MONTE Python for Deep Space Navigation

Abstract

The Mission Analysis, Operations, and Navigation Toolkit Environment (MONTE) is the Jet Propulsion Laboratory's (JPL) signature astrodynamic computing platform. It was built to support JPL's deep space exploration program , and has been used to fly robotic spacecraft to Mars, Jupiter, Saturn, Ceres, and many solar system small bodies. At its core, MONTE consists of low-level astrodynamic libraries that are written in C++ and presented to the end user as an importable Python language module. These libraries form the basis on which Python-language applications are built for specific astrodynamic applications , such as trajectory design and optimization, orbit determination, flight path control, and more. The first half of this paper gives context to the MONTE project by outlining its history, the field of deep space navigation and where MONTE fits into the current Python landscape. The second half gives an overview of the main MONTE libraries and provides a narrative example of how it can be used for astrodynamic analysis. For information on licensing MONTE and getting a copy visit montepy.jpl.nasa.gov or email mdn_software@jpl.nasa.gov. The United States began its reconnaissance of the solar system in the early 1960s. As NASA developed new technologies to build and operate robotic probes in deep space, JPL was working out how to guide those probes to their destinations. In order to fly spacecraft to Mars or Jupiter, engineers needed a way to model their trajectories through interplanetary space. This was partly a problem of astrodynamics, a field of study that mathematically describes how man-made objects move through space. It was also a problem of computation because engineers needed a way to solve these complex astrodynamic equations for real spacecraft. Beyond modeling the motion of spacecraft, engineers needed a way to measure the location of spacecraft over time so they could make informed corrections to their models. They also needed a way of designing engine burns, or maneuvers, that would nudge a wayward probe back on course. These efforts, collectively known as deep space navigation, quickly became coupled with software and computing. The first programs JPL wrote to navigate spacecraft were written on punch-cards and processed through an IBM 7090 mainframe. [Eke05] Advances in computing technology were eagerly consumed by navigators, as more storage and faster processing meant the models used to fly spacecraft could be made increasingly detailed and sophisticated.