Functionality of materials and biodiversity under space conditions
(ESA: INTERFILA, SURE) An experiment of TPCI and ESA at the international space station (ISS): Viability of bio-diversity under extreme space conditions (10-2Pa, 10K, VUV (110-180 nm) solar irradiation)
Experiment Launched delivered at ISS and returned with the final trip flight of Space Shuttle on July 21, 2011. Distance 240 miles, Duration : 11 days
(a) Optical image of one Aspergillus terreus spore immobilized on the silica wafer. The average size of spores is ~3 microns.
(b) 2D-AFM image of one Aspergillus terreus spore with 100-200 nm granular star structure around the periphery of its elliptic shape.
This work is a part of ESA/EU SURE project aiming to quantify the survival probability of fungal spores in space under solar irradiation in the vacuum ultraviolet (VUV) (110-180 nm) spectral region. The contribution and impact of VUV photons, vacuum, low temperature and their synergies, on the survival probability of Aspergillus terreus spores is measured at simulated space conditions on Earth. To simulate the solar VUV irradiation, the spores are irradiated with a continuous discharge VUV hydrogen photon source and a molecular fluorine laser, at low and high photon intensities at 1015 photon m-2 s-1 and 3.9 x 1027 photons pulse-1 m-2 s-1 respectively. The survival probability of spores is independent from the intensity and the fluence of photons, within certain limits, in agreement with previous studies. The spores are shielded from a thin carbon layer, which is formed quickly on the external surface of the proteinaceous membrane at higher photon intensities at the start of the VUV irradiation. Extrapolated the results in space conditions, for an interplanetary direct transfer orbit from Mars to Earth, the spores will be irradiated with 3.3 x 1021 solar VUV photons m-2 . This photon fluence is equivalent to the irradiation of spores on Earth with 54 laser pulses with an experimental ~92% survival probability, disregarding the contribution of space vacuum and low temperature, or to continuous solar VUV irradiation for 38 days in space near the Earth with an extrapolated ~61% survival probability. The experimental results indicate that the damage of spores is mainly from the dehydration stress in vacuum. The high survival probability after 4 days in vacuum (~34 %), is due to the exudation of proteins on the external membrane, preventing thus further dehydration of spores. In addition, the survival probability is increasing to (~54%) at 10 K with 0.12 K/s cooling and heating rate.
(a) 3D-AFM image of a part of the surface of Aspergillus terreus spore with rough vesicle structures.
(b) 2D-AFM image of conidiophore elongated structure.
(a) AFM high resolution image (phase mode) of one A. terreus spore with 20 nm wide rodlet structure on granular domains.
(b) AFM image of damaged A. terreus spores after 24h at 10-4 Pa. The damaged spores appear with extende drod-like structure on the surface (Point A), indicating excessive biologicalactivity.
(a) Optical image of an area of the wafer with spores prior to exposure in vacuum.
(b)Theoptical image of the same area after 24h at 10-4 Pa and 298K.
The density of spores is lesser than of the non-exposed sample due to dehydration.
(a) AFM image of a damaged dehydrated A. terreus spore exposed at 10K and 10-4 Pa for 24h.
(b)AFM of an intact spore (A)and a damaged one(B)at the same experimental conditions.
(a) AFM image of A. terreus spores following 24h at VUV irradiation at 10-4 Pa and 10K.Some cracks and holes appear on the external membrane of spores(A). The cellular content of exploded spores,100–200nm wide is spread around (B).
(b) AFM image of A. terreus spore exposed at 10K in vacuum 10-4 Pa for 24h. One spore with dimension 2 microns X 1.6 microns together with the spore’s remnants is indicated.
(a) AFM image of damaged dehydrated spores after 24h at 10-4 Pa and 298K. The shape of cells is deformed and some parts of spores are squeezed. The cellular content of exploded spores is spread around.
(b) AFM image of a damaged A. terreus spores after 60 min of laser irradiation in vacuum with a hole at the centre. Part of the cellular content is shown next to the spore.
(a) AFM image of damaged spores after 60min of laser irradiation at 10-4 Pa. The cellular content is scattered around.
(b) Survival probability of spores following laser irradiation at 157nm, 15Hz at 10-4 Pa and in nitrogen at 105 Pa at 10, 30 and 60 min,respectively.
Interplanetary survival probability of Aspergillus terreus spores under simulated solar vacuum ultraviolet irradiation.
E. Sarantopoulou, I. Gomoiu, Z. Kollia and A.C. Cefalas,
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Preventing biological activity of Ulocladium sp spores in artifacts using 157nm laser.
E. Sarantopoulou, Z. Kollia and I. Gomoiu,
Appl. Phys. A 83, 663 (2006). DOI: 10.1007/s00339-006-3554-8
Removing Foxing stains from old paper at 157 nm.
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Appl. Surf. Sci. 208-209, 311 (2003). DOI: 10.1016/S0169-4332(02)01379-X
Efficient removing of foxing from a medieval Ptolemaic map using a molecular laser at 157nm.
A. C. Cefalas, E. Sarantopoulou and Z. Kollia.
Appl. Phys. A, 73, 571 (2001).
Lasers and Biodeterioration.
I. Gomoiu, R. Radvan, E. Sarantopoulou and A. C. Cefalas,
M. Schreiner, M. Strlic (eds.)
Handbook on the Use of Lasers in Conservation and Conservation Science, COST G7 (2006).
Preparing ulocladium cultures for studies in microgravity conditions.
I. Gomoiu, E. Sarantopoulou and Z. Kollia,
ELGRA-AIMAS Symposium,“Plant Biology 2” session, Florence, Italy, 4-7 september (2007).