Papers by Elmar Jessberger
Space Science Reviews, 1991
The discussion was chaired by E. Anders. Panel members were J.M. Greenberg, Th. Encrenaz, J.F. Ke... more The discussion was chaired by E. Anders. Panel members were J.M. Greenberg, Th. Encrenaz, J.F. Kerridge, L. Mukhin, and G. Strazzulla ANDERS opened the discussion by presenting a list of what should be done prior to a comet sample return. Firstly, realistic simulations should be performed for the major processes forming and altering organic matter in interstellar space, e.g. irradiation and heating of condensates. The products of these experiments should be comprehensively analysed, especially in the informative mass range 20-300 amu. Particular attention should be given to the recent observation that the lack of sufficient reaction time in the laboratory could not easily be traded off by an increase of flux.
Space Science Reviews, 1991
PEPIN introduced the topic and explained in detail the primary geochemical case for the origin of... more PEPIN introduced the topic and explained in detail the primary geochemical case for the origin of the SNC meteorites on Mars: the shock-implanted gases which closely resemble those determined in situ on Mars by VIKING experiments. He then asked what measurement unequivocally could test the Martian origin of the SNCs and gave highest priority to a determination of the oxygen isotopic composition of the Martian atmosphere since O in SNCs is displaced from the terrestrial ffactionafion line by about 0.2 permil. Such a precision can only be reached in the laboratory and certainly not with an in situ experiment. Consequently, he advocated an atmospheric Martian sample return as the first priority mission to Mars. With an atmospheric sample also the distinct peculiarities of the noble gases, especially At, Kr, and Xe, found in SNCs, would provide supportive evidence as well as the H and N isotopic compositions and the chemical composition of the non-noble gases. A 150 cm 3 container weighs on the order of 100 g and, when filled with Martian atmospheric gases 120 km above the surface using ram pressure collection, then contains 1 cm 3 STP of gas, an amount sufficient for all required measurements. Landing was not necessary and the sampling could well be part of the planned Martian aeronomy mission. ANDERS agreed with that, but noted that even such a simple mission will not come very soon and in the meantime quite a number of important problems and open questions should be worked on: -What is the explanation for the fact that the SNCs were ejected from Mars by several different impacts on young terrain which, as had been noted before by BEGEMANN, is rather improbable because there is only little young terrain? -Why is the material ejected from Mars only mildly shocked despite the escape velocity of 5 km/sec? This question should be re-addressed using the depth information which can be obtained in the case of the lunar meteorites.
Data extracted so far on the dust composition from the PIA and PUMA experiments on board Giotto a... more Data extracted so far on the dust composition from the PIA and PUMA experiments on board Giotto and Vega 1 and 2 are reviewed. It is found that Halley's dust is composed of two end-member components: a refractory organic phase (CHON) and a Mg-rich silicate phase. The CHON component is argued to be coating silicate cores. The refractory organics are
Experimental Astronomy
The Triple F (Fresh From the Fridge) mission, a Comet Nucleus Sample Return, has been proposed to... more The Triple F (Fresh From the Fridge) mission, a Comet Nucleus Sample Return, has been proposed to ESA’s Cosmic Vision program. A sample return from a comet enables us to reach the ultimate goal of cometary research. Since comets are the least processed bodies in the solar system, the proposal goes far beyond cometary science topics (like the explanation of cometary activity) and delivers invaluable information about the formation of the solar system and the interstellar molecular cloud from which it formed. The proposed mission would extract three sample cores of the upper 50 cm from three locations on a cometary nucleus and return them cooled to Earth for analysis in the laboratory. The simple mission concept with a touch-and-go sampling by a single spacecraft was proposed as an M-class mission in collaboration with the Russian space agency ROSCOSMOS.
Sections of three stratospheric particles (U2015G1, W7029*A27, and L2005P9) were analyzed with TO... more Sections of three stratospheric particles (U2015G1, W7029*A27, and L2005P9) were analyzed with TOF-SIMS (Time Of Flight-Secondary Ion Mass Spectrometry) continuing our efforts to investigate the element distribution in interplanetary dust particles (IDP's) with high lateral resolution (approximately 0.2 micron), to examine possible atmospheric contamination effects, and to further explore the abilities of this technique for element analysis of small samples.
LEO is planned to be launched in 2012 and shall orbit the Moon for about four years at low altitu... more LEO is planned to be launched in 2012 and shall orbit the Moon for about four years at low altitude (<50 km) in order to map the Moon geomorphologically, geochemically, and geophysically with resolutions down to less than 1 m globally.
Planetary in-situ analysis is going to become one of the most important tools for exploring the a... more Planetary in-situ analysis is going to become one of the most important tools for exploring the accessible celestial bodies. Chemical, mineralogical, structural, isotopic, and molecular information will provide stringent boundary conditions for the origin and evolution of these bodies and hence of the solar system. The past showed some unprecedented examples of operating in-situ analysis instruments and even rather complex instrument facilities are at present underway. Although their capabilities are remarkable, these "first generation" instruments still suffer from constraints in terms of size, mass, and operations for the accommodating systems. They pose restrictions in particular on the most recently projected explorative missions such as ESA's EXOMARS mission that aims at large operating radii of some kilometers or some tens of kilometers. Whereas the classical operational scenario was more or less stationary, the high degree of mobility calls for a new type of in...
The Astrophysical Journal, 2003
The average properties of interstellar dust have previously been inferred from remote astronomica... more The average properties of interstellar dust have previously been inferred from remote astronomical observations of interstellar extinction and from gas depletion measurements. In addition to recent high-resolution observations of gas absorption spectra, in situ measurements of dust in the solar system provide an alternative approach to deducing the properties of interstellar dust, in particular, those of dust in the Local Interstellar Cloud (LIC), in which the Sun resides. We constrain the composition and structure of dust in the LIC by the dust-phase elemental abundances derived from gas absorption measurements and by the dynamical behavior inferred from dust impact measurements. The elemental abundances of the LIC dust are consistent with coremantle grains consisting of Mg-rich pyroxene and Mg-rich olivine with inclusions of troilite, Fe-rich kamacite, and corundum in the core and organic refractory compounds of C, N, and O in the mantle. The mass of the organic refractory mantle is comparable to the mass of the silicate core that is abundant in pyroxene compared to olivine. Taking into account these results, the dynamical behavior of the LIC dust in the solar system indicates that bare silicates and bare carbonaceous materials may be present as grains smaller than 10 À17 kg. The LIC grains with mass exceeding 10 À17 kg are most likely aggregates of submicron-sized silicate core, organic mantle grains. The mass distribution of dust in the LIC can be well explained by coagulation growth of core-mantle grains but is scarcely explained by severe destruction of grains in interstellar shocks.
The Astrophysical Journal, 2003
Observationally derived gas-phase abundances and appropriate assumptions for the total elemental ... more Observationally derived gas-phase abundances and appropriate assumptions for the total elemental abundances of dust and gas determine the elemental composition of dust and the elemental depletion from gas in the interstellar medium (ISM). In addition to the elemental abundances, the total mass ratio of hydrogen atoms to dust grains per spatial volume is a measure of the interaction between dust and gas in the ISM. Recent remote astronomical observations and in situ measurements provide the opportunity of estimating the elemental abundances and the hydrogen gas-to-dust mass ratio of the Local Interstellar Cloud (LIC), in which the Sun is currently embedded. We show that the composition of dust in the LIC is similar to that of cometary dust in the solar system, although the nitrogen abundance remains uncertain. Depletions of elements from the LIC gas are consistent with measurements of warm neutral clouds in the Galactic disk, except for Mg and Si, which are heavily depleted in the LIC. Remote astronomical observations and in situ measurements give essentially the same value for the gas-to-dust mass ratio of the LIC, which is comparable to the average value of the diffuse ISM in the Galaxy. This indicates the association of dust with gas in the LIC, which is also inferred from the depletion pattern in the LIC. Neither the depletions of elements nor the gasto-dust mass ratio show evidence for severe grain destruction that would result from shocks with velocity $1:5 Â 10 7 cm s À1 as suggested by a model that postulates the LIC to be a fragment of the expanding Loop I superbubble shell. Our results rather favor an alternative model that describes the origin of the LIC as being one of H i cloudlets expelled from the interaction zone between the Loop I superbubble and the Local Bubble, which encloses the LIC and similar clouds in the solar neighborhood.
Icarus, 2002
Observations of sungrazing comets, all of which belong to the Kreutz family, provide the opportun... more Observations of sungrazing comets, all of which belong to the Kreutz family, provide the opportunity of studying the properties of dust in the comae and tails of the comets. On the basis of available information on cometary and interplanetary dust as well as observations of dust in the tails of sungrazers, we model dust in sungrazing comets as fluffy silicate aggregates of submicrometer sizes. To better interpret observational data, we numerically calculate the solar radiation pressure, the equilibrium temperature, and the sublimation and crystallization rates of silicate grains near the Sun. Our results show that the dust tails contain aggregates of submicrometer crystal grains, but not amorphous grains, since amorphous silicates mostly crystallize after release from the comets. The peak in the lightcurves of the dust comae observed either at 11.2 or 12.3 solar radii (R ) seems to result from sublimation of fluffy aggregates consisting of crystalline or amorphous olivines, respectively. We attribute an additional enhancement in the lightcurves inside 7 R to increasing out-flow of crystalline and amorphous pyroxenes composed fluffy aggregates. According to our model, the observed lightcurves indicate a high abundance of olivine and a low abundance of pyroxene in the comets, which may bear implications about the dynamical and thermal history of the sungrazers and their progenitor. c 2002 Elsevier Science (USA)
Geochimica et Cosmochimica Acta, 1992
This is a report on the first comparative study of the effects of experimental and natural shock ... more This is a report on the first comparative study of the effects of experimental and natural shock on the K-Ar system. First, mineral separates from a 45 1 + 1 Ma old gneiss, experimentally shocked up to 60 GPa, were investigated by stepwise heating 40Ar-39Ar technique. Compared with an unshocked sample, the shocked samples have lower 40Ar-39Ar ages, and the diffusion properties have changed depending on peak shock pressure and mineralogic composition. Total resetting of the K-Ar clock did not occur. Secondly, to compare these results with the effects of natural shock, samples from the -23 Ma old Haughton impact crater, Devon Island, Canada, with different shock stages were investigated. Up to shock stage III, no total resetting of the K-Ar clock was observed, but severe argon losses, depending on shock pressure, result in 40Ar-39Ar plateau ages which are incorrect in terms of the true crater age, yet they provide an upper limit to the time of the cratering event. selection and preparation and helpful discussions, and P. Kunz for technical assistance. We acknowledge U. Homemann from the Emst-Mach-Institut ( Weil/Rhein, Germany) for carrying out the shock experiments. This work was supported by Deutsche Forschungsgemeinschaft (Grants StolOl/21-1 and De401/2-2). Helpful reviews by F. H&z, I. Kaneoka, R. C. Wiens, and D. Bogard are gratefully acknowledged.
Earth and Planetary Science Letters, 1974
A new method to date uranium-bearing minerals exclusively by means of a mass spectrometric determ... more A new method to date uranium-bearing minerals exclusively by means of a mass spectrometric determination of Xe and/or Kr isotopic ratios has been developed and experimentally tested. It is based on the compositional differences between Xe produced by spontaneous fission of 2 3 8~ in nature and Xe from fission induced by thermal neutrons in a nuclear reactor. Xe is extracted in 5 -10 release fractions at successively higher temperatures.
Earth and Planetary Science Letters, 1984
This is a report on the isotopic composition of argon found in neutron-irradiated quartz ampoules... more This is a report on the isotopic composition of argon found in neutron-irradiated quartz ampoules which contain samples of Allende coarse-grained inclusions or aluminum wrap only, and of argon released from one of these inclusions by stepwise heating. Besides atmospheric argon all ampoules contain, with varying concentrations but in constant proportions, 3BAr from C1 and 39Ar from K corresponding to CI/K -1. No 39Ar which has recoiled out of the samples and no argon which has diffused out of the samples has been observed in the ampoule gas.
… , Part 1 p 503-516(SEE …, 1992
SIMS chemical analysis of extended impact features from the trailing edge portion of experiment A... more SIMS chemical analysis of extended impact features from the trailing edge portion of experiment AO 187-2. SACHIKO AMARI, JOHN FOOTE, CHARLES SIMON, ELMARK JESSBERGER, GUNDOLF LANGE, FRANK STADERMANN ...
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Papers by Elmar Jessberger