How many {member of} are for {Neil Armstrong} ?
How many space experts support Neil Armstrong?
SELECT (COUNT(?obj) AS ?value ) { wd:Q1615 wdt:P463 ?obj }
SELECT (COUNT(?obj) AS ?objs ) {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q1615> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P463> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> ?obj .
} 

Neil Armstrong is supported by how many space experts?