Cassini Swarm
Proposed Schedule
The following is a breakdown of the planning, design, integration, and testing phases of the project. Work is ready to begin in early Q4 2014 following wrap-up of Requirements Analysis and Planning tasks. Although the schedule is aggressive, the lessons learned from the Cassini mission and several enabling technoligies such as software-defined radio and CubeSat standardization will allow rapid development and testing phases.
References:
[1] http://solarsystemscope.com
Proposed Mission Timeline
The dominating consideration in the Cassini Swarm mission timeline is the navigation of its trajectory en route to Titan. There are several aspects to consider including low-energy trajectories enabled by gravitational assists from planets, the phasing of the planets' orbits around the Sun, and the potential use of deep space maneuvers (DSMs) to change intermediate trajectories with on-board propulsion.
Our goal is to rendezvous with Titan by 2025. In order to support this goal, we want to take advantage of a gravitational assist from Jupiter, the massive gas giant. Orbital phasing predicts that Jupiter will be in a desirable position with respect to Saturn (and therefore Titan) during summer of 2019 [1]. A launch date has not yet been selected.
TitanTech is leveraging Open Source Software (OSS) tools developed by the Advanced Concepts Team (ACT) at the European Space Agency (ESA) to design potential trajectories from Earth to Titan. The Keplerian Toolbox and nonlinear solver tools they have developed allow the design of trajectories that minimize the propulsive changes in velocity (delta-V) needed in DSMs while constraining the search space to an allowable range of total time-of-flight.
The trajectory is modeled as partial segments of heliocentric elliptical orbits connected by events that change the orbiter's velocity and therefore its orbit. The two mechanisms by which the orbiter changes its orbit are by a DSM with its on-board propulsion system or by an approach to an intermediate planet. The planet gives the orbiter a gravitational assist as the orbiter speeds up while traversing a hyperbolic "orbit" near the planet. The orbiter's trajectory is aimed such that it will not be captured by the gravitational pull of the planet.
The phasing of the planets in their orbits around the Sun is a major factor constraining when planets will be available to provide gravitational assists. The simulation below shows the planets Mercury through Saturn in motion around the Sun.