Cometary exploration

abundance albedo Arizona Press assumed Astron Astrophys black sites brightness C0MET calculations charge exchange chemical collisions column density Comet Halley Comet West cometary atmosphere cometary coma cometary ions cometary nuclei cometary plasma component condensation curve Delsemme dissociation distribution dust grains dynamics effect electron emission energy equations Festou flow flux giant molecular clouds heat Houpis Huebner hydrogen hydrogen atoms Icarus infrared inner coma interaction interplanetary interstellar cloud ion tail ionization ionosphere long-period comets magnetic field mantle Marconi and Mendis mean free path molecular clouds molecules negative ions neutral nuclear nucleus number density observed orbital Orion outflow P/Halley parameters parent molecules percolation theory perihelion photodissociation photometric photons physical Planet plasma protons radiative radii radius ratio reactions region rotational Saturn's family Schmidt Sekanina short-period comets solar nebula solar wind species spectral sublimation surface temperature thermal tion variation velocity Whipple