The 6 ton UARS satellite that is due to re-enter the atmospere (this Friday), will likely survive re-entry-meaning that a big hnk of it may hit someone or something.
Why don’t satellites incorporate explosive charges, so that they could be blown up during re-entry? It wold be a lot safer to have smaller chunks coming down.
Also, who insures the SG against damage claims form satellite collisions?
If a building is hit, there may well be extensive loss of life.
They’d probably do damage to other satellites/space stations if they were detonated. It’d put a lot of little pieces of flak in orbit.
Why?
1.) Bombs have weight and take up real estate, both pretty precious on a satellite.
2.) as noted, if you blow up your satellite, parts of it might go into orbits that would endanger other satellites, even if they don’t last long in orbit. We already have too much orbital junk.
3.) The question reminds me of the TV movie Something’s Out There, about an alien ship with a humanoid female and some sort of Alien-esque monster on Board. The Earth guy asks “Don’t you have a self-destruct mechanism on board?” and the alien woman sensibly asks “Why would we have that?” This is one of those SF tropes that has escaped and taken on a life of its own. While “Self Destruct” mechanisms act as a sort of space-age equivalent of “scuttling” wet-navy ships, there’s something unsettling about the idea of your vessel being filled with explosives. I’m sure they wouldn’t tell me if they were doing it, but I doubt if modern military surface ships or airplanes are so equipped. Why would spaceships be? The idea was used believably in the 1964 flick Robinson Crusoe on Mars and arguably in Star Trek III, but it’s still a freaky idea. The explosive might, after all, be set off by accident. TOS The Corbomite Maneuver, after all, was a trick.
4.) Large satellites generally break up on entry. Loo at the size of the pieces of Skylab that hit the ground. Or, regrettably, the space shuttle Columbia.
I see the thought process here - blow it up into many tiny bits that will then all get burned up in the atmosphere instead of having this big honking hunk of metal hit the earth.
However, I’d imagine that once the satellite is blown to smitherines, now you have thousands of objects that would be orbiting earth and pose danger to other satellites and orbiting objects. Those small bits might not have a decaying orbit nearly as quickly as the original satellite, so they could spend years in orbit being litter.
Then there is the issue of detonation - once the satellite orbit decays enough to ensure re-entry, you may be at a point where radio transmission to blow up the explosives is subject to interference. If it doesn’t blow up, now you have an explosive hunk of material that hits the ground and could go kablooie.
Also, due to international treaties, it may be illegal to put any sort of ordinance on orbiting satellites. Not that we in the US like to abide by international treaties - but thats another discussion.
Then, there might be the danger of hauling explosives into space in the first place.
But all those are possibilities that crop up into my mind - but I’d bet dollars to donuts the real reason is that by keeping it in one piece, they can more accurately predict where it will fall - and that probably has a high degree of value. In reality, there is relatively little surface area on earth where a fallen satellite would cause major damage.
NASA’s launch vehicles are typically equipped with auto-destruct devices, but these are intended to be used only during the launch phase so as to protect civilians from an out-of-control vehicle that might otherwise land outside of the exclusion zone (intact and with a substantial quantity of fuel remaining on board).
Although rockets (launchers) do have “range safety” mechanisms for terminating flight, in case they veer off course and threaten populated areas. Even manned spacecraft like the Shuttle have such mechanisms.
But for satellites, I suspect a controlled deorbit is considered equally effective, and wouldn’t require any additional hardware. Some large satellites are deorbited under control at the end of life (e.g. Compton Gama-Ray Observatory). I’m not sure why UARS wasn’t - perhaps the risk wasn’t (and isn’t) considered to be big enough (it’s about 1/3 the mass of CGRO).
Nah, most SF self-destruct mechanisms aren’t actually an explosive charge, anyway, they use the ship’s own power supply or weaponry to cause the damage. In your case of a modern ship, say an aircraft carrier, it’s full of jet fuel, bombs, a high pressure steam system, a nuclear reactor, so on and so forth; of course the crew could destroy or irradiate their own ship if they wanted to, even without a big red button labeled Scuttle. You just have to look at any of the major industrial accidents to see how much damage can be done with minor malfunctions or misuse of tame, conventional machinery. Add an experienced engineer intentionally trying to cause problems and problems will be caused.
None of which is too relevant to a real life satellite, which has the bare minimum of power needed to perform its function. Position-holding thrusters are weak and not up to the task of blowing the thing apart even if they improbably had the function designed in ahead of time. A self-destruct in this case would require a special charge, which means more mass and space, two things that get very expensive when it comes to space launch. What benefit would it provide? It’s not likely to come down, it’s not likely to come down in big enough parts to be dangerous, and it’s not likely to hit anything with those parts even if it does, and it’s not likely to cause liability for the satellite owner anyway due to the legal gray area. It’s costly management of a risk that is very remote.
Nobody in the history of the world has ever been injured by a falling (man made) satellite.
Also, the debri field for this particular satellite is expected to be around 500 miles. I can’t imagine it being “blow up to bits” any more than a bomb would do.
What is SG in this context?
Sorry-I meant “USG”-damn that “U” key!
Which is what, “US Government”? If so, NASA is “self-insured” so it’s responsible for paying any damages.
Would it be against the Space Weapons Treaty?
Being on the launch vehicle, they don’t cost valuab;le satellite cargo space, or fuel (the device on the launch vehicle only has to go partway up – the satellite has to go all the way into orbit, and the launch vehicle needs to carry the fuel to carry the fuel to loft the mass of the sattelite. It’s a helluva lot cheaper putting it on the launch vehicle.
Not to mention that the possibility of malfunction causing detonation is also much, much smaller on the short-livede launcher than on the satellite.
The idea of explosively breaking up the satellite once it’s well into reentry isn’t so silly.
As many people above noted, blowing it up while it’s fully in orbit is a very bad idea. But once it’s actually into the upper reaches of the atmosphere & *just *starting to heat up, the idea of busting the large chunks into smaller chunks to ensure burn-up or slow aero-braked falling rather than an intact high-speed impact makes a certain sense.
The argument against it now is simply that the Earth is very big, and the inhabited parts are a very small fraction of it. And the cost to orbit is very high for each pound of payload. So the cost to prevent the danger is far higher than the cost of the mishap times it’s likelihood.
And no, Ralph, nobody insures the US government against anything. When it has a surprise liability, it just writes a check. As do an awful lot of big companies for a lot of their potential liabilities.
If they put a couple of sticks of dynamite in the satellite, the heat from entering the atmosphere would set off the dynamite and blow it into small enough pieces to burn up.
It wouldn’t have to be a nuclear warhead or anything remotely controlled and by the time it blew up, it would be out of range of the other satellites that we want to keep.
Not to mention that the chance of a problem during launch generally -is- high enough to deserve risk mitigation. The history of spaceflight is full of catastrophic launch failures, and even today they’re still far from unheard of.
It looks like the relevant treaty would be the Outer Space Treaty of 1967, and as far as I can tell it would be OK to place a bomb in orbit so long as it was a conventional explosive and not a nuclear bomb (or a “weapon of mass destruction”–putting nerve gas on your satellite would also be a big no-no, and presumably also something exotic like antimatter). The Soviets reportedly orbited some conventional rapid-fire cannons on their Almaz (military “Salyut”) space stations.
No one I know in the aerospace industry would ever advocate an explosive device to “bring” down a spacecraft. There’s nothing to be gained with weight, volume, increased risk of accidental detonation, and AFAIK, zero flight heritage. The risks of damaging or destroying other satellites makes the idea untenable. And, as one nation found out (indirectly), it wasn’t the brightest idea…
If the satellite detonates in orbit, some the debris will, of course, re-enter the earths atmosphere, but a vast amount of debris will be sent individually into their own unique orbital path. After one orbit, IIRC, that same debris will re-converge back at the point of the explosion’s frame of reference. Should any of this debris hit other spacecraft, given the right circumstances, you can go super-critical, and the debris cloud generated would result with the inability to safely traverse LEO for decades or even hundreds of years.
Witness the case of the PRC: they did an anti-sat test a few years ago and caught hell for the debris field that resulted. The story from what I could gather from aerospace and arms control blogs stated that the leadership signed off on the test, failing to understand what the technical repercussions involved. The leadership presumed the military knew what they were doing. The Chinese military saw this as a way to show off their ASAT capabilities to the US and Russia and decided to hit the S/C in a higher LEO. The result was a debris field that will end up lasting for years and years.
The firestorm that followed (not just by the US and Russia, but Japan, ESA, NASA along with and international businesses) was not anticipated by the PRC’s leadership. Apparently, the PRC’s rocket forces (my term) got a pretty good smack down for test. The PRC hasn’t stop work on ASATs, but you can bet the next test will be on a dead-sat on the hairy edge of reentry, or more practically speaking, launching a target into a very LEO. It also says a lot about the command and control structure between the PRC’s leadership and military (re: not the best).
But getting back to the OP, its so much simpler (presuming you have the fuel) to either 1) decelerate a LEO S/C to allow a burn up during re-entry (you reduce your LEO velocity by several hundred feet per second; gravity will do the rest), or 2) park it into a higher orbit (e. g., GEOs). All GEO’s require station-keeping maneuvers to remain in their respective slots, otherwise they drift into other assigned slots and bad things happen to the owners. Both operations have been done for decades; the risks to other S/C are essentially nil.
Dynamite can burn without exploding; you need a blasting cap to set it off. And both items would require some sort of specification and certification by a military or civilian space agency before they would allowed to launch said items. Not seeing any in my Google-fu