O. Korablev - Academia.edu (original) (raw)

Papers by O. Korablev

Advances in Space Research, 2002

Experimental Astronomy, 2009

Michael Küppers · HU Keller · E. Kührt · MF A'Hearn · K. Altwegg · R. Bertrand · H. Busemann... more Michael Küppers · HU Keller · E. Kührt · MF A'Hearn · K. Altwegg · R. Bertrand · H. Busemann · MT Capria · L. Colangeli · B. Davidsson · P. Ehrenfreund · J. Knollenberg · S. Mottola · A. Rathke · P. Weiss · M. Zolensky · E. Akim · A. Basilevsky · E. Galimov · M. Gerasimov · O. Korablev ...

Space Science Reviews, 2007

In light of assessing the habitability of Mars, we examine the impact of the magnetic field on th... more In light of assessing the habitability of Mars, we examine the impact of the magnetic field on the atmosphere. When there is a magnetic field, the atmosphere is protected from erosion by solar wind. The magnetic field ensures the maintenance of a dense atmosphere, necessary for liquid water to exist on the surface of Mars. We also examine the impact of the rotation of Mars on the magnetic field. When the magnetic field of Mars ceased to exist (about 4 Gyr ago), atmospheric escape induced by solar wind began. We consider scenarios which could ultimately lead to a decrease of atmospheric pressure to the presently observed value of 7 mbar: a much weaker early martian magnetic field, a late onset of the dynamo, and high erosion rates of a denser early atmosphere.

Planetary and Space Science, 2007

The Mercury&amp;amp;amp;amp;amp;amp;#x27;s sodium atmosphere spectral imager (MSASI) on B... more The Mercury&amp;amp;amp;amp;amp;amp;#x27;s sodium atmosphere spectral imager (MSASI) on BepiColombo (BC) will address a range of fundamental scientific questions pertaining to Mercury&amp;amp;amp;amp;amp;amp;#x27;s exosphere. The measurements will provide new information on regolith–exosphere–magnetosphere coupling as well as new understanding of the dynamics governing the exosphere bounded by the planetary surface, the solar wind and interplanetary space. MSASI is a high-dispersion visible spectrometer working

Optics Letters, 2011

To suppress starlight for direct exoplanet observation, we propose a common-path achromatic rotat... more To suppress starlight for direct exoplanet observation, we propose a common-path achromatic rotational-shearing coronagraph (CP-ARC), which is an interferocoronagraph with an angular-adjustable field rotator. The CP-ARC aims to maintain unwanted detection of stellar light, which can be suppressed incompletely by interference because of the finite diameter of the star. Compared to the previous interferocoronagraph, which had a nonadjustable 180° field rotation, the proposed CP-ARC can improve the coronagraphic contrast by several orders if the CP-ARC is combined with medium or large telescopes where the companion-star separation is optically resolved by more than a few Airy radii. The CP-ARC is made robust against mechanical disturbances due to the common-path interferometer principle.

Nature, 2007

7 & the SPICAV/SOIR team* Venus has thick clouds of H 2 SO 4 aerosol particles extending from alt... more 7 & the SPICAV/SOIR team* Venus has thick clouds of H 2 SO 4 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 1,2 . The mesosphere has a light haze of variable optical thickness, with CO, SO 2 , HCl, HF, H 2 O 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, H 2 O and HDO. HCl is less abundant than reported 40 years ago 3 . HDO/H 2 O is enhanced by a factor of 2.5 with respect to the lower atmosphere, and there is a general depletion of H 2 O around 80-90 km for which we have no explanation. The use of solar (at the terminator: the circle on the planet that separates the day side from the night side) and stellar occultation technique (at night), applied for the first time to the atmosphere of Venus with the SPICAV/SOIR spectrometers on board the Venus Express spacecraft, allows us to measure the atmospheric transmission and to derive information about the vertical structure and composition of the 60-140 km region. In this region, many processes (transport, chemistry, temperature, aerosols condensation and evaporation) govern the three-dimensional distribution of haze and chemical species. In the ultraviolet range (110-310 nm) of the SPICAV ultraviolet spectrometer (a copy of the SPICAM ultraviolet instrument in orbit around Mars 4 ), the most important absorbers are CO 2 (the main Venus atmospheric constituent) at l , 200 nm, and aerosol particles of the haze layer at all wavelengths. The CO 2 local density and temperature profiles are derived by assuming that the atmosphere is in hydrostatic equilibrium 5 (Supplementary Information).

Journal of Geophysical Research, 2009

Journal of Geophysical Research, 2008

1] Solar Occultation at Infrared (SOIR), which is a part of the Spectroscopy for Investigation of... more 1] Solar Occultation at Infrared (SOIR), which is a part of the Spectroscopy for Investigation of Characteristics of the Atmosphere of Venus (SPICAV) instrument on board Venus Express, combines an echelle-grating spectrometer with an acoustooptical tunable filter. It performs solar occultation measurements in the IR region at a high spectral resolution better than all previously flown planetary spectrometers. The wavelength range probed allows for a detailed chemical inventory of the Venus atmosphere above the cloud layer, with an emphasis on the vertical distribution of the gases. A general description of the retrieval technique is given and is illustrated by some results obtained for CO 2 and for a series of minor constituents, such as H 2 O, HDO, CO, HCl, and HF. Detection limits for previously undetected species will also be discussed.

ABSTRACT The European Venus Explorer (EVE) is a mission proposed to the European Space Agency (ES... more ABSTRACT The European Venus Explorer (EVE) is a mission proposed to the European Space Agency (ESA) under the Cosmic Vision Call for Ideas, for launch in 2016-2018. The central goal of this mission is to investigate the evolution of Venus and its climate, in order to understand better the 'life cycle' of Earth-like planets everywhere. After the excellent results being obtained from ESA's Venus Express orbiter, in situ measurements will be required to answer many of the outstanding questions, specially relating to the evolution of the planet, its complex cloud chemistry and the stability of its climate. The baseline EVE mission consists of one balloon platform floating at an altitude of 50-60 km, one descent probe provided by Russia, and an orbiter with a polar orbit which will perform science observations as well as relay data from the balloon and descent probe. The minimum lifetime of the balloon is 7 days, required for one full circle around the planet, much longer than the 48 hour data returned from Russia's VEGA balloons. Earth-based VLBI and Doppler measurements provide tracking information for the orbiter, allowing measurement of the variations in the planet's gravity field, and for the balloon and descent probe to yield wind measurements in the lower atmosphere. The descent probe's fall through the atmosphere is expected to last 60 minutes, followed by a lifetime of 30 minutes on the surface. The Japanese space agency (JAXA) also proposes to include another independent platform, a small water vapour-inflated balloon which would be deployed at 35 km altitude and would communicate directly to Earth. Further details of the EVE mission, including proposals for Education & Outreach schemes, can be viewed at the mission website: http://www.aero.jussieu.fr/EVE/

Advances in Space Research, 2008

The Mercury's Sodium Atmosphere Spectral Imager (MSASI) on BepiColombo (BC) will address a range ... more The Mercury's Sodium Atmosphere Spectral Imager (MSASI) on BepiColombo (BC) will address a range of fundamental scientific questions pertaining to Mercury's exosphere. The measurements will provide new information on regolith-exosphere-magnetosphere coupling as well as new understanding of the dynamics governing the exosphere bounded by the planetary surface, the solar wind and interplanetary space. MSASI is a high-dispersion visible spectrometer working in the spectral range around sodium D2 emission (589 nm). A tandem Fabry-Perot etalon is used to achieve a compact design. We presents a design of the spectral analyzer using Fabry-Perot interferometer. We conclude that: (1) The MSASI optical design is practical and can be implemented without new or critical technology developments; (2) The thermally-tuned etalon design is based on concepts, designs and materials that have good space heritage.

Advances in Space Research, 2005

SPectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) Ligh... more SPectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) Light, a light-weight (4.7 kg) UV-IR instrument to be flown on Mars Express orbiter, is dedicated to the study of the atmosphere and ionosphere of Mars. A UV spectrometer (118-320 nm, resolution 0.8 nm) is dedicated to nadir viewing, limb viewing and vertical profiling by stellar and solar occultation (3.8 kg). It addresses key issues about ozone, its coupling with H 2 O, aerosols, atmospheric vertical temperature structure and ionospheric studies. UV observations of the upper atmosphere will allow studies of the ionosphere through the emissions of CO, CO + , and CO þ 2 , and its direct interaction with the solar wind. An IR spectrometer (1.0-1.7 lm, resolution 0.5-1.2 nm) is dedicated primarily to nadir measurements of H 2 O abundances simultaneously with ozone measured in the UV, and to vertical profiling during solar occultation of H 2 O, CO 2 , and aerosols. The SPICAM Light near-IR sensor employs a pioneering technology acousto-optical tunable filter (AOTF), leading to a compact and light design. Overall, SPICAM Light is an ideal candidate for future orbiter studies of Mars, after Mars Express, in order to study the interannual variability of martian atmospheric processes. The potential contribution to a Mars International Reference Atmosphere is clear.

Spectral measurements with high resolution give access to planetary atmospheres when observing fr... more Spectral measurements with high resolution give access to planetary atmospheres when observing from the Earth. Very high spectral resolution allows Doppler separation of the spectral lines in the planetary atmosphere from telluric ones, thus enabling to detect and to measure minor constituents and isotopic composition. These measurements, however, are generally full-disk averaged; also it is difficult to measure molecules abundant in the Earth's atmosphere. Therefore, spacecraft measurements at high spectral resolution are of great value in planetary missions. A review of spectrometers used in deep space missions and on the Earth orbit will be given; in particular, solar occultation high-resolution measurements will be addressed. The mass of existing state-of-the-art instruments (several tens to hundreds of kilograms) prevents them from being sent toward other planets. Even in the remote sensing of the Earth the tendencies are that compact and lightweight instrumentation has more chances to be flown. A new concept of a high-resolution near-IR spectrometer consisting of an echelle grating combined with an acousto-optic tunable filter (AOTF) for separation of diffraction orders, is developed for space-borne studies of planetary atmospheres. An AOTF spectrometer with lower resolution (no echelle grating, λ v/Δλ s≈ 1200, mass 800 g) has been qualified and is now operational on the Mars Express orbiter. New compact design within the mass budget of 3-5 kg allows to reach the resolving power λ v/Δλ s of 20000-30000. A spectrometer, based on this principle, SOIR (Solar Occultation InfraRed) is being built for Venus Express (2005) ESA mission to study atmospheric structure and composition above clouds. The concept and the potential of such instrument for the studies of Mars and the Earth atmospheres, in particular, measurements of isotopes of water in the atmosphere, either in solar occultation profiling, or (on the Earth) observing solar glint for integral quantities of the components. Small size of hardware makes the instrument ideal for micro-satellites, which are now agile enough to provide necessary pointing for solar occultation or glint observations.