whAt hAvE givEn mAnkinD A nEw viEwpoint on thE EArth AnD its nEighBors in spACE
A．thosE ExplorAtions.
B．thE ADvAnCE oF nEw tEChnologiEs.
C．spACECrAFt stuDiEs.
D．sCiEntiFiC DisCovEriEs.