Today, there are three main types of space sail: solar ( the one NASA plans to test), electric (being developed in Finland) and magnetic (a concept popular in the 1980s that never quite took off).
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由此证明磁记忆信号的幅度和梯度既与材料所处的整体应力有关,也与该部位的局部应力集中度有关。
The amplitude and gradient of MMMT signals not only relied on the average stress of the shell, but also relied on the local stress concentration.