Search Publications
Contributions from Accreted Organics to Titan’s Atmosphere: New Insights from Cometary and Chondritic Data
Miller, Kelly E.; Glein, Christopher R.; Waite, J. Hunter, Jr.
Since its discovery in the first half of the 20th century, scientists have puzzled over the origins of Titan’s atmosphere. Current models suggest that atmospheric N2 on Titan may have originated from NH3-bearing ice with N-isotopic ratios similar to those observed in NH2 in cometary comae (14N/15
Tensile Strength of Porous Dust Aggregates
Kataoka, Akimasa; Tatsuuma, Misako; Tanaka, Hidekazu
Comets are thought to have information about the formation process of our solar system. Recently, detailed information about comet 67P/Churyumov-Gerasimenko was found by Rosetta. It is remarkable that its tensile strength was estimated. In this paper, we measure and formulate the tensile strength of porous dust aggregates using numerical simulatio…
Simulations of Ice Chemistry in Cometary Nuclei
Garrod, Robin T.
The first computational model of solid-phase chemistry in cometary nuclear ices is presented. An astrochemical kinetics model, the Model for Astrophysical Gas and Ice Chemical Kinetics And Layering, is adapted to trace the chemical evolution in multiple layers of cometary ice, over a representative period of 5 Gyr. Physical conditions are chosen a…
How Comets Work
Blum, J.; Fulle, M.; Rotundi, A.
Two major questions regarding comets have been up to now far from any solution. (i) How is it possible that water-ice sublimation from the nucleus surface does not lead to an insulating crust, stopping every gas and dust ejection within a few days? (ii) How is it possible that the gas flow crossing the refractory surface crust ejects dust particle…
The Role of Clathrate Formation in Europa’s Ocean Composition
Mousis, Olivier; Bouquet, Alexis; Danger, Grégoire +2 more
We use a thermodynamic statistical model to evaluate how the composition of Europa’s internal ocean may have been affected by clathrate hydrate formation. Assuming an input of the observed O2 and CO2 from the surface into a mildly acidic ocean (pH < 6), and considering the possibility of contributions by reduced (with CH
Implications of Philae Magnetometry Measurements at Comet 67P/Churyumov-Gerasimenko for the Nebular Field of the Outer Solar System
Auster, Hans-Ulrich; Heinisch, Philip; Glassmeier, Karl-Heinz +3 more
The remanent magnetization of solar system bodies reflects their accretion mechanism, the space environment in which they formed, and their subsequent geological evolution. In particular, it has been suggested that some primitive bodies may have formed large regions of coherent remanent magnetization as a consequence of their accretion in a backgr…
The Evolution of the Electron Number Density in the Coma of Comet 67P at the Location of Rosetta from 2015 November through 2016 March
Henri, P.; Edberg, N. J. T.; Rubin, M. +6 more
A comet ionospheric model assuming the plasma moves radially outward with the same bulk speed as the neutral gas and not being subject to severe reduction through dissociative recombination has previously been tested in a series of case studies associated with the Rosetta mission at comet 67P/Churyumov-Gerasimenko. It has been found that at low ac…
Exposure Experiments of Amorphous Silicates and Organics to Cometary Ice and Vapor Analogs
Takigawa, Aki; Kimura, Yuki; Davidsson, Björn +2 more
Hydration is a major mineral alteration process in primitive asteroids and it might occur in comet nuclei; however, it is poorly understood at low temperatures, especially below the freezing point of water. Long-duration experiments were performed with exposures of amorphous silicate nanoparticles and organic compounds (glycine and ribose) to D
Rovibrational Spectral Analysis of CO3 and C2O3: Potential Sources for O2 Observed in Comet 67P/Churyumov-Gerasimenko
Fortenberry, Ryan C.; Peters, Daniel; Ferrari, Brian C. +1 more
The recent ROSETTA mission to comet 67P/Churyumov-Gerasimenko detected surprisingly high levels of molecular oxygen (O2; hypervolatile species) in the coma. Current models predict that considerable levels of other hypervolatiles (such as molecular nitrogen, N2, methane, CH4, and Argon) should be found at similar le…
Kinetic Theory of Ion Acoustic Waves Observed at Comet 67P/Churyumov-Gerasimenko
Rehman, Saeed ur; Shah, Asif; Haque, Qamar ul
This work presents the resonance interaction of ion acoustic waves with the cometary plasma as observed at comet 67P/Churyumov-Gerasimenko. The plasma is comprised of cold, warm, and suprathermal electron populations and water ions such that the quasineutrality is satisfied. The cold electron population is found to play a dominant role in the damp…