‘Too Close for Comfort’: Two Satellites Nearly Collide Above Earth
29 Feb 2024 15:13:20 UTC
Topic 230821
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FYI ; Though this short article has nothing to do with Einstein or BOINC, I thought it was interesting to say the least.
https://gizmodo.com/satellite-near-miss-leo-labs-fcc-rules-space-safety-1851293980
George
Proud member of the Old Farts Association
For a while they had the Big
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For a while they had the Big Space Theory ie. there's so much volume that a collision would be well nigh impossible, so just launch away and don't worry. Now there's a bazillion such objects ( trackable or not ) and it's a layer of fuzz in low Earth orbit now. To launch you have to time the moment with respect to mission objectives but also in regard to that layer.
This is similar to the Big Sky Theory for aeroplanes. I was once on a passenger jet and I looked out the window - it was a fine day above the clouds - and a plane came from the distance and kept coming in at a constant bearing, the sign of intersecting tracks. Fortunately it passed below us about 1000 feet away. I believe that's classed as a close encounter and so I turned to my wife and said that we had just had a close encounter, but the comment fell flat as she thought I was talking of UFOs!
Now I know there are rules about flight height levels visa vee direction of motion - I forget the exact rules I learnt when I was piloting small planes - but that can still be unnerving when it happens. That's why you have to set your altimeter at the deemed/measured sea level pressure ( called QNH ) when in some flight area. Then everyone agrees on the flight levels. You actually follow a varying curve if one stays at the same height as measured by air pressure, as you cross weather systems, but everyone will also vary likewise.
Now in Earth orbit space, assuming you don't have infinite fuel, the tracks are governed by Newton etc and so twenty metres is really close. One wonders what the relative velocity b/w these satellites was. I know that occasionally they slightly alter the space station's orbit to reduce chances of collision. Sadly, we have made a mess of low Earth orbit.
If you want really bigger volumes then outer space is the go. For instance the Voyager craft, and others going to the outer planets, can just go through the asteroid belt without much concern as the asteroids are really quite separated in fact. That way one can pump up Sun orbits by using inner planetary encounters to boost speed for an asteroid belt transit.
Cheers, Mike.
(edit) “Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.”
― Douglas Adams, The Hitchhiker’s Guide to the Galaxy
But his best quote, IMHO, is "I'd far rather be happy than right any day” which nicely summarises much of what passes for science these days - String Theory etc ..... but not here at E@H though.
(edit) Also see this report
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal
One would think the US
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One would think the US Space Force would be able to hop into one of it's vehicles and jet up there and attach a retrograde device to it and direct it back down to Earth in a way it ends up over an ocean. Look out below ships!! That would certainly be alot better than lasering it to bits and 'hoping' it comes down safely.
Mike Hewson who 'owns' satellites like that? Does the launching country/agency/people still own it or because it's defunct is it 'fair game' for recyclers? Also would it just be easier to send it towards the Asteroid Belt or the Sun instead of back to Earth? What about the difficulties to send it away or towards the Earth if you exclude the cost of getting yourself to the satellite with the proper hardware to do it? What about sending it towards another planet besides Earth, ie a gas giant or even Mercury or Venus? Before you answer I'm not looking for a graduate degree in Science just a quick thumbnail idea of the difficulties of each. Thank you for your time!!
As for the Science part of it I'd think Elon Musk would be all over this as he has access to the funding and Science people to launch small devices that can clamp onto a satellite and then direct them this way or that as he already does that with his Direct tv satellites by moving them around now. The 'hard' part would be matching speeds and orbital tracks so you aren't meeting at 17K kph and trying to grab them as they go whizzing by. The movies already showed the improbabilities of doing that when they caught Whatley in the movie The Martian with Matt Damon.
Ah, yes. We could send Matt
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Ah, yes. We could send Matt Damon up there! :-)
I suspect it is the entity that launched it that owns the defunct satellite, that's what ChatGPT says, but I don't know what little space law there is.
However there's no law of physics stopping anyone removing satellites from orbit. Retrograde into the atmosphere to burn up harmlessly would be my favourite, if you do it over a big ocean. It's the expense and the will to do it that is lacking really. Low Earth orbit is, well, low. So to send it elsewhere - the Sun or a planet - would require rising out of Earth's potential well before going elsewhere. That costs a lot of fuel and not likely to be kept onboard an LEO craft. Look at the size of the Saturn 5 stack at launch, and that was merely to send a few tonnes to the Moon. But you are right about the velocity matching, it's a matter of some finesse to do that right. But it certainly worked in the James Bond movie You Only Live Twice, as long as you creep up from behind it with the right music!
Forward looking one could 'require' by treaty perhaps that each such craft when launched contain the instruments of it's demise. It is not uncommon for geostationary satellites to have some fuel left at the end of it's useful career, that would suit to 'park' the craft out of the way. It is quite crowded up at the favoured geostationary band already.
Cheers, Mike.
(edit) I can't even rendezvous with KSP (without Mechjeb). The 'whizz-by factor' is strong in this one. :-(
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal
Mike Hewson wrote: Ah, yes.
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Thank you
One of the articles that popped up said that there is an International Treaty that everyone abides by now that says when a satellite has reached it's end of life that it be de-orbited but that the old Russian one the other day was sent up before that so it is just flying junk. Both the Russians and the US send up small 'unmanned' space planes now, they used to be manned but now they are truly unmanned, supposedly anyway, but again the 'whizz-by factor' means alot of extra fuel just to catch up to something, or slow down so it only slowly catches you as the case may be.
I too thought that de-orbiting would be much easier but thought of 'being in Space' could offset that so thanks for debunking that idea for me. If there wasn't so much stuff up there a slight Earthward nudge would eventually send it back down but with all the stuff between it and the path back to Earth more than a gentle nudge would be needed.
Thank you both for commenting
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Thank you both for commenting on my "interesting" link.
If the 'new' law or rule for de-orbiting a satellite after it's normal usage was executed to bring it down over a big ocean, would it not also be prudent to set an explosive devise in the satellite to explode once it was in the high atmosphere so that many of the smaller debris items - including fuel - were to burn up in the atmosphere before actually reaching the ocean? Also, this would be much better than exploding it in space and having all of the debris just be much more junk items in space to potentially collide with another satellite or manned spacecraft.
It would seem to me that this would be a better solution than having a big satellite come down with some of it still being big enough to do a splash down in the ocean and potentially contaminating the ocean or even affecting the animal life in the ocean.
Proud member of the Old Farts Association
GWGeorge007 wrote: Thank you
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I think the answer is both yes and no, yes if the timing was perfect but NO if it was off by even a few seconds. Too early and you have stuff still in orbit that could hit other things, too late and you can't control where it comes down anymore. I think bigger pieces can be easier to control where they come down, though there are problay a gazillion things that can affect it like what if there's a hurricane where you want it to come down, etc etc. Sometimes it's just coming down no matter what you do so planning to put it in a large body of water means it will probably never again be seen by man. Look how long it took to find the Gus Grissom capsule and they KNEW where it hit the water!!
I understand the thought
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I understand the thought process. However the place you need to send a command to detonate 99% won't be in range of a ground station. Also at that point on the way down there is a huge ionization cloud around the item blocking radio transmission.
Plan B design the craft into sections with the connections between the sections made to easily melt apart At least you have now smaller pieces to melt. Fuel tank still likely makes it to the ground.
Gary Charpentier wrote: I
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HEADS UP!!!
The SpaceX Starlink
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The SpaceX Starlink satellites are designed under a requirement that no piece of them survives re-entry. Apparently this was somewhat difficult to comply with for the laser interlinks.
While not schoolbus size, the Starlink satellites are not at all tiny. Other makers could do this, if they took the trouble. Of course most other makers are not planning to get up past 10,000 in orbit either.
archae86 wrote: The SpaceX
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Hmm I thought they were small, countertop microwave sized, but that's cool that they are designed to disintegrate on reentry. I also know they can be moved, don't know how much though, as he deorbited some not long ago and 'moved' others that were only slightly out of position.