Recent advances in electric propulsion systems have demonstrated that these engines have the potential to be used for long-duration travels, with applications such as cargo and human transportation for interplanetary voyages. The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) is an example of this type of engine, possessing the ability to operate at a wide range of specific impulse levels. This chapter presents the results of a study comparing three different thrust control strategies for Earth-Mars trajectories, using the VASIMR engine at a power of 150 kW. These are constant thrust trajectories, trajectories with coasting periods, and trajectories with variable specific impulse, resulting in variable thrust. To achieve this, an optimization tool was created using spherical coordinates to model the dynamics of the spacecraft, optimal control theory to setup the optimization problem, and a differential evolution algorithm to minimize the cost function. A novel approach to model variable specific impulse and coast-arcs in the trajectories for spherical coordinates is presented as well. The optimization tool was utilized to find optimal trajectories from Earth to Mars orbit, and it was concluded that using variable thrust reduces propellant consumption for a variety of trajectories, when compared to the other two methods.
Upgrading the energy performance of the UK’s entire building stock is the central pillar of any credible and cost-effective strategy to meeting net zero. This research aims to open up the revenue of using thermal infrared data from satellites to assist in processes on building energy performance improvement. High-resolution thermal infrared data output from space offers the potential for fast and effective monitoring provision that can cover large areas and targeted buildings or sites. We have interviewed a set of stakeholders from government, industry and community groups to build the specific use cases and find out detailed user requirements.
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