A-train constellation exit orbit analysis: when missions exit the 705KM constellation IT is required, at a minimum, that their orbits are lowered to an altitude that is considered safe by the…

A-train constellation exit orbit analysis: when missions exit the 705KM constellation IT is required, at a minimum, that their orbits are lowered to an altitude that is considered safe by the constellation members. As currently defined, an exit orbit that is considered safe has an apogee below the perigee of the existing constellation mission orbits (19KM circular below the nominal 705KM operational orbit). However, members are now considering an alternate minimum exit orbit altitude of as little as 4KM below the constellation. NASA flight dynamics teams have verified the safety of this closer disposal location from an orbital mechanics perspective, but if a mission placed in the proposed 4KM-lower orbit is subsequently HIT by another on-orbit object to form a debris cloud, IT is suspected that some additional risk may be posed to the remaining constellation members. In general aerospace shall provide systems engineering support. The contractor shall perform a parametric study to analyze disposal orbits from a debris perspective. The contractor will examine 19 KM and 4 KM orbits to determine the increased risk of collision to the constellation from a debris cloud formed at either altitude by the terra spacecraft. They will also perform this analysis for both a partial (10%) and complete (100%) terra breakup. As a potential follow-up analysis, should the elevated risks from either scenario in task item #1 be considered potentially problematic, the contractor may be directed to perform a second task. They are also to perform a study to determine, given the collision described in task item #1, a trade space of risk factors VS. Exit altitude from a minimum of the PC of the background risk at 705 up to some higher value in increments of 5 KM. If directed by the task monitor, one person will travel from chantilly, VA to norfolk, VA for presentation of interim analysis results to constellation working group meeting.