Normal Solar Conditions Research Articles

IDP detection in Earth environment: Prediction of plasma capture efficiency and detector response to high-energy particles

Interplanetary dust particles exist everywhere in the space between any two planets. These particles are originated from sources like Asteroid belt, Kuiper belt or comets and they evolve through their orbital paths. Various planets like Mars, Earth or Venus may capture such particles during their inward travel. Flux of dust particles at a given planet is important to understand total inflow of material and also, metal ion layers formed in atmosphere due to ablation. Using past observations around Earth and an existing flux model, a power law model is suggested for incoming particle flux at Earth. Expected particle number density around Earth is presented based on the suggested model. To detect such dust particles, an impact ionization dust detector is proposed for planetary application and it is under development at Physical Research Laboratory. A dust impact on detector target produces charge carriers, which are captured by voltage biased electrodes for further processing. For the dust detector, bias optimization is worthwhile to reduce resources required on board a satellite. In this regard, prediction of plasma capture efficiency is presented here using SIMION software, to get first hand estimate of detector performance. In addition, the detector receives high-energy solar wind particles and Galactic Cosmic Rays in space, along with the dust. Therefore, understanding detector response to high-energy particles is utmost important during normal solar conditions and also during SEP events. Through an extensive simulation using Geant4 software and ACE, GOES as well as SPENVIS datasets, it is found that high-energy particles act as noise for the detector in electron channel only. The dust impact can easily be identified from the background noise using the signal coincidence. The results could be useful to understand dust flux at Earth and also for the detector optimization.

Sensitivity limits of space-based interferometric gravitational wave observatories from the solar wind

Space-based interferometric gravitational wave instruments such as the ESA/NASA Laser Interferometer Space Antenna (LISA) observe gravitational waves by measuring changes in the light travel time between widely-separated spacecraft. One potential noise source for these instruments is interaction with the solar wind, in particular the free electrons in the interplanetary plasma. Variations in the integrated column density of free electrons along the laser links will lead to time-of-flight delays which directly compete with signals produced by gravitational waves. In this paper we present a simplified model of the solar plasma relevant for this problem, anchor key parameters of our model using data from the NASA \emph{Wind}/SWE instrument, and derive estimates for the effect in the LISA measurement. We find that under normal solar conditions, the gravitational-wave sensitivity limit from the free-electron effect is smaller than other noise sources that are expected to limit LISA's sensitivity.

Scientific rationale for the D-CIXS X-ray spectrometer on board ESA's SMART-1 mission to the Moon

The D-CIXS X-ray spectrometer on ESA's SMART-1 mission will provide the first global coverage of the lunar surface in X-rays, providing absolute measurements of elemental abundances. The instrument will be able to detect elemental Fe, Mg, Al and Si under normal solar conditions and several other elements during solar flare events. These data will allow for advances in several areas of lunar science, including an improved estimate of the bulk composition of the Moon, detailed observations of the lateral and vertical nature of the crust, chemical observations of the maria, investigations into the lunar regolith, and mapping of potential lunar resources. In combination with information to be obtained by the other instruments on SMART-1 and the data already provided by the Clementine and Lunar Prospector missions, this information will allow for a more detailed look at some of the fundamental questions that remain regarding the origin and evolution of the Moon.

The D-CIXS X-ray spectrometer, and its capabilities for lunar science

The purpose of the D-CIXS (Demonstration of a Compact Imaging X-ray Spectrometer) instrument on the ESA SMART-1 mission is to provide high quality spectroscopic mapping of the Moon by imaging fluorescence X-rays emitted from the lunar surface. In order to obtain adequate statistics for what can be very weak sources, it is essential to have a large effective area, while maintaining a low mass. The solution is to make a thin, low profile detector, essentially a modern version of “X-ray detecting paper”. D-CIXS will achieve a spatial resolution on the ground of 42km from a spacecraft at 300 km altitude, with a spectral resolution of 200 eV or better. The instrument is based around the use of advanced dual microstructure collimator and Swept Charge Device X-ray detector technologies. Swept Charge Device X-ray detectors, a novel architecture based on proven CCD technology, have the virtue of providing superior X-ray detection and spectroscopic measurement capabilities, while also operating at room temperature. Thus we avoid the need for the large passive cooling radiator that was previously required to cool large X-ray focal plane CCDs. The advanced low profile microstructure collimation and filter design builds on expertise developed in solid state and microwave technology to enable us to dramatically reduce the instrument mass. The total mass of D-CIXS, including an X-ray solar monitor is ∼4.6 kg. D-CIXS will provide the first global map of the Moon in X-rays. During normal solar conditions, it will be able to detect absolute elemental abundances of Fe, Mg, Al and Si on the lunar surface, using the on-board solar monitor to obtain a continuous measurement of the input solar spectrum. During solar flare events, it will also be possible to detect other elements such as Ca, Ti, V, Cr, Mn, Co, K, P and Na. The global mapping of Mg, Al and Si, and in particular deriving Mg#, the magnesium number (MgO/[MgO+FeO]), represents the prime goal of the D-CIXS experiment.

The D-Cixs X-Ray Spectrometer On Esa's Smart-1 Mission To The Moon

The D-CIXS (Demonstration of a Compact Imaging X-ray Spectrometer) instrument will provide high quality spectroscopic mapping of the Moon, the primary science target of the ESA SMART-1 mission. At the same time it will demonstrate a radically novel approach to building a type of instrument essential for the Mercury cornerstone mission. It consists of a high throughput spectrometer, which will perform spatially localised X-ray fluorescence spectroscopy, and a solar monitor to provide the calibration of the illumination necessary to produce a global map of absolute lunar elemental abundances. D-CIXS will provide the first global coverage of the lunar surface in X-rays, providing absolute measurements of Fe, Mg, Al and Si under normal solar conditions and several others during solar flare events. In combination with information to beobtained by the other instruments on SMART-1 and from previous missions, thisinformation will enable a more detailed look at some of the fundamental questions that remain regarding the origin and evolution of the Moon and will help us to map Lunar resources more effectively.