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Low Earth Orbit Visualization

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Re: Low Earth Orbit Visualization

#91

Post by ricksunny »

perihelions wrote: post #42
ricksunny wrote: post #40

Earlier quoted context omitted.

(May I ask what definition of ‘passivate’ you are applying here? Even allowing for flexibility in the definition or autocorrect, and applying context, I can’t fathom what is intended to be conveyed by ‘upper stages - which were thought to have been completely passivated’)

https://en.wikipedia.org/wiki/Passivation_(spacecraft) ( "Passivation (spacecraft)" ) And used in context (this context), > "The incident is the fourth time a Centaur upper stage has broken up since 2018. In the earlier three cases, the breakups created hundreds of pieces of debris, but no known collisions. That has raised questions about a potential design flaw with the stage or a failure to “passivate” the stage by…

Thanks! I will update my word definitions search to include context keywords instead of ordinary dictionaries :)

Re: Low Earth Orbit Visualization

#92

Post by fragmede »

NedF wrote: post #43
dhosek wrote: post #12

Earlier quoted context omitted.

Proper scale makes the visualization impractical. I wrote about this with respect to a US map showing mountains on my mailing list: https://dahosek.substack.com/p/one-million-stories “any accurate depiction of elevation would be indistinguishable from a flat map at that scale. The coast-to-coast measure of the US is a bit under 3000 miles, while the highest elevation in the continental US is a bit under 4½ miles abov…

> Proper scale makes the visualization impractical. So lie? You can see from the comments most Hacker News users can't handle the abstraction. Your blog post is great, but most people don't know the Earth is a perfect sphere or simple things like the sun is white, the real "Don't Look Up" Universities have become pop culture, they are Gravity (2013), not 'science', whatever that word means now. We cross mountains so…

> Your blog post is great, but most people don't know the Earth is a perfect sphere

Typo? The Earth is a an oblate spheroid, slighly flattened out at the poles and wider at the equator.

Re: Low Earth Orbit Visualization

#93

Post by lukan »

rtkwe wrote: post #86
lukan wrote: post #82

Earlier quoted context omitted.

"there's not really a reasonable way to print a to scale in both size and distance in a book." There is. Just one picture of small dots in lots of black space can give perspective, .. next to the other visualisations. And some books do that.

Did you check the actual dimensions it would be?! If you're being accurate in both distance and size scales your smallest dot would be Mercury and the distance from the Sun to Neptune (assuming this is a modern text book and we're dropping Pluto) would be 922000 of those dots. Even if we print it at the higher 1200 PPI [0] used for line art that's ~770 inches, that's a huge image far larger than any reasonable book.…

I was talking about rough illustrations with picture in picture (with a lense) to give a basic idea. But I do remember maps that could be folded out.

Re: Low Earth Orbit Visualization

#94

Post by schiffern »

elliottkember wrote: post #8

Objects not to scale. Not even close, and no mention of it (that I saw). Graphing scale honestly is extremely important. A lot of people are convinced our sky is full of satellites because of visualizations like this.

Objects are not to scale for unavoidable reasons, but time is also not to scale. These two effects tend to cancel out.

People look at this visualization for what, 60 seconds? But the issue is that objects are zooming around up there for years-to-centuries.[0] The total volume of space swept out is massive.

Invariably the "not to scale" comments always get pointed out every time this is posted, but the temporal distortion (which makes people underestimate collisions) is never mentioned. Unless I mention it[1] of course... ;)

There's a much much better educational ESA video[2] which addresses some of the misconceptions in this thread, found via (of all places) Don Kessler's personal website.

---

If you want an expert perspective on orbital debris (vs..... whatever these HN threads always turn into :D ) I highly recommend you check out NASA Johnson's Orbital Debris Quarterly.[3]

Sources:

[0] What really matters is altitude as this graph shows: https://commons.wikimedia.org/wiki/File:Orbital_Debris_Lifet...

[1] https://news.ycombinator.com/item?id=33210261

[2] As this video points out, collisions scale as density squared, which is why all major collisions have happened near 80 degrees latitude: http://www.youtube.com/watch?v=RvZ3Lr-Tj6A

[3] https://www.orbitaldebris.jsc.nasa.gov/quarterly-news/

Re: Low Earth Orbit Visualization

#95

Post by corrino1 »

philipwhiuk wrote: post #70
corrino1 wrote: post #7

Earlier quoted context omitted.

[flagged]

It's more that Golden Dome is taking advantage of the architecture that Starlink has proved to be realistic. It will use separate satellites managed by the Space Development Agency (Tranche 0 consisting of proof of concept stuff launched a while ago

Total coincidence that the founding members of SpaceX and Mars Society were former Star Wars people..

https://en.wikipedia.org/wiki/Citizens%27_Advisory_Council_o...

Re: Low Earth Orbit Visualization

#96

Post by schiffern »

mlindner wrote: post #21
officehero wrote: post #15

Earlier quoted context omitted.

Yes and to be clear on what "practical" means here. If there's a mountain between origin-destination for a road trip it's relevant to highlight it. In the case of orbits the objects may be small but they're very fast and very dangerous.

I think calling them dangerous is even a bit misleading as they're well tracked. Some of them even autonomously precisely position themselves rather than be on ballistic trajectory.

Only the largest objects are trackable. Objects in the 1-10 cm range are large enough to destroy satellites instantly but too small to track. Obviously any visualization will only show known objects.

This explains both why "dangerous" is accurate, and why autonomous avoidance based on tracked objects (ala Starlink) is 'necessary but not sufficient.'

Re: Low Earth Orbit Visualization

#97

Post by schiffern »

jillesvangurp wrote: post #72
elliottkember wrote: post #8

Objects not to scale. Not even close, and no mention of it (that I saw). Graphing scale honestly is extremely important. A lot of people are convinced our sky is full of satellites because of visualizations like this.

Yep, it looks much more dramatic than that is. A realistic scale would make objects invisible, unfortunately. So I can see why they make things bigger than they are. The reason why there are so few incidents is that low earth orbit is simply a very large volume of space. It would be a mistake to think of it in 2D terms, it's a few hundred km in height and it has an area even at the lowest orbit that is larger than th…

"Floating around" isn't accurate. "Screaming around at 8 kilometers per second" is more accurate.

The fact that debris objects swee through an enormous volume of space per year (and are up there for years to centuries) makes it much worse.

https://commons.wikimedia.org/wiki/File:Orbital_Debris_Lifet...

http://www.youtube.com/watch?v=RvZ3Lr-Tj6A

Re: Low Earth Orbit Visualization

#98

Post by schiffern »

philipwhiuk wrote: post #67
cantalopes wrote: post #61

Earlier quoted context omitted.

Actually the Kesler syndrome, a space debriss cascade is a very real threat and a real concern. I suggest an interview with the commander of the space control quadron in a radiolab episode "Little Big Questions"

That's true but not because the objects are massive. It's because they fly very fast and there's limited traffic management. We risk solving the wrong problem due to bad visualisations of the situation.

It's actually mostly because we allow objects to fly too high. Small height differences have a huge difference in orbital lifetime (and therefore risk).

https://commons.wikimedia.org/wiki/File:Orbital_Debris_Lifet...

Re: Low Earth Orbit Visualization

#100

Post by JumpCrisscross »

cantalopes wrote: post #61
elliottkember wrote: post #8

Objects not to scale. Not even close, and no mention of it (that I saw). Graphing scale honestly is extremely important. A lot of people are convinced our sky is full of satellites because of visualizations like this.

Actually the Kesler syndrome, a space debriss cascade is a very real threat and a real concern. I suggest an interview with the commander of the space control quadron in a radiolab episode "Little Big Questions"

> the Kesler syndrome, a space debriss cascade is a very real threat and a real concern

It’s also widely misunderstood.

The risk is in trashing specific orbits. Below 600 km, that would mean certain orbits are too polluted to use for a few months to years. (A dense, compact object above 600 km could stay lofted for decades to over a century. But again, only within a predictable volume.)

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