Assertion: exobiology | /r/HasProperty | understood
Facets:
value: thoroughly
type: DEGREE
Source sentences:
text: Sagan and Coleman assumed that about 60 missions to the Mars surface would occur before the exobiology of Mars is thoroughly understood, 54 of those successful, and 30 flybys or orbiters, and the number was chosen to endure a probability to keep the planet free from contamination of at least 99.9% over the duration of the exploration period.