Browsing Peer Reviewed by Title
Now showing items 12-24 of 24
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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 ... -
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 ... -
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 ... -
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 ... -
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 ... -
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 ... -
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 ... -
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 ... -
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 ... -
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 ... -
Telemetry Fault-Detection Algorithms: Applications for Spacecraft Monitoring and Space Environment Sensing
(2018-05-19)Algorithms have been developed that identify unusual behavior in satellite health telemetry. Telemetry from solid-state power amplifiers and amplifier thermistors from 32 geostationary Earth orbit communications satellites ... -
Trapped photoelectrons during spacecraft charging in sunlight
(Institute of Electrical and Electronics Engineers, 2015-09)For a dielectric spacecraft charging in sunlight, the potentials are different on the sunlit and dark sides. Differential charging of spacecraft surfaces can trap low-energy electrons by means of potential wells and barriers. ... -
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 ...