Assertion: mercury's atmosphere | /r/HasProperty | surface-bound exosphere
Facets:
value: according to nasa
type: OTHER
Source sentences:
text: According to NASA, the atmosphere of Mercury is a "surface-bound exosphere, essentially a vacuum.
text: Mercury has a very tenuous and highly variable atmosphere (surface-bound exosphere) containing hydrogen, helium, oxygen, sodium, calcium, potassium and water vapor, with a combined pressure level of about 10−14 bar (1 nPa).