Planetary Defense: Shielding Earth from Asteroids

[Panoptic Perceptions]

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The Chelyabinsk event in 2013 stands as a stark reminder. A relatively small asteroid resulted in extensive damage, injuring over 1,200 people. On a more colossal scale, the catastrophic asteroid impact 65 million years ago disrupted Earth's ecosystem and led to the extinction of the dinosaurs.

In responding to this challenge, agencies like NASA's Planetary Defense Coordination Office have been at the forefront. Their mission? Detect, track, and strategize against these celestial threats. The advanced techniques employed, from kinetic impactors to gravity tractors, are a testament to human ingenuity in safeguarding our planet.

Furthermore, this defense is a collective endeavor. Renowned global organizations, including the UN's Office for Outer Space Affairs and the International Asteroid Warning Network, collaborate to create an integrated response to asteroid threats.

In essence, while the vastness of space presents uncertainties, our commitment to planetary defense and collaborative efforts ensure a proactive stance against potential dangers. Dive into this exploration to grasp the seriousness and science of preserving Earth's safety in the face of celestial challenges.

#asteroidimpact #asteroidhittingearth #planetarydefense #nearearthasteroid #asteroidlive #nasa

 

[swansont]

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[Ken Fabian]

I do think planetary meteor defense is an excellent long term goal for space agencies, one that can be international and cooperative in nature and large scale, long running and wide ranging enough to support significant ongoing space technology R&D. Like national defense or insurance there is no innate requirement to have a self supporting commercially viable basis, whilst still having the potential for spin offs that do. But I suspect the pursuit of defense industry relevant technological excellence and international rivalries will remain greater drivers of space programs than any shared "common good" type goals.

[Panoptic Perceptions]

6 hours ago, Ken Fabian said:

I do think planetary meteor defense is an excellent long term goal for space agencies, one that can be international and cooperative in nature and large scale, long running and wide ranging enough to support significant ongoing space technology R&D. Like national defense or insurance there is no innate requirement to have a self supporting commercially viable basis, whilst still having the potential for spin offs that do. But I suspect the pursuit of defense industry relevant technological excellence and international rivalries will remain greater drivers of space programs than any shared "common good" type goals.

Thank you for sharing your thoughtful perspective! Balancing cooperative meteor defense goals with industry advancements is key for space progress.

[Ken Fabian]

15 hours ago, Panoptic Perceptions said:

Thank you for sharing your thoughtful perspective! Balancing cooperative meteor defense goals with industry advancements is key for space progress.

On the other hand I remain unconvinced and very pessimistic about space colonisation - that without commercial profitability to enable a colony (which I think has to be at least equivalent to an advanced industrial economy to have a chance) to pay it's way and be self supporting human habitation of space won't happen and without extraordinary transport cost reductions - far beyond anything in progress, at least 1/1000th current best or better - commercial profitability that can make it an opportunity will remain out of reach.

I also have the unpopular view that uncrewed exploration delivers more with much better value for money than crewed and the greater scientific/exploration achievements will continue to come from that. But, being Australian my influence - posting opinions on science forums - is minimal, even less than the vote an America gets.

[StringJunky]

9 minutes ago, Ken Fabian said:

On the other hand I remain unconvinced and very pessimistic about space colonisation - that without commercial profitability to enable a colony (which I think has to be at least equivalent to an advanced industrial economy to have a chance) to pay it's way and be self supporting human habitation of space won't happen and without extraordinary transport cost reductions - far beyond anything in progress, at least 1/1000th current best or better - commercial profitability that can make it an opportunity will remain out of reach.

I also have the unpopular view that uncrewed exploration delivers more with much better value for money than crewed and the greater scientific/exploration achievements will continue to come from that. But, being Australian my influence - posting opinions on science forums - is minimal, even less than the vote an America gets.

Your assumption seems to be that we don't need representatives to leave Earth to maximize our survivability.. It's just going to stay the same for all time and existential anxieties are just that.... figments of the imagination. I'm for spreading my bets.

[mistermack]

7 minutes ago, Ken Fabian said:

On the other hand I remain unconvinced and very pessimistic about space colonisation - that without commercial profitability to enable a colony (which I think has to be at least equivalent to an advanced industrial economy to have a chance) to pay it's way and be self supporting human habitation of space won't happen and without extraordinary transport cost reductions - far beyond anything in progress, at least 1/1000th current best or better - commercial profitability that can make it an opportunity will remain out of reach.

I don't think that the motivation will be financial for a long time. But they went to the Moon without any prospect of a payoff. The motivation for space colonisation for me, (if I was in charge) would be insurance against total wipeout by the Earth being hit by a big asteroid. Or by humans being wiped out by a devastating virus. (possibly more likely)

But once you conquer colonising space, you have the advantage of limitless nearly free energy, and the ability to do things without having to fight gravity and to fly around with hardly any energy input. And the truly limitless extent of space itself, which we are running out of rapidly here on Earth. 

[Genady]

41 minutes ago, StringJunky said:

assumption seems to be that we don't need representatives to leave Earth to maximize our survivability

Do we?

I am really neutral about this question and would like to hear arguments about it.

[iNow]

8 minutes ago, Genady said:

I <…> would like to hear arguments about it.

It takes a ridiculous amount of engineering and resources to 1) reach other planets and then 2) make them habitable for us for more than a few years that we’d likely realize a far higher return for a much lower expenditure simply by focusing those same energies and resources here on Earth fixing the things which made us wish to flee terra firma in the first place. 

[Steve81]

17 minutes ago, Genady said:

Do we?

I am really neutral about this question and would like to hear arguments about it.

IMHO, we will never leave the solar system, but that doesn't mean we can't set up space stations in a ring around the sun to collect solar energy, mine asteroids for resources, etc.

 

With respect to asteroid shielding, it would be more asteroid deflection by altering its trajectory early enough to cause a miss. 

Edited August 25, 2023 by Steve81

[Genady]

11 minutes ago, iNow said:

fixing the things which made us wish to flee terra firma in the first place. 

 

7 minutes ago, Steve81 said:

we will never leave the solar system

Yes, these arguments are very clear. The only argument on the other side that I know of is, that it will come to an end one way or another. My honest question then is, so what?

[mistermack]

20 minutes ago, Steve81 said:

IMHO, we will never leave the solar system, but that doesn't mean we can't set up space stations in a ring around the sun to collect solar energy, mine asteroids for resources, etc. .  .  .With respect to asteroid shielding, it would be more asteroid deflection by altering its trajectory early enough to cause a miss. 

Never say never. But I agree, space stations will be the main development, and they will be gigantic and living in them will be Earth-like only much better eventually. Once life up there became truly self-sustaining, the threat of asteroids hitting Earth wouldn't mean total extinction of everything, you could store dna up there for nothing in the universe's deep freeze. 

[Steve81]

1 minute ago, mistermack said:

Never say never. But I agree, space stations will be the main development, and they will be gigantic and living in them will be Earth-like only much better eventually. Once life up there became truly self-sustaining, the threat of asteroids hitting Earth wouldn't mean total extinction of everything, you could store dna up there for nothing in the universe's deep freeze. 

Agreed.

[Genady]

10 minutes ago, mistermack said:

wouldn't mean total extinction of everything, you could store dna up there for nothing in the universe's deep freeze. 

I don't think so.

But regardless, what does stop us from storing DNA up there now?

[mistermack]

16 minutes ago, Genady said:

But regardless, what does stop us from storing DNA up there now?

All of the materials would have to be lifted up off the Earth using rockets at the moment. In the future, they will be mining the moon for materials, much much cheaper. A dna store would of course need heavy shielding which would be absolutely prohibitive to bring from the Earth. And of course, if the Earth was hit tomorrow, how would anybody access the dna store and use it? But if people were living independently up there, that's an option. 

[Genady]

This seems like humans becoming "nomadic aliens", which have been discussed a bit here: https://www.scienceforums.net/topic/129082-are-uapsufos-finally-being-taken-seriously/?do=findComment&comment=1242201

 

[Ken Fabian]

1 hour ago, StringJunky said:

Your assumption seems to be that we don't need representatives to leave Earth to maximize our survivability.. It's just going to stay the same for all time and existential anxieties are just that.... figments of the imagination. I'm for spreading my bets.

No, my assumption is it isn't feasible. If it were close to feasible -and I do think the economics of it is indicative - maybe but it isn't anything like close. That thousand fold lowering of costs - more like 10,000 fold to get near across the planet ocean shipping costs underpinning global trade - makes a barrier that wishful thinking cannot overcome. That there are real extinction risks is why I support meteor defense as an enduring space program objective. If drastic cost reductions emerge then we can reassess where that line for feasible is. Space is not the place for depending on improvising or any go there then figure it out "bootstrapping" - everything needs foresight, planning and preparation.

1 hour ago, mistermack said:

But once you conquer colonising space, you have the advantage of limitless nearly free energy, and the ability to do things without having to fight gravity and to fly around with hardly any energy input. And the truly limitless extent of space itself, which we are running out of rapidly here on Earth. 

I don't think that is true, even leaving aside just how out of reach "once you conquer colonising space" is. Sure, you can throw a stone in space and it will keep going but getting it to reach a specific destination is a whole lot harder; getting to and from actual destination in space is still hugely energy expensive and technically challenging. Just going from low Earth orbit to Geostationary costs about 1/3 of the delta-v ie fuel requirements and wear and tear of what it took from ground to low orbit - that is still a LOT - and requires a lot of reaction mass as well as energy to do it. From low orbit to moon takes 2/3rd of what reaching orbit did. To Mars from Earth orbit it takes about as much as reaching Earth orbit, but without atmospheric braking to save fuel. Solar power does seem to offer some potential where low accelerations suffice - I'd suggest very high temperature vaporisation, maybe to plasma, of (probably) water rather than attempting to turn it into chemical fuel, but the reaction mass to payload ratio is still going to be very high.

There are some useful resources in great abundance out there, with nickel-iron the pick of them, with 10's of ppm of platinum group metals included, if you can refine them, but not every resource is abundant. For example I struggle to see how fission rockets can be fueled in space without accessing fissionable materials from Earth - which may be in high demand. Fusion is still a work in progress. But even with such energy sources there is a lot of reaction mass needed.

I'm not opposed per se - just think it is a lot harder than the optimists like to think.

[mistermack]

7 hours ago, Ken Fabian said:

Just going from low Earth orbit to Geostationary costs about 1/3 of the delta-v ie fuel requirements and wear and tear of what it took from ground to low orbit - that is still a LOT - and requires a lot of reaction mass as well as energy to do it.

Maybe so, but if that's the case it just means that low Earth orbit is not an attractive place to use. Lifting up off the Moon is much less energy intensive. And going from one space station to another in that region would be very low in energy requirements. And of course, with large amounts of water on the Moon, you can make hydrogen and oxygen fuel cheaply using solar energy.

I saw a tv program the other day about the Moon, and they mentioned that Moon Dust is an excellent material for making bricks, you just heat it and set it in a mould. They are much stronger than concrete when set. They could be like Lego, interlocking, with no need for mortar, so re-useable. 

I don't think Earth would be much use to a mature colony of Space Stations, other than for extremely rare and valuable stuff that can't be accessed from the Moon or Asteroids. It's too energy-hungry to lift stuff off. And Mars is much the same and worse, it's less use than Earth because it's just as energy hungry, but far more hostile to live on. Although Mars does have moons that might be of use. So once technology is mature for living in space, I think nearly all of the activity will be centred around the Moon, for Materials and industry, and Space stations, for living and working long-term. 

I think that with the low gravity of the Moon, it's possible to shoot materials off the surface into orbit using a cannon, so the cost of getting heavy materials away from the Moon would not be high. In any case, it didn't take much fuel or rocket power to lift the American astronauts off the Moon. 

8 hours ago, Ken Fabian said:

Fusion is still a work in progress.

Yes of course, it's all about the distant future. But fusion would be probably easier to achieve and run on the Moon or in space, because you have access to super low temperatures for the superconductors, and cheap and reliable solar energy for electrical input, if needed. And maybe, without the complication of gravity, plasmas might be a bit easier to control. 

[Genady]

On the one hand,

1 hour ago, mistermack said:

... it's possible ... it's all about the distant future ... maybe ...

On the other hand,

10 hours ago, Ken Fabian said:

... it isn't feasible ... it isn't anything like close ... a barrier ...

Thank you all for presenting arguments from two different perspectives. I am not neutral anymore, at least for the next 65,000 years. Then, we can discuss it again.

Why this number? The last catastrophic asteroid event has occurred 65 million years ago. Assuming we are in a random point between that and the next similar event, with 99.9% confidence we have at least 65,000 years until the next one. If it happens sooner, somebody will perhaps update the probabilities using Bayesian inference.

[mistermack]

The chances are we will see it coming, if it's that kind of size, and doesn't happen in the next 100 years. And we will all be advised to duck. 

[swansont]

11 hours ago, Genady said:

But regardless, what does stop us from storing DNA up there now?

It’s not actually a deep freeze in earth orbit, for one. On the moon, for example, the temperature can hit 100 degrees C.

[mistermack]

3 minutes ago, swansont said:

It’s not actually a deep freeze in earth orbit, for one. On the moon, for example, the temperature can hit 100 degrees C.

Yes, but not in the shade. We had that conversation before. 

[Genady]

Why we would need to store DNA, when we could just store the sequence?

[mistermack]

1 minute ago, Genady said:

Why we would need to store DNA, when we could just store the sequence?

That's a good point. It's all speculative anyway, you would need the technology to reconstruct an organism from the dna. Extremophiles could maybe stored whole, but to reproduce an elephant from dna or even fertilized eggs might be a challenge. 

[swansont]

Just now, mistermack said:

Yes, but not in the shade. We had that conversation before. 

Yes. Perhaps you need to refresh your memory of it. You can’t stay in the shade, and even mirrors heat up. You have to get away from earth to leverage the cold of space. In LEO, where it’s relatively accessible, it’s difficult to maintain something cold. Out where you have the Webb telescope, you can. What’s the point of storing it where you can’t get it?