The scaling isn't linear either. By setting the threshold 10x lower, SpaceX performs more than 10x as many maneuvers.
Essentially they're complaining because SpaceX is too cautious.
[0] https://www.space.com/starlink-satellite-conjunction-increas...
So it seems like the 1:10k vs 1:100k threshold would be a function of the cost of a loss from a particular incident rather than the risk of a single incident among the 4k satellites.
Thinking from an insurance standpoint, the cost to insure probably depends on the number of satellites overall and total potential loss, not just insuring for a single loss.
To compare: I find it interesting that, according to Britannica, the odds of someone dying in the United States from a lightning strike is about 1 in 15,300... over the course of one's entire lifetime.
For example, “forced to swerve” is very different from “adjust course to avoid collision.”
There are 4,000 starlink satellites with an eventual plan for 12-40k [0] so it seems reasonable to need to maneuver to avoid crashes. Satellites weren’t “forced to swerve” 25,000 times, they just changed their course.
It would be like me describing my morning commute as “swerving 600 times” because I had to adjust around every object in my way during my 14 mile drive.
There’s traffic in space.
Ridiculous. Per this chart, the # of satellites has also gone up by a factor of 10 in that same 2 year time period from ~400 to ~4000. Maneuvers-per-satellite does not appear to be increasing, given available data.
https://en.wikipedia.org/wiki/List_of_Starlink_and_Starshiel...
But it is a dilemma. Having both so many more satellites than anyone else (SpaceX semi recently crossed the line to having more than half the satellites in orbit) and by having such a lower risk tolerance, I have to wonder if it is a phase shift for LEO.
It feels like orbital tracking models have, for a while, been fairly static. We know where everything is & where it's headed, & only have to make a couple of updates. Operators jobs are relatively simple in this world.
But as the number of satellites keeps increasing, and as they become more likely to manuver, it feels like we shift into a new phase, where we have to have much more dynamic planning. The article says we are up to 69 avoidances a day, 69 times where every other operators now need to see, am I still ok and for how long?
We're probably not there yet, but this idea of space going from mostly static to dynamic would be a huge shift. Also note, SpaceX has lightweight low cost craft with cheap argon thrusters & semi disposable craft; most operators have bigger heavier craft with more limited & expensive maneuvering capabilities: structurally SpaceX is set up to survive a chaotic system, and others will have more expense/difficulty if orbital planning becomes increasingly dynamic.
What do you mean by this? The article says that NASA makes an avoidance maneuver when the chance of crash is over 1 : 10 000, SpaceX does it when it's over 1 : 100 000.
I didn't see anything in the article that implied what sort of odds we're looking at, nor what the consequences of individual collisions would be. Without anything like that, it's hard to understand why this is a bad or meaningfully risky thing. I understand Kessler syndrome is a problem, but is there really nothing less than that that can cause serious issues? The article doesn't really touch on any specific dangers.
So SpaceX does a smart, responsible thing here. They make a course adjustment if the probability is above a small threshold (probably 10^-5). From my understanding this is all automated. It's not a "swerve" or an emergency. Their satellite simply needs to adjust its normal orbit-keeping thrust a small amount at some point in the next 12-24 hours. It's table-stakes for constellation management at this point. Planet does the same tracking with their 100-200 Dove satellites.
Additionally, SpaceX and other operators like Planet have higher fidelity tracking data than the USSF's radar data (available at https://www.space-track.org with a free account or through https://celestrak.org). They publish their tracking data for other operators (https://ephemerides.planet-labs.com). Having lower error-bounds reduces the number of potential collisions that need to be avoided and tracked.
Inflammatory language like this is frustrating because it feeds an emotional "have you heard about Kessler Syndrome!?!" gut response. Many people and VCs have been duped into spending time on exotic stuff like harpoon capture and trash collecting satellites. But the answer, to anyone who actually works on this problem and does any research, is already there. What SpaceX and Planet are doing is responsible. Debris mitigation agreements and deorbit timeline restrictions from the FCC/other bodies are enough. If someone truly does launch 10-100k satellites, there are great solutions available with defined orbital bands.
If SpaceX had done 0 of these maneuvers it's unlikely anything bad would have happened. But they're doing the right thing here. And Starlink satellites are very low and don't stick around as junk when they're not being used. Basically, the tone here should be "wow SpaceX does a great job with automating collision avoidance", not "satellites constantly swerving in space".
Here's some of their Starlink data: https://celestrak.org/NORAD/elements/table.php?GROUP=starlin...
More on the TLE format from wikipedia: https://en.wikipedia.org/wiki/Two-line_element_set
And I don't think these are big enough to have serious radars on board capable of seeing hundreds of kilometers away. That just leaves ground control I guess?
The article says there are 10,000 satellites in orbit, including dead ones. 4,000 of those are Starlink. I'm guessing that since they have similar altitudes, Starlink satellites are more likely to come near other Starlink satellites.
I imagine a human controlled object wouldn't be placed on a collision course with a Starlink sat, so it shouldn't come to them having to negotiate how to dodge each other.
It'll only take something like a starlink satellite punching a hole through the ISS for this to register or change anything ...
c.f. light pollution
I also wonder at what altitude are most of the maneuvers. Are they during the phase between achieving orbit and boosting to their 550km final orbit altitude, or at the final altitude? I have a vague recollection of reading that the 550km altitude was selected partly due to low traffic, and is SpaceX' traffic itself causing the maneuvers?
Also, the maneuvers are based on orbital data several days in advance. How close are we to the point where multiple satellites maneuver simultaneously, but without accounting for the other satellite's maneuver, and wind up causing a crash?
Is there? I mean obviously there are other satellites, but typically the framing has been that space and LEO is so big that it doesn't matter. That even with all the other satellites you typically don't need any sort of course correction except in very rare circumstances.
Isn't the better analogy 'I used to never need to do any swerving at all on my morning commute, but now I need to do it 600 times'?
You can filter to "Low Earth Orbit" and play at 100x speed to get an idea of how things are moving around. There's a lot of intersecting paths, a lot of them Starlink satellite trains.
There's enough atmosphere in those low orbits that chain reactions aren't a huge concern for the rest of human spaceflight, but they are a concern for keeping the Starlink constellation alive.
That's a misleading description.
While a collision may increase an object's apogee, it will be in an elliptical orbit: it will always intersect the orbit where the collision happened.
This isn't just a collision thing either: all spacecraft do this[1] as a first step (move to an elliptical orbit), and then typically relight their engines at the apogee in order to circularize their orbit.
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Orbits are circular and constant (accurate enough for my argument). An impact might cause some debris to go up, but when the debris that went up comes back around to the same spot in its orbit, it will again be going up. Well, extrapolate that backward a bit and you realize the debris that is going up was inside the atmosphere moments before.
In other words, if an instant impulse causes an orbit to have a higher apoapsis, it must also lower its periapsis. Which means the piece will go deeper into the atmosphere, and you don't come back from deep in the atmosphere.
Only at apoapsis. But, any item thrown into an orbit with a significantly higher apoapsis will very likely have a significantly lower periapsis. So even for high-energy fragments, each orbit should have a period of passing through a higher-drag part of its orbit, and lose energy relatively quickly.
Significantly, the periapsis can never be lower than the altitude that the collision occurred. The worst case, IIRC, is for fragments ejected in the direction of orbital travel at the time of collision. But even then, they'll still spend some time in whatever drag environment they were in beforehand.
That's not to say collisions are fine, but nothing is going to get thrown into random high low-eccentricity orbits where they hang around and pose a threat for decades or more.
Also it is stuck with a relatively 2D format. Are the satellites really intersecting or is there 10km of vertical distance between them? Its hard to tell with these forms of visualization.
Sort of.
1. Modern satellites don't really shed junk - and almost all satellites today have to be launched with a plan to make sure that they deorbit in a timely manner. Doesn't always work out, but most are pretty safe.
2. For space junk, the time to deorbit increases super-linearly with orbital height. Which means that you are correct - stuff in higher orbits will slowly "fall" through the Starlink orbits on their way to Earth. But it's a very slow process which means there's really only a thin trickle of stuff falling from above.
What that means is that, Starlink will always have to avoid objects. But the bulk of the problem, which was caused by this[1] Russian anti-satellite missile strike will go away after a decade or so.
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