Radiation other than UV Reaching Mars.
This page updated on 11/19/2015.
NOTE: OUR ULTRAVIOLET RADIATION DATA FOR AT LEAST THE
FIRST 1,165 SOLS OF MSL ON MARS ARE AT http://davidaroffman.com/photo2_15.html.
This article discusses an article entitled Mars’ Surface Radiation Environment Measured with the Mars Science Laboratory’s Curiosity Rover. It is important to note upfront that the Hassler et al. (2014) article does not discuss ultraviolet radiation, but the the Rover Environmental Monitoring Station (REMS) reports only shows daily ultraviolet radiation.The focus of the Hassler article is with galactic cosmic rays (GCRs) and solar energetic particles (SEPs).
Cosmic rays are immensely high-energy radiation, mainly originating outside the Solar System. They may produce showers of secondary particles that penetrate and impact the Earth's atmosphere and sometimes even reach the surface. Composed primarily of high-energy protons and atomic nuclei, they are of mysterious origin. Data from the Fermi space telescope (2013) have been interpreted as evidence that many of the primary cosmic rays originate from the supernovae of massive stars. However, active galactic nuclei probably also produce cosmic rays.
Solar energetic particles (SEP) are high-energy particles coming from the Sun. They consist of protons, electrons, and HZE ions with energy ranging from a few tens of keV to GeV (the fastest particles can reach speed up to 80% of the speed of light). They are of particular interest and importance because they can endanger life in outer space (especially particles above 40 MeV). Solar energetic particles can originate from energetization at a solar-flare site or by shock waves associated with coronal mass ejections (CMEs). However, only about 1% of the CMEs produce strong SEP events.
Ultraviolet (UV) light is an electromagnetic radiation with a wavelength from 400 nm to 100 nm, shorter than that of visible light but longer than X-rays. Though usually invisible, under some conditions children and young adults can see ultraviolet down to wavelengths of about 310 nm, and people with aphakia (missing lens) can also see some UV wavelengths. Near-UV is visible to a number of insects and birds.
The most important parts of the Hassler article that we are discuss here are as follows:
The diurnal dose rates vary by a few percent because of diurnal change in the Mars atmospheric column, as can be seen in Fig. 2A, which shows data obtained between sols 290 and 302 diurnal variation of the total atmospheric column mass is related to the daily thermal tides that Mars experiences each sol, by which the direct heating of the martian atmosphere by the Sun produces global-scale waves that redistribute atmospheric mass (33). Comparison of the RAD dose rate to the Rover Environment Monitoring Station (REMS) (34) atmospheric pressure measurements shows there is an anti-correlation between total dose rate and atmospheric pressure (Fig. 2B), which in turn is directly related to column depth.
- J. T. Schofield et al., The Mars Pathfinder atmospheric structure investigation/meteorology (ASI/MET) experiment. Science 278, 1752–1758 (1997). doi: 10.1126/science.278.5344.1752; pmid: 9388169
- J. Gómez-Elvira et al., REMS: The Environmental Sensor Suite for the Mars Science laboratory Rover. Space Sci. Rev. 170, 583–640 (2012). doi: 10.1007/s11214-012-9921-