A. J. Coates
A5000196624- Astro and Planetary Science
- Planetary Science and Exploration
- Geomagnetism and Paleomagnetism Studies
- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Space Exploration and Technology
- Space Science and Extraterrestrial Life
- Stellar, planetary, and galactic studies
- Isotope Analysis in Ecology
- Astrophysics and Star Formation Studies
- Geology and Paleoclimatology Research
- Spacecraft and Cryogenic Technologies
- Atomic and Molecular Physics
- Laser-induced spectroscopy and plasma
- Spacecraft Design and Technology
- Atmospheric Ozone and Climate
- Gamma-ray bursts and supernovae
- High-pressure geophysics and materials
- Space exploration and regulation
- Scientific Research and Discoveries
- Spaceflight effects on biology
- Space Satellite Systems and Control
- Nuclear Physics and Applications
- Plasma Diagnostics and Applications
- Earthquake Detection and Analysis
University College London
2016-2025
Surrey Satellite Technology (United Kingdom)
2025
Mars Space (United Kingdom)
1999-2022
Southwest Research Institute
2004-2021
University of Washington
2021
Globe University
2021
Centre National de la Recherche Scientifique
2021
Cornell University
2021
Goddard Space Flight Center
2021
Ames Research Center
2021
Titan's lower atmosphere has long been known to harbor organic aerosols (tholins) presumed have formed from simple molecules, such as methane and nitrogen (CH4 N2). Up now, it assumed that tholins were at altitudes of several hundred kilometers by processes yet unobserved. Using measurements a combination mass/charge energy/charge spectrometers on the Cassini spacecraft, we obtained evidence for tholin formation high (approximately 1000 kilometers) in atmosphere. The observed chemical mix...
The second ExoMars mission will be launched in 2020 to target an ancient location interpreted have strong potential for past habitability and preserving physical chemical biosignatures (as well as abiotic/prebiotic organics). deliver a lander with instruments atmospheric geophysical investigations rover tasked searching signs of extinct life. equipped drill collect material from outcrops at depth down 2 m. This subsurface sampling capability provide the best chance yet gain access...
Titan's ionosphere contains a rich positive ion population including organic molecules. Here, using CAPS electron spectrometer data from sixteen Titan encounters, we reveal the existence of negative ions. These ions, with densities up to ∼100 cm −3 , are in mass groups 10–30, 30–50, 50–80, 80–110, 110–200 and 200+ amu/charge. During one low encounter, ions per charge as high 10,000 amu/q seen. Due their unexpectedly at ∼950 km altitude, these must play key role chemistry they may be...
We analyze the radial distribution of electron populations inside 20 R s in Saturn's magnetosphere, and we calculate moments for these by a forward modeling method using composite spectra produced CAPS/ELS (0.6 eV to 26 keV) MIMI/LEMMS (15 keV 10 MeV) instruments on board Cassini. first harmonize both data sets physical units apply corrections taking into account biases introduced spacecraft interaction with magnetospheric environment. then test different bimodal isotropic models, deciding...
During Cassini's initial orbit, we observed a dynamic magnetosphere composed primarily of complex mixture water-derived atomic and molecular ions. We have identified four distinct regions characterized by differences in both bulk plasma properties ion composition. Protons are the dominant species outside about 9 RS (where is radial distance from center Saturn), whereas inside, consists corotating comet-like mix ions with approximately 3% N+. Over A B rings, found an ionosphere which O2+ O+...
The damaging effect of ionising radiation on cellular structure is one the prime limiting factors survival life in potential astrobiological habitats. Here we model propagation solar energetic protons and galactic cosmic ray particles through Martian atmosphere three different surface scenarios: dry regolith, water ice, regolith with layered permafrost. Particle energy spectra absorbed dose are determined for at regular depths underground, allowing calculation microbial times. Bacteria or...
The Analyzer of Space Plasma and Energetic Atoms (ASPERA) on board the Mars Express spacecraft found that solar wind plasma accelerated ionospheric ions may be observed all way down to pericenter 270 kilometers above dayside planetary surface. This is very deep in ionosphere, implying direct exposure martian topside atmosphere forcing. low-altitude penetration energization due irregularities or perturbations, magnetic anomalies at Mars, both.
On 4 July 2005, many observatories around the world and in space observed collision of Deep Impact with comet 9P/Tempel 1 or its aftermath. This was an unprecedented coordinated observational campaign. These data show that (i) there new material after impact compositionally different from seen before impact; (ii) ratio dust mass to gas ejecta much larger than (iii) activity did not last more a few days, by 9 comet's behavior indistinguishable pre-impact behavior; (iv) were interesting...
During the 14 July 2005 encounter of Cassini with Enceladus, Plasma Spectrometer measured strong deflections in corotating ion flow, commencing at least 27 Enceladus radii (27 x 252.1 kilometers) from Enceladus. The Radio and Wave Science instrument inferred little plasma density increase near These data are consistent formation via charge exchange pickup by Saturn's magnetic field. occurs between neutrals atmosphere ions inner magnetosphere. Pickup observed a total mass loading rate about...
The magnetotails of Jupiter and Earth are known to be hinged so that their orientation is controlled by the magnetic field planet at small distances asymptotically approach direction flow solar wind large distances. In this paper we present Cassini observations showing Saturn's magnetosphere also similarly hinged. Furthermore, find not only in tail but on dayside, contrast Jovian terrestrial magnetospheres. Over midnight, dawn, noon local time sectors current sheet displaced above rotational...
The shape and location of a planetary magnetopause can be determined by balancing the solar wind dynamic pressure with magnetic thermal pressures found inside boundary. Previous studies have kronian magnetosphere to show rigidity (like that Earth) as well compressibility Jupiter) in terms its dynamics. In this paper we expand on previous work present new model Saturn's magnetopause. Using Newtonian form balance equation, estimate at each crossing Cassini spacecraft between Saturn Orbit...
Observations with the Venus Express magnetometer and low-energy particle detector revealed magnetic field plasma behavior in near-Venus wake that is symptomatic of reconnection, a process occurs Earth's magnetotail but not expected nonmagnetized planet such as Venus. On 15 May 2006, flow this region was toward planet, component transverse to reversed. Magnetic reconnection changes topology results energy exchange between plasma. Thus, energetics resembles terrestrial tail, where stored later...
Photochemically produced aerosols are common among the atmospheres of our solar system and beyond. Observations models have shown that photochemical direct consequences on atmospheric properties as well important astrobiological ramifications, but mechanisms involved in their formation remain unclear. Here we show Titan’s upper atmosphere is directly related to ion processes, provide a complete interpretation observed mass spectra by Cassini instruments from small large masses. Because all...