The ESA X-ray Multi Mirror mission, XMM-Newton, carries two identical Reflection Grating Spectrometers (RGS) behind two of its three nested sets of Wolter I type mirrors. The instrument allows ...high-resolution ($E/\Delta E = 100$ to 500) measurements in the soft X-ray range (6 to 38 Åor 2.1 to 0.3 keV) with a maximum effective area of about 140 cm2 at 15 Å. Its design is optimized for the detection of the K-shell transitions of carbon, nitrogen, oxygen, neon, magnesium, and silicon, as well as the L shell transitions of iron. The present paper gives a full description of the design of the RGS and its operational modes. We also review details of the calibrations and in-orbit performance including the line spread function, the wavelength calibration, the effective area, and the instrumental background.
We performed an endurance test with single-mode vertical-cavity surface-emitting lasers (VCSEL) under vacuum condition and increased operational parameters (laser current and laser temperature) to ...accelerate the aging of the lasers. During the endurance test the emitted polarization-dependent and polarization-independent optical light power from the lasers was detected. Additionally, electro-optical characterisations including measurements of the combination of laser current and laser temperature to excite the
87
Rb D
1
transition (
λ
= 795 nm), the current and temperature tuning coefficients, laser line width, threshold current and the polarization ellipse were performed for the aged lasers. The test was started with a number of 12 VCSELs consisting of 4 lasers each from 3 different suppliers. The aging behaviour of VCSELs was investigated with respect to the development of a new optical magnetometer prototype for space missions with a mission duration of up to 17 years. Only a limited change of the electro-optical parameters can be tolerated by the instrument design over the mission duration. The endurance test and the electro-optical characterizations revealed clear differences in the aging behaviour of the three suppliers. Lasers from one supplier showed that they can be operated for more than 17 years under vacuum conditions without major degradation of their operational parameters.
Context.Icy grains in the inner coma of a comet may play an important role in the energy balance and in the production of certain gas coma species. Their existence has therefore been assumed ...repeatedly to explain a variety of observed phenomena. However, owing to their extremely short life time no evidence for the presence of icy grains had been found in any active comet close to the Sun.Aims.We observed Comet 9P/Tempel 1 during the Deep Impact mission to look for phenomena induced by the impact.Methods.The comet was observed with the XMM-Newton Observatory. We used the EPIC camera for X-ray imaging and the Optical Monitor for monitoring in the ultraviolet and visible spectral range.Results.An outburst of the comet nucleus was observed as a result of the impact and the evolution of the coma was monitored in gas and dust. Our observations led to the first detection of icy grains in a comet at 1.5 AU from the Sun.Conclusions.We showed for the first time that the material ejected from the nucleus of a comet contains icy grains, even at small heliocentric distance.
Calibration of the C1XS instrument on Chandrayaan-1 Narendranath, S.; Sreekumar, P.; Maddison, B.J. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2010, Letnik:
621, Številka:
1
Journal Article
Recenzirano
The Chandrayaan-1 X-ray spectrometer (C1XS) experiment on the Chandrayaan-1 mission was designed to carry out spectroscopic observations in the 1–10
keV range for deriving lunar chemistry. We present ...results from the ground calibration of the Swept Charge Devices (SCDs) on C1XS at the RESIK X-ray beam facility at Rutherford Appleton Laboratory, Chilton, UK. The spectral redistribution function of the SCDs are determined in the energy range from 2.3–8
keV using discrete line energies from a monochromatic X-ray beam. The detection efficiency of the SCDs are determined relative to a reference Si-PIN detector. The Si-PIN detector itself has been calibrated at the beamlines of the synchrotron facility at PTB/BESSY II. A non-Gaussian response matrix which includes probability for partial absorption events in the SCD is constructed using instrument parameters obtained from ground calibration. The calibration spectra from the
55Fe radioactive isotopes obtained from C1XS while in the lunar orbit, are used to validate the response matrix derived on ground.
Context. The Crab pulsar emits across a large part of the electromagnetic spectrum. Determining the time delay between the emission at different wavelengths will allow to better constrain the site ...and mechanism of the emission. We have simultaneously observed the Crab Pulsar in the optical with S-Cam, an instrument based on Superconducting Tunneling Junctions (STJs) with μs time resolution and at 2 GHz using the Nançay radio telescope with an instrument doing coherent dedispersion and able to record giant pulses data. Aims. We have studied the delay between the radio and optical pulse using simultaneously obtained data therefore reducing possible uncertainties present in previous observations. Methods. We determined the arrival times of the (mean) optical and radio pulse and compared them using the tempo2 software package. Results. We present the most accurate value for the optical-radio lag of $255 \pm 21$ μs and suggest the likelihood of a spectral dependence to the excess optical emission asociated with giant radio pulses.
In this paper, we provide a detailed review of Ganymede's characteristics that are germane to any consideration of its planetary protection requirements. Ganymede is the largest moon in our solar ...system and is the subject of one of the main science objectives of the JUICE mission to the jovian system. We explore the probability of the occurrence of potentially habitable zones within Ganymede at present, including those both within the deep liquid ocean and those in shallow liquid reservoirs. We consider the possible exchange processes between the surface and any putative habitats to set some constraints on the planetary protection approach for this moon. As a conclusion, the "remote" versus "significant" chance of contamination will be discussed, according to our current understanding of this giant icy moon. Based on the different estimates we investigate here, it appears extremely unlikely that material would be exchanged downward through the upper icy layer of Ganymede and, thus, bring material into the ocean over timescales consistent with the survival of microorganisms.
The RS CVn binary system HR 1099 was extensively observed by the XMM-Newton observatory in February 2000 as its first-light target. A total of 570 ks of exposure time was accumulated with the ...Reflection Grating Spectrometers (RGS). The integrated X-ray spectrum between 5-35 Åis of unprecedented quality and shows numerous features attributed to transitions of the elements C, N, O, Ne, Mg, Si, S, Fe, and Ni. We perform an in-depth study of the elemental composition of the average corona of this system, and find that the elemental abundances strongly depend on the first ionisation potential (FIP) of the elements. But different from the solar coronal case, we find an inverse FIP effect, i.e., the abundances (relative to oxygen) increase with increasing FIP. Possible scenarios, e.g., selective enrichment due to Ne-rich flare-like events, are discussed.
Past exploration of Jupiter's diverse satellite system has forever changed our understanding of the unique environments to be found around gas giants, both in our solar system and beyond. The ...detailed investigation of three of Jupiter's Galilean satellites (Ganymede, Europa, and Callisto), which are believed to harbour subsurface water oceans, is central to elucidating the conditions for habitability of icy worlds in planetary systems in general. The study of the Jupiter system and the possible existence of habitable environments offer the best opportunity for understanding the origins and formation of the gas giants and their satellite systems. The JUpiter ICy moons Explorer (JUICE) mission, selected by ESA in May 2012 to be the first large mission within the Cosmic Vision Program 2015–2025, will perform detailed investigations of Jupiter and its system in all their inter-relations and complexity with particular emphasis on Ganymede as a planetary body and potential habitat. The investigations of the neighbouring moons, Europa and Callisto, will complete a comparative picture of the Galilean moons and their potential habitability. Here we describe the scientific motivation for this exciting new European-led exploration of the Jupiter system in the context of our current knowledge and future aspirations for exploration, and the paradigm it will bring in the study of giant (exo) planets in general.
► A description of the ESA-led JUICE (Jupiter Icy moons Explorer) mission. ► The emergence of habitable worlds around gas giants. ► Future exploration of the Jovian system.
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