https://www.bbc.com/news/articles/cpwrr58801yo
Somebody moved UK's oldest satellite, and no-one knows who or why
Launched in 1969, just a few months after humans first set foot on the Moon, Skynet-1A was put high above Africa's east coast to relay communications for British forces.
Almost certainly, it was commanded to fire its thrusters in the mid-1970s to take it westwards. The question is who that was and with what authority and purpose?
"It's still relevant because whoever did move Skynet-1A did us few favours," says space consultant Dr Stuart Eves.
[...] "It's now in what we call a 'gravity well' at 105 degrees West longitude, wandering backwards and forwards like a marble at the bottom of a bowl. And unfortunately this brings it close to other satellite traffic on a regular basis.
"Because it's dead, the risk is it might bump into something, and because it's 'our' satellite we're still responsible for it," he explains.
If it didn't become sentient and moved it self, years before the Terminator movie and Skynet became a thing, then someone else did ... or you know Aliens (possibly not of the movie franchise variety -- I really hope those are not real).
Something something the value of proper documentation?
(Score: 5, Insightful) by Rosco P. Coltrane on Monday November 11, @03:52PM (5 children)
.
There, FTFY.
Satellites don't get taken over by randos with a big antenna. That's just not a thing.
(Score: 1, Interesting) by Anonymous Coward on Monday November 11, @04:59PM (2 children)
You'd be surprised.
(Score: 2) by corey on Monday November 11, @09:04PM (1 child)
By what? Share your insight. 🙂
(Score: 3, Informative) by driverless on Tuesday November 12, @01:11AM
It was done some time in the 1980s or early 90s, can't remember the details ATM. Given that this is a 1960s satellite it'd presumably be even easier than the 1980s hack.
(Score: 5, Interesting) by zocalo on Monday November 11, @06:15PM (1 child)
I think we probably just need to apply Occam's Razor here; that it was just moved as part of a maintenance cycle and never moved back for some reason. Maybe they sent it a bad command and locked themselves out, or maybe it just failed during the maintenace and they couldn't move it to a better parking orbit but, whatever the cause, either the USAF never formally sent the UK an update for the official record to say the satellite was dead, or the UK didn't bother logging it and closing out the record properly. Wouldn't be the first time pencil pushers- seperated by an ocean no less - failed to tick all the boxes when the file's going to get closed and archived anyway.
UNIX? They're not even circumcised! Savages!
(Score: 1, Informative) by Anonymous Coward on Monday November 11, @06:38PM
"it's now right over the US, and co-incidentally quite close to the USAF's "Blue Cube" in Sunnyvale, where they'd have undertaken that maintenance from."
The Blue Cube no longer exists.
As I understand it, all operations come through Colorado Springs now.
(Score: 5, Interesting) by pTamok on Monday November 11, @04:29PM (8 children)
Without active station-keeping, geostationary satellites will fall into a (local) gravity well. It's inevitable. It is not unreasonable that if Skynet-1A were almost out of fuel for thrust, you manoeuvre it into the least populated gravity well that it can reach to reduce the likelihood of it damaging something else.
These days, geostationary (and, I think, geosynchronous) satellites are meant to boost themselves into a higher 'graveyard' orbit at the end of their useful life. The delta-V required to de-orbit them is rather large, so that is not an option. Occasionally, people talk about disposing of things by 'throwing them into the Sun' - from the Earth;s orbit, you will use more energy de-orbiting into the Sun than boosting out of the Solar System completely. Orbital mechanics is weird like that.
Unfortunately, gravity wells are popular places, precisely because you need to expend less fuel station keeping. So 'least populated' doesn't mean empty.
(Score: 1, Interesting) by Anonymous Coward on Monday November 11, @04:55PM (7 children)
> Occasionally, people talk about disposing of things by 'throwing them into the Sun' - from the Earth;\'s orbit, you will use more energy de-orbiting into the Sun than boosting out of the Solar System completely.
This seems counter-intuitive, can you provide more detail or point to an explanation?
Thanks in advance...
(Score: 2, Interesting) by Anonymous Coward on Monday November 11, @05:03PM (6 children)
Try calculating solar system escape velocity from Earth's orbit, then figure out velocity due to Earth orbiting the Sun, then add on the velocity of orbit around the Earth. What do you get? I've never done it but would like to know the answer. Maybe later.
(Score: 5, Insightful) by VLM on Monday November 11, @05:52PM (5 children)
Oh I love these math problems on SN.
Earths orbit is 29.78 KM/s around the sun. Note that I'm being lazy because bielliptic transfers take half of forever. Thats like an inclination plane change except you cheat and also do a height change. Its a long story. If you want to take less than a couple hundred years you can't do bielliptic in the solar system. Now if you were writing a hard sci fi story about a civilization that was stable enough for a thousand year project, year mining gold from asteroids and taking "a century" to get it home is quite plausible.
Relative to the sun, you need 42.1 KM/s to escape the solar system. Remember we get 29.78 KM/s "for free" unless you do something idiotic like intentionally try to escape by flying the opposite direction. So it takes about 42.1 - 29.8 KM/s equals 12.3 KM/s to escape the solar system.
Lets do the old fashioned "Guess and check" by checking what it takes to run space probes. What's the delta V for the voyager probes? Now yes yes I realize they did a bunch of gravity assist slingshot nonsense, but apparently voyager 1 separated from the centaur stage around 18.3 KM/s and there was a propulsion module that gave it an extra kick of a couple KM/s (unclear?)
https://en.wikipedia.org/wiki/Voyager_2#/media/File:Voyager_2_velocity_vs_distance_from_sun.svg [wikipedia.org]
There's a cool heliocentric velocity vs the sun showing like 37 ish KM/s peak right after launch?
https://en.wikipedia.org/wiki/MESSENGER [wikipedia.org]
This mission to Mercury took a ton of gravity assists and I can't find actual figures (because I'm lazy) but they burned an entire Delta II and it only weighs 400 Kg so it must have been going fast as hell.
https://en.wikipedia.org/wiki/Delta-v_budget#Interplanetary [wikipedia.org]
Its kind of cheating to just look it up, but delta V to hit the sun seems to be 29.8 KM/s (as you'd guess) and delta V to hit 1 light year (out of solar gravity field) is only 12.3 KM/s Oh yeah that's what I calculated above, good for me!
Note because of the cost of fuel vs the cost to run a RTG for decades, it MIGHT be cheaper to step on the gas and go faster than a Hohmann orbit. 31 years to Neptune is a long time.
(Score: 3, Disagree) by DrkShadow on Monday November 11, @08:51PM (4 children)
Wait, that conclusion doesn't work.
So they wold have to come to a complete stop relative to the sun, and then start going in a reverse orbit a little bit? That doesn't make any sense..
It feels like anything less than the speed of Earth would cause an orbital decay, over some (long? but hastening?) period of time. So it's really a matter of how quickly you want it to happen. The closer you get to the sun, the faster your orbital rate must be (Mercury, 88 days; earth, 365 days; jupiter, 12 earth-years). Then, anything less than the planets in your local vicinity will result in decay-into-the-sun, but may take a while. So it's just how quickly you want that to happen.
The balancing factor to this would be: how easy is it to boost orbit away from the sun? Is it easier to slow down, or easier to boost away? If you boost away, your maintained speed will cause you to leave the solar system, over a prolonged period of time.
There are mulitple variables that can be tweaked, so some decisions must be made. For the same amount of energy (accel) imparted, you should be able to reach two conclusions (one into-sun, one solarsystem-escape), where perhaps the other variable is "time required".
(Score: 2) by corey on Monday November 11, @09:12PM
In my mind-geometry, I’d think if you went into an orbital decay like you describe, you would end up in an elliptical orbit. But it would be good to model it.
(Score: 3, Insightful) by mhajicek on Tuesday November 12, @01:57AM
If you're in solar orbit at 1AU and you slow down a bit, you drop your periapsis and have an elliptical orbit. If you slowed down 25 KM/S, you'd have a very elliptical orbit, but would still miss the sun and come back up to a 1AU apoapsis.
The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek
(Score: 2) by VLM on Tuesday November 12, @01:40PM
Orbital mechanics don't really work that way. Its more like disrupting a spinning top, like precession, if you don't nudge it hard enough it just wobbles.
For a velocity change that's "too small to matter" its more like the following Wikipedia article. Obviously you're firing a rocket to nudge it not relying on a nearby planet but the math is about the same as long as the velocity change is very small.
https://en.wikipedia.org/wiki/Perturbation_(astronomy) [wikipedia.org]
Generally, changing speed at the start point means you'll change a position far away but still more or less pass thru the start point. Unless the change is huge or re-enters the atmosphere or something. Most orbit changes take two burns at opposite "ends" of the orbit.
(Score: 0) by Anonymous Coward on Thursday November 14, @10:30PM
For one body to be in orbit around another, the centripetal acceleration has to balance out acceleration due to gravity exactly. Consider a very large, massive body with a much smaller and less massive one in orbit around it so you can neglect the gravity of the smaller object.
The smaller orbit is in "freefall" around the larger one. Gravity is accelerating it down towards the centre of the larger object and its tangential motion (velocity) must be such that its centripetal acceleration balances the gravitational pull. If the orbiting body is sped up, its orbit becomes higher. It settles at a new height. Conversely, if it's tangential velocity decreases, its orbit lowers and it settles at a lower altitude.
Satellites can be deorbited by slowing them down either by firing thrusters in the opposite direction to the orbit until they encounter atmospheric drag or, if they are already low enough, by angling the solar panels to create drag in the thin atmosphere. This continuously and gradually slows them down until they burn up or fall down to Earth.
To get from Earth to the Sun you would need to slow the spacecraft down considerably to lower its orbit around the Sun. Then, you would probably try to do something with the Sun's outer atmosphere to catch the spacecraft.
The point about escape velocity is that you put in enough kinetic energy (speed) (0.5mv^2) to climb out of the gravitational potential well that you started in. Gravitational potential energy is zero at infinity so the craft gradually slows down and achieves a zero velocity an infinite distance away.
(Score: 2) by Tork on Monday November 11, @07:58PM (4 children)
🏳️🌈 Proud Ally 🏳️🌈
(Score: 3, Insightful) by Frosty Piss on Monday November 11, @08:55PM (3 children)
No. It would certainly have been documented, and probably was. The logs and other documentation almost certainly still exist sts, but is classified at a level that "protects" it's disclosure both in content and existence. This is a point which makes this very interesting in terms of speculation.
(Score: 3, Insightful) by zocalo on Monday November 11, @10:00PM
Besides a simple and genuine clerical error, one other explanation for that did occur to me. The military and intelligence community like to classify things for seemingly arbitrary timescales that quite often seem a far longer than might be realistically be necessary, just in case. It's not uncommon for the UK to set a declassification date for such records a set number of decades after an event, or the death of a given involved individual, and the UK media sometimes reports on these when they concern significant events and new information is finally declassified. Maybe it's simply a case that the RAF and USAF wanted to bury any explicit confirmation that the bird was dead away from any foreign intelligence communities, and thereby keep them guessing. We're just shy of 50 years since the last logfile, so perhaps we'll get an answer in 2027, or just have to wait another number of decades beyond that before the missing records are finally made public.
UNIX? They're not even circumcised! Savages!
(Score: 3, Funny) by mhajicek on Tuesday November 12, @02:01AM (1 child)
That documentation would have been on paper. Paper can be accidentally lost or destroyed much more easily than digital records on a system with proper backups.
The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek
(Score: 0) by Anonymous Coward on Thursday November 14, @10:43PM
Punched cards [wikipedia.org]
(Score: 1, Funny) by Anonymous Coward on Tuesday November 12, @08:37AM