Assertion: solar system's planet | /r/HasProperty | early targets
Facets:
value: for exploration
type: PURPOSE
value: because of this
type: CAUSE
value: because of their relative closeness to earth
type: CAUSE
Source sentences:
text: Accordingly, the planets in this zone have long been viewed as possible abodes of life and were early targets for exploration because of this and because of their relative closeness to Earth.