Collision Avoidance: Coordination, Precedence, Dispute Resolution

[Alastor]

I think in general, the conjunction avoidance protocol could be as simple as :
 - Decide on a global safety threshold where avoidance has to be performed (1/40000 or 1/10000 seems to be industry standard).
 - When someone detects a conjunction with higher risk than that inform all involved party of the calculated risk and uncertainties (or use a global platform if it exists).
 - If someone has an estimate with lower uncertainties, communicate it to all involved parties.
 - Based on best available information, decide if avoidance has to be performed.
 - Owners of the satellites inform each other of if they can perform the maneuver and the cost of the maneuver (based on cost of building and launching the satellite and propellant cost of the maneuver. An algorithm has to be applied there, but it can be pretty easy and pretty standard)
 - Whoever has the lower cost for the maneuver performs it and both parties share the cost of the avoidance 50/50.

Then you can add a few exceptions about things that should not move for other reasons.

I think the sharing of the cost of an avoidance is the key element here. That way, you can always say to the other "Ok, I don't want to move, I'll give you money for it" if it's essential for you not to move. But you have incentive to do so if it's not essential.

Edit :
Thinking a bit more about it, with this protocol, there needs to be an agreement that looks like :
"You don't go on purpose on an orbit that would put you on a collision course with someone else for a predetermined amount of time (unless you have their agreement). If you do, you'll have to perform all necessary avoidance maneuvers and support their full cost unless you come to an agreement with the other party (and of course if they have to perform the avoidance because you wouldn't or couldn't, they can charge you for its full cost). "

[Lar]

SDA is today only commerical and not all of them, but that could change. I'm not saying it's the ideal org, but I think some voluntary org that has the right membership is a better approach than trying to ask the UN to do this. If not SDA then some new one.

Also, Alastor makes a great point. Actually calculating cost and paying back and forth can really sharpen thinking. Economic incentives work.

[ChrisWilson68]

Also, Alastor makes a great point. Actually calculating cost and paying back and forth can really sharpen thinking. Economic incentives work.

Economic incentives work a lot of the time.  In some cases, though, they lead to unintended consequences, so they have to be very carefully set up.

Who decides the costs for each organization?  It seems like this system would heavily incentivize each organization controlling a satellite to give the highest possible cost estimate for its avoidance, and that can lead to intentional or unintentional distortion and sub-optimal behavior.

[Lar]

Also, Alastor makes a great point. Actually calculating cost and paying back and forth can really sharpen thinking. Economic incentives work.

Economic incentives work a lot of the time.  In some cases, though, they lead to unintended consequences, so they have to be very carefully set up.

Who decides the costs for each organization?  It seems like this system would heavily incentivize each organization controlling a satellite to give the highest possible cost estimate for its avoidance, and that can lead to intentional or unintentional distortion and sub-optimal behavior.

Valid.

One thing that works in other domains (and I forget the term for it) is the notion that if you don't want to PAY the price, you can instead turn around and say "I'll do it, but you pay ME the price YOU quoted"

Example to clarify: Two partners own a business together, equal shares. They want to dissolve the partnership via buyout. They can't agree on a fair price but they don't have to.   Partner A says "I want 1M for my share" and then Partner B can either say "OK here you go, 1M" OR can say "Pass... you pay me 1M for MY share instead"  That tends to get the costs much closer to ground truth, because if your price is too high, you'll end up paying what you quoted instead of getting it.

[Alastor]

Economic incentives work a lot of the time.  In some cases, though, they lead to unintended consequences, so they have to be very carefully set up.

Who decides the costs for each organization?  It seems like this system would heavily incentivize each organization controlling a satellite to give the highest possible cost estimate for its avoidance, and that can lead to intentional or unintentional distortion and sub-optimal behavior.

Good point.
We could imagine that launch contracts and satellite procurement contract all have to be disclosed to a single third party (of course with the right confidentiality requirements) that would be tasked with calculating collision avoidance fees, but there are cases where this wouldn't even be feasible.
Starlink is a great example of that. Since everything is done in an integrated way, there is no launch contract or satellite building contract and this would at best be declarative.
Military or intelligence satellites would be another corner case (but they are a corner case for satellite avoidance anyway. With these you just have to assume that they will perform all necessary maneuvers themselves and not tell nor charge anyone since they don't want details about what they are doing to be disclosed).

You could also just say that you have to declare to a third party what you will charge per maneuver per kg of fuel at launch and have that be public data and that's it. Then if you don't want to maneuver or if you want to play a game of charging all the maneuver cost to other parties, you'll declare a high price and probably end up being the one that pays most of the time.
The downside is that small satellites that have very low maneuvering costs may try to make a benefit of this  because they are so much bellow bigger ones.

In the end, I think most of the cases are handled by the rule I added in my edit : If you are intentionally putting yourselves on a collision course with the intent of "collision trolling" other parties (this is why this second rule is essential), you'll end up supporting all the costs of subsequent maneuvers. So in most of the cases, either it's an accidental conjunction and it's very rare, so someone charging a bit more than they should isn't really a concern or if there is an orbit that ends up being shared, there will be an agreement before anything happens that would cover who pays what and who does what.

Another point in favour of a system that makes people share the costs comes from something ESA mentioned, which is that most avoidance maneuvers involve dead satellites. Which means that would put an economic incentive on deorbiting or avoid populated areas to park dying satellites. It might help reducing LEO clutter if done properly.

P.S. : I also like the "pay me what you'd charge" idea. Although again, you have to be careful with the risk of a small provider "collision trolling" big sats.

[Tywin]

Economic incentives work a lot of the time.  In some cases, though, they lead to unintended consequences, so they have to be very carefully set up.

Who decides the costs for each organization?  It seems like this system would heavily incentivize each organization controlling a satellite to give the highest possible cost estimate for its avoidance, and that can lead to intentional or unintentional distortion and sub-optimal behavior.

Good point.
We could imagine that launch contracts and satellite procurement contract all have to be disclosed to a single third party (of course with the right confidentiality requirements) that would be tasked with calculating collision avoidance fees, but there are cases where this wouldn't even be feasible.
Starlink is a great example of that. Since everything is done in an integrated way, there is no launch contract or satellite building contract and this would at best be declarative.
Military or intelligence satellites would be another corner case (but they are a corner case for satellite avoidance anyway. With these you just have to assume that they will perform all necessary maneuvers themselves and not tell nor charge anyone since they don't want details about what they are doing to be disclosed).

You could also just say that you have to declare to a third party what you will charge per maneuver per kg of fuel at launch and have that be public data and that's it. Then if you don't want to maneuver or if you want to play a game of charging all the maneuver cost to other parties, you'll declare a high price and probably end up being the one that pays most of the time.
The downside is that small satellites that have very low maneuvering costs may try to make a benefit of this  because they are so much bellow bigger ones.

In the end, I think most of the cases are handled by the rule I added in my edit : If you are intentionally putting yourselves on a collision course with the intent of "collision trolling" other parties (this is why this second rule is essential), you'll end up supporting all the costs of subsequent maneuvers. So in most of the cases, either it's an accidental conjunction and it's very rare, so someone charging a bit more than they should isn't really a concern or if there is an orbit that ends up being shared, there will be an agreement before anything happens that would cover who pays what and who does what.

Another point in favour of a system that makes people share the costs comes from something ESA mentioned, which is that most avoidance maneuvers involve dead satellites. Which means that would put an economic incentive on deorbiting or avoid populated areas to park dying satellites. It might help reducing LEO clutter if done properly.

P.S. : I also like the "pay me what you'd charge" idea. Although again, you have to be careful with the risk of a small provider "collision trolling" big sats.

In that case I see two thing that should be add...Insurance policy (who pay and how many pay for maneuvering)...and mutual fund for any case of collision somebody pay anyway to the company that was a victim of this collision...

Because if a small company do wrong stuff in the space, and for any reason cause a collision, and the cost that will need to pay is a lot more that the asset that have that company... still somebody have to pay to the victim company, and somebody should be pay for clean that orbit of debris...

[Alastor]

In that case I see two thing that should be add...Insurance policy (who pay and how many pay for maneuvering)...and mutual fund for any case of collision somebody pay anyway to the company that was a victim of this collision...

Because if a small company do wrong stuff in the space, and for any reason cause a collision, and the cost that will need to pay is a lot more that the asset that have that company... still somebody have to pay to the victim company, and somebody should be pay for clean that orbit of debris...

Yeah, being able to cover the costs of an accident or litigate seems essential.

So in the end, we always come back to the same conclusion :
There needs to be an international institution whose authority on space matters is recognized by all space using countries.

This is not a small feat to achieve, and I think the good news here is that we can see that this institution, even though it needs to exist to handle money, say who's right or just serve as a database on who charges what, can be mostly mechanical. Not have a lot of decision power.

The reason I think this is essential is that I don't see any space using country delegating some of its power to an international institution that might end up being controlled by others (think about the mess it would be if we had to create the W3C right now ...). I can imagine them however agreeing on creating some institution that has a predetermined set of rules and just applies it. Anyone can do it, and anyone can check if they follow the rules.
So in the end, nobody looses power in favour of anybody. Everybody looses some power, but it can mechanically only benefit everyone.

[Arb]

Well at least in the sea I think so is the contrary...if you are in the ocean with you yatch and you are in a collision course with a Oil tanker ship...you are the ship that have to move...becuase the bigger ship have priority...

It's complicated but, in general, that is not correct. For the details see Part B (Steering & Sailing Rules) of the 36 page INTERNATIONAL REGULATIONS FOR PREVENTING COLLISIONS AT SEA, 1972 (aka the COLREGs).

And to bring it back on topic, you can be sure that a formal International Regulations for Preventing Collisions in Earth Orbit / Outer Space (how wide do we want the scope to be?) would be even more voluminous once all the edge cases are incorporated.

^{Edit: Typo}

[Alastor]

And to bring it back on topic, you can be sure that a formal International Regulations for Preventing Collisions in Earth Orbit / Outer Space (how wide do we want the scope to be?) would be even more voluminous once all the edge cases are incorporated.

Very interesting.
The navigating rules of this regulation don't appear to be that complicated though. Most of the document (which is already quite short) describes a communication protocol. So I'd say that's quite encouraging.

It however does remind me of an important point that I discussed in another thread : fully autonomous collision avoidance

If you want to generalize (or at least popularize) an automated collision avoidance system, you will probably need to develop some inter-spaceship communication protocol dedicated to that so that the ships that would be on a collision course can share their status, capabilities, orbit and determine which action to take.

Maybe an other way would be to have well defined avoidance protocols that both ships can follow to take action without risking staying on a collision course and have a distance at which a ship determines that if the other hasn't taken action yet, it means it's dead and some more maneuvering might be needed.
This, however, despite not needing communication, needs ship detection capabilities (radar or something like that), which might make things even more complicated, especially if they are orbiting around something.

If you factor in the fact that possibly ships on a collision course when orbiting a body might need to be aware of it several orbits in advance, and won't be able to communicate nor see each other through the body, fully autonomous collision avoidance, even though a nice idea on paper, probably becomes a real headache in reality.

[A_M_Swallow]

That right there is the one no-brainer rule.  If you're at end-of-life, might as well off yourself.

As for electric propulsion in general, not sure what the thrust is.  If they want to scootch a few km over a period of hours, that's not trivial. Over days, probably more feasible.

Not sure if it was even an option here, but the most important thing is - there is no agreed upon obligation, and ESA can't (or rather shouldn't) run around insinuating SpaceX broke some rule or understanding.

To avoid a collision we are talking of moving a satellite about 10 metres in a few hours.

[Asteroza]

I've been harping on the need for the equivalent of a Coast Guard for space for a long time, especially since it will suffer from the tragedy of commons quickly, and risking kessler syndrome. In the context of extracting money from the parties involved to operate said organization's operations, which could include things debris removal (subcontracted out to providers), rescue and safety (subcontracting out tug/OTV services?), and in this thread's context traffic control, fee structures that force the one being most inconvenienced (due to expenditure of propellant or disruption in service) to be paid by the intruder seem more equitable. We have ICAO for airplanes roughly, IMO for ships, and ITU covers space telecomms roughly (which the majority of commercial sat operators would have to interact with now).

Shifting some COLREG's stuff like EPIRB detection network responsibilities to a Space Guard could be a foundational start as well.

In the past, there were discussions about a launch tax/debris deposit to go into an escrow fund to cover problems. Though this has a lot of connections to space insurance itself, as an interconnected industry. Is there a space insurance trade group that could better get a handle on the whole perspective? Insurance has to regularly deal with freeriders and actual risk assessments, as well as the actuarial tables on the probabilities of things happening.

That, and pecking orders is non trivial for avoidance. Such as

manned
national scientific/public service (weather observation, GNSS)
commercial
amateur
national military

while greatly simplified, misses a lot of subtlety.

This also puts unequal pressures on sats without propulsion (by design or by accident), and owners of larger debris/spent stages, if we assume the non-maneuvering has to pay the cost of the avoidance, as cubesat operators are generally poorly funded to begin with, so self-removal or paying for third party removal/tow is a troublesome aspect representing a potential barrier to entry. Though one might argue that is actually good as it encourages an OTV/garbage scow debris removal industry.

[A_M_Swallow]

Are the Russian and Chinese military members of SDA?
Or willing to appoint ambassadors?

[Tywin]

I've been harping on the need for the equivalent of a Coast Guard for space for a long time, especially since it will suffer from the tragedy of commons quickly, and risking kessler syndrome. In the context of extracting money from the parties involved to operate said organization's operations, which could include things debris removal (subcontracted out to providers), rescue and safety (subcontracting out tug/OTV services?), and in this thread's context traffic control, fee structures that force the one being most inconvenienced (due to expenditure of propellant or disruption in service) to be paid by the intruder seem more equitable. We have ICAO for airplanes roughly, IMO for ships, and ITU covers space telecomms roughly (which the majority of commercial sat operators would have to interact with now).

Shifting some COLREG's stuff like EPIRB detection network responsibilities to a Space Guard could be a foundational start as well.

In the past, there were discussions about a launch tax/debris deposit to go into an escrow fund to cover problems. Though this has a lot of connections to space insurance itself, as an interconnected industry. Is there a space insurance trade group that could better get a handle on the whole perspective? Insurance has to regularly deal with freeriders and actual risk assessments, as well as the actuarial tables on the probabilities of things happening.

That, and pecking orders is non trivial for avoidance. Such as

manned
national scientific/public service (weather observation, GNSS)
commercial
amateur
national military

while greatly simplified, misses a lot of subtlety.

This also puts unequal pressures on sats without propulsion (by design or by accident), and owners of larger debris/spent stages, if we assume the non-maneuvering has to pay the cost of the avoidance, as cubesat operators are generally poorly funded to begin with, so self-removal or paying for third party removal/tow is a troublesome aspect representing a potential barrier to entry. Though one might argue that is actually good as it encourages an OTV/garbage scow debris removal industry.

Excellent you comment...I think will be urgent create that organism that regulate the outer space constellations and future business...

About the debris removal industry, Astroscale, is one of the pioneer...

https://forum.nasaspaceflight.com/index.php?topic=43371.msg1702709#msg1702709

This report was premonitory:

If all the mega-constellations launched, Peterson found that current tracking technologies would generate over 67,000 “collision alerts” annually. Operators would then have to choose whether to make hundreds of precautionary satellite maneuvers a day, or risk the small chance of a collision.

https://www.technologyreview.com/s/613239/why-satellite-mega-constellations-are-a-massive-threat-to-safety-in-space/

[Wargrim]

Thank you for making this thread!

It is a really important topic, and it does not take a genious to see that political questions and a mindset of "protecting your turf" in space are currently the bigger obstacles to a fully automated and mandatory collision avoidance system in space than the (still substantial) technical questions of how to implement such a system.

For the political / economic turf war / law as a tool to suppress competitors aspect, i think the analogies of airspace and international waters are models that work quite ok to get a picture of what could or could not be achieved.

Fact: Nobody will give full authority to an international body. Some players, like military and intelligence agencys, will always stay outside the jurisdiction or reach of any regulating or coordinating body in the commercial/civilian sphere, but may very well accept its procedures and rules as the de-facto standard to use during peacetime.

In order for all big space using powers (and the growing number of smaller space using powers) to agree to a set of collision avoidance rules and procedures in the commercial and civilian sphere, and ultimately implement a common and automated system, the set of rules needs to be as simple, neutral and founded in technical reasoning as possible.

Generally, in the long run the economic common sense that open airspace/water/space on average benefits everybody seems to prevail, but there are certainly counter-tendencies and exceptions. Right now, big clashes of interests can still be observed. E.g. everyone who already has his birds up has a strong incentive to favour a system where it is first come first served, i have my orbital slot with a nice big exclusion zone and how you get around that is your problem new player number #xyz. Just one example of many arguments you can bring.

Imho, as long as a priority debate (Science>commercial? Old>new? National Asset>anyone?) is raging, there will be no agreed uppon solution. What the worldwide space industry & scientific community could agree on however would be a set of rules that is based on simple technical facts and that is designed to minimize the overall risk and costs for all actors.

That would mean fully automated, based on the best available collision calculation data and designed to minimize service interruption.

The best metric i can think of to keep the manouvers and the service interruptions as small as possible is to calculate the avoidance solution that uses the least amount of energy to achieve a safe flyby. The catch of course is that a satellite with better mobility will on average have to give way much more often than a fat immobile one. But the same is true for oceangoing ships and it is accepted practice there.

So my proposal would be to only have 3 fixed rules for how avoidance has to be calculated:
- Manned craft get priority over unmanned
- The manouver needs to restore the accepted safety margin
- The manouver must use the least amount of energy to restore the accepted safety margin

From a technical perspective, you would need not only very good orbital data, a very good collision risk calculation, very good communication with both involved spacecraft, but also you would need to know the manouvering characteristics of boths crafts and the option to safely order them to manouver. Some hard nuts to crack, and i highly doubt a retrofit to existing satelites would work out. Best case would be to have such a system on all birds starting from launchdate X. All the living old stuff will still require the old manual intervention, and the dead stuff up there is dead. But there would be an increasing economic incentive to get rid of old "manual" birds and replace them with new "automatic" ones, as the cost to keep the manual system working will steadily increase.

A relatively lowhanging fruit is to improve the knowledge of the orbital parameters of all sats. That allows you to have tighter safety margins. But the sooner a general collision avoidance ruleset and automated system are implemented, the better.

We will probably see some bad accidents though before the need and pressure for a general system prevails. It was true for shipping and airflight, for the same reasons we have the squabbles and turf wars in space today. Humans in a competitive area seem to tend to act more reactive than proactive when it comes to common interest matters.

[edzieba]

Fwiw the situation is symmetrical.  Don't demand that the other guy move - move your own damn bird.

If you can't (say low on fuel) ask nicely and hope.

Also, an oz of early maneuver is worth a pound of late maneuver.

The point the ESA was trying to make was not so much the need to hash out who moves their spacecraft (and just as importantly, who doesn't move), but that there needs to be a formal framework by which these communications occur rather than through ad-hoc emails and phone calls between operators. There is no current analogue to ADS-B.

[meekGee]

Fwiw the situation is symmetrical.  Don't demand that the other guy move - move your own damn bird.

If you can't (say low on fuel) ask nicely and hope.

Also, an oz of early maneuver is worth a pound of late maneuver.

The point the ESA was trying to make was not so much the need to hash out who moves their spacecraft (and just as importantly, who doesn't move), but that there needs to be a formal framework by which these communications occur rather than through ad-hoc emails and phone calls between operators. There is no current analogue to ADS-B.

And they did it in the least constructive way possible, especially given what we know right now about there being channels and cooperation. 

It was just a PR hit, bad for everyone. The way Wyler and Forbes jumped in was highly indicative.

[edzieba]

In direct contradiction of claims from a certain unsourced Forbes piece, ESA themselves have been pretty clear that they were very happy with how SpaceX corresponded:

by Wednesday 28 August the team decided to reach out to Starlink to discuss their options. Within a day, the Starlink team informed ESA that they had no plan to take action at this point.
[...]
Contact with Starlink early in the process allowed ESA to take conflict-free action later, knowing the second spacecraft would remain where models expected it to be.

[Lar]

It was just a PR hit, bad for everyone. The way Wyler and Forbes jumped in was highly indicative

Wyler appears to be in the process of getting his head handed to him for that... PR stunts often backfire.

[Tywin]

It was just a PR hit, bad for everyone. The way Wyler and Forbes jumped in was highly indicative

Wyler appears to be in the process of getting his head handed to him for that... PR stunts often backfire.

Well looks like he don't give up...

https://twitter.com/greg_wyler/status/1168988584818425857

[meekGee]

It was just a PR hit, bad for everyone. The way Wyler and Forbes jumped in was highly indicative

Wyler appears to be in the process of getting his head handed to him for that... PR stunts often backfire.

Well looks like he don't give up...

https://twitter.com/greg_wyler/status/1168988584818425857

Jesus can you imagine being in business with him?  Sleazeball.