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Eu_sst: 20% probability for large satellite collision

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Re: Eu_sst: 20% probability for large satellite collision

#61

Post by mindslight »

airza wrote: post #41
est31 wrote: post #19

Earlier quoted context omitted.

You're running Javascript. It's sandboxed, which is why I have it enabled by default, but often the javascript in a website is made to spy on you and your behaviour. It's not on your side but on the side of the people who made the website. Personally I'm ok when something like discord breaks as it contains real time updates. But twitter just displays a bunch of text and pictues in a non real time manner. Even video c…

That's not arbitrary code in the security sense though. It's the very narrow range of things which are permitted to run in a javascript sandbox (more or less "things javascript can do in a web browser context, minus the extremely small chance someone is trying to drop a JS 0day on you using this link")

> That's not arbitrary code in the security sense though

Yes it is. It's not system level, but it is indeed arbitrary code - users have no lasting visibility into what it's doing, and little ability to control it.

> It's the very narrow range of things which are permitted to run in a javascript sandbox

Browsers have had a pretty naive threat model, up until recent Firefox with its new resist fingerprinting feature. Seemingly innocuous things like reporting your window size are vulnerabilities that are being used to track you, because the groups who designed the various web APIs had no security mindset besides sandboxing. One of the chief browser makers is even an unabashed surveillance company! It's going to take a long time to close or mitigate all those holes.

Re: Eu_sst: 20% probability for large satellite collision

#63

Post by iSnow »

marshmallow_12 wrote: post #47

it's 2021 now. They have presumably been tracking the orbits of there large objects for years now. Yes this is literally rocket science, but this collision is only a few hours away. Why can't they do better then a vague 20%?

My guess would be because sats are not perfect spheres but - esp in the case of a rocket stage like here - complex objects which have non-trivial rotation patterns because the center of gravity might be off the visible center. So I doubt they model each and every piece of space junk out there to get a super detailed prediction - after all, what can you do if you know 95% it's going to be a hit between do dead sats vs if you know 80%.

Radar resolution of civil orgs might also be a limit.

Re: Eu_sst: 20% probability for large satellite collision

#64

Post by Rebelgecko »

marshmallow_12 wrote: post #47

it's 2021 now. They have presumably been tracking the orbits of there large objects for years now. Yes this is literally rocket science, but this collision is only a few hours away. Why can't they do better then a vague 20%?

The objects are about 500 miles up in the sky, potentially thousands of miles from the sensors looking at them, and traveling at 15,000 miles per hour with respect to us. Think about how precise your measurements would need to be to accurately predict the objects' positions in 24 hours to the nearest foot!

And that's the difficulty with the simplifying (and wrong) assumption that that outside forces don't alter the orbit- even 2021, we have a lot of room for improvement when it comes to predicting many of the other factors that come into play, like solar activity and the Earth's climate.

Re: Eu_sst: 20% probability for large satellite collision

#65

Post by iSnow »

junon wrote: post #54
marshmallow_12 wrote: post #47

it's 2021 now. They have presumably been tracking the orbits of there large objects for years now. Yes this is literally rocket science, but this collision is only a few hours away. Why can't they do better then a vague 20%?

You're right; do some analysis yourself and tell us your findings ASAP please :)

Snarky replies aren't really helpful as an answer to a question - even if it was in loaded form.

Re: Eu_sst: 20% probability for large satellite collision

#67

Post by mikewarot »

marshmallow_12 wrote: post #47

it's 2021 now. They have presumably been tracking the orbits of there large objects for years now. Yes this is literally rocket science, but this collision is only a few hours away. Why can't they do better then a vague 20%?

You have random pieces of objects which may have already been impacted, tumbling, being pushed on by the solar wind, faint traces of Earth's atmosphere, and being tugged by electromagnetic and tidal effects.

These pieces are in orbit at many thousands of miles per hour, and have a random radar cross section, depending again, on whatever random impacts have already done to them, their orientation, composition.

The radar itself to track them must pass through the ionosphere, which itself causes variable time delays and phase shifts. Smaller objects return signals just above the noise after correlation in the receiver, most of them are just at the noise floor.

Observations only happen when the objects are in site of the tracking ground stations, which only cover a small portion of the sky, not including the expected collision volume.

All of that is just what I could recall might effect predictions off the top of my head... I'm amazed they can make predictions with any level of certainty.

Re: Eu_sst: 20% probability for large satellite collision

#68

Post by superkuh »

andrepd wrote: post #48
superkuh wrote: post #2

Here's the text without having to execute arbitrary code from twitter. --- Update: according to #EUSST's latest estimates using data from its surveillance radars, the close approach between #space objects SL-8 R/B & OPS 6182 expected by tomorrow will have a miss distance under 10m and a Scaled Probability of Collision over 20%! +updates to follow soon See the below plot for the conjunction plane at Time of Close Appr…

Replace `twitter.com` with `nitter.eu`: https://nitter.eu/EU_SST/status/1380120766071635968

I was pretty excited when I found out about nitter. After some months I realized that every nitter mirror only stays up for a few weeks before it becomes so popular it's throttled most of the time (like nitter.net).

Also, it's 17:41 UTC now... the events of this post should be occuring now. Or not occuring.

Re: Eu_sst: 20% probability for large satellite collision

#69

Post by gerikson »

salamander014 wrote: post #46
mikewarot wrote: post #38

Tangent: I went to find UTC, and they've redesigned time.gov, it looks great on my desktop. https://time.gov/

My personal favorite time/NTP website is https://time.is/ https://time.is/UTC

Love time.is. You can embed JS from them in your own webpages for custom clocks.
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