scholarly journals Inter-Calibration of the OSIRIS-REx NavCams with Earth-Viewing Imagers

2019 ◽  
Vol 11 (22) ◽  
pp. 2717 ◽  
Author(s):  
David Doelling ◽  
Konstantin Khlopenkov ◽  
Conor Haney ◽  
Rajendra Bhatt ◽  
Brent Bos ◽  
...  
Keyword(s):  
Spectral Band ◽  
Field Of View ◽  
Space Probe ◽  
Gravity Assist ◽  
Tropical Ocean ◽  
Sensor Performance ◽  
Earth Gravity ◽  
The Earth ◽  
Current Constellation ◽  
Navigation Errors

The Earth-viewed images acquired by the space probe OSIRIS-REx during its Earth gravity assist flyby maneuver on 22 September 2017 provided an opportunity to radiometrically calibrate the onboard NavCam imagers. Spatially-, temporally-, and angularly-matched radiances from the Earth viewing GOES-15 and DSCOVR-EPIC imagers were used as references for deriving the calibration gain of the NavCam sensors. An optimized all-sky tropical ocean ray-matching (ATO-RM) calibration approach that accounts for the spectral band differences, navigation errors, and angular geometry differences between NavCam and the reference imagers is formulated in this paper. Prior to ray-matching, the GOES-15 and EPIC pixel level radiances were mapped into the NavCam field of view. The NavCam 1 ATO-RM gain is found to be 9.874 × 10−2 Wm−2sr−1µm−1DN−1 with an uncertainty of 3.7%. The ATO-RM approach predicted an offset of 164, which is close to the true space DN of 170. The pre-launch NavCam 1 and 2 gains were compared with the ATO-RM gain and were found to be within 2.1% and 2.8%, respectively, suggesting that sensor performance is stable in space. The ATO-RM calibration was found to be consistent within 3.9% over a factor of ±2 NavCam 2 exposure times. This approach can easily be adapted to inter-calibrate other space probe cameras given the current constellation of geostationary imagers.

Absolute Magnetometer Attitude Reconstruction using Magnetospheric Modelling

2020 ◽  
Author(s):  
Johannes Z. D. Mieth ◽  
Daniel Heyner ◽  
Karl-Heinz Glassmeier
Keyword(s):  
Main Magnetic Field ◽  
Main Field ◽  
Gravity Assist ◽  
Earth Gravity ◽  
Simultaneous Measurements ◽  
The Earth ◽  
Sensor Orientation ◽  
The Absolute ◽  
Modelling Approach

<p>One of the main goals of the magnetometer experiment MPO-MAG on board of the Magnetospheric Planetary Orbiter (MPO) during the BepiColombo mission is the determination of the Mercury main magnetic field, epecially in constraining the characteristics of the magnetic dipole offset.<br>In April 2020 BepiColombo had its Earth Gravity Assist manoeuvre on its way to planet Mercury.<br>The topocentric distance was lower than three Earth radii and offered a unique opportunity to compare the magnetometer measurements to a multitude of simultaneous measurements of the magnetospheric environment of the Earth performed by several other spacecraft like THEMIS and MMS.<br>Using a great number of probing points to constrain models of the Earh magnetosphere and compare models to actual measurements of the MPO-MAG sensors enables us to determine the absolute sensor attitude to an accuracy of only a few arc minutes.<br>Knowing the absolute attitude of a magnetometer sensor in planetary orbiter missions is a key component for the magnetic main field determination.<br>We present the modelling approach to compare to measurements from MPO-MAG and a study showing the dependence of a mainfield determination on the accuracy of the sensor orientation.</p>

Nuclear Safety Analysis for Cassini Accidental Earth Reentries

1999 ◽  
Author(s):  
Richard L. Baker ◽  
Duane A. Nelson
Keyword(s):  
Nuclear Fuel ◽  
Radiative Heating ◽  
Sensitivity Analyses ◽  
Analysis Model ◽  
Heating Rates ◽  
Gravity Assist ◽  
Earth Gravity ◽  
The Earth ◽  
Uncertainty Estimates ◽  
Major Factors

Abstract An engineering analysis model for predicting the response and potential breakup of Cassini spacecraft nuclear fuel modules during accidental Earth reentries is described. Physical aspects considered include aerodynamics, aerothermodynamics, thermostructural loads and ablation response. The extreme velocity, 19 km/sec, of an inadvertent reentry during the Earth gravity-assist flyby requires the development of a new model to predict the dominant radiative heating rates. Uncertainty estimates are established for each of the major factors in the model. Sensitivity analyses are also carried out to determine the effect of off-nominal environments on the predicted outcome. This allows output from the calculations to be expressed as a probability density function for atmospheric fuel release. It is concluded that 18 to 36 percent of the nuclear fuel contained in the spacecraft will be released as respirable material if reentry occurs.

scholarly journals AN ARTIFICIAL EXPERIMENT AIMED TO SPECIFY THE GRAVITY LAW IN THE SOLAR SYSTEM

Metaphysics ◽  
2020 ◽  
pp. 137-146
Author(s):  
A. P Yefremov
Keyword(s):  
Gravitational Field ◽  
Solar System ◽  
Impact Parameter ◽  
Einstein Gravity ◽  
Test Body ◽  
The Sun ◽  
Space Probe ◽  
Gravity Assist ◽  
The Earth ◽  
Ballistic Trajectory

Ultra-sensitivity of a planet’s gravity assist (GA) to changes of the test-body impact parameter prompts a space experiment testing the nature of gravitational field in the Solar system. The Sun, Earth and Venus serve as the space lab with a primitive space probe (ball) as a test body moving on a ballistic trajectory from the Earth to Venus (rendering GA) and backwards to the Earth’s orbit. We show that in Newton and Einstein gravity, the probe’s final positions (reached at the same time) may differ greatly; an Earth’s observer can measure the gap.

Gravity assists maneuver in the problem of extension accessible landing areas on the Venus surface

2021 ◽  
Vol 30 (1) ◽  
pp. 103-109
Author(s):  
Natan A. Eismont ◽  
Vladislav A. Zubko ◽  
Andrey A. Belyaev ◽  
Ludmila V. Zasova ◽  
Dmitriy A. Gorinov ◽  
...  
Keyword(s):  
Gravitational Field ◽  
Entry Angle ◽  
Gravity Assist ◽  
Flight Duration ◽  
The Earth ◽  
Gravity Assists ◽  
Primary Basis ◽  
Venusian Surface ◽  
Research Show

Abstract This study discusses the usage of Venus gravity assist in order to choose and reaching any point on Venusian surface. The launch of a spacecraft to Venus during the launch windows of 2029 to 2031 is considered for this purpose. The constraints for the method are the re-entry angle and the maximum possible overload. The primary basis of the proposed strategy is to use the gravitational field of Venus to transfer the spacecraft to an orbit resonant to the Venusian one – with the aim of expanding accessible landing areas. Results of the current research show that this strategy provides an essential increase in accessible landing areas and, moreover, may provide an access to any point on the surface of Venus with a small increase in ∆V required for launch from the Earth and in the flight duration. The comparison with the landing without using gravity assist near planet is also given.

scholarly journals Simulation study for the Stratospheric Inferred Winds (SIW) sub-millimeter limb sounder

2018 ◽  
Author(s):  
Philippe Baron ◽  
Donal Murtagh ◽  
Patrick Eriksson ◽  
Jana Mendrok ◽  
Satoshi Ochiai ◽  
...  
Keyword(s):  
Simulation Study ◽  
Spectral Band ◽  
Chemical Species ◽  
Field Of View ◽  
Emission Lines ◽  
Horizontal Wind ◽  
Line Of Sight ◽  
Heterodyne Receiver ◽  
Vertical Field ◽  
Wind Measurements

Abstract. Stratospheric Inferred Winds (SIW) is a Swedish mini sub-millimeter limb sounder selected for the 2nd InnoSat platform launch planned near 2022. It is intended to fill the altitude gap between 30–70 km in atmospheric wind measurements and also aims at pursuing the limb observations of temperature and key atmospheric constituents between 10–90 km when current satellite missions are probably stopped. Line-of-sight winds are retrieved from the Doppler shift of the emission lines introduced by 5 the wind field. Observations will be performed with two antennas pointing toward the limb with perpendicular directions to reconstruct the 2-D horizontal wind vector. Each antenna has a vertical field of view of 5 km. The chosen spectral band near 655 GHz contains a dense group of strong O3 lines suitable for exploiting the small wind information in stratospheric spectra. Using both sidebands of the heterodyne receiver, a large number of chemical species will be measured including O3-isopotologues, H2O, HDO, HCl, ClO, N2O, HNO3, NO, NO2, HCN, CH3CN and HO2. This paper presents the simulation study for assessing the measurement performances. The line-of-sight winds are retrieved between 30–90 km with the best sensitivity between 35–70 km where the precision (1-sigma) is 5–10 m s−1 for a single scan. Similar performances can be obtained during day and night conditions except in the lower mesosphere where the photo-dissociation of O3 in day-time reduces the sensitivity by 50 % near 70 km. Profiles of O3, H2O and temperature are retrieved with a high precision up to 50 km (

BepiColombo – Mercury Swing-Bys

2021 ◽  
Author(s):  
Joe Zender ◽  
Johannes Benkhoff ◽  
Go Murakami ◽  
Elsa Montagnon
Keyword(s):  
Remote Sensing ◽  
Space Exploration ◽  
Terrestrial Planet ◽  
Field Of View ◽  
Space Craft ◽  
Joint Project ◽  
The Earth ◽  
Space Agency ◽  
Euro Pean ◽  
French Guyana

<p><strong>Abstract</strong></p> <p>The BepiColombo spacecraft was launched on 20 October 2018 from the European spaceport in French Guyana and is currently on its way to Mercury. On its way, the spacecraft will swing-by Mercury six times in its stacked configuration, before releasing the Mercury Magnetospheric Orbiter (MMO) and the Mercury Planetary Orbiter (MPO) in their corresponding orbits around the target planet.</p> <p><strong>Introduction</strong></p> <p>Mercury is in many ways a very different planet from what we were expecting. On 20 October 2018 the BepiColombo spacecraft [1] started its 7 year journey to the innermost terrestrial planet to investigate on the fundamental questions about its evolution, composition, interior, magnetosphere, and exosphere.</p> <p>BepiColombo is a joint project between the Euro- pean Space Agency (ESA) and the Japanese Aero- space Exploration Agency (JAXA). The Mission con- sists of two orbiters, the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (MMO). From their dedicated orbits the two space- craft will be studying the planet and its environment.</p> <p>The mission has been named in honor of Giuseppe (Bepi) Colombo (1920–1984), who was a brilliant Italian mathematician, who made many significant contributions to planetary research and celestial mechanics.</p> <p>During the cruise phase, the spacecraft flies in a stacked configuration: the MMO and MPO are mounted ontop of the Mercury Transfer Module (MTM). As a consequence, most remote sensing instruments onboard the MPO are mounted towards the MTM and have a fully obstructed field-of-view. The MMO instrumentation is shielded by a protection shield (MOSIF) and several instruments still await the deployment on measurement booms.</p> <p>Despite the reduced instrument availability, scientific and engineering operations will be scheduled during the cruise phase, especially during the swing-bys.</p> <p><strong>Mercury Swing-bys</strong></p> <p>Following the Earth and two Venus swing-bys, six Mercury swing-bys are foreseen from October 2021 until 9 January 2025. The poster will discuss the flyby geometries and potential operation opportunities, in comparison with the three MESSENGER Mercury swing-bys from 2008 and 2009 [2][3].</p> <p><strong>References: </strong>[1] Benkhoff, J., et al. (2010) <em>Planet. Space Sci. </em>58, 2-20. [2] Baker, D.N. et al. (2011) Planet. Space Sci 59, 2066-2074. [3] McNutt, R.L. et al. (2010), Acta Astronautica V67, Iss 7-8, p 681-687</p>

Light Optical System Design with Wide Spectral Band, Large Field of View for Deep Space Exploration

2015 ◽  
Vol 44 (1) ◽  
pp. 122001
Author(s):  
孟庆宇 MENG Qing-yu ◽  
董吉洪 DONG Ji-hong ◽  
曲洪丰 QU Hong-feng ◽  
王维 WANG Wei ◽  
曹智睿 CAO Zhi-rui
Keyword(s):  
System Design ◽  
Optical System ◽  
Space Exploration ◽  
Spectral Band ◽  
Field Of View ◽  
Large Field ◽  
Deep Space ◽  
Optical System Design ◽  
Deep Space Exploration

scholarly journals Space Debris – The Short Term Orbital Evolution in the Earth Gravity Field

1997 ◽  
Vol 165 ◽  
pp. 71-78
Author(s):  
Edwin Wnuk
Keyword(s):  
Space Debris ◽  
Orbital Evolution ◽  
Gravity Potential ◽  
Short Term ◽  
Near Earth Space ◽  
Earth Gravity ◽  
The Earth ◽  
Geopotential Models ◽  
Theory Of Motion

AbstractTwo aspects of the orbital evolution of space debris – the long-term evolution and the short-term one – are of interest for an exploration of the near- Earth space. The paper presents some results concerning the estimation of the accuracy of predicted positions of Earth-orbiting objects for the short-term: a few revolutions or a time-span interval of a few days. Calculations of predicted positions take into account the influence of an arbitrary number of spherical coefficients of the Earth gravity potential. Differences in predicted positions due to differences in the best contemporary geopotential models (JGM-2, JGM-3 and GRIM4-S4) are estimated with the use of an analytical theory of motion and a numerical integration.

MOCASS: A Satellite Mission Concept Using Cold Atom Interferometry for Measuring the Earth Gravity Field

2019 ◽  
Vol 40 (5) ◽  
pp. 1029-1053 ◽  
Author(s):  
Federica Migliaccio ◽  
Mirko Reguzzoni ◽  
Khulan Batsukh ◽  
Guglielmo Maria Tino ◽  
Gabriele Rosi ◽  
...  
Keyword(s):  
Gravity Field ◽  
Cold Atom ◽  
Atom Interferometry ◽  
Satellite Mission ◽  
Earth Gravity Field ◽  
Earth Gravity ◽  
The Earth
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