what were the results of the sample-return missions in 1969, 1970, 1971 1974 and 1975?
the sample-return missions failed were kosmos 300 and kosmos 305 in 1969, luna e-8-5 no. 405 in 1970, luna e-8-5m no. 412 in 1975 at unsuccessful launches and luna 18 in 1971 and luna 23 in 1974 at unsuccessful landings on the moon.