SPACE 478

hazard analysis

method to identify potential system failures and classify risks

Fault Tree Analysis

qualitative and quantitative approach to analyzing how faults cause failures of systems

minimal cut sets

set of basic events that can cause a failure

Event Tree Analysis

bottom up approach to analyzing how faults cause failures of systems

reliability

probability that a system performs its specified functions under certain operational enviornment conditions over a specified amount of time

frost line

distance from a star where H-compounds condense into ice crystals

planetary elongation

angular separation between the Sun and the planets, as viewed from Earth

granules

top of convective cells that reach the photosphere

supergranules

large aggregations of granules that persist for 1-2 days

faculae

short-lived convection cells 1000+ km in diameter, observed as bright spots between granules

plages

faculae that extend into the chromosphere

sunspots

cooler regions of the Sun that appear darker

radiation pressure

force created by absorption and partial reflection of solar illumination from the spacecraft surface, force on a differential area from radiation that is absorbed and partially reflected

irradiance

radiation incident on the surface

exitance

radiation emitted from the surface

intensity

radiation emitted per solid angle

radiance

radiation flux emitted, reflected, transmitted, or received by a surface per unit solid angle, per projected area

emittance

ratio of the integrated spectral radiant exitance compared to that of a blackbody

absorptance

fraction of the integrated spectral irradiance absorbed by a body

reflectance

fraction of integrated spectral irradiance that is reflected by an object

transmittance

fraction of irradiance that is transmitted through an object

Core

innermost later of the Sun (15.7 MK; 0Rs<R<0.3Rs), generates 99% of power in the Sun

Radiative Zone

Second innermost layer of the Sun (7MK; 0.3Rs<R<0.7Rs), stable to convection

Convective Zone

Second outermost layer of the Sun (2MK<T<6000K; 0.7Rs<R<1Rs), unstable to convection