The Multi Unit Spectroscopic Explorer (MUSE) is a second-generation VLT panoramic integral-field spectrograph currently in manufacturing, assembly and integration phase. MUSE has a field of 1x1 arcmin² sampled at 0.2x0.2 arcsec² and is assisted by the VLT ground layer adaptive optics ESO facility using four laser guide stars. The instrument is a large assembly of 24 identical high performance integral field units, each one composed of an advanced image slicer, a spectrograph and a 4kx4k detector. In this paper we review the progress of the manufacturing and report the performance achieved with the first integral field unit.
Venus has thick clouds of H2SO4 aerosol particles extending from altitudes of 40 to 60 km. The 60-100 km region (the mesosphere) is a transition region between the 4 day retrograde superrotation at the top of the thick clouds and the solar-antisolar circulation in the thermosphere (above 100 km), which has upwelling over the subsolar point and transport to the nightside. The mesosphere has a light haze of variable optical thickness, with CO, SO2, HCl, HF, H2O and HDO as the most important minor gaseous constituents, but the vertical distribution of the haze and molecules is poorly known because previous descent probes began their measurements at or below 60 km. Here we report the detection of an extensive layer of warm air at altitudes 90-120 km on the night side that we interpret as the result of adiabatic heating during air subsidence. Such a strong temperature inversion was not expected, because the night side of Venus was otherwise so cold that it was named the 'cryosphere' above 100 km. We also measured the mesospheric distributions of HF, HCl, H2O and HDO. HCl is less abundant than reported 40 years ago. HDO/H2O is enhanced by a factor of approximately 2.5 with respect to the lower atmosphere, and there is a general depletion of H2O around 80-90 km for which we have no explanation.
Spectroscopy for the investigation of the characteristics of the atmosphere of Venus (SPICAV) is a suite of three spectrometers in the UV and IR range with a total mass of 13.9 kg flying on the Venus Express (VEX) orbiter, dedicated to the study of the atmosphere of Venus from ground level to the outermost hydrogen corona at more than 40,000 km. It is derived from the SPICAM instrument already flying on board Mars Express (MEX) with great success, with the addition of a new IR high-resolution spectrometer, solar occultation IR (SOIR), working in the solar occultation mode. The instrument consists of three spectrometers and a simple data processing unit providing the interface of these channels with the spacecraft. A UV spectrometer (118–320 nm, resolution 1.5 nm) is identical to the MEX version. It is dedicated to nadir viewing, limb viewing and vertical profiling by stellar and solar occultation. In nadir orientation, SPICAV UV will analyse the albedo spectrum (solar light scattered back from the clouds) to retrieve SO2, and the distribution of the UV-blue absorber (of still unknown origin) on the dayside with implications for cloud structure and atmospheric dynamics. On the nightside, γ and δ bands of NO will be studied, as well as emissions produced by electron precipitations. In the stellar occultation mode the UV sensor will measure the vertical profiles of CO2, temperature, SO2, SO, clouds and aerosols. The density/temperature profiles obtained with SPICAV will constrain and aid in the development of dynamical atmospheric models, from cloud top (not, vert, similar60 km) to 160 km in the atmosphere. This is essential for future missions that would rely on aerocapture and aerobraking. UV observations of the upper atmosphere will allow studies of the ionosphere through the emissions of CO, CO+, and CO2+, and its direct interaction with the solar wind. It will study the H corona, with its two different scale heights, and it will allow a better understanding of escape mechanisms and estimates of their magnitude, crucial for insight into the long-term evolution of the atmosphere. The SPICAV VIS-IR sensor (0.7–1.7 μm, resolution 0.5–1.2 nm) employs a pioneering technology: an acousto-optical tunable filter (AOTF). On the nightside, it will study the thermal emission peeping through the clouds, complementing the observations of both VIRTIS and Planetary Fourier Spectrometer (PFS) on VEX. In solar occultation mode this channel will study the vertical structure of H2O, CO2, and aerosols. The SOIR spectrometer is a new solar occultation IR spectrometer in the range λ=2.2–4.3 μm, with a spectral resolution λ/Δλ>15,000, the highest on board VEX. This new concept includes a combination of an echelle grating and an AOTF crystal to sort out one order at a time. The main objective is to measure HDO and H2O in solar occultation, in order to characterize the escape of D atoms from the upper atmosphere and give more insight about the evolution of water on Venus. It will also study isotopes of CO2 and minor species, and provide...
A new compact spaceborne high-resolution spectrometer developed for the European Space Agency's Venus Express spacecraft is described. It operates in the IR wavelength range of 2.2 to 4.3 microm and measures absorption spectra of minor constituents in the Venusian atmosphere. It uses a novel echelle grating with a groove density of 4 lines/mm in a Littrow configuration in combination with an IR acousto-optic tunable filter for order sorting and an actively cooled HgCdTe focal plane array of 256 by 320 pixels. It is designed to obtain an instrument line profile of 0.2 cm(-1). First results on optical and spectral properties are reported.
[1] The SPICAM IR spectrometer on Mars Express mission (1.0-1.7 mm, spectral resolution 0.5-1.2 nm) is dedicated primarily to nadir measurements of H 2 O abundance. It is one of two channels of SPICAM UV-IR instrument. In this spectrometer we applied for the first time in planetary research the technology of an acousto-optic tunable filter (AOTF) that allowed unprecedented mass reduction for such an instrument: 0.75 kg. SPICAM IR is a point nadir-looking spectrometer with sequential scanning of the spectrum by the AOTF. Sun occultations are performed with a help of dedicated solar port. We describe instrumentation, calibrations, and the modes of operations of the device and discuss its in-flight performances. A brief overview of the scientific measurements includes water vapor measurements and the mapping of intensity of the O 2 (a 1 D g ) emission at 1.27 mm, described in detail in separate papers. Measurements in reflected solar light allow clear detection of H 2 O and CO 2 ices on the surface or in the atmosphere of Mars. We discuss solar occultation measurements by SPICAM and present resulting vertical profiles of aerosol optical depth.
The aim of this trial was to study the effects of cereal (corn or sorghum) and of the presentation of the diet (pelleted diet or a mixture with cereal) on the performance of geese. In total, 480 one-day-old geese were divided into 4 groups differing in the diet they received between 52 and 102 d of age: a pelleted diet containing 500 g of sorghum/kg (CS group; AMEn 11.29 MJ/kg, CP 16.70%); a mixture containing 500 g of protein-rich pellets and 500 g of sorghum whole seeds/kg (MS group; AMEn 11.61 MJ/kg, CP 14.30%); a pelleted diet containing 500 g of corn/kg (group CC; AMEn 11.33 MJ/kg, CP 16.40%); and a mixture containing 500 g of protein-rich pellets and 500 g of corn mash/kg (group MC; AMEn 11.48 MJ/kg, CP 14.50%). From 102 to 117 d, 33 birds/sex/group were force-fed with corn. Between 52 and 102 d of age, individual BW and collective feed intake (40 birds/pen) were measured weekly. Body traits were measured at 69, 96, and 117 d and the volume of the crop was measured at 102 d of age. The cereal had no significant effect on total feed intake (15,028 g, NS) or BW (5,811 g, NS) but the breast development at 102 d was less in birds fed sorghum compared with corn (-4.9%; P<0.05). Feed intake (+8.4% between 69 and 102 d; P<0.001), BW (+3.9%; P<0.001) and gut development (+9.3%; P<0.001) were higher when the diet was offered as a mixture compared with a complete pelleted diet. The birds fed the complete pelleted diets had a larger crop (+10.1%; P<0.05) than others. The cereal and the presentation of the diet had no effect on the body traits at the end of the force feeding. The results suggest that the use of sorghum whole seeds is interesting for feeding geese.
We present the first far infrared (FIR) dust emission polarization map covering the full extent Milky Way's Central molecular zone (CMZ). The data, obtained with the PILOT balloon-borne experiment, covers the Galactic Center region −2 • < < 2 • , −4 • < b < 3 • at a wavelength of 240 µm and an angular resolution 2.2 . From our measured dust polarization angles, we infer a magnetic field orientation projected onto the plane of the sky that is remarkably ordered over the full extent of the CMZ, with an average tilt angle of 22 • clockwise with respect to the Galactic plane. Our results confirm previous claims that the field traced by dust polarized emission is oriented nearly orthogonal to the field traced by GHz radio synchrotron emission in the Galactic Center region. The observed field structure is globally compatible with the latest Planck polarization data at 353 GHz and 217 GHz. Upon subtraction of the extended emission in our data, the mean field orientation that we obtain shows good agreement with the mean field orientation measured at higher angular resolution by the JCMT within the 20 km/s and 50 km/s molecular clouds. We find no evidence that the magnetic field orientation is related to the 100 pc twisted ring structure within the CMZ. We propose that the low polarization fraction in the Galactic Center region and the highly ordered projected field orientation can be reconciled if the field is strong, with a 3D geometry that is is mostly oriented 15 • with respect to the line-of-sight towards the Galactic center. Assuming equipartition between the magnetic pressure and ram pressure, we obtain magnetic field strengths estimates as high as a few mG for several CMZ molecular clouds.
Future cosmology space missions will concentrate on measuring the polarization of the Cosmic Microwave Background , which potentially carries invaluable information about the earliest phases of the evolution of our universe. Such ambitious projects will ultimately be limited by the sensitivity of the instrument and by the accuracy at which polarized foreground emission from our own Galaxy can be subtracted out. We present the PILOT balloon project which will aim at characterizing one of these foreground sources, the polarization of the dust continuum emission in the diffuse interstellar medium. The PILOT experiment will also constitute a test-bed for using multiplexed bolometer arrays for polarization measurements. We present the results of ground tests obtained just before the first flight of the instrument.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.