A5040062779- Astro and Planetary Science
- Planetary Science and Exploration
- Space Science and Extraterrestrial Life
- Origins and Evolution of Life
- Isotope Analysis in Ecology
- Spacecraft and Cryogenic Technologies
- Nuclear Issues and Defense
- Astrophysics and Star Formation Studies
- Bacillus and Francisella bacterial research
- Methane Hydrates and Related Phenomena
- Space Exploration and Technology
- Geomagnetism and Paleomagnetism Studies
- Biotechnology and Related Fields
- Solar and Space Plasma Dynamics
- Atmospheric Ozone and Climate
- Photoreceptor and optogenetics research
- Space exploration and regulation
- Genetics, Bioinformatics, and Biomedical Research
- Scientific Research and Discoveries
- Stellar, planetary, and galactic studies
- Earth Systems and Cosmic Evolution
- Geophysics and Gravity Measurements
- High-pressure geophysics and materials
- Magnetic and Electromagnetic Effects
- Relativity and Gravitational Theory
Princeton University
2010-2025
Princeton Public Schools
2010-2021
American Academy of Arts and Sciences
2020
President's Council of Advisors on Science and Technology
2020
Woodrow Wilson International Center for Scholars
1982-2012
Cornell University
1987-2008
Search for Extraterrestrial Intelligence
1998-2006
Stanford University
1998-2005
University of California, San Diego
2000
Palo Alto University
1999
Voyager 2 images of Neptune reveal a windy planet characterized by bright clouds methane ice suspended in an exceptionally clear atmosphere above lower deck hydrogen sulfide or ammonia ices. Neptune's is dominated large anticyclonic storm system that has been named the Great Dark Spot (GDS). About same size as Earth extent, GDS bears both many similarities and some differences to Red Jupiter. zonal wind profile remarkably similar Uranus. three major rings at radii 42,000, 53,000, 63,000...
It has long been speculated that Earth accreted prebiotic organic molecules important for the origins of life from impacts carbonaceous asteroids and comets during period heavy bombardment 4.5 × 10 9 to 3.8 years ago. A comprehensive treatment comet-asteroid interaction with atmosphere, surface impact, resulting pyrolysis demonstrates organics will not survive at velocities greater than about kilometers per second even as small 100 meters in radius cannot be aerobraked below this velocity...
Atmospheric mixing ratios of ∼10 −5 ± 1 for ammonia on the early Earth would have been sufficient, through resulting greenhouse warming, to counteract temperature effects faint sun. One argument against such model atmospheres has short time scale photodissociation by solar ultraviolet light. Here it is shown that absorption steady-state amounts high-altitude organic solids produced from methane photolysis may shielded sufficiently resupply rates were able maintain surface temperatures above freezing.
Earth rotates through the axisymmetric part of its own magnetic field, but a simple proof shows that it is impossible to use this generate electricity in conductor rotating with Earth. However, we previously identified implicit assumptions underlying and showed theoretically these could be violated circumvented. This requires using soft material topology satisfying particular mathematical condition composition scale favoring diffusion, i.e., having low Reynolds number <a:math...
Europa is a prime target for astrobiology. The presence of global subsurface liquid water ocean and composition likely to contain suite biogenic elements make it compelling world in the search second origin life. Critical these factors, however, may be availability energy biological processes on Europa. We have examined production oxidants carbon-containing reductants better understand habitability ocean. Data from Galileo Near-Infrared Mapping Spectrometer were used constrain surface...
October 01 2004 Proliferation Rings: New Challenges to the Nuclear Nonproliferation Regime Chaim Braun, Braun Vice President of Altos Management Partners Inc. and a Science Fellow at Center for International Security Cooperation (CISAC) in Stanford University's Institute Studies. Search other works by this author on: This Site Google Scholar Christopher F. Chyba Co-director CISAC Associate Professor Stanford's Department Geological Environmental Sciences. Author Article Information Online...
▪ Abstract Astrobiology is the study of living universe. Astronomy provides context for origin and evolution life on Earth. Conversely, discoveries about terrestrial biosphere—from extremophilic microbes to intelligence—inform our thinking prospects elsewhere. includes search extraterrestrial via in situ exploration, spectroscopy solar extrasolar planetary atmospheres, intelligence. This review situates astrobiology within philosophical issues definition biological compatibility It reviews...
Abstract— A significant fraction of the Earth's prebiotic volatile inventory may have been delivered by asteroidal and cometary impacts during period heavy bombardment. The realization that comets are particularly rich in organic material seemed to strengthen this suggestion. Previous modeling studies, however, indicated most organics would be entirely destroyed large comet asteroid impacts. availability new kinetic parameters for thermal degradation amino acids solid phase made it possible...