Another additional hurdle, developing tiny GPS receiver chips that could be embedded yet still be sensitive enough to receive signals from thousands of miles out in space.

• 而另一个不可忽视的因素则是全球定位系统信息接收芯片，它不但要能植入人体内，并且还应有足够的灵敏度，以接收来自几千英里外的太空定位卫星群发来的信息。