Browsing Space, Telecommunication, Astronomy, & Radiation Lab by Issue Date
Now showing items 1-20 of 34
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Radio science measurements of atmospheric refractivity with Mars Global Surveyor
(American Geophysical Union, 2006-05-20)Radio occultation experiments with Mars Global Surveyor measure the refractive index of the Martian atmosphere from the surface to ~250 km in geopotential height. Refractivity is proportional to neutral density at low ... -
Characterization of a semidiurnal eastward-propagating tide at high northern latitudes with Mars Global Surveyor electron density profiles
(American Geophysical Union, 2007-08-03)Apparent phase velocities of zonal structure, estimated from Mars Global Surveyor (MGS) electron density profiles, are used to identify and characterize SE1, the semidiurnal eastward-propagating tide with zonal wave number ... -
Physical characteristics and occurrence rates of meteoric plasma layers detected in the Martian ionosphere by the Mars Global Surveyor Radio Science Experiment
(American Geophysical Union, 2008-12-30)Low-altitude plasma layers are present in 71 of 5600 electron density profiles from the Martian ionosphere obtained by the Mars Global Surveyor Radio Science experiment. These layers are produced by the ablation of meteoroids ... -
First results on a new PIAA coronagraph testbed at NASA Ames
(SPIE - The International Society for Optical Engineering, 2009-01-01)Direct imaging of extrasolar planets, and Earth-like planets in particular, is an exciting but difficult problem requiring a telescope imaging system with 1010 contrast at separations of 100 mas and less. Furthermore, the ... -
Combining laser frequency combs and iodine cell calibration techniques for Doppler detection of exoplanets
(SPIE - The International Society for Optical Engineering, 2010)Exoplanets can be detected from a time series of stellar spectra by looking for small, periodic shifts in the absorption features that are consistent with Doppler shifts caused by the presence of an exoplanet, or multiple ... -
Exoplanet Albedo Spectra and Colors as a Function of Planet Phase, Separation, and Metallicity
(The Astrophysical Journal, 2010-11-20)First generation space-based optical coronagraphic telescopes will obtain images of cool gas- and ice-giant exoplanets around nearby stars. Exoplanets lying at planet-star separations larger than about 1 AU—where an exoplanet ... -
Direct imaging of exoEarths embedded in clumpy debris disks
(SPIE - The International Society for Optical Engineering, 2012)The inner solar system, where the terrestrial planets formed and evolve, is populated by small grains of dust produced by collisions of asteroids and outgassing comets. At visible and infrared wavelengths, this dust cloud ... -
Atmospheric characterization of cold exoplanets with a 1.5-m space coronagraph
(Amsterdam Netherlands: SPIE - The International Society for Optical Engineering, 2012)Several small space coronagraphs have been proposed to characterize cold exoplanets in reflected light. Studies have mainly focused on technical feasibility because of the huge star/planet flux ratio to achieve in the ... -
CubeSat deformable mirror demonstration
(SPIE - The International Society for Optical Engineering, 2012)The goal of the CubeSat Deformable Mirror Demonstration (DeMi) is to characterize the performance of a small deformable mirror over a year in low-Earth orbit. Small form factor deformable mirrors are a key technology needed ... -
Atmospheric characterization of cold exoplanets using a 1.5-m coronagraphic space telescope
(EDP Sciences S.A., 2012-05)High-contrast imaging is currently the only available technique for the study of the thermodynamical and compositional properties of exoplanets in long-period orbits, comparable to the range from Venus to Jupiter. The ... -
Mars atmospheric CO2 condensation above the north and south poles as revealed by radio occultation, climate sounder, and laser ranging observations
(Journal Of Geophysical Research-Planets, 2012-07-10)We study the condensation of CO2 in Mars' atmosphere using temperature profiles retrieved from radio occultation measurements from Mars Global Surveyor (MGS) as well as the climate sounding instrument onboard the Mars ... -
SPICES: spectro-polarimetric imaging and characterization of exoplanetary systems.
(Experimental Astronomy, 2012-10)SPICES (Spectro-Polarimetric Imaging and Characterization of Exoplanetary Systems) is a five-year M-class mission proposed to ESA Cosmic Vision. Its purpose is to image and characterize long-period extrasolar planets and ... -
Quantifying the average and the likelihood of increases in space weather indices and in situ measurements during Solar Cycles 20–23
(International Journal of Space Science and Engineering, 2013-01)It is known that space weather harshly affects spacecraft performance, yet spacecraft operations and understanding the cause of anomalies can be challenging due to the complexity of environmental metrics. In this work, we ... -
Space weather radiation effects on geostationary satellite solid-state power amplifiers
(American Geophysical Union, 2013-08)In order to understand and mitigate the effects of space weather on the performance of geostationary (GEO) communications satellites, we analyze 16 years of archived telemetry data from Inmarsat, the UK-based telecommunications ... -
Wavefront control in space with MEMS deformable mirrors for exoplanet direct imaging
(SPIE-SOC Photo-Optical Instrumentation Engineers, 2013-10)To meet the high contrast requirement of 1 x 10(-10) to image an Earth-like planet around a sun-like star, space telescopes equipped with coronagraphs require wavefront control systems. Deformable mirrors (DMs) are a key ... -
Radiometer Calibration Using Colocated GPS Radio Occultation Measurements
(Institute of Electrical and Electronics Engineers, 2014-10)We present a new high-fidelity method of calibrating a cross-track scanning microwave radiometer using Global Positioning System (GPS) radio occultation (GPSRO) measurements. The radiometer and GPSRO receiver periodically ... -
Planetary Imaging Concept Testbed Using a Recoverable Experiment-Coronagraph (PICTURE C)
(SPIE, 2015)An exoplanet mission based on a high-altitude balloon is a next logical step in humanity's quest to explore Earthlike planets in Earthlike orbits orbiting Sunlike stars. The mission described here is capable of spectrally ... -
Response of geostationary communications satellite solid-state power amplifiers to high-energy electron fluence.
(American Geophysical Union, 2015-05)The key components in communications satellite payloads are the high-power amplifiers that amplify the received signal so that it can be accurately transmitted to the intended end user. In this study, we examine 26 amplifier ... -
Effect of Longitude-Dependent Cloud Coverage on Exoplanet Visible Wavelength Reflected-Light Phase Curves
(IOP Publishing, 2015-05-10)We use a planetary albedo model to investigate variations in visible wavelength phase curves of exoplanets. Thermal and cloud properties for these exoplanets are derived using one-dimensional radiative-convective and cloud ... -
Response of geostationary communications satellite solid-state power amplifiers to high-energy electron fluence
(AGU Space Weather, 2015-05-25)The key components in communications satellite payloads are the high-power amplifiers that amplify the received signal so that it can be accurately transmitted to the intended end user. In this study, we examine 26 amplifier ...