Results 51 to 60 of about 2,302 (180)

Bistability in Interstellar Gas‐Phase Chemistry [PDF]

open access: yesThe Astrophysical Journal, 2006
We present an analysis of "bistability" in gas-phase chemical models of dark interstellar clouds. We identify the chemical mechanisms that allow high- and low-ionization solutions to the chemical rate-equations to coexist. We derive simple analytic scaling relations for the gas densities and ionization rates for which the chemistry becomes bistable. We
Boger, Gai I., Sternberg, Amiel
openaire   +2 more sources

From Flybys to Sample Return: A Review of Space Probes and Robotic Sampling Technologies for Small Bodies

open access: yesJournal of Field Robotics, EarlyView.
ABSTRACT As a crucial puzzle piece of deep space exploration, exploring small bodies can provide significant scientific insights and valuable mineral resources. Unlike missions to the Moon and Mars, small‐body missions pose distinct technical challenges, including communication delays, weak gravity, and uncertain environments. This paper reviews a full
Xin Zhang   +3 more
wiley   +1 more source

Spaceborne and spaceborn: Physiological aspects of pregnancy and birth during interplanetary flight

open access: yesExperimental Physiology, EarlyView.
Abstract Crewed interplanetary return missions that are on the planning horizon will take years, more than enough time for initiation and completion of a pregnancy. Pregnancy is viewed as a sequence of processes – fertilization, blastocyst formation, implantation, gastrulation, placentation, organogenesis, gross morphogenesis, birth and neonatal ...
Arun V. Holden
wiley   +1 more source

Survival of polycyclic aromatic hydrocarbon knockout fragments in the interstellar medium

open access: yesNature Communications, 2021
Ion storage rings allow reactions to be studied over orders of magnitude in time, bridging the gap between typical experimental and astronomical timescales.
Michael Gatchell   +8 more
doaj   +1 more source

Organic Chemistry in the H2-bearing, CO-rich Interstellar Ice Layer at Temperatures Relevant to Dense Cloud Interiors

open access: yesThe Astrophysical Journal
Ice chemistry in the dense, cold interstellar medium (ISM) is probably responsible for the formation of interstellar complex organic molecules (COMs). Recent laboratory experiments performed at T ∼ 4 K have shown that irradiation of CO:N _2 ice samples ...
Rafael Martín-Doménech   +3 more
doaj   +1 more source

Chemical Kinetics of 2‐, 4‐, and 2,4‐Seleno‐Uracils at Low Temperatures: Tautomerizations and Rotamerizations on Inert Matrices

open access: yesInternational Journal of Chemical Kinetics, Volume 58, Issue 10, Page 881-889, October 2026.
ABSTRACT In the interstellar medium, chemical reactions proceed under conditions vastly different to those on Earth; these include extremely low temperatures and densities and take place in the gas phase and on water–ice grains. Understanding the energetics and more importantly the kinetics of such reactions is of relevance to the consequences on how ...
Judith Wurmel, John M. Simmie
wiley   +1 more source

Different Frontier, Same Legal Script? On the Course of Replicating Earth's Patterns in Space

open access: yesThe Modern Law Review, Volume 89, Issue 5, Page 723-759, September 2026.
As states and private actors expand their activities in outer space, the international legal framework governing this domain risks extending longstanding structures of global inequality beyond Earth. This article examines how international space law, shaped by a broader disciplinary pattern of reactive legal development, is poised to reproduce ...
Sivan Shlomo‐Agon, Michal Saliternik
wiley   +1 more source

Chemistry on interstellar grains

open access: yesJournal of Physics: Conference Series, 2005
In this review, our current knowledge of the chemistry that occurs on cold interstellar grain surfaces is examined. The formation of molecular hydrogen from hydrogen atoms is emphasized. Various methods of modeling diffusive reactions on grain surfaces are illustrated, including the rate equation method, and two basic stochastic approaches. The results
E Herbst, Q Chang, H M Cuppen
openaire   +1 more source

When Communication Enables Catastrophe: Nuclear Risk and the Short Lifetimes of Technological Civilizations

open access: yesRisk Analysis, Volume 46, Issue 9, September 2026.
ABSTRACT The Fermi paradox may partly reflect technological self‐destruction acting as a Great Filter during post‐industrial development. Because the empirical record consists of a single civilization observed over an eighty‐year nuclear age, the exercise reported here is best understood as a structured, historically anchored scenario analysis rather ...
Vincenzo Alfano
wiley   +1 more source

Strong inverse kinetic isotope effect observed in ammonia charge exchange reactions

open access: yesNature Communications, 2020
Inverse kinetic isotope effects (KIEs) are rarely observed. Here, the authors report an inverse KIE in the charge transfer reaction of $${{\rm{Xe}}}^{+}$$ Xe+ with ammonia.
L. S. Petralia   +4 more
doaj   +1 more source

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