Detecting the light of the night sky in Mars

Abstract

In this paper a new methodology is outlined to detect the dust content in the Martian atmosphere during nighttime. In the previous Lander missions to Mars, scientists were able to determine the dust load in the Martian atmosphere during daylight using spectral lines of the Sun. Since the dynamics of Martian dust storms had been determined to be very rapid changing over times of hours and not days, it is imperative to determine the dust load during nighttime, so future astronauts to Mars can take protective measures for their equipment. They can also factor this effect for their planned activities during daytime. The new methodology greatly improves on the classical method for determining the extinction in the Earth’s atmosphere. The classical method uses observations of bright stars from which the optical depth, ?total, can then be deduced from the classical brightness equation. The classical method succeeds reasonably well at high elevation angles from the horizon but fails dramatically at low elevation angles. It also determines ?total from the slope of a plot of observed brightness of a bright star vs. air mass at all elevations. The plot shows a straight line at high elevations angles, which then curves and becomes uncertain at low elevation angles. The new methodology bypasses this severe difficulty by simply eliminating this plot, and by acquiring the brightness of a bright star above the atmosphere (no extinction) and compares it to the observed bright- ness of the same star below the atmosphere at all elevations.