Interplanetary Trajectories

Resistojet Design Project

The final project for Advanced Propulsion involved designing a resistojet rocket engine. The resistojet electrical design consisted of using a coil of Nichrome as the heating element. Nichrome was selected for its resistance to oxidation and its resistivity. The Nichrome coils were tightly wound and lined the interior walls of the inlet tube. The nichrome heating element was insulated from the walls of the tube, and each loop of wire was insulated from its neighboring loop with insulation of negligible thickness. These assumptions allowed for the assumption that all electrical power was converted to heat. Note: Depending on the thickness of the wire, there would have been a ramp-up time to get the coil to temperature before fuel valves could be opened. Therefore, the larger the wire diameter, the larger the electrical inefficiency. This analysis was not included.

Human Factors Experiment

In the context of spacecraft operations, it's important to understand how well tasks can be performed at different levels of workload. The Yerkes-Dodson Law is a theory that explains how performance is affected by workload: at low or high workloads, performance can suffer due to issues like decreased vigilance or tunnel vision. To better understand this relationship, a study was conducted that involved having participants play a game of pong on a computer, with varying ball speeds to create different workload levels.

Thirteen participants took part in the two-phase experiment. In the first phase, they played 13 games of pong in order to establish a baseline for their performance. This data was used for normalization purposes. In the second phase, each participant played 15 games of pong, during which they also had to answer True/False math problems and give subjective assessments of their workload. This was done in order to measure their workload levels and how it affected their performance in the game.

The study found that there is an indirect relationship between performance, which was defined as game length, and workload, which was defined as ball speed. Essentially, when ball speed was increased, participants tended to perform worse in the game. However, the relationship was not straightforward and there were other factors at play as well.

The researchers plan to conduct future studies that will aim to better understand the relationship between workload and performance in more complex systems. This could have important implications for designing automation systems that can help humans perform tasks more effectively in spacecraft operations.

Orbital Mechanics

A computer program was written in order to help plan interplanetary missions, as it allowed for the calculation of trajectories between any two planets in the solar system. The program used patched conics, which is a simplification of a multi-body problem, and Hohmann transfers, which are a type of orbital transfer between two coplanar circular orbits. The inclusion of models for elliptical and hyperbolic orbits allowed for more complex mission planning. The initial parking orbit was typically a low Earth orbit, and the delta v parameters were calculated based on the mass of the spacecraft and the desired transfer trajectory. The program also took into account gravitational assists from planets, which could be used to reduce the amount of delta v required for the transfer.

Orbit Determination

A program that computes the Orbit Parameters of a spacecraft is an essential tool in space mission planning and execution. It enables space engineers and scientists to accurately predict the spacecraft's path and motion in space, which is crucial for successful mission outcomes.

The program works by taking in the position and velocity vectors of the spacecraft at a particular point in time and converting them into the Keplerian Orbital Elements. These elements describe the shape, size, and orientation of the spacecraft's orbit around the central body. The program can determine the type of orbit by analyzing the eccentricity of the orbit. An eccentricity of less than one indicates an elliptical orbit, while an eccentricity of one indicates a parabolic orbit, and an eccentricity greater than one indicates a hyperbolic orbit.

Another critical function of the program is to assess whether the spacecraft will impact the central body. This is determined by calculating the distance between the spacecraft and the central body and comparing it to the central body's radius. If the distance is less than the radius, the spacecraft is predicted to impact the central body.

The program can also plot the spacecraft's trajectory and perform checks to ensure that boundary conditions are satisfied. Boundary conditions refer to the constraints on the spacecraft's motion, such as the minimum and maximum altitude and velocity, and the maximum angular momentum. By checking these conditions, the program can ensure that the spacecraft is on a safe and stable path.