ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1573-0875
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The present biosphere is shielded from harmful solar near ultraviolet (UV) radiation by atmospheric ozone. We suggest here that elemental sulfur vapor could have played a similar role in an anoxic, ozone-free, primitive atmosphere. Sulfur vapor would have been produced photochemically from volcanogenic SO2 and H2S. It is composed of ring molecules, primarily S8, that absorb strongly throughout the near UV, yet are expected to be relatively stable against photolysis and chemical attack. It is also insoluble in water and would thus have been immune to rainout or surface deposition over the oceans. The concentration of S8 in the primitive atmosphere would have been limited by its saturation vapor pressure, which is a strong function of temperature. Hence, it would have depended on the magnitude of the atmospheric greenhouse effect. Surface temperatures of 45 °C or higher, corresponding to carbon dioxide partial pressures exceeding 2 bars, are required to sustain an effective UV screen. Two additional requirements are that the ocean was saturated with sulfite and bisulfite, and that linear S8 chains must tend to reform rings faster than they are destroyed by photolysis. A warm, sulfur-rich, primitive atmosphere is consistent with inferences drawn from molecular phylogeny, which suggest that some of the earliest organisms were thermophilic bacteria that metabolized elemental sulfur.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1573-0875
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Icarus 95 (1992), S. 1-23 
    ISSN: 0019-1035
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 343 (1990), S. 251-254 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] When Alvarez et al2 made their impact proposal, the conventional view of impact mechanics was that crater ejecta would be thrown into the stratosphere5 where it would mix with the air (assuming it was dispersed as a sufficiently fine dust) and would thence spread worldwide. Although this view ...
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Icarus 84 (1990), S. 502-527 
    ISSN: 0019-1035
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Icarus 108 (1994), S. 1-17 
    ISSN: 0019-1035
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Publication Date: 2004-10-05
    Description: We use several independent constraints on the number of ecliptic comets to estimate impact cratering rates on the Jupiter moons. The impact rate on Jupiter by 1.5-km diameter ecliptic comets is currently NY(d 〉 1.5km) = 0.005(+0.006)(-0.003) per annum. Asteroids and long period comets are currently unimportant. The size-number distribution of ecliptic comets smaller than 20 km is inferred from size-number distributions of impact craters on Europa, Ganymede, and Triton. For comets bigger than 50 km we use the size-number distribution of Kuiper Belt Objects. The overview of the impact rate at Jupiter in general and at Europa in particular are given. These impact rates imply cratering rates on Europa of 0.5 per Ma per 10(exp 6) sq km for impact craters bigger than 1 km, and of 0.015 per Ma per 10(exp 6) sq km for impact craters bigger than 20 km. The latter corresponds to an average recurrence time of 2.2 Ma for 20 km craters. The best current estimates for the number of 20 km craters on Europa appear to range between about twelve to thirty. This implies that the average age of Europa's surface is between 30 and 70 Ma. The average density of craters with diameter greater than 1 km on well-mapped swaths on Europa is 30 per 10(exp 6) sq km. The corresponding nominal surface age would be 60 Ma. These two estimates are not truly independent because we have used size-number distribution of the Europan craters to help generate the size-number distribution of comets. The uncertainty of the best estimate - call it 42 Ma for specificity - is at least a factor of 3.
    Keywords: Lunar and Planetary Science and Exploration
    Type: Workshop on Europa's Icy Shell: Past, Present, and Future; 98-99; LPI-Contrib-1195
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Publication Date: 2011-08-19
    Description: The recent discovery of an apparently global soot layer at the Cretaceous/Tertiary boundary indicates that global wildfires were somehow ignited by the impact of a comet or asteroid. It is shown here that the thermal radiation produced by the ballistic reentry of ejecta condensed from the vapor plume of the impact could have increased the global radiation flux by factors of 50 to 150 times the solar input for periods ranging from one to several hours. This great increase in thermal radiation may have been responsible for the ignition of global wildfires, as well as having deleterious effects on unprotected animal life.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature (ISSN 0028-0836); 343; 251-254
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Publication Date: 2011-08-24
    Description: The partitioning of relative nitrogen in the Arctic and the sub-Arctic troposphere based on measurements conducted during the 1988 Arctic Boundary Layer Expedition (ABLE 3A) is described. The first set of comprehensive odd nitrogen and O3 measurements from the Arctic/sub-Arctic free troposphere shows that a highly aged air mass that has persisted under very cold conditions is present. A large fraction of the odd nitrogen appears to be present in the form of reservoir species such as PAN. Significant quantities of as yet unknown reactive nitrogen species, such as complex alkyl nitrates and pernitrates, are expected to be present. Together with PAN, these nitrate and pernitrate reservoir species could control the entire NO(x) availability of the high-latitude troposphere and in turn influence the O3 photochemistry of the region. The role of PAN in influencing the O3 reservoir is shown to be important and may be responsible for the increasing O3 temporal trend observed at high latitudes.
    Keywords: ENVIRONMENT POLLUTION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 97; D15; p. 16,523-16,530.
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Publication Date: 2011-08-19
    Description: The present biosphere is shielded from harmful solar near ultraviolet (UV) radiation by atmospheric ozone. It is suggested that elemental sulfur vapor could have played a similar role in an anoxic, ozone-free, primitive atmosphere. Sulfur vapor would have been produced photochemically from volcanogenic SO2 and H2S. It is composed of ring molecules, primarily S8, that absorb strongly throughout the near UV, yet are expected to be relatively stable against photolysis and chemical attack. It is also insoluble in water and would thus have been immune to rainout or surface deposition over the oceans. Since the concentration of S8 in the primitive atmosphere would have been limited by its saturation vapor pressure, surface temperatures of 45 C or higher, corresponding to carbon dioxide partial pressures exceeding 2 bars, are required to sustain an effective UV screen. A warm, sulfur-rich, primitive atmosphere is consistent with inferences drawn from molecular phylogeny, which suggest that some of the earliest organisms were thermophilic bacteria that metabolized elemental sulfur.
    Keywords: LIFE SCIENCES (GENERAL)
    Type: Origins of Life and Evolution of the Biosphere (ISSN 0169-6149); 19; 2, 19
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...