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211.
We report the discovery of fossilized filamentous structures in samples of the lithified, volcaniclastic apron of Gran Canaria, which were obtained during Leg 157 of the Ocean Drilling Program (ODP). These filamentous structures are 2-15 μm in diameter and several hundred micrometers in length and are composed of Si, Al, Fe, Ca, Mg, Na, Ti, and C. Chitin was detected in the filamentous structures by staining with wheat germ agglutinin dye conjugated with fluorescein isothiocyanate (WGA-FITC), which suggests that they are fossilized fungal hyphae. The further elucidation of typical filamentous fungal morphological features, such as septa, hyphal bridges, and anastomosis and their respective sizes, support this interpretation. Characteristic structures that we interpreted as fossilized spores were also observed in association with the putative hyphae. The fungal hyphae were found in pyroxene phenocrysts and in siderite pseudomorphs of a basalt breccia. The fungal colonization of the basalt clasts occurred after the brecciation but prior to the final emplacement and lithification of the sediment at ~16-14 Ma. The siderite appears to have been partially dissolved by the presence of fungal hyphae, and the fungi preferentially colonized Fe-rich carbonates over Fe-poor carbonates (aragonite). Our findings indicate that fungi may be an important geobiological agent in subseafloor environments and an important component of the deep subseafloor biosphere, and that hydrothermal environments associated with volcanism can support a diverse ecosystem, including eukaryotes. 相似文献
212.
Using the SONG detector onboard the CORONAS-F satellite, gamma-ray emission of high energies (>100 MeV) was recorded during four solar flares. In the sequential spectra
of gamma rays the peculiarity caused by generation and decay of neutral pions was isolated, which made it possible to determine
with a high accuracy the moments of appearance in the solar atmosphere of protons accelerated up to energies above 300 MeV. 相似文献
213.
Euan Nisbet Kevin Zahnle M. V. Gerasimov Jörn Helbert Ralf Jaumann Beda A. Hofmann Karim Benzerara Frances Westall 《Space Science Reviews》2007,129(1-3):79-121
The factors that create a habitable planet are considered at all scales, from planetary inventories to micro-habitats in soft
sediments and intangibles such as habitat linkage. The possibility of habitability first comes about during accretion, as
a product of the processes of impact and volatile inventory history. To create habitability water is essential, not only for
life but to aid the continual tectonic reworking and erosion that supply key redox contrasts and biochemical substrates to
sustain habitability. Mud or soft sediment may be a biochemical prerequisite, to provide accessible substrate and protection.
Once life begins, the habitat is widened by the activity of life, both by its management of the greenhouse and by partitioning
reductants (e.g. dead organic matter) and oxidants (including waste products). Potential Martian habitats are discussed: by
comparison with Earth there are many potential environmental settings on Mars in which life may once have occurred, or may
even continue to exist. The long-term evolution of habitability in the Solar System is considered. 相似文献
214.
K. J. Seidensticker D. Möhlmann I. Apathy W. Schmidt K. Thiel W. Arnold H.-H. Fischer M. Kretschmer D. Madlener A. Péter R. Trautner S. Schieke 《Space Science Reviews》2007,128(1-4):301-337
SESAME is an instrument complex built in international co-operation and carried by the Rosetta lander Philae intended to land
on comet 67P/Churyumov-Gerasimenko in 2014. The main goals of this instrument suite are to measure mechanical and electrical
properties of the cometary surface and the shallow subsurface as well as of the particles emitted from the cometary surface.
Most of the sensors are mounted within the six soles of the landing gear feet in order to provide good contact with or proximity
to the cometary surface. The measuring principles, instrument designs, technical layout, operational concepts and the results
from the first in-flight measurements are described. We conclude with comments on the consequences of the last minute change
of the target comet and how to improve and to preserve the knowledge during the long-duration Rosetta mission. 相似文献
215.
Harald Krüger Markus Landgraf Nicolas Altobelli Eberhard Grün 《Space Science Reviews》2007,130(1-4):401-408
The Ulysses spacecraft has been orbiting the Sun on a highly inclined ellipse almost perpendicular to the ecliptic plane (inclination
79°, perihelion distance 1.3 AU, aphelion distance 5.4 AU) since it encountered Jupiter in 1992. The in situ dust detector
on board continuously measured interstellar dust grains with masses up to 10−13 kg, penetrating deep into the solar system. The flow direction is close to the mean apex of the Sun’s motion through the
solar system and the grains act as tracers of the physical conditions in the local interstellar cloud (LIC). While Ulysses
monitored the interstellar dust stream at high ecliptic latitudes between 3 and 5 AU, interstellar impactors were also measured
with the in situ dust detectors on board Cassini, Galileo and Helios, covering a heliocentric distance range between 0.3 and
3 AU in the ecliptic plane. The interstellar dust stream in the inner solar system is altered by the solar radiation pressure
force, gravitational focussing and interaction of charged grains with the time varying interplanetary magnetic field. We review
the results from in situ interstellar dust measurements in the solar system and present Ulysses’ latest interstellar dust
data. These data indicate a 30° shift in the impact direction of interstellar grains w.r.t. the interstellar helium flow direction,
the reason of which is presently unknown. 相似文献
216.
The ionic charge distributions of solar energetic particles (SEP) as observed in interplanetary space provide fundamental
information about the origin of these particles, and the acceleration and propagation processes at the Sun and in interplanetary
space. In this paper we review the measurements of ionic charge states of energetic particles in interplanetary space and
discuss their implication for our understanding of SEP sources, and acceleration and propagation processes. 相似文献
217.
G. Klingelhöfer J. Brückner C. D’uston R. Gellert R. Rieder 《Space Science Reviews》2007,128(1-4):383-396
The Alpha Particle X-Ray Spectrometer (APXS) is a small instrument to determine the elemental composition of a given sample.
For the ESA Rosetta mission, the periodical comet 67P/Churyumov-Gerasimenko was selected as the target comet, where the lander
PHILAE (after landing) will carry out in-situ observations. One of the instruments onboard is the APXS to make measurements
on the landing site. The APXS science goal is to provide basic compositional data of the comet surface. As comets consist
of a mixture of ice and dust, the dust component can be characterized and compared with known meteoritic compositions. Various
element ratios can be used to evaluate whether chemical fractionations occurred in cometary material by comparing them with
known chondritic material. To enable observations of the local environment, APXS measurements of several spots on the surface
and one spot as function of temperature can be made. Repetitive measurements as function of heliocentric distance can elucidate
thermal processes at work. By measuring samples that were obtained by drilling subsurface material can be analyzed. The accumulated
APXS data can be used to shed light on state, evolution, and origin of 67P/Churyumov- Gerasimenko. 相似文献
218.
219.
J. Kissel K. Altwegg B. C. Clark L. Colangeli H. Cottin S. Czempiel J. Eibl C. Engrand H. M. Fehringer B. Feuerbacher M. Fomenkova A. Glasmachers J. M. Greenberg E. Grün G. Haerendel H. Henkel M. Hilchenbach H. von Hoerner H. Höfner K. Hornung E. K. Jessberger A. Koch H. Krüger Y. Langevin P. Parigger F. Raulin F. Rüdenauer J. Rynö E. R. Schmid R. Schulz J. Silén W. Steiger T. Stephan L. Thirkell R. Thomas K. Torkar N. G. Utterback K. Varmuza K. P. Wanczek W. Werther H. Zscheeg 《Space Science Reviews》2007,128(1-4):823-867
The ESA mission Rosetta, launched on March 2nd, 2004, carries an instrument suite to the comet 67P/Churyumov-Gerasimenko. The COmetary Secondary Ion Mass Anaylzer – COSIMA – is one of three cometary dust analyzing instruments onboard Rosetta. COSIMA is based on the analytic measurement method of secondary ion mass spectrometry (SIMS). The experiment’s goal is in-situ analysis of the elemental composition (and isotopic composition of key elements) of cometary grains. The chemical characterization will include the main organic components, present homologous and functional groups, as well as the mineralogical and petrographical classification of the inorganic phases. All this analysis is closely related to the chemistry and history of the early solar system. COSIMA covers a mass range from 1 to 3500 amu with a mass resolution m/Δm @ 50% of 2000 at mass 100 amu. Cometary dust is collected on special, metal covered, targets, which are handled by a target manipulation unit. Once exposed to the cometary dust environment, the collected dust grains are located on the target by a microscopic camera. A pulsed primary indium ion beam (among other entities) releases secondary ions from the dust grains. These ions, either positive or negative, are selected and accelerated by electrical fields and travel a well-defined distance through a drift tube and an ion reflector. A microsphere plate with dedicated amplifier is used to detect the ions. The arrival times of the ions are digitized, and the mass spectra of the secondary ions are calculated from these time-of-flight spectra. Through the instrument commissioning, COSIMA took the very first SIMS spectra of the targets in space. COSIMA will be the first instrument applying the SIMS technique in-situ to cometary grain analysis as Rosetta approaches the comet 67P/Churyumov-Gerasimenko, after a long journey of 10 years, in 2014. 相似文献
220.
Navigation for balloon payloads: Recent experience with OMEGA in the US and a new slant range system
E. Kendziorra E. Götz R. Staubert 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1983,3(6):81-85
The replacement of OMEGA station G from Trinidad to Australia has recently caused some problems for balloon navigation in the United States. We report on recent experience with OMEGA during a balloon flight of the hard X-ray astronomy payload HEXE1) from Palestine, Texas on September 28/29, 1981. In this flight three different OMEGA receivers were used. In view of the degraded receiving conditions for OMEGA we have developed a simple slant range system which may easily be adapted to other standard PCM systems. We show that a combination of range, azimuth and one OMEGA line of position (e.g. C-D) provides reasonably accurate balloon positions. 相似文献