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SpaceX Starlink satellites had to make 25,000 collision-avoidance maneuvers

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Re: SpaceX Starlink satellites had to make 25,000 collision-avoidance maneuvers

#41

Post by yreg »

wereHamster wrote: post #14
supermatt wrote: post #9

if they are basing avoidance on the known trajectory of other orbital objects, what happens when those object also manoeuvre?

Presumably if the other object is human-controlled, they coordinate (the counter-party also has interest in avoiding collision). If the other object is debris, they coordinate with physics which is highly predictable.

At least a portion of those maneuvers has to be autonomous, it averages to one every 10 minutes.

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.

Re: SpaceX Starlink satellites had to make 25,000 collision-avoidance maneuvers

#42

Post by yreg »

jauntywundrkind wrote: post #23

The article is hurting itself with it's slant. 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…

>by having such a lower risk tolerance

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.

Re: SpaceX Starlink satellites had to make 25,000 collision-avoidance maneuvers

#43

Post by causi »

What's the story here? Is this an unusually-high number of maneuvers that's resulting in excess fuel usage and shortened lifespan? Orphan statistics are worthless. I make dozens of collision-avoidance maneuvers in my half-hour drive to work every morning.

Re: SpaceX Starlink satellites had to make 25,000 collision-avoidance maneuvers

#44

Post by Zancarius »

somenameforme wrote: post #34

Okay so the data they offer is that the satellites are, on average, making one orbital correction per month to avoid any possible trajectory with a greater than 1 in 100,000 chance of a collision. Those satellites are around LEO, which corresponds to a mean velocity of ~17,000 mph. So they're claiming that making one course adjustment per month, traveling at 17,000 mph, to avoid a 1 in 100,000 chance of a collision,…

Thank you for putting this into perspective! It's a shame science journalism has become so sensationalist.

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.

Re: SpaceX Starlink satellites had to make 25,000 collision-avoidance maneuvers

#45

Post by Symmetry »

nordsieck wrote: post #17
schiffern wrote: post #13

It's important to note that Starlink satellites will maneuver when they calculate a 1-in-100,000 probability of collision.[0] Most other satellite operators will only maneuver when they predict a 1-in-10,000 chance. 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…

Another thing is that Starlink is low enough that space junk spontaneously de-orbits relatively quickly. I think within ~10 years, all of the junk SpaceX is maneuvering around shouldn't be a concern to them any more.

10 years for the satellites. Any debris coming off them will tend to be smaller, have a lower ballistic coefficient, and deorbit faster.

Re: SpaceX Starlink satellites had to make 25,000 collision-avoidance maneuvers

#46

Post by mrtranscendence »

somenameforme wrote: post #34

Okay so the data they offer is that the satellites are, on average, making one orbital correction per month to avoid any possible trajectory with a greater than 1 in 100,000 chance of a collision. Those satellites are around LEO, which corresponds to a mean velocity of ~17,000 mph. So they're claiming that making one course adjustment per month, traveling at 17,000 mph, to avoid a 1 in 100,000 chance of a collision,…

Not exactly. The quote about highway collisions referred to a time in the future where there are substantially more satellites in orbit. If it’s true that these maneuvers are increasing exponentially, that could be a genuine problem.

Re: SpaceX Starlink satellites had to make 25,000 collision-avoidance maneuvers

#48

Post by Stephen304 »

yreg wrote: post #42
jauntywundrkind wrote: post #23

The article is hurting itself with it's slant. 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…

>by having such a lower risk tolerance 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.

They seem to mean exactly what you quoted - a lower risk tolerance means they tolerate less risk, meaning they are more cautious. Doing an avoidance maneuver if the risk exceeds 1/100K instead of 1/10K is being more cautious because 1/100K is a lower threshold than 1/10K.

Re: SpaceX Starlink satellites had to make 25,000 collision-avoidance maneuvers

#49

Post by prepend »

wongarsu wrote: post #22
schiffern wrote: post #13

It's important to note that Starlink satellites will maneuver when they calculate a 1-in-100,000 probability of collision.[0] Most other satellite operators will only maneuver when they predict a 1-in-10,000 chance. 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…

If you have 4000 satellites a 1-in-10,000 chance doesn't seem that unlikely anymore. The scale of their operation forces them to be more cautious

Not really though as the risk is still per satellite. They have a greater chance of an individual loss but their individual risk per satellite is the same (or maybe higher because the collision could be with another starlink).

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.

Re: SpaceX Starlink satellites had to make 25,000 collision-avoidance maneuvers

#50

Post by prepend »

mrtranscendence wrote: post #46
somenameforme wrote: post #34

Okay so the data they offer is that the satellites are, on average, making one orbital correction per month to avoid any possible trajectory with a greater than 1 in 100,000 chance of a collision. Those satellites are around LEO, which corresponds to a mean velocity of ~17,000 mph. So they're claiming that making one course adjustment per month, traveling at 17,000 mph, to avoid a 1 in 100,000 chance of a collision,…

Not exactly. The quote about highway collisions referred to a time in the future where there are substantially more satellites in orbit. If it’s true that these maneuvers are increasing exponentially, that could be a genuine problem.

It still won’t be accurate as every 10 meters is extremely common. The amount of junk can increase 100Mx and their analogy will still be stupid and make the author’s physics (or maybe stats) teacher feel like a little bit of a failure.
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