Chart Shows Variation In Solar Power Available For Mars Rovers

MARSDAILY

Image Credit: NASA/JPL-Caltech. See larger image.

Pasadena CA (JPL) Dec 09, 2005
This chart illustrates the variation in available solar power for each of NASA's twin Mars Exploration Rovers over the course of approximately two Mars years. Two factors affect the amount of available power: the tilt of Mars' axis and the eccentricity of the Mars' orbit about the sun.

The horizontal scale is the number of Martian days (sols) after the Jan. 4, 2004, (Universal Time) landing of Spirit at Mars' Gusev Crater. The vertical scale on the right indicates the amount of available solar power as a ratio of the amount available at the equator when Mars is closest to the sun (perihelion). The red line indicates power availability at Spirit's landing site (Gusev). The blue line indicates power availability at Opportunity's landing site (Meridiani).

The vertical scale on the right applies to the dotted line, indicating the latitude north or south of Mars' equator where the noon sun is overhead at different times of the Martian year.

Solar-Panel Dust Accumulation and Cleanings

Image Credit: NASA/JPL-Caltech. See larger image.
Air-fall dust accumulates on the solar panels of NASA's Mars Exploration Rovers, reducing the amount of sunlight reaching the solar arrays. Pre-launch models predicted steady dust accumulation. However, the rovers have been blessed with occasional wind events that clear significant amounts of dust from the solar panels.

This graph shows the effects of those panel-cleaning events on the amount of electricity generated by Spirit's solar panels. The horizontal scale is the number of Martian days (sols) after Spirit's Jan. 4, 2005, (Universal Time) landing on Mars.

The vertical scale indicates output from the rover's solar panels as a fraction of the amount produced when the clean panels first opened. Note that the gradual declines are interrupted by occasional sharp increases, such as a dust-cleaning event on sol 420.

MARSDAILY

Mars Rovers Continue To Explore And Amaze One Year Later

Pasadena CA (SPX) Dec 06, 2005
NASA's durable twin Mars rovers have successfully explored the surface of the mysterious red planet for a full Martian year (687 Earth days). Opportunity starts its second Martian year Dec. 11; Spirit started a new year three weeks ago. The rovers' original mission was scheduled for only three months.

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