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.
在这20 个研发收缩的行业中，超过半数行业（11 个）披露研发投入的企业数量仍在增加，可能存在整体研发投入的结构性调整。
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This story was originally featured on Fortune.com
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