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from the what-goes-up-must-come-down-oops dept.
It seems that China has done it again, they have a history of dropping rocket parts on their own people. This time no one was hurt, but Tech Review mentions some previous events that didn't have a happy ending.
It's the latest incident in China's long history with falling rocket parts causing destruction below. The most infamous crash occurred in 1996, when the first Long March 3B launch saw the rocket veer off course and crash into a village, killing an unknown number of people (possibly hundreds, by some Western estimates).
"Any time you have stuff going up, there's a possibility it's going to come down where you don't plan for it," says Victoria Samson at the Secure World Foundation. "So there's a reason why you don't fire over populated land." That's why most countries launch over water.
So why doesn't China? "This entire issue is down to geography," says Thomas Roberts, a former aerospace security fellow at the Center for Strategic and International Studies. All three of China's main spaceports are located in the mainland, including the Xichang site. They all save money by flying missions east (which requires less fuel to get into space), but that route takes them over vulnerable populations.
China issues evacuation notices to communities downrange, but even if people aren't harmed or killed by the physical impact of a crash or by direct exposure to rocket fuel (which can lead to severe organ failure or cancer), the wreckage could pollute nearby rivers and streams used for irrigation and drinking water. Launches from the Soviet Union's old Baikonur Cosmodrome in Kazakhstan, built in 1955, have caused more than 2,500 tons of debris to rain down on the surrounding region, leading to health problems for thousands.
[...] China could also just change its flight paths. For example, Israel's Palmachim Airbase can't launch to the east because of obvious geopolitical conflicts. So it sends rockets over the Mediterranean Sea and through the Strait of Gibraltar. This requires putting a satellite in a retrograde orbit—one that moves in the opposite direction of Earth's rotation. This requires much more fuel, but it entirely avoids populated areas.
(Score: 0) by Anonymous Coward on Sunday December 01 2019, @02:56PM (4 children)
∆v is indeed the amount of force needed to maneuver mass against gravitational forces. It's not a fixed value because it depends on the mass of the object being moved, the gravity acting against it, and the aerodynamics from atmospheric drag.
(Score: 0) by Anonymous Coward on Sunday December 01 2019, @02:59PM
And he doubles down on dumb. Isn't the internet awesome?
(Score: 1) by khallow on Sunday December 01 2019, @03:19PM (2 children)
No. Gravitational losses are a thing, but delta-v still is not a force. And no matter how awesome your engines could be, you're limited by how much force your payload can endure and in turn that acceleration limit constrains just how much you can reduce gravity losses. For example, humans just aren't going to handle 250 G of acceleration without pancaking, so there is always going to be some loss of delta-v to gravity losses (effectively 100-200 m/s out of 7-8 km/s to orbit with max acceleration under 5 G, IIRC).
(Score: 2) by FatPhil on Sunday December 01 2019, @10:51PM (1 child)
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 2, Interesting) by khallow on Monday December 02 2019, @02:14AM