ESA satellite dodges 'mega constellation' | Hacker News Reader

ESA satellite dodges 'mega constellation'

theregister.co.uk

41 pointsbaud14725853 comments

Two things from this article that surprised me:

> The ESA operations team confirmed that this morning's manoeuvre took place approximately half an orbit before the potential pileup.

Half an orbit is mightily late. It's a last minute emergency correction in space terms. Given that both Aeolus and Starlink satellites are active missions, how come they didn't realize and correct this sooner?

And related:

> If plans to orbit thousands more satellites (to bring broadband to remote areas, or inflict it on air-travellers, for example) come to fruition, the ESA team reckons that things will need to be a lot more automated.

Maybe it's because I didn't get far enough in the space industry handbook I'm reading, but I was sure orbital tracking and detecting potential collisions was automated already. There should be continuously running simulations that are constantly fed fresh TLEs from tracking stations, that check whether or not anything is going to collide with anything else in the nearby future.

According to the other article I read about it (https://www.forbes.com/sites/jonathanocallaghan/2019/09/02/s...) they knew about it earlier but Starlink refused to move their satelite.

So, they were playing chicken? And Starlink won?

No.

Jonathan O’Callaghan published his extremely biased and inflammatory clickbait before waiting for SpaceX to present their side of the story (time from ESA tweet to Jonathan’s story was about three hours).

What actually happened is that SpaceX communicated their intention to take no action based on a much earlier estimate of extremely low collision risk. A later update from the US Air Force got lost in the mail filter, so SpaceX never read it otherwise they would have contacted ESA immediately.

Here is Loren Grush with a more mature and less inflammatory take on the topic: https://www.theverge.com/2019/9/3/20847243/spacex-starlink-s...

In time we will get a more thorough understanding of what happened, but the ESA’s fundamental point is emphasised by SpaceX’s experience: having to coordinate satellite operations through email that is handled by humans is fundamentally unworkable, and something needs to be done about automating everything before the megaconstellations take to the sky.

Probably because Aeolus is a more expensive asset than a StarLink sat, their threshold is also higher.

They didn't "refuse" since they were never asked to move their satellite. They chose not to, possibly because the risk did not meet their threshold for avoidance.

There's a bit more analysis over at the SpaceX subreddit [1]. Basically it seems that they are dodging one of the Starlink satellites that's going through deorbit testing. Some speculation over there as to why but likely it just seems the two companies have different risk appetite.

[1] https://www.reddit.com/r/spacex/comments/cypvjv/this_morning...

That subreddit is such a weird place.

It's 100% the best source for information about SpaceX, about future launches, past launches, history, future, everything. If you want the latest information on SpaceX, you cannot find a better place. Well moderated, well maintained, up to date info- they achieve what we all thought the internet would be capable of.

But it's also, imho, a bit too far into the "SpaceX/Elon can do no wrong" echo chamber. Well, some of the folks there are. They want what SpaceX is promising (Starship! Mars colonies!) so very badly. Heck, I do too. But it's not a great place to criticize the company. I've found that people there judge SpaceX on their best intentions and everyone else on their actual results.

That said, if I type "re" into my URL bar, it autocompletes to "reddit.com/r/spacex/" immediately. Because seriously, what a great source of information for space nerds like me.

>should be continuously running simulations that are constantly fed fresh TLEs from tracking stations, that check whether or not anything is going to collide

I'm ready to bet that they do this already, and that collision detection is automated indeed. However given the very high cost of orbital maneuvers (can't refuel a sat, so there's a limited quantity of delta v corrections you can do) there's probably a backlog of possible collisions to be checked and acted on manually. The ops team gets to it when they get to it.

I think there is somewhat of a wild west on orbit. Even in the case of known, active missions the parties in a "potential collision" may have different opinions about actual likelihood of the collision: "collision likely" usually means an estimate that both bodies will occupy the same 10-50m volume, but they may or may not actually collide. Based on this each party may decide whether they want to spend limited fuel on maneuver. Or take their chances. Or wait if the other party blinks first.

Add a ton of sats launched by spooks from multiple governments and agencies (who do not want positions of their sats known and may maneuver more frequently) add a whole new layer to this. Just my 2c -- I am not an expert; current setup may be better managed.

>Half an orbit is mightily late.

It makes perfect sense. If you did the manoeuvre earlier, there's more chance that drift in both satelite's orbits will bring them back closer again. By doing it half an orbit before, they can work from the most precise measurements of the two satelite's relative positions and calculate a minimum burn for an avoidance trajectory.

Also a burn at a given point offsets your relative altitude by the maximum amount at the opposite point in the orbit, half an orbit away. So you'll want to burn half an orbit (or an odd number of half orbits) from the point of intersection.

Yes, I knew how burns affect orbits, I was just surprised that they did that burn at the last possible optimal moment, and not, say, 10 and a half orbit before.

Why is half an orbit late? Admittedly, my knowledge of orbital dynamics mostly comes from kerbal space program but isn't half an orbit exactly when you'll have the most maneuverability relative to the collision point? 1/2+n orbits and you're just spending more time in the alternate orbit without increasing your ability to avoid the collision.

It's late because it's the last moment you can do this cheaply in terms of Δv. I expected them to do it n + 1/2 orbit before potential collision, with n = being at least 1, and more like 10 or 20.

From the author of a Forbes article on the same subject:

https://twitter.com/Astro_Jonny/status/1168859502067834881

"Just to quickly clarify again @FastCompany et al, ESA did NOT ask SpaceX to move. SpaceX simply said they would not move their #Starlink satellite, necessitating an evasive manoeuvre from #Aeolus."

https://twitter.com/Astro_Jonny/status/1168833920118480898

"I'm not sure on the exact timeline but yes, ESA was alerted to the event five days before. Three days prior, they noted a raised collision risk. One day before, they decided to move. SpaceX sent one email saying they had no plans to manoeuvre."

That was published before the author had any response from SpaceX (it looks like he gave them an hour or two to respond before publishing).

Here’s Loren Grush with more info: https://www.theverge.com/2019/9/3/20847243/spacex-starlink-s...

This is hardly a 'first'. ESA felt their satellite was being obstructed by SpaceX who moved into the space much later and didn't act responsibly as they should have. So ESA decided to send out a press release.

Yeah, you can feel the bad blood behind the press release.

Basically ESA nicely asked SpaceX to maneuver their sat and shorten its lifetime - they don't have a legal basis or enforcement mechanism anyway. SpaceX pretended not to hear until it was too late and ESA went ahead with their contingency plan of burning their own sat's fuel and lifetime instead.

ESA said they didn't ask spacex to move their sat, they just said they let them know. Spacex replied they had no intention to move their sat, since it was in deorbit testing.

If it was really about burning fuel, ESA would not have waited until half an orbit before. The longer you wait, the more you have to burn.

Not really.

a. They did an altitude increase. There's no real gains from an earlier burn that one might get when doing something like a hohmann transfer.

b. Half an orbit before out means more/better telemetry to work with.

c. They are from a quick google, well within the range where atmospheric drag plays a role, and you need to do station keeping. leaving it this late means you don't "waste" fuel from drag.

Admittedly, my only credentials for this are a few thousand hours in KSP and reading around the subject. Anyone with a proper degree on this is welcome to correct me.

In that case they were simply adjusting their station keeping schedule and minimum (if any) fuel would be wasted.

If that wasn't the case, they could raise or lower the altitude slightly several orbits before the "event" causing them to arrive at the intersection point earlier or later. For a desired time delta, the sooner your perform your altitude change the smaller the changed required.

Sure, but I'm positive the ESA's argument is their fuel burn should have been zero.

I haven't seen any mention of ESA "nicely asking" SpaceX to maneuver. Is that referenced in another article?

The sat in question was in deorbit testing, it's lifetime was already short.

Yeah, but ESA message is clear that space needs some regulation, now there is no rule who should do the avoidance, with more and more satellites you need some defined rules and coordination on handling this incidents. Also I am wondering if some cheap satellite destroys a expensive scientific one is there a law that could apply for recovering some damages and act as a incentive to prevent such a thing?

As far as I know, everything that is sent into space is the responsibility of the nation that launched it and governed by its laws. So if two satellites were owned by organizations from the same country, that country's legal system would have to deal with the damages. I am not sure if the space treaties actually cover the case where multiple nations are involved. I wouldn't bet on it.

As for the second question yes, the Space Liability Convention contemplates joint launches, see article V here: http://www.unoosa.org/pdf/gares/ARES_26_2777E.pdf

> I am not sure if the space treaties actually cover the case where multiple nations are involved. I wouldn't bet on it.

I would.

https://en.wikipedia.org/wiki/Space_Liability_Convention

> States (countries) bear international responsibility for all space objects that are launched within their territory. This means that regardless of who launches the space object, if it was launched from State A's territory, or from State A's facility, or if State A caused the launch to happen, then State A is fully liable for damages that result from that space object.

So for cars we have clear rules like on intersection who has the priority, on an incline, etc . It seems that in this case there are no rules, the SpaceX was following the rules but ESA thinks it was to risky or SpaceX are incompetent and could not do anything and couldn't even produce a response in time.

Yeah, at the moment, this sort of issue is an after-the-fact thing. Determining fault would probably be a diplomatic and multi-national legal fuss that stretches for years.

ESA felt no such thing. What you are recalling here is Jonathan O’Calaghan’s opinion that whoever was in an orbit first automatically has right of way.

ESA’s take on the matter is that it was annoying that they couldn’t contact SpaceX, and that relying on email and phone calls between humans is not going to work when there are tens of thousands of satellites in orbit.

The Twitter thread which started this was about ESA’s plans to automate their entire collision detection and avoidance process, and a call for an industry consensus on processes and protocols for communicating facts and intentions between satellite operators, and a set of rules and policies for managing space traffic, similar to what is done for international air traffic today.

This all happened at 320km, which is way below the Starlink constellation operating elevation. So the satellite in question is either one that is undergoing de-orbit testing, or is not functioning correctly which likely means SpaceX couldn't move it if they wanted to.

Very, very misleading to say the ESA had to dodge the "mega constellation".

They were doing de-orbit testing on that satellite, "Starlink 44" [0]

[0] https://www.technologyreview.com/f/614250/one-of-spacexs-sta...

The register does seem to have a penchant for hyperbole.

Penchant? It's why they get out of bed in the morning.

That it was a single satellite, in de-orbit testing, was mentioned in the text of the article.

> Hmmm. We move our satellites on average once a week and don't put out a press release to say who we maneuvered around...

- https://twitter.com/IridiumBoss/status/1168582141128650753

> Normal part of flying satellites (or should be). Does BA announce every time one of its airplanes steers around a Ryanair aircraft?

- https://twitter.com/IridiumBoss/status/1168607146646364160

CEO of Iridium, an existing not-mega constellation that Starlink is arguably going to make obsolete. When a competitor is coming in and calling this unnecessary drama, you have to wonder if the ESA has a leg to stand on or is doing this for political pandering.

They have lots of political reasons to do this too. Attempting to acquire more regulatory authority. Attempting to acquire funding for projects like AI collision avoidance (https://twitter.com/esaoperations/status/1168540912282165248). Maybe even attempting to slow down a competitor to their Ariane rocket family...

PS. the other recent tweets by the CEO of iridium are also interesting and relevant: https://twitter.com/IridiumBoss/with_replies

This article has some questionable word choices.

"We contacted SpaceX to get its take on ESA's antics, but nothing has yet emerged from Musk's media orifice"

"In 2018, the boffins keeping track of things"

Is this considered professional journalism nowadays?

Many British publications use the term.

boffin: Noun (British informal) A person engaged in scientific or technical research. [1]

It appears regularly in the Economist, too [2].

[1] https://www.lexico.com/en/definition/boffin

[2] https://www.economist.com/middle-east-and-africa/2019/08/08/...

You don't often hear Orifice though

That's just the Register. Check out some of their other articles, they pretty much have the same kind of jokes.

El-Reg has been a staple of IT news reporting since the 90's, this is their house style. It's an irreverent play on the red top style of reporting used by British tabloids.

I love that publication and how the register makes fun of the big tech companies, like calling google "the chocolate factory".

That and "fondle slabs" for Apple devices. It's been my daily coffee-break read since they started all those years ago. I don't know if it's the case now, but they wore their ban from Apple events (for not showing enough fawning) as a badge of pride for many years.

This is the normal style of The Register.

The register is a very reputable news site, known for their tabloid-parody style with crude jokes, but very good reporting. They've been around since 1994.

"Is this considered professional journalism nowadays?". No, it's just how that site uses English. They probably think it's funny or something. It's trivial to find an alternative sites for the story.

Don't confuse professional with dry and boring.

> Our starlink team last exchanged an email with the Aeolus operations team on August 28, when the probability of a collision was only in the 2.2e-5 range (or 1 in 50k), well below the 1e-4 (or 1 in 10k) industry standard threshold and 75 time slower than the final estimate. At that point, both SpaceX and ESA determined a maneuver was not necessary. Then, the U.S. Air Force's updates showed the probability increased to 1.69e-3 (or more than 1 in 10k) but a bug in our on-call paging system prevented the Starlink operator from seeing the follow on correspondence on this probability increase - SpaceX is still investigating the issue and will implement corrective actions. However, had the Starlink operator seen the correspondence, we would have coordinated with ESA to determine best approach with their continuing with their maneuver or our performing a maneuver."

Reportedly an official SpaceX Statement (typos are probably mine)

https://twitter.com/lorengrush/status/1168917747109191681?s=...

"[...]but nothing has yet emerged from Musk's media orifice."

Typo or colorful word choice?

You don't know _The Register_? Take a look at the rest of the site: wordplay like that is their chosen style.

While space may be infinite, the parking spots closest to the door ain’t - why are we even talking about letting commercial entities taking up so much LEO space without some kind of ride share clause? This is ESA we are talking about, a pan-national agency working solely for the common good of humanity. Should they move for a prototype of the next AT&T global monopoly?

Reply on news.ycombinator.com