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Results for “subsurface sounding ionosphere radar”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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31 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS2005

Workshop on Radar Investigations of Planetary and Terrestrial Environments

Contents include the following: Salt Kinematics and InSAR. SAR Interferometry as a Tool for Monitoring Coastal Changes in the Nile River Delta of Egypt. Modem Radar Techniques for Geophysical Applications: Two Examples. WISDOM Experiment on the EXOMARS ESA Mission. An Ice Thickness Study Utilizing Ground Penetrating Radar on the Lower Jamapa. Probing the Martian Subsurface with Synthetic Aperture Radar. Planetary Surface Properties from Radar Polarimetric Observations. Imaging the Sub-surface Reflectors : Results From the RANETA/NETLANDER Field Test on the Antarctic Ice Shelf. Strategy for Selection of Mars Geophysical Analogue Sites. Observations of Low Frequency Low Altitude Plasma Oscillations at Mars and Implications for Electromagnetic Sounding of the Subsurface. Ionospheric Transmission Losses Associated with Mars-orbiting Radar. A Polarimetric Scattering Model for the 2-Layer Problem. Radars for Imaging and Sounding of Polar Ice Sheets. Strata: Ground Penetrating Radar for Mars Rovers. Scattering Limits to Depth of Radar Investigation: Lessons from the Bishop Tuff.

Source record↗
NASA NTRS2006

MARSIS antenna flight deployment anomaly and resolution

This paper summarizes the resolution of an in flight anomaly that occurred during the deployment of the first of three MARSIS antenna booms. Characteristics of this deployment are described, along with a correlation to finite element models and measured spacecraft inertias, which allowed the intermediate state of the boom to be accurately determined. Based on this information, a spacecraft maneuver was performed that warmed the stalled hinge and led to the first boom successfully locking into its designed geometry. The confirmed partially deployed boom shape was then used to develop a thermal model of the stalled hinge both in its initial solar attitude and during the successful spacecraft maneuver. Results from the hinge thermal model and component level testing were evaluated in order to determine the root cause of the anomaly and the probability of its recurrence on subsequent deployments. These conclusions were then utilized in planning mitigating actions that were implemented during the remaining two boom deployments. Final flight data are presented for both dipole booms indicating a correctly deployed and healthy antenna. The monopole boom deployment was detected but the final state of the boom is unknown.

Mars↗
NASA NTRS2006

Analysis of the Lenticular Jointed MARSIS Antenna Deployment

This paper summarizes important milestones in a yearlong comprehensive effort which culminated in successful deployments of the MARSIS antenna booms in May and June of 2005. Experimentally measured straight section and hinge properties are incorporated into specialized modeling techniques that are used to simulate the boom lenticular joints. System level models are exercised to understand the boom deployment dynamics and spacecraft level implications. Discussion includes a comparison of ADAMS simulation results to measured flight data taken during the three boom deployments. Important parameters that govern lenticular joint behavior are outlined and a short summary of lessons learned and recommendations is included to better understand future applications of this technology.

Dynamic↗
NASA NTRS2005

The Mars Express/NASA Project at JPL

An overview of the Mars Express/NASA Project at JPL is presented. The topics include: 1) Mars Express Mission Experiments and Investigators; 2) Mars Advanced Radar for Subsurface and Ionospheric Soundig (MARSIS) Overview; 3) MARSIS Experiment Overview; 4) Interoperability Concept; 5) Mars Express Science Operations; 6) Mars Express Schedule (2003-2007);

radar↗
NASA NTRS2006

Verification of Numerical Solutions for the Deployment of the Highly Nonlinear MARSIS Antenna Boom Lenticular Joints

The MARSIS antenna booms are constructed using lenticular hinges between straight boom segments in a novel design which allows the booms to be extremely lightweight while retaining a high stiffness and well defined structural properties once they are deployed. Lenticular hinges are elegant in form but are complicated to model as they deploy dynamically and require highly specialized nonlinear techniques founded on carefully measured mechanical properties. Results from component level testing were incorporated into a highly specialized ADAMS model which employed an automated damping algorithm to account for the discontinuous boom lengths formed during the deployment. Additional models with more limited capabilities were also developed in both DADS and ABAQUS to verify the ADAMS model computations and to help better define the numerical behavior of the models at the component and system levels. A careful comparison is made between the ADAMS and DADS models in a series of progressive steps in order to verify their numerical results. Different trade studies considered in the model development are outlined to demonstrate a suitable level of model fidelity. Some model sensitivities to various parameters are explored using subscale and full system models. Finally, some full system DADS models are exercised to illustrate the limitations of traditional modeling techniques for variable geometry systems which were overcome in the ADAMS model.

Mars↗
NASA NTRS2006

Deployment of the MARSIS Radar Antennas On-Board Mars Express

On the first European planetary mission, the deployment of the two 20-meter long MARSIS antennas onboard the ESA Mars Express spacecraft has represented an unprecedented technological challenge, in the middle of a successful science mission. While Mars Express was already performing regular observations at Mars, a complex process has been performed on Earth, involving the ESA Project, coordination between ESA, NASA and ASI, the Mars Science community, the spacecraft manufacturer EADS Astrium and the Mission Control Centre at ESOC. This paper describes the steps that led from an initial nogo in 2004 to deployment one year later, as well as the conditions and difficulties encountered during the actual deployment. It provides insights in the technical and managerial processes that made it a success, and analyses the rationale behind the decisions.

deployment↗
NASA NTRS2005

Ionospheric Transmission Losses Associated with Mars-orbiting Radars

There are a number of obstacles to radar sounding of the deep Martian subsurface from orbit, including signal losses from the medium conductivity, layer reflective losses, and ground clutter. Another adverse process is signal loss as radio waves propagate through the ionospheric plasma medium. The ionosphere is a plasma consisting of free electrons, ions and neutrals that can effectively damp/attenuate radar signals via electrodneutral collisions. The effect is most severe for transmissions at lower frequencies, which, unfortunately, are also favorable transmissions for deep penetration into the subsurface.

Farrell, W. M.↗
NASA NTRS2001

Radar Sounding of Mars: A Focus on MARSIS

Radar has the unique capability of looking under the dry and cold surfaces of Mars. The depth of penetration of radio waves depends on a number of surface and subsurface parameters such as surface topography, subsurface geological structure and surface and subsurface electromagnetic properties. Among these parameters, the surface topography is known best largely due to valuable data provided by Mars Global Surveyor's MOLA instrument. However, little information is available on the electromagnetic properties and subsurface characteristics of Mars.

radar sounding↗
NASA NTRS2004

Surface Penetrating Radar Simulations for Europa

The space environment above the icy surface of Europa is a source of radio noise in this frequency range from natural sources in the Jovian magnetosphere. The ionospheric and magnetospheric plasma environment of Europa affects propagation of transmitted and return signals between the spacecraft and the solid surface in a frequency-dependent manner. The ultimate resolution of the subsurface sounding measurements will be determined, in part, by a capability to mitigate these effects. We discuss an integrated multi-frequency approach to active radio sounding of the Europa ionospheric and local magnetospheric environments, based on operational experience from the Radio Plasma Imaging @PI) experiment on the IMAGE spacecraft in Earth orbit, in support of the subsurface measurement objectives.

Markus, T.↗
NASA NTRS2001

Radar Sounding of Mars: A Focus on MARSIS

Radar has the unique capability of looking under the dry and cold surfaces of Mars. The depth of penetration of radio waves depends on a number of surface and subsurface parameters such as surface topography, subsurface geological structure, and surface and subsurface electromagnetic properties. Among these parameters, the surface topography is known best largely due to valuable data provided by Mars Global Surveyor's MOLA (Mars Orbiter Laser Altimeter) instrument. However, little information is available on the electromagnetic properties and subsurface characteristics of Mars. In addition to dispersion, the ionosphere will also attenuate the radio wave. The level of attenuation depends on the ionosphere's electron density and its profile shape and the electron-neutral collision frequency. Fortunately, information from past missions can provide some information on the expected level of attenuation. A figure shows expected total radio wave attenuation under three different ionospheric conditions. Additional information is contained in the original extended abstract.

Safaeinili, A.↗
NASA NTRS2004

Radio Sounding Techniques for the Galilean Icy Moons and their Jovian Magnetospheric Environment

Radio sounding of the Earth's topside ionosphere and magnetosphere is a proven technique from geospace missions such as the International Satellites for Ionospheric Studies (ISIS) and the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE). Application of this technique to Jupiter's icy moons and the surrounding Jovian magnetosphere will provide unique remote sensing observations of the plasma and magnetic field environments and the subsurface conductivities, of Europa, Ganymede, and Callisto. Spatial structures of ionospheric plasma above the surfaces of the moons vary in response to magnetic-field perturbations from (1) magnetospheric plasma flows, (2) ionospheric currents from ionization of sputtered surface material, and (3) induced electric currents in salty subsurface oceans and from the plasma flows and ionospheric currents themselves. Radio sounding from 3 kHz to 10 MHz can provide the global electron densities necessary for the extraction of the oceanic current signals and supplements in-situ plasma and magnetic field measurements. While radio sounding requires high transmitter power for subsurface sounding, little power is needed to probe the electron density and magnetic field intensity near the spacecraft. For subsurface sounding, reflections occur at changes in the dielectric index, e.g., at the interfaces between two different phases of water or between water and soil. Variations in sub-surface conductivity of the icy moons can be investigated by radio sounding in the frequency range from 10 MHz to 50 MHz, allowing the determination of the presence of density and solid-liquid phase boundaries associated with oceans and related structures in overlying ice crusts. The detection of subsurface oceans underneath the icy crusts of the Jovian moons is one of the primary objectives of the Jupiter Icy Moons Orbiter (JIMO) mission. Preliminary modeling results show that return signals are clearly distinguishable be&een an ice crust with a thickness of 7 km on 1) an ocean and 2) a layer of bedrock. Knowledge of the ionospheric contributions to the time delay of the low-frequency subsurface radar is shown to be important in obtaining accurate depth information.

Green, James L.↗