visible light. Any light reflected back into space without being converted to heat is energy that is somebody else's problem.
Allowing CO2 to increase without bound would eliminate the fisheries billions of people rely on for their protein.
What happens when those space shades get hit by micro meteorites causing them to alter or de orbit?
I don't think there's a big micro meteorite problem at the Lagrange point, but if there were for arguments sake, then you need to plan for it and have a way to replace shades that get knocked out of position. It's not like the whole system would fail if you lose one shade. That's what engineering is about, planning for all the likely eventualities.
"0.6-meter diameter and a thickness of about 5 micrometers. The mass of each disk would be about a gram..."
Each pound of methane would produce 2.75 pounds of CO2: https://www.engineeringtoolbox.com/co2-emission-fuels-d_1085...
And each launch burns 240 tonnes of methane (launch mass minus rocket mass is 1200 but that's 4/5 oxygen): https://en.wikipedia.org/wiki/SpaceX_Starship
So that's 660 tonnes CO2 per launch times about 150,000 launches, or about a hundred megatons CO2. Given that we're emitting 36GT annually, that seems a good trade.
That's just launch to LEO, we need extra delta-v to L1, but potentially that could be from a fleet of solar-powered ion drive tugs. My quick google didn't turn up Starship payload capacity to L1.
If the shades can be manufactured on the moon from local materials, potentially this could be a lot cheaper, with almost zero emissions. It'd take longer to get started, but it'll take a long time before people agree on something like this anyway; if we're setting up lunar manufacturing anyway, this would be something to keep in mind.
Our energy consumption and production continues increasing as society keeps advancing, and it will continue to do so as we unlock more diverse ways of harvesting and storing energy and using it. A mark of a technological civilization is the conversion of starlight into heat energy - the civilization converts the energy from the star into useful work which produces heat. The heat has to go somewhere.
Up until now, it's been fine just letting earth manage it (but we're obviously running into the limits of that with global warming), but as we start approaching planetary levels of energy consumption, we're going to start producing planetary levels of heat, and we're going to need to do something about it. The simplest and most straightforward way is by putting sunshades into orbit to limit the amount of sunlight that comes in to cool the planet. This works especially well if the sunshades are solar panes that can collect energy while they shield heat. It's attractive because it doesn't involve changing delicately balanced atmospheric composition, and they can be moved or rotated to adjust the amount of light coming in on demand.
I did the math once, and a square of 300x300km of solar panels in the Sahara would cover all the world electricity demands.
The issue is with green house gases, cutting forests which alter the way Earth handles Sun's light, not out actual heat output which is minuscule compared to the heat of planet Earth.
Joking aside, much like with memory, bandwidth and storage, we'll invent ways to use (all of the) energy if it is cheap enough.
But let's assume somehow miraculously we find a way to put objects at L1 as cheaply as the geosynchronous orbit. Your proposal would still cost $66 trillion. That's roughly the entire world's gdp. Do you really think this is going to be cheaper than reducing carbon emission?
Although it might be significantly easier with gravity assists.
So the shades would stay in equilibrium in a bit higher solar orbit than their velocity would permit without the light pressure.
L1 orbits do require station keeping.
Perhaps you could cheat a bit by making the shades black or oscilating/slanting them a bit forward/rearwards as to do the station keeping with very little fuel?
Or shaping them like a lense to direct most light away from Earth, but not to experience too much net force?
Or they are just designed to be expendable?
You can't station-keep indefinitely anyway (your fuel will run out), so just launching lots more dumb sunshades seem like the more effective and cheaper solution.
Any sort of station keeping is going to add significant mass, complexity, and cost.
And keep in mind that, absent active station-keeping, you need a mix of many different orientations to block out the Sun throughout the year. And you're not going to perfectly remove any spin anyway.
But we're both very wrong- I read the whole paper. Some aspects are well thought out and highly technical, while others are glossed over as requirements tbd.
Briefly: He does intend to steer/ orient the discs using radiative pressure from a network of control satellites and gps-like navigation "beacons", but overlap is also required to take into account the required oblique angles and transparency of the discs.
I'm left being very impressed with the provided technical details of the disk constellation, but even more skeptical overall, mostly due to lack of detail on some major supporting elements. He offers no detail of the required deployment method, or even the scope of the required navigation and control network. He also states each disk will require a gps-like receiver, 2 cameras, some power and processing capability, and a method of communicating with said networks, all while still assuming 1g per disc and no added cost...
It's not conceptual level, so much as it's conceptual for maybe one out of dozens of required massively scaled elements.
Also, it addresses no risk management / mitigation concerns.
We're talking about retrieval difficulty in a worst case scenario. Even if it disintegrates, you've left a cloud of particulate matter that's going to create even more unintended consequences and is more difficult to collect / move / mitigate.
So if you feel the need to correct my use language, please do it in a constructive manner.
But it certainly didn't dissolve.
Would we need to spin the cloud? (perhaps forming a galaxy-like shape)
Looks like the circle would be approximately 1100 kilometers in radius (per wikipedia), according to this random calculator  20 million tons at 1100 km creates a force of 0.000000000001103 N/kg.
I don't think gravity is likely to be the biggest problem.
 Solar wind will push them, the lagrange point they would sit as is actually a "point" and anywhere nearby you slowly drift out of it
Then put up another shield.
Drop yields more.
Put up another shield.
If we can keep the poles cooler, we could increase the ice cap, reduce melt, and affect only a small number of living creatures.
My initial searches have turned up nothing related to this, and I'm a total novice, so just asking the question.
And more ice means a higher albedo, so more sunlight is reflected back into space. But I see the challenges of partial blocking as a lot higher than in the general case - you need to keep two hemispheres in place and synchronise them with the tilt of the planet as it orbits the sun.
I find it amusing that people who think 2-4 degrees over decades is an insurmountable problem, but creating an entire hospitable atmosphere on another planet is doable.
Even removing the co2 that we've added to the atmosphere and sequestering it may not be free of negative consequences. That is the magnitude of uncertainty we need to be discussing and debating. At this point, blocking the sun is just crazy, and not because of feasibility, constructibility, or cost.
Edit: Look at the disaster of updating the Washington DC water system for a supposed "fully understood" lead mitigation project that went unbelievably wrong, because of bad assumptions and factors not initially considered to relevant (unknown unknowns). And there was no controversy over such a conservative "fix" (other than maybe cost given necessity).
It really breaks basically every human spaceflight architecture. It's a two element architecture (with common propulsion, simplifying development for the booster) that accomplishes every goal of virtually every other interplanetary human spaceflight architecture conceived. This simple architecture (while avoiding the huge penalties of single-stage vehicles) means that it can be developed extremely cheaply.
It really is a gamechanger in spaceflight. All of spaceflight.
400 satellites per launch? For maybe an incremental price of about $40 million near-term and $4 million long-term? That's, um, $10,000 per satellite. That breaks every model of space development.
And it's not like all of this was unforeseeable. Even Werner Von Braun proposed refueling-dependent human spaceflight architectures in the 1940s (in his fictional book about exploring Mars) that would enable low cost. But for historical reasons, human spaceflight took another path.
"In late 2001, Mueller began developing a liquid-fueled rocket engine in his garage and later moved his project to a friend's warehouse in 2002. His design was the largest amateur liquid-fuel rocket engine, weighing 80 lb (36 kg) and producing 13,000 lbf (58 kN) of thrust. His work caught the attention of Elon Musk, PayPal co-founder and CEO of Tesla Motors, and in 2002 Mueller joined Musk as a founding employee of SpaceX."
that's a hell of a lucky find by Musk and a hell of a roll of the dice by Mueller. Around the same time is when Shotwell joined, she's equally incredible but in a different way. i don't now how Musk found her.
Even then, what followed has been black swan territory. Every major development announcement at SpaceX is met with "you're crazy" and laughter from the industry and yet, a few years down the road, there it is working. Again, i really want to know what went so right.
The reason he was tinkering on small engines in his garage instead of designing big engines for his employer, TRW, was that after designing the best American first stage engines (the TR-106 and TR-107), it became clear that it didn't matter that his engines were better, for political reasons it was impossible to kill the RS-25 program (also known as SSME, or Space Shuttle Main Engine), and therefore any future vehicle would use them instead, despite them being strictly worse for any use other than for the Space Shuttle. This was immensely demoralizing to him, and he was considering just quitting the industry and doing rockets as his hobby. Then Musk managed to convince him to work at SpaceX, for a much lower wage (and stock options, but the rational early valuation for rocket company stock is $0), mostly on the promise that at SpaceX, his engines would actually fly.
The NASA program of record heavy lifter, SLS, is still using the designed-in-70's RS-25 now, 25 years later, and plans to toss 4 of the $40M engines into the ocean on every flight. SpaceX is what happens when you build rockets with actually modern technology, instead of all the components NASA is forced to use because some senator needed to maintain employment in his home district.
NASA did no such thing. They were ordered to use the engine by the Senate.
(When the Constellation program was canceled and the SLS program was created, Senate ordered NASA to pick solutions that "minimize contract cancellation costs". Not minimize total costs, minimize costs related to cancelling contracts. This of course means that the contractors you are already using can offer any solution they want, at any price they want, and so long as they are willing to waive the contract cancellation penalties as part of their package, you have to pick that solution.
They all offered a really expensive, really bad deal. I know several NASA engineers who quit in disgust because of this.)
Even when dedicated non-military rockets began to appear, e.g. the Ariane range and the Space Shuttle, they had dependencies on legacy infrastructure that was originally designed for strategic weapons (i.e. it was intended to work at peak performance, just once). The payloads evolved to reflect the launch system constraints, so very expensive, one-of-a-kind comsats and earth resources satellites, each of them a bespoke design (or at most one of a dozen or so).
SpaceX isn't building missiles; it's optimizing for reliability and cost (which means reusability). More like airliners than missiles. This doesn't mean low performance (the efficiency and power density of a modern civil airliner turbofan would have been a jaw-dropper to 1940s military aviation engineers) but it does mean the performance goals are different.
I am still extremely skeptical that Heavy/Starship will facilitate a Mars colony ... but that's because I'm skeptical about the economics and practicalities of building an off-planet colony when the externalities we normally take for granted (like a compatible biosphere) aren't available and nobody's really done the necessary R&D work on self-contained biospheres -- even the ISS is effectively an open-loop system dependent on constant resupply. (Biology and ecology are much harder than they look to a naive outsider.)
Neal Stephenson has a pretty good article about path dependence in space exploration: https://slate.com/technology/2011/02/space-stasis-what-the-s...
I wouldn't be surprised to see a small settlement for research or something in my lifetime. Maybe something like what we have in Antarctica.
The next step would then be something like a Bigelow B330 module in LEO, which is close enough to get the astronauts home from in a hurry if something goes badly wrong.
(These steps can be commenced with current tech: Heavy/Starship not required.)
Step 3 would be a bigger test hab out beyond the Van Allen belts, preferably a couple of habs revolving around a hub to provide centrifugal "gravity" at Lunar or Martian levels. Goal is to test systems for use on planetary surfaces exposed to cosmic/solar radiation (because outside our atmosphere). Starship is probably mandatory for this phase, because it's a lot more massive and a lot further away. Alternatively: conduct this experiment on the Lunar surface, once astronaut return capability is available (but why waste expensive reaction mass if you can simulate a gravity well?)
Without a lot of R&D work under these conditions, a closed-circuit life support system for Mars is a huge safety risk for the astronauts who set it up (and who are too far away to rush home in a hurry if it goes badly).
And without closed-loop life support, a Mars "colony" is no more a colony than an Antarctic research station reliant on resupply for everything except air and water.
Also his system strategy is : the best design to use is one that doesn't require the design in the first place. Ie get rid of many systems. Keep it simple. Less can go wrong, and the schedule is reduced. "Tight is right. Long is wrong".
He did a great talk last month.
You guys might like a video I'm releasing on Halloween, "the actual, physical, reason why time slows at the speed of light". My channel is "TheRainHarvester". Stay tuned...
I don't know much about SpaceX, but I do follow Tesla closely: how much of this is reality versus "things we'd like to be able to do in the future"?
For example: is the rocket really "rapidly reusable"? Or is it theoretically "rapidly reusable"?
In the same way that all Tesla's sold since 2017 have the hardware capable of self-driving. Are they really capable of it, or theoretically capable? Until you have self-driving software or have rapidly reused the rocket, how do you know? In the same sense, until they landed a rocket, saying "we have a rocket capable of landing" didn't matter; landing it did.
I may not be articulating it properly, or perhaps I'm misunderstanding how they test these claims.
We assume Falcon-9 first stages are really reusable, right? Not that they are claimed to be reusable, or they are theoretically reusable, but really reusable.
Then the question is, what is the criteria to be really reusable? Would only direct demonstration be enough? Then of course Starship isn't real. If there are other ways to claim real reusability, then maybe Elon's plans are real(istic). Also, historically, Elon claimed something for SpaceX before which later became real.
There aren't currently proofs that Starship isn't possible to create (with parameters similar to stated).
I think we might just do stuff in space because we WANT to do it. Stuff like space tourism, etc.
To take asteroid mining as an example: The entire platinum group metal market on Earth is only about $10-20 billion per year. Adding a huge supply is likely to crash the market price well before you drive demand up high enough to compensate for the far lower price. So platinum-group metal mining is not huge.
Mining water is also a very small market. You're primarily replacing rocket propellant for launch vehicles or maneuvering, but this is a small market. The entire commercial launch market is about $3 billion per year in revenue. Adding non-commercial launch may more than double it, but you're still talking less than $10 billion per year. And propellant (or propellant services) is going to be a small part of that. It won't help get payloads to LEO, so you're left with just providing services from LEO to GEO or something like that. Maybe for deep space missions... But even that market is very small. NASA makes up the majority of world funding for deep space exploration, about $10 billion per year optimistically. Propellant is a small fraction of that.
So for water propellant, we're looking at maybe $100 million to $1 billion per year in revenue.
For structural materials, the market is even more speculative and less proven.
Space settlements are going to be small revenue, too, for the foreseeable future. NASA human spaceflight, philanthropic, and space tourism are really the only consistent funding sources there. The settlers themselves won't be super rich as they'll need to be sustaining themselves, but let's just say we have 10,000 settlers each able to spend $100,000 for your services per year. That's just $1 billion per year. To get truly sizable, you need like a million people living in space, and it's still only $100 billion per year.
So it's primarily telecom that is the big space market. The others are much smaller and less profitable. It turns out that serving billions of Earthling consumers is where the real money is in space.
There are 3 big (trillion dollar) markets:
3) high speed transport (aviation)
Space can in principle address all three. The first one is the only real "slam dunk," the other two are questionable to one degree or another. SpaceX is pursuing 1 and 3.
The profitability of mining asteroids doesn't come from bringing the metals back to earth and selling them on the traditional market: It represents the ability for spacefaring communities to build their own ships for a much lower cost than building and launching terrestrial rockets on Earth.
Furthermore - Space Stations, orbital manufacturing plants, multi-generation starships, solar arrays - all of these become incredibly cost effective when the metals used to make them become hypersaturated from asteroid mining. It's a means to an end, but by no means is it without value.
Space based energy requires a way to send the energy to the surface for monetization. The three ways to do this would be
1) Wireless transmission -- infeasible with current level tech at the distances required.
2) Wired transmission -- requires materials with very high tensile strength in quantities never before produced.
3) Deorbit batteries -- You spend more energy launching/deorbiting and distributing batteries than you gain.
High speed transport (ground to orbit, and interplanetary) have huge problems in scaling, but it mostly can be solved with current level engineering.
It's just a difference in scale. To get high efficiency, low cost radio amplifiers, you need to operate at relatively low frequency (think microwave oven magnetron, but modified to follow a phase and frequency input). Rectification of this has also been done. But you're going to need an enormous aperture on both sides to make it happen. That means, to me, you need on the order of 10 Gigawatts to be feasible (rough, back-of-envelope calculations). And even then, you need an enormous plot of land, preferably in the desert. So you're basically competing with cheap solar power backed by cheap batteries. Both of those are improving in cost every year. So it's possible. Feasible, even, if we had no other options. But it's not going to be competitive from what I can tell.
So it's the same type of scaling problem as #3. Except the main issue with #3 is safety: passenger aviation is just so ridiculously safe it's extremely hard to compete with.
Not the most ethical business plan, mind you....
Aluminum was a precious metal for a few decades. Royalty used it for their best forks and spoons. Now we make airliners out of it and the aluminum producers are doing just fine.
Space mining is made out to be the pie-in-the-sky paydirt of space dreams, but it's still a much smaller market than telecoms.
1. make more space habitats
Once you have orions, you can move a lot of heavy stuff quickly around the solar system. Orions can probably go interstellar if we fire off fuel pellets for them to catch up to, or can somehow doe antimatter catalyzed fission/fusion.
Orion drives are great if you just consider performance, but not cost. It gets it's great ISP and thrust at the cost of being very inefficient in it's use of fissiles. If you can lift propellant into orbit at the cost SpaceX is projecting, for any in-system work it is more economical to use much less flashy nuclear thermal rockets with much worse ISP, because the propellant is cheaper than the fissiles.
Other downsides include "using it for take-offs will leave a large crater that will glow blue for several hundred million years, as will everything downwind in the fallout area", but who really cares about takeoff areas? (That's for the silly plebs left behind on the ground to worry about - you're headed to SPACE!)
almost halfway down, the article is long but so well worth the time.
As for in-situ resource utilization, how about this: Apollo astronauts found nearly 40% iron ore in some areas of lunar regolith. That may be unusually high, but you can do magnetic separation, then pass hydrogen gas through the ore to get iron and water. Crack the water molecules, recycle the hydrogen, and then use the oxygen to refuel "starships", where it accounts for 4/5 of the propellant mass. In the meantime you get iron by the hundreds of tons on La Luna that you can use to make pressure tanks to store that oxygen, live in, etc.
(It's been a long trope in sci-fi and speculation that a lunar economy would be an aluminium economy, and that people who seek iron will go for the asteroids, but it is very easy to get iron + oxygen as described on the moon, it is much harder to reduce other common metals on the moon.)
Here is the mass driver that Gerard K. O'Neill told you about, available off the shelf:
That can send a 10kg projectile at 2.5 km/s which can get to the Earth-Moon L1 or L2 points.
If you can increase the velocity to 3.1 km/s you could graze the Earth's atmosphere and deliver oxygen and other materials to LEO. Either way you need something that can soak up excess momentum at the end, but you could greatly reduce the need for tanker launches.
Using pre-Starship capabilities, 15 launches is a lot. At $5M/launch, 3 launches per day that they're forecasting for Startship, 15 launches would be a tiny part of the budget.
The main trouble is you also want to build up a carbon stock for biological applications... But it is the nitrogen stock that I haven't figured out.
That would potentially enable getting mass (like water or lunar regolith) into space (alas from the Moon, not Earth) at even lower cost than Starship.
Recommended related link: http://ssi.org/ssi-supermodels-part-2-make-your-own-ssi-mass...
The moon has other challenges, like the slow day/night cycle, radiation, and the damn dust.