An ultraviolet simulator for the incident Martian surface radiation and its applications

Abstract

: Ultraviolet (UV) radiation can act on putative organic/biological matter at the Martian surface in several ways. Only absorbed, but not transmitted or reflected, radiation energy can be photo-chemically effective. The most important biological UV effects are due to photochemical reactions in nucleic acids, DNA or RNA, which constitute the genetic material of all cellular organisms and viruses. Protein or lipid effects generally play a minor role, but they are also relevant in some cases. UV radiation can induce wavelengths-specific types of DNA damage. At the same time it can also induce the photo-reversion reaction of a UV induced DNA photoproduct of nucleic acid bases, the pyrimidine dimers. Intense UVB and UVC radiation, experienced on early Earth and present-day Mars, has been revealed to be harmful to all organisms, including extremophile bacteria and spores. Moreover, the formation of oxidants, catalytically produced in the Martian environment through UV irradiation, may be responsible for the destruction of organic matter on Mars. Following this, more laboratory simulations are vital in order to investigate and understand UV effects on organic matter in the case of Mars. We have designed a radiation apparatus that simulates the anticipated Martian UV surface spectrum between 200 and 400 nm (UVC-UVA). The system comprises a UV enhanced xenon arc lamp, special filter-sets and mirrors to simulate the effects of the Martian atmospheric column and dust loading. We describe the technical setup and performance of the system and discuss its uses for different applications. The design is focused on portability, therefore, the Mars-UV simulator represents a device for several different Mars simulation facilities with specific emphasis on Mars research topics.

Investigating the Effects of Simulated Martian Ultraviolet Radiation onHalococcus dombrowskiiand Other Extremely Halophilic Archaebacteria

“…This led to the formation of flat halite crystals with embedded haloarchaeal cells. For each exposure time, three quartz discs of each sample were used (placed in plastic petri dishes of 55 mm diameter) and exposed to the Mars-UV simulator lamp at the Austrian Academy of Sciences (Kolb et al ., 2005) for times ranging from 1 to 3600 s. The spot of the lamp had a 50 mm diameter at a distance of 300 mm. The intensity of the irradiation of the lamp was in the range of 39.15–42 W/m 2 , as measured with a spectroradiometer (Typ UL 754, Optronic Laboratories Ltd., Orlando, USA); the data were acquired and edited with OL 754 version nr.…”

“…In this study, we chose to develop and test methods for the evaluation of haloarchaeal survival in small desiccated samples. The Mars-UV simulator lamp for examining the effects on organisms and on different complex organic substances at the same UV flux intensity as on the martian surface, developed by Kolb et al . (2005), was used for the experiments with cells of Halococcus dombrowskii and two noncoccoid haloarchaea ( Halobacterium salinarum , Haloarcula japonica ).…”

“…(2005), was used for the experiments with cells of Halococcus dombrowskii and two noncoccoid haloarchaea ( Halobacterium salinarum , Haloarcula japonica ). A comparison of the spectral intensity output of the lamp between 200 and 400 nm with the theoretical flux on Mars was published by Kolb et al . (2005).…”

A Facility for Long-Term Mars Simulation Experiments: The Mars Environmental Simulation Chamber (MESCH)

“…It should be noted that Kolb et al (2005) recently developed a solar simulation lamp that more accurately reproduces the spectrum and intensity in the martian UV range. The lamp used in our simulation system can be exchanged with any other type of lamp or radiation source if a different spectral composition and intensity are desired.…”

“…The nature of the UV radiation applied in the different studies has generally been poorly defined in terms of either alent to those found on Mars (Zill et al, 1979;Schuerger et al, 2003;Kolb et al, 2005).…”