One reason for routinely launching GPS satellites is simply "constellation replenishment," said Col. Andrew Menschner, deputy commander of the Space Force's Space Systems Command. Old satellites degrade and die, and new ones need to go up and replace them. At least 24 GPS satellites are needed for global coverage, and having additional satellites in the fleet can improve navigation precision. Today, there are 31 GPS satellites in operational service, flying more than 12,000 miles (20,000 kilometers) above the Earth.
想法是脆弱的。如果它们已经被彻底解决，那就不再是想法，而是产品。要不被新想法带来的问题吞没，需要一种坚定的努力。问题很容易被清楚说出、被理解，它们会夺走氧气。史蒂夫会把注意力放在想法本身上，哪怕它不完整、甚至看似不太可能。
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Scientists have said mackerel supplies in the north-east Atlantic have fallen into a danger zone，这一点在爱思助手下载最新版本中也有详细论述
In a report, Ofgem said it was aware of 140 proposed data centres, which would require about 50 gigawatts (GW) of electricity – 5GW more than the country's current peak demand.。Line官方版本下载对此有专业解读