This comprehensive study of comet C/1995 O1 focuses first on investigating its orbital motion over a period of 17.6 yr ( 1993–2010 ) .
The comet is suggested to have approached Jupiter to 0.005 AU on - 2251 November 7 , in general conformity with Marsden ’ s ( 1999 ) proposal of a Jovian encounter nearly 4300 yr ago .
The variations of sizable nongravitational effects with heliocentric distance correlate with the evolution of outgassing , asymmetric relative to perihelion .
The future orbital period will shorten to \sim 1000 yr because of orbital-cascade resonance effects .
We find that the sublimation curves of parent molecules are fitted with the type of a law used for the nongravitational acceleration , determine their orbit-integrated mass loss , and conclude that the share of water ice was at most 57 % , and possibly less than 50 % , of the total outgassed mass .
Even though organic parent molecules ( many still unidentified ) had very low abundances relative to water individually , their high molar mass and sheer number made them , summarily , important potential mass contributors to the total production of gas .
The mass loss of dust per orbit exceeded that of water ice by a factor of \sim 12 , a dust loading high enough to imply a major role for heavy organic molecules of low volatility in accelerating the minuscule dust particles in the expanding halos to terminal velocities as high as 0.7 km s ^ { -1 } .
In Part II , the comet ’ s nucleus will be modeled as a compact cluster of massive fragments to conform to the integrated nongravitational effect .