美国从1972年～1984年先后发射了5颗陆地卫星。目前,轨道上运行的卫星有陆地卫星4和陆地卫星5。陆地卫星4已发生故障,原拟将其用航天飞机回收修理后再放回轨道飞行,但由于1986年1月挑战者号航天飞机爆炸未能实现。目前只有陆地卫星5在轨正常工作。1989年底若不发射陆地卫星6,则有业务中断之虑。法国从1986年2月发射第一颗斯波特卫星1以后,欲在1989年下半年发射斯波特2卫星,1991年发射斯波特3卫星。前两颗斯波特卫星加上地面上的接收站设备在内耗资约 The United States has successively launched five land satellites from 1972 to 1984. Currently, orbiting satellites are Landsat 4 and Landsat 5. Landsat 4 had failed and was originally planned to be recovered and put into orbital flight by a space shuttle, but due to the unmanageable explosion of the Challenger space shuttle in January 1986. Currently, only terrestrial satellites 5 are in normal working order. If the land-based satellites were not launched at the end of 1989, 6 there would be some business interruptions. After France launched the first Spur satellite 1 in February 1986, it wants to launch a second Scott-2 satellite in the second half of 1989 and a Sprint 3 satellite in 1991. The first two Sputter satellites plus receiving equipment on the ground, including about