A5052349061- Astro and Planetary Science
- Planetary Science and Exploration
- Space Exploration and Technology
- Isotope Analysis in Ecology
- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Atmospheric Ozone and Climate
- Solar and Space Plasma Dynamics
- Geomagnetism and Paleomagnetism Studies
- Ionosphere and magnetosphere dynamics
- Geology and Paleoclimatology Research
- High-pressure geophysics and materials
- Spacecraft and Cryogenic Technologies
- Laser-induced spectroscopy and plasma
- Space Science and Extraterrestrial Life
- Atmospheric aerosols and clouds
- Space exploration and regulation
- History and Developments in Astronomy
- Geological and Geochemical Analysis
- Historical Astronomy and Related Studies
- Spaceflight effects on biology
- Nuclear physics research studies
- Astronomical Observations and Instrumentation
- Astronomical and nuclear sciences
- Atmospheric and Environmental Gas Dynamics
University of Colorado Boulder
2015-2025
Laboratory for Atmospheric and Space Physics
2015-2025
University of Colorado System
1991-2021
Metabolism and Renal Physiology
2010
Jet Propulsion Laboratory
1979-2006
Central Arizona College
2004-2006
Space Environment Technologies (United States)
2006
University of Southern California
2004-2005
Max Planck Institute for Solar System Research
2004
Space Research Institute
1993
The Cassini spacecraft flew close to Saturn's small moon Enceladus three times in 2005. Cassini's UltraViolet Imaging Spectrograph observed stellar occultations on two flybys and confirmed the existence, composition, regionally confined nature of a water vapor plume south polar region Enceladus. This provides an adequate amount resupply losses from E ring be dominant source neutral OH atomic oxygen that fill Saturnian system.
The Voyager 2 photopolarimeter was reprogrammed prior to the August 1981 Saturn encounter perform orthogonal-polarization, two-color measurements on Saturn, Titan, and rings. Saturn's atmosphere has ultraviolet limb brightening in mid-latitudes pronounced polar darkening north of 65 degrees N. Titan's opaque shows strong positive polarization at all phase angles (2.7 154 ), no single-size spherical particle model appears fit data. A single radial stellar occultation darkened, shadowed rings...
[1] The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed an occultation of the Sun by water vapor plume at south polar region Saturn's moon Enceladus. Extreme (EUV) spectrum is dominated spectral signature H2O gas, with a nominal line-of-sight column density 0.90 ± 0.23 × 1016 cm−2 (upper limit 1.0 cm−2). upper for N2 5 1013 cm−2, or <0.5% in plume; lack has significant implications models geochemistry Enceladus' interior. inferred rate injection into magnetosphere ∼200 kg/s....
Pioneer Venus ultraviolet spectra from the first 5 years of operation show a decline (by more than factor 10) in sulfur dioxide abundance at cloud tops and amount submicron haze above clouds. At time encounter, values for both parameters greatly exceeded earlier upper limits. However, had similar appearance late 1950's, implying episodic injection possibly caused by volcanism. The middle atmosphere is about ten times that found Earth's stratosphere after most recent major volcanic eruptions,...
An imaging photopolarimeter aboard Pioneer 11, including a 2.5-centimeter telescope, was used for 2 weeks continuously in August and September 1979 imaging, photometry, polarimetry observations of Saturn, its rings, Titan. A new ring optical depth < × 10 –3 discovered at 2.33 Saturn radii is provisionally named the F ring; it separated from by division. division between B C gap near center Cassini division, detail A, B, rings have been seen; nomenclature divisions gaps redefined. The...
The Cassini Ultraviolet Imaging Spectrometer (UVIS) observed the extinction of photons from two stars by atmosphere Titan during flyby. Six species were identified and measured: methane, acetylene, ethylene, ethane, diacetylene, hydrogen cyanide. observations cover altitudes 450 to 1600 kilometers above surface. A mesopause is inferred extraction temperature structure located at 615 km with a minimum 114 kelvin. asymptotic kinetic top determined this experiment 151 higher order hydrocarbons...
Ultraviolet spectroscopy of the Venus cloud tops reveals absorption features attributed to sulfur dioxide in atmosphere above tops. Measurements scattered sunlight at 2663 angstroms show evidence for horizontal and vertical inhomogeneities structure. Images planet SO(2) wavelengths albedo similar those seen 3650 from Mariner 10. Airglowv emissions are consistent with an exospheric temperatuire approximately 275 K, a night airglows emission has been detected, indicating precipitation energy...
Information about the nature of UV absorbing agents in Venus' atmosphere has been obtained from a comparison model predictions with variety photometric data Pioneer Venus probes and orbiter as well earth. The theoretical simulations were performed numerically accurate radiative transfer codes that incorporated spacecraft constraints on properties aerosols gases atmosphere. We find at least two absorbers are needed: gaseous SO 2 , which is major source opacity wavelengths shortward 0.32 µm,...
The Pioneer Venus Orbiter Ultraviolet Spectrometer sees variable disk brightness features similar to the well‐known "UV markings" seen at longer wavelengths. bright are consistent with a homogeneous cloud of H 2 SO 4 aerosols. darker show presence broad‐band absorber, which is some depth in layer. Additional contrast arises from absorption. observed strength absorption as function wavelength rules out uniform mixing ratio for . data well fitted by an inhomogeneous light scattering model...
Ultraviolet spectroscopy from the Pioneer Venus Orbiter shows a decline in cloud top abundance of SO 2 about 100 ppb to 10 period 1978–1986. A consistent polar haze has occurred over same period, with correlation coefficient between these two observables r = 0.8. Star calibrations determine instrument sensitivity within 10%, which rules out possibility that this is an instrumental effect. Systematic errors could increase twice inferred values later orbits. Tracking features and power...
Neutral oxygen in the saturnian system shows variability, and total number of atoms peaks at 4 x 10(34). Saturn's aurora brightens response to solar-wind forcing, auroral spectrum resembles Jupiter's. Phoebe's surface variable water-ice content, data indicate it originated outer solar system. rings also show water abundance, with purest ice outermost A ring. This radial variation is consistent initially pure bombarded by meteors, but smaller structures may collisional transport recent...