| Observations made by Voyager 1 of the low energy ion component of the anomalous cosmic rays from 83 AU (astronomical units) to 91 AU, which relates to the years 2002 and 2003, are studied. During this time period, specifically 2002/200 to 2003/044, Voyager 1 encountered a previously unobserved environment. This 209 day period will be the focus of this research.; Investigation of this period involved the calculation of a count rate for the main particle species (protons, alpha particles, and oxygen) to study changes in the particle density, and the comparison of the resulting fluxes with those done at other energies to see if there is consistency in the energy spectrum. Also, temporal correlations are done to study the count rate behavior between the first and second halves of 2002 at Voyager 1, and for 2002 at Voyager 2 for the three main particle species. Additionally, the kinetic pressure components parallel and perpendicular to the interplanetary magnetic field are calculated for the 2002/200 to 2003/044 period to see if the conditions were sufficient for a firehose or mirror plasma instability to occur.; Results indicate that the observations by Voyager 1 during this period can be interpreted as showing the signature characteristics of a MHD-described termination shock crossing, and therefore may indicate the first encounter with the termination shock. However, during this period conditions were sufficient for a firehose instability to occur allowing for an alternative explanation for the Voyager 1 observations, as well as the need of a MHD-described termination shock.; Therefore, a definitive resolution as to what Voyager 1 observed during 2002/200 to 2003/044, whether a MHD-described termination shock or a plasma instability region, or some other phenomenon, is still unknown. This period is of extreme importance, and may have a profound impact on current theory pertaining to the structure of the termination shock, even its existence, and continued analysis of this period is therefore needed to arrive at a more conclusive answer. |
