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At least 55 records · Page 3

Working with orbits

Orbit calculations for size and shape of orbit, required velocity at perigee and apogee, and gravitational effects on satellite orbit

Gerster, D. E.

The rotational spectra of HCNH/+/ and COH/+/ from quantum mechanical calculations

A description is provided of ab initio molecular orbital calculations designed to provide accurate predictions for the J = 1 to 0 rotational line of the candidate interstellar molecules HCNH(+) and COH(+). The former is believed to be important in the formation of both HCN and HNC in the interstellar medium. The latter, a metastable isomer of HCO(+), was first proposed as an interstellar molecule by Herbst et al. (1976). Attention is given to thermochemical arguments that this molecule can be formed in the same reactions which are proposed to form HCO(+), taking into account theoretical data which establish its stability to intramolecular rearrangement. Rotational constants are derived by applying an empirical correction to the ab initio rotational constants.

Defrees, D. J.

Thermal and orbital analysis of Earth monitoring Sun-synchronous space experiments

The fundamentals of an Earth monitoring Sun-synchronous orbit are presented. A Sun-synchronous Orbit Analysis Program (SOAP) was developed to calculate orbital parameters for an entire year. The output from this program provides the required input data for the TRASYS thermal radiation computer code, which in turn computes the infrared, solar and Earth albedo heat fluxes incident on a space experiment. Direct incident heat fluxes can be used as input to a generalized thermal analyzer program to size radiators and predict instrument operating temperatures. The SOAP computer code and its application to the thermal analysis methodology presented, should prove useful to the thermal engineer during the design phases of Earth monitoring Sun-synchronous space experiments.

Killough, Brian D.

ORDEM 3.0 and the Risk of High-Density Debris

NASA’s Orbital Debris Engineering Model was designed to calculate orbital debris fluxes on spacecraft in order to assess collision risk. The newest of these models, ORDEM 3.0, has a number of features not present in previous models. One of the most important is that the populations and fluxes are now broken out into material density groups. Previous models concentrated on debris size alone, but a particle’s mass and density also determine the amount of damage it can cause. ORDEM 3.0 includes a high-density component, primarily consisting of iron/steel particles that drive much of the risk to spacecraft. This paper will outline the methods that were used to separate and identify the different densities of debris, and how these new densities affect the overall debris flux and risk.

Matney, Mark