Probably few. The US has excellent observers and comms sats by the dozens are not very big. It's true you can get some photos but the kind you're thinking of, where you can track vehicles in a meaningful way or something, has to be done by something closer to the hubble telescope (pointed backwards).
> has to be done by something closer to the hubble telescope (pointed backwards).
state of the art is about 2x diameter, with adaptive optics methodologies that avoid needing to polish a giga-mirror over several years
Even if it would just deliver 1 or even just 10 meter resolution, I would imagine the high revisit frequency would make it commercially valuable, and potentially also provide some value to military/intelligence groups because it would make it harder to hide activity through careful timing and the data would come with fewer secrecy requirements.
And I have no clue what is doable with SAR, but I'd imagine multiple satellites following each other would enable some interesting features, as it essentially gives you a giant antenna.
Kessler cascades as depicted in Gravity aren’t really possible [1]. Instead, a Kessler cascade would proceed linearly, within a tight orbit, and over the course of decades if not centuries. In LEO, the timeline for a Kessler cascade is on the order of natural decay times.
It's comments like these that sadden me. It's this mindset that make me pessimistic about the long-term viability of humanity as I think it is shared among many people. When we (individuals/groups/society) don't plan far ahead (even for the loosest sense/meaning of the word "plan"), that will tend to lead to short-term benefits with long-term detriments. That even applies even for things that can occur past our lifespan. In my opinion, we should strive to benefit/help our decedents. Climate change is the most obvious case of this, but it applies to other cases like solar flares on the scale of the Carrington event or greater or like Kessler syndrome here (both perhaps on the order of hundreds of years). If Kessler syndrome is a legitimate concern to be a problem in the not crazy distant future, we shouldn't dismiss it outright just because the issue is unlikely to be a problem within our lifetime.
There's no incentive to do this, it's politically untenable to plan that far ahead. The beauty of humanity is we're always changing and evolving because we only do things within the scope of our lifetime.
The curse of humanity is having a brain that lets us think too hard about what we want to be rather than acknowledging what we are which is a bunch of mortal animals with finite time spans that like to fuck, make babies, raise families and occasionally we come together and do shit together in the form of work so we can further those three other priorities.
Legislation would certainly require political will, which we don't have now for tackling anything on such a time scale. To tackle the problem through laws and government enforcement, it would have to become politically tenable at some point, but how would we go from where we are now to something that is closer to this? It's difficult to say with any confidence. But I do know politicians are still human, influenced by their biases and beliefs inherited through biology and life experiences. If our future politicians are to grow up in an environment in which a larger (than today) proportion of people care about problems on a longer time scale, they are more likely to care as well. Consequently, a larger proportion of individuals getting into politics will care about these types of problems, increasing the likelihood of them being addressed.
In parallel but as a separate point, fewer people will be willing to use products or services provided by organizations that they believe are doing wrong or harm by contributing to such problems, thus making it less profitable within capitalism. We already see this to some degree today (Harry Potter comes to mind). Even if the reduction in customers and profit is small, it would decrease compounding and ever so slightly disincentivize the company from making such a pursuit.
It's impressive how adaptive humans are, I must admit. We are quite good at tackling problems we see right in front of us if we set our minds to it. But that doesn't mean we should dismiss problems that are not causing an issue right here and now. We shouldn't wait until it becomes an actual problem because there could be irreversible consequences (or rather, we cannot reverse on reasonable timescale).
> The beauty of humanity is we're always changing and evolving because we only do things within the scope of our lifetime.
This is just simply not true. For thousands of years, humans have done things that are meant to endure beyond our lifetimes - from building monuments like the the pyramids to conducting scientific research to creating art. Our ability to look beyond the here and now is actually one of the defining characteristics of humanity.
We better make double-sure than any leftover value past your life is purely meted out through hereditary lines and couldn't possibly benefit any but a tiny minority of people. Like, if you had three houses and two kids at death, there ain't no way some poor fool is getting that leftover house for free!
That's what they thought in the 70s when they discovered climate change. Look where we are now. Is basic concern for others a sin in our current world?
We're living out the consequences of a system where the Nash equilibrium is everyone maximizing their individual benefit at the expense of all else. And that extends to being an unapologetic jerk--as long as that face looks like a stepping stone, climb on. And screw future people and animals.
Late update: if you look at the fancy full version of the IPCC graphs[0], there's a funny (ehh...) observation: the human destruction of stratospheric ozone was one of the largest climate radiative forcing factors—and it was on the "cooling" side!
It's the negative-side, green (O₃) bar in the third row, "halocarbons". There's multiple human contributions to ozone I don't fully understand, but, *that* one's the stratospheric ozone destruction due to CFC's. (That's not to to say CFC's were good for the climate: as that same row illustrates, CFC's themselves are also ultrapotent greenhouse gases. If you trust the fancy graph, the CFC's direct heating effect slightly outweighed their cooling effect via destroying ozone).
Here's one more. CICO ignores the effects of the types of food (CI) and activities (CO) that might make you hungry quicker than others, for example from sugar or fatigue or anything else. Appetite control is very difficult. Those soft factors make it poor guidance as well.
It doesn't though, at the end of the day there's an objective amount of CI and an objective amount of CO. Further, CO isn't just "activities", for instance you burn calories merely by existing. Things you're describing will impact CI and CO, but at the end of the day if one had the ability to fully and 100% accurately measure CI & CO it'd be apparent that the math works.
But this is why "it's just CICO" is at best a tricky phrase. Because the hard part is in the nuance you describe.
I get this over and over on every issue where "math" becomes "guidance". Let me try to bridge by restating:
Math truth is not always good policy guidance.
It is true that CI==CO. It must.
It is not true that telling someone that CI==CO is a good way to get them to manage their weight, because (as mentioned) it's hard to measure and (as I added) even if you measure correctly, you _reduce likelihood of compliance_ by ignoring appetite effects when you call all calories equal.
I think we agree, just trying to find the right words anyway.
I have never once had to make a build.rs file, except to make python bindings for some of my own rust libraries. Are people out here using build.rs for everyday driving?
Bindings, and generally any form of code generation, is the most common form of build.rs I see in the wild.
One such example of "daily driving" is for gRPC, where the canonical way to generate the protobuf and gRPC bindings using Tonic+Prost is through build.rs. Another is C-to-Rust bindings, for all of those -sys crates.
Though I've also seen it used to circumvent limitations of Cargo, e.g. for invocations of dependent cargo build steps, etc. Overall, it's less common (or more robust?) than it used to be 5-ish years ago.
Which to me is fine. It's not a great hobby language but it is a fantastic professional language, precisely because of the ease of refactors and speed of development that comes with the type system and borrow checker.
> It's not a great hobby language but it is a fantastic professional language,
I never thought I'd live to see the day when someone would say this. The first 5 years of Rust were all "this is interesting for hobby projects but nobody will ever adopt this in industry".
Former Cpp dev here. If I never have to debug a template barf it'll be too soon. By the end of my time in C/Cpp land I'd written more C than anything, with occasional "structs with con/de-structors". Happily the next gen of systems languages fit about in that niche already!
First class SIMD vector support is awesome. The complaint about that not being first class matrix support kind of misses the mark: it's all vectors all the way down.
This is one glaring omission from Rust. Their SIMD integration is library specific and patchwork but improving.
Automation is one way to do that.
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