what is the {start time} for {John Glenn} has {occupation} as {astronaut} ?
In what year did John Glenn achieve becoming an astronaut?
When did John Glenn become an astronaut?
SELECT ?u WHERE { ?p property:start_time ?u . resource:John_Glenn property:occupation ?p . ?p property:occupation resource:astronaut }
select distinct ?value  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q182642> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P106> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q11631> .
?statement <http://www.wikidata.org/entity/P580> ?value. 
} 

SELECT ?value WHERE { wd:Q182642 p:P106 ?s . ?s ps:P106 wd:Q11631 . ?s pq:P580 ?value}