Search Publications
New results on planetary lightning
Yair, Yoav
We present the latest observations from spacecraft and ground-based instruments in search for lightning activity in the atmospheres of planets in the solar system, and put them in context of previous research. Since the comprehensive book on planetary atmospheric electricity compiled by Leblanc et al. (2008), advances in remote sensing technology …
Detection of sub-kilometer craters in high resolution planetary images using shape and texture features
Stepinski, Tomasz F.; Bandeira, Lourenço; Ding, Wei
Counting craters is a paramount tool of planetary analysis because it provides relative dating of planetary surfaces. Dating surfaces with high spatial resolution requires counting a very large number of small, sub-kilometer size craters. Exhaustive manual surveys of such craters over extensive regions are impractical, sparking interest in designi…
What are the physical mechanisms of eruptions and CMEs?
Aulanier, Guillaume; Schmieder, Brigitte
CMEs are due to physical phenomena that drive both, eruptions and flares in active regions. Eruptions/CMEs must be driven from initially force-free current-carrying magnetic field. Twisted flux ropes, sigmoids, current lanes and pattern in photospheric current maps show a clear evidence of currents parallel to the magnetic field. Eruptions occur s…
Refinements in the data analysis of VIRTIS-M-IR Venus nightside spectra
Drossart, Pierre; Piccioni, Giuseppe; Haus, Rainer +2 more
The successful long-duration radiation measurements performed by the VIRTIS instrument aboard ESA's Venus Express spacecraft have provided an excellent collection of atmospheric and surface data that stand out due to their high temporal and spatial coverage of the planet and due to a high diversity of measurement and environmental conditions. A de…
Co-registration of Chang'E-1 stereo images and laser altimeter data with crossover adjustment and image sensor model refinement
Di, Kaichang; Hu, Wenmin; Liu, Yiliang +1 more
Topographic information is of fundamental importance for various scientific investigations in lunar and planetary exploration. To provide high-precision, seamless mapping capability, it is critical to co-register image and altimetry data, the two major data sources for topographic modeling. This paper presents a method for co-registration of Chang…
Late stages of stellar evolution - Herschel's contributions
Decin, Leen
Cool objects glow in the infrared. The gas and solid-state species that escape the stellar gravitational attraction of evolved late-type stars in the form of a stellar wind are cool, with temperatures typically ≲1500 K, and can be ideally studied in the infrared. These stellar winds create huge extended circumstellar envelopes with extents approac…
New insights into SNR evolution revealed by the discovery of recombining plasmas
Yamaguchi, Hiroya; Ozawa, Midori; Ohnishi, Takao
We report the discovery of recombining plasmas in three supernova remnants (SNRs) with the Suzaku X-ray astronomy satellite. During SNR's evolution, the expanding supernova ejecta and the ambient matter are compressed and heated by the reverse and forward shocks to form an X-ray emitting hot plasma. Since ionization proceeds slowly compared to sho…
Quasi-periodic frequency fluctuations observed during coronal radio sounding experiments 1991-2009
Pätzold, M.; Bird, M. K.; Efimov, A. I. +5 more
Coronal radio sounding experiments were carried out using the dual-frequency signals of the spacecraft Ulysses, Galileo, Mars Express, Venus Express, and Rosetta. The change in differential frequency recorded at the NASA and ESA ground stations, a quantity sensitive only to the plasma along the radio ray path from spacecraft to receiver, has been …
Solar and interplanetary parameters of CMEs with and without type II radio bursts
Moon, Y. -J.; Shanmugaraju, A.; Umapathy, S. +1 more
We have analyzed 101 CMEs, and their associated ICMEs and interplanetary (IP) shocks observed during the period 1997-2005. The main aim of the present work is to study the interplanetary characteristics of metric and DH type II associated CMEs such as, shock strength, IP shock speed, ICME speed, stand off distance and transit time. Among these 101…
Application of electrical propulsion for an active debris removal system: a system engineering approach
Covello, Fabio
One of the main challenge in the design of an active removal system for space debris is the high ΔV required both to approach space debris lying in different orbits and to de-orbit/re-orbit them. Indeed if the system does not target a number of objects during its lifetime the cost of the removal will be far too high to be considered as the basis o…