Low Earth Orbit Visualization

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.

> 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 that abstraction has a use, here it is for the nihilist crowd.

That would also mean that whenever I see a flat geo image, it could be a heightmap from a creator that was just too honest about scale.

While I totally agree with the logic, this particular visualization might mislead unsuspecting viewers into believing that our LEO is almost fully saturated. In reality, the satellites are so small that they would miss each other even if placed on the same orbit.

"A poster of our solar system where the sun and planets are at scale would look like a black piece of paper with a tiny white dot in the center."

Yes. And therefore a very valuable visualisation of reality.

Visualisations at scale are nice and useful, too, but they are misleading if the actual sizes are never shown to the target audience.

Absolutely. Common sense and critical thinking is less common than you may think.

> that there are city sized satellites flying above them

I don't think this is so much the issue, as much as that I didn't think about it.

I opened it and my first thought was wow, it's packed up there. Didn't consider the size of the things it's displaying relative to things on the surface.

There is certainly some merit in ensuring that first impression is accurate.

Yeah but I caught myself 3 seconds later.

Enough HN users are retarded enough that they'll start talking about Kessler syndrome because they don't understand what they're looking at.

Yes. I once overheard a flat earther argue that spare reporting is fake because there are supposed to be tens of thousands of satellites, yet photos from the ISS don't show any of them.

My dude, some people look up at the sky and see airplane contrails and clouds and conclude all sorts of outlandish nonsense.

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.

> 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.)

"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

The instrument is the particular radar. They usually have two at each location. Each radar is essentially a linear phased array that creates multiple possible beam locations in the radar plane. They light up a beam as a satellite passes through in order to collect measurements. TLDR an instrument has multiple beams.

Specific orbits (732km with a 28 degree inclination and 130 degree longitude of the ascending node), but impacts also instantaneously spread debris out over anything close to any of those numbers (700-760, 27-29, 125-135); most debris get spread not in a normal distribution but in a bimodal distribution between the orbital elements of the two impactors, with an additional perimeter of debris kicked out with some random modest dV in every direction from the explosion according to how much impact energy they absorbed. To start with.

But then, debris start to decay, and they decay unevenly, polluting all orbits lower than that. As this debris spreads to a crowded lower orbit it generates additional collisions.

Orbits are cleared to lower orbits according to mass cross section at roughly 10x the rate for every 100km altitude drop. So everything that decays from an accumulation of higher orbits has to eventually pass through a 300km circular orbit, but it's relatively safe because it spends so little time there.

Going full exponential cascade at 1000km might increase the number of impactors by a millionfold, though, which then proceed to rain down over the years on lower orbits.

Starlink is just under 600km in order to target a specific voluntary threshold of 25 year decay. Most of their finished birds are going to make around 5 years without propulsion or impacts.

Three things about that -

Profitability generates competition, which may or may not respect precedent. Right now Starlink is only really worried about collisions with other parts of Starlink. We cannot afford a Starlink-inspired future to happen at 600km.

Debris generating events can spin out an object with much higher cross sectional mass than an intact satellite. Think of it in terms of what we use drag for on Earth, like a kid building kites. A heavy metal bolt works worse as a kite than a long thin panel.

These calendar decay timelines are blind to density. If there are a billion satellites with a natural lifespan of 5 years flying at 551km then they are going to go into an exponential cascade in a matter of weeks. If you plan to launch very large constellations, you need very fast decay timelines to keep that safe. It is much safer at very low altitude. There is decay 'room' for >10x as many satellites at 300km as at 400km, and >10x as many at 400km as at 500km, and >10x as many at 500km as 600km.

...

It would also be nice to set aside something for manned spaceflight. Unlike with a satellite collision, if a pressure vessel gets penetrated everybody dies and nobody wants to go back. The ISS and Tianhe are going to have to deal with debris risk slowly raining down from a collision at 971km.

Then what do the large red blobs signify? Individually tracked pieces of debris are indeed a different layer.

> That's the debris toggle, I guess

No, unfortunately I don't think so. Startlinks are there even when you "disable debris".