A5040093231- Astro and Planetary Science
- Planetary Science and Exploration
- Space Exploration and Technology
- Geomagnetism and Paleomagnetism Studies
- Ionosphere and magnetosphere dynamics
- Geology and Paleoclimatology Research
- Satellite Communication Systems
- Space exploration and regulation
- Isotope Analysis in Ecology
- Space Science and Extraterrestrial Life
- Historical Astronomy and Related Studies
- Spacecraft and Cryogenic Technologies
- Advanced Wireless Communication Techniques
- Radio Astronomy Observations and Technology
- Archaeology and ancient environmental studies
- Stellar, planetary, and galactic studies
- Wireless Communication Networks Research
- Molecular Spectroscopy and Structure
- earthquake and tectonic studies
- Atmospheric Ozone and Climate
- Advanced Power Amplifier Design
- Distributed systems and fault tolerance
- Antenna Design and Optimization
- Gamma-ray bursts and supernovae
- PAPR reduction in OFDM
Jet Propulsion Laboratory
2002-2022
California Institute of Technology
1995-2019
The interior structure of Saturn, the depth its winds, and mass age rings constrain formation evolution. In final phase Cassini mission, spacecraft dived between planet innermost ring, at altitudes 2600 to 3900 kilometers above cloud tops. During six these crossings, a radio link with Earth was monitored determine gravitational field rings. We find that Saturn's gravity deviates from theoretical expectations requires differential rotation atmosphere extending least 9000 kilometers. total is...
Nineteen new radio occultations of the ionosphere Saturn have been obtained since 2006. Sixteen these were from midlatitude and high latitudes thus provided important, information for regions. A degree variability in electron densities observed, but grouping averaging observations as low‐, middle‐, high‐latitude ones clearly showed that increase with latitude. The topside scale heights also indicate small increases latitude, changes are enough so may not be statistically significant.
The first set of near‐equatorial occultations the Saturn ionosphere was obtained by Cassini spacecraft between May and September 2005. occurred at latitudes, 10°N 10°S, solar zenith angles from about 84° to 96°. entry observations correspond dusk conditions exit ones dawn. An initial look data indicates that average peak densities are lower altitude higher dawn than dusk, possibly result ionospheric decay during night hours. There also significant differences individual occultations; thought...
An ionosphere has been detected at Callisto by the Galileo spacecraft, using radio occultation technique. There were four usable occultations Callisto, providing eight observation opportunities, all equatorial and near terminator (entry exit observations). Detectable electron densities obtained from six of opportunities. It was found that a detectable only present observed location when trailing hemisphere which is one impacted corotating plasma Jupiter's magnetosphere, illuminated Sun. Two...
[1] A series of near-equatorial radio occultations Cassini by Saturn occurred in 2005 and again 2009–2010. Comparison the temperature-pressure profiles obtained from two sets shows evidence a descending pattern stratosphere that is similar to those associated with equatorial oscillations Earth's middle atmosphere. This first time this descent has been observed another planetary If absorption upwardly propagating waves drives descent, implied absorbed flux 0.05 m2 s−2, at least as large if...
Abstract The Ultra Stable Oscillator aboard the Cassini spacecraft failed in late 2011, which means that all radio occultations after date have to be done two‐way mode, using a ground‐based signal transmitted as frequency reference. Here we present numerical technique use analyze data from atmospheric of both Saturn and Titan occurred since (USO) failure, along with theoretical reasons behind this technique. Since our is based upon earlier one‐way used USO reference, also for prior loss USO.
Abstract Fifty‐nine ionsopheric radio occultation observations of the vertical electron density profile in Saturn ionosphere have been made since Cassini spacecraft was inserted orbit around 2004. Significant to variations were observed, but general trend noted earlier orbits, namely, increasing densities with latitude reconfirmed and bolstered this extended data base. This is likely be due some combination ionization rates decreasing water influx latitude.
The Perseverance rover represents NASA's latest achievement in Mars exploration. Landing successfully on 18 Feb 2021, the rover's transmitted data during its entry, descent, and landing (EDL) were captured by Reconnaissance Orbiter (MRO) Atmosphere Volatile Evolution (MAVEN) orbiter. This data, broadcast near-realtime to world, allowed everyone share excitement (and "terror") of day. images returned thereafter included first new site, video itself taken from a variety vantage points,...
Abstract We describe the first demonstration of a Southern Hemisphere planetary radar system to detect two near‐Earth asteroids (NEAs). The was conducted in bistatic manner, with 70 m antenna Canberra Deep Space Communications Complex transmitting at 2.1 GHz and reception Parkes Radio Telescope, outfitted multiple receivers, Australia Telescope Compact Array. This initial used NEAs (43577) 2005 UL5 (33342) 1998 WT24 during their close approaches 2015 November December, respectively....
The Mars Science Laboratory (MSL) strategic communications planning toolset selects orbiter relay opportunities that the rover will use for transmitting data back to Earth. was extensively reworked in preparation Interior Exploration using Seismic Investigations, Geodesy and Heat Transport's (InSight) arrival at November 2018 regular of Atmosphere Volatile Evolution (MAVEN) Trace Gas Orbiter (TGO) orbiters as assets addition Reconnaissance (MRO) 2001 Odyssey (ODY). Overflight selection...
Flight software updates are among the hardest and most dangerous activities for Mars Science Laboratory (MSL) Curiosity team. While danger is often mitigated by backups, fallback strategies, incremental installation with ground-in-the-loop cycles which provide a safety net process, update described in this paper was unable to use many of common practices due nature fault addressed update. The MSL rover (landed August 2012) encountered problem one its computer's non-volatile storage chips...