Haze aerosols in the atmosphere of early Earth: manna from heaven

An organic haze layer in the upper atmosphere of Titan plays a crucial role in the atmospheric composition and climate of that moon. Such a haze layer may also have existed on the early Earth, providing an ultraviolet shield for greenhouse gases needed to warm the planet enough for life to arise and evolve. Despite the implications of such a haze layer, little is known about the organic material produced under early Earth conditions when both CO(2) and CH(4) may have been abundant in the atmosphere. For the first time, we experimentally demonstrate that organic haze can be generated in different CH(4)/CO(2) ratios. Here, we show that haze aerosols are able to form at CH(4) mixing ratios of 1,000 ppmv, a level likely to be present on early Earth. In addition, we find that organic hazes will form at C/O ratios as low as 0.6, which is lower than the predicted value of unity. We also show that as the C/O ratio decreases, the organic particles produced are more oxidized and contain biologically labile compounds. After life arose, the haze may thus have provided food for biota.     

Miniaturized laser-induced plasma spectrometry for planetary in situ analysis – The case for Jupiter’s moon Europa

Jupiter’s icy moon Europa is one of most promising places in our Solar System where possible extraterrestrial life forms could exist either in the past or even presently. The Europa Lander mission, an exciting part of the international Europa Jupiter System Mission (EJSM/Laplace), considers in situ planetary exploration of the moon. The distance of Europa from the Earth and the Sun asks for autonomous analytical tools that maximize the scientific return at minimal resources, demanding new experimental concepts. We propose a novel instrument, based on the atomic spectroscopy of laser generated plasmas for the elemental analysis of Europa’s surface materials as far as it is in reach of the lander for example by a robotic arm or a mole, or just onboard the lander. The technique of laser-induced plasma spectrometry provides quantitative elemental analysis of all major and many trace elements. It is a fast technique, i.e. an analysis can be performed in a few seconds, which can be applied to many different types of material such as ice, dust or rocks and it does not require any sample preparation. The sensitivity is in the range of tens of ppm and high lateral resolution, down to 50 μm, is feasible. In addition, it provides the potential of depth profiling, up to 2 mm in rock material and up to a few cm in more transparent icy matrices. Key components of the instrument are presently developed in Germany for planetary in situ missions. This development program is accompanied by an in-depth methodical investigation of this technique under planetary environmental conditions.     

Cyanobacterial emergence at 2.8 gya and greenhouse feedbacks

Apparent cyanobacterial emergence at about 2.8 Gya coincides with the negative excursion in the organic carbon isotope record, which is the first strong evidence for the presence of atmospheric methane. The existence of weathering feedbacks in the carbonate-silicate cycle suggests that atmospheric and oceanic CO2 concentrations would have been high prior to the presence of a methane greenhouse (and thus the ocean would have had high bicarbonate concentrations). With the onset of a methane greenhouse, carbon dioxide concentrations would decrease. Bicarbonate has been proposed as the preferred reductant that preceded water for oxygenic photosynthesis in a bacterial photosynthetic precursor to cyanobacteria; with the drop of carbon dioxide level, Archean cyanobacteria emerged using water as a reductant instead of bicarbonate (Dismukes et al., 2001). Our thermodynamic calculations, with regard to this scenario, give at least a tenfold drop in aqueous CO2 levels with the onset of a methane-dominated greenhouse, assuming surface temperatures of about 60 degrees C and a drop in the level of atmospheric carbon dioxide from about 1 to 0.1 bars. The buildup of atmospheric methane could have been triggered by the boost in oceanic organic productivity that arose from the emergence of pre-cyanobacterial oxygenic phototrophy at about 2.8-3.0 Gya; high temperatures may have precluded an earlier emergence. A greenhouse transition timescale on the order of 50-100 million years is consistent with results from modeling the carbonate-silicate cycle. This is an alternative hypothesis to proposals of a tectonic driver for this apparent greenhouse transition.     

Influence of the equinoctial asymmetry on the semi-annual anomaly in NmF2 near noon in the northern geographic hemisphere: A statistical study

Hourly values of NmF2 measured by 72 ionosondes near noon from 1957 to 2012 at low and middle geomagnetic latitudes of the northern geographic hemisphere are used to study the spring and autumn semi-annual anomalies in NmF2. The spring/summer, autumn/summer, spring/winter, and autumn/winter geomagnetically quiet NmF2 ratios, X_M, X_S, Y_M, and Y_S, respectively, taken near noon over each ionosonde for approximately the same winter, spring, summer, and autumn solar activity conditions are analyzed. The probabilities of occurrences of X_M, X_S, Y_M, and Y_S in intervals of change of these parameters, together with its most frequent and the mean expected values, and the probabilities to observe the F2-region spring and autumn semi-annual anomalies are calculated and studied for the first time for low, moderate, and high solar activity conditions. The geomagnetic latitude range between 10 and 55 degrees, where the ionosondes are located, is divided into 9 intervals of the same length of 5 degrees, the statistical parameters are averaged over each 5 degree interval, and the trends in these averaged statistical characteristics of the NmF2 spring and autumn semi-annual anomalies are calculated and studied for the first time. It is shown that the NmF2 equinoctial asymmetry can significantly affect the statistical parameters of the semi-annual anomaly in NmF2.     

Disk wing to main rotor conversion mechanics

A mathematical model of spatial motion of the disk wing blades converted to the main rotor is presented. The system linkage parameters are defined.     

The low and middle latitude semi-annual anomaly in NmF2 near noon: A statistical study

Hourly values of the F2-layer peak density, NmF2, measured by 99 ionosonde stations near noon from 1957 to 2010 at low and middle geomagnetic latitudes of the northern and southern geographic hemispheres are used in a statistical study of the F2-region semi-annual anomaly. The equinox/winter and equinox/summer geomagnetically quiet NmF2 ratios, X and Y, taken near noon over each ionosonde for approximately the same winter, equinox, and summer solar activity conditions are analyzed. The conditional probabilities of occurrences of X and Y in intervals of X and Y, the most frequent values of X and Y, the mean expected values of X and Y, and the conditional probability to observe the F2-region semi-annual anomaly are calculated and studied for the fist time for low, moderate, and high solar activity conditions. These statistical parameters are averaged over 5° geomagnetic latitude interval in the northern and southern geographic hemispheres, and the trends in these averaged statistical characteristics of the NmF2 semi-annual anomaly are calculated and studied for the fist time. It is shown that the median approach can produce the incorrect conclusions about the absence of the NmF2 semi-annual anomaly.     

December 2006 solar extreme events and their influence on the near-Earth space environment: “Universitetskiy-Tatiana” satellite observations

The Russian microsatellite “Universitetskiy-Tatiana” was launched on Jan. 20, 2005 and was both a scientific and educational mission. Its two main aims were declared as: (1) monitoring of the energetic particles dynamics in the near-Earth space environment after solar events and during quiet times, (2) educational activities based on experimental data obtained from the spacecraft. In this paper observations acquired during Dec. 5–16, 2006, known as “Solar Extreme Events 2006”, were analyzed. The “Universitetskiy-Tatiana” microsatellite orbit permits one to measure both solar energetic particle dynamics, variations of the boundary of solar particle penetration, as well as relativistic and sub-relativistic electrons of the Earth’s outer radiation belt during and after magnetic storms. Both relativistic electrons of the Earth’s outer radiation and solar energetic particles are an important source of radiation damage in near-Earth space. Therefore, the presented experimental results demonstrate the successful application of a small educational spacecraft both for scientific and educational programs.     

Disk wing as a solution of some “eternal” problems of main rotor

A possibility of using the main rotor in designing a vertical takeoff and landing aircraft with a disk wing is analyzed. We propose integrating the main rotor and a disk wing for solving some problems of main rotors.