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.
在城市化和房地产的浪潮中，我们似乎都在奔向一个更广阔的世界。但我已经在这里，见过世界最好的模样。
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更重要的是，这里的医护人员，能和患者建立长期稳定的关系，工作有成就感；再加上宜居的生活环境，很多医护人员一旦入职，就愿意长期留下来。
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