The reason for these two year gaps between missions is because the easiest and most cost-effective time to send spacecraft is when Mars and the Earth are the closest together. This happens about every two years, so most spacecraft will be sent between February and September in odd numbered years. (14 mars 1969 – 14 mars 1971)
Ajouté au bande de temps:
Date:
14 mars 1969
14 mars 1971
~ 2 years
