Abstract
Designing an interplanetary mission is a complex task and requires the choice of the launch opportunity and of the exact launch and arrival dates. Depending on these choices, the trajectory must be defined and, in case of continuous thrust, also the thrust profile needs to be optimized.. Traditionally, these choices are made using some plots which allow to find a good compromise between the travel duration and the cost of the mission, which is often expressed in terms of initial mass in Earth orbit (IMLEO). IRMA (InterPlanetary Mission Analysis) code, based on the MATLAB®environment, is here described. It allows to deal with both impulsive propulsion (using the patched conics approach) and low continuous thrust (Solar or Nuclear electric or propellantless, like solar sails). A specific solver, based on indirect optimization techniques, has been developed specifically for this program, but IRMA can be used also as an interface for standard solvers, based on direct methods, like the FALCON.m code.
Highlights
The planets of our Solar System move in a complex way around the Sun, and this causes the performances of any space mission to depend on the launch opportunity and, once the latter has been chosen, on the exact launch date
While historically ephemerides consisted in tables where the positions of the celestial bodies of interest were reported as functions of time, modern ephemerides are based on mathematical models allowing to compute the position of the solar system bodies at any given time
Precise reference frames and time reference must be stated: at present the ephemerides made available by NASA-JPL [1, 2] are based on the International Celestial Reference Frame (ICRF) and on the Julian time
Summary
The planets of our Solar System move in a complex way around the Sun, and this causes the performances of any space mission to depend on the launch opportunity and, once the latter has been chosen, on the exact launch date. In case of low thrust systems, i.e. the thrust is not much higher than the other forces acting on the spacecraft and is applied for long times, possibly up to the whole travel time, the same scheme can be applied by subdividing the trajectory in arcs performed in the sphere of influence of a single body. This patched arcs approach is the simplest, approximate, way of computing the trajectory of a spacecraft in the solar systemb It is generally applied for the early phases of the design of interplanetary missions, when the departure and arrival dates are chosen and a vey large number of trajectories (tens or hundreds of thousands) must be computed. The choice of the launch and arrival dates can be performed in a few hours using a laptop computer
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