Cosmo Baraona

A dust characterization experiment for solar cells operating on Mars

During the Viking and Pathfinder missions to Mars, significant amounts of dust accumulated on the spacecraft. In Pathfinders case, the dust obscured the solar panels on the lander and the rover degrading their output current. The material adherence experiment aboard the Pathfinder rover quantified the rate of decrease in short circuit current at 0.28% per day. This rate is unacceptably high for long duration missions. In response, NASA has developed the Dust Accumulation and Removal Technology (DART) experiment. DART has 3 instruments for characterizing dust settling out of the atmosphere and tests two methods to keep dust from settling on solar cells.

Verification of Mars solar radiation model based on Mars Pathfinder data

The solar radiation model for the Martian surface was developed based on the images taken by the two Viking Landers VL1 and VL2 cameras, and calculation of the solar flux function. This model was used for the design of the Pathfinders photovoltaic arrays. The Pathfinder is equipped with various instruments capable of measuring data from which solar radiation quantities may be derived. In the present study, the authors use data of the Lander and Rover, and perform correlation calculations to the solar radiation model. This study shows that the solar radiation model predicts with good accuracy the solar radiation on the Martian surface for horizontal photovoltaic arrays and for an optical depth of 0.5 of the Martian atmosphere.

Spectral Content of Solar Radiation on Martian Surface Based on Mars Pathfinder

Photovoltaicarrayswereused successfully to power thevarious instrumentsfortheMars Pathe nder.To identify the type of the solar cell most suitable for Mars surface missions in the future, the spectral content of Mars’ s solar radiation must e rst be determined. The response of photovoltaic cells depends on the solar cell type and the wavelengths of the incident light. The suspended dust particles of Mars’ s atmosphere affect the intensity and spectralcontent of the solarradiation reaching theplanet’ s surface. ThePathe nderemployed fourbandpasse lters formeasuring theatmosphericoptical depth during the courseof themission that lasted for about80 sols (Martian days). Thecentral wavelengths of thesee lterswere 450, 670, 883, and 989 nm. This paper deals with theanalysis of theopticaldepthoftheMartian atmospherebased ontheMarsPathe ndermeasurementsand includes1 ) variation of the monochromatic optical depth with the time of the day, 2 ) variation of the monochromatic optical depth with sol for the duration of the mission, 3 ) variation of the optical depth with wavelength, 4 ) transmittance of the direct beam with wavelength, and 5 ) solar cell response on the Martian surface of the direct beam irradiance.

Photovoltaic power for Space Station Freedom

The Space Station Freedom is described with special attention to its electric power system. The photovoltaic arrays, the battery energy storage system, and the power management and distribution system are discussed. The current design of Freedoms power system and the system requirements, trade studies, and competing factors which lead to system selections are referenced. This will be the largest power system ever flown in space. This system represents the culmination of many developments that have improved system performance, reduced cost, and improved reliability. Key developments and their evolution into the current space station solar array design are briefly described. The features of the solar cell and the array, including the development, design, test, and fight hardware production status, are given.<<ETX>>