ENGG1001 Programming for Engineers Assignment 2 Brief Semester 1 2025 | UQ

Introduction 

Engineers need to design, operate and maintain systems. This assignment concerns the operation and maintenance aspect of engineering, specifically within the realm of low Earth satellites. Satellites are important in today's technological landscape because they provide communications, internet and telephone services. The availability of smart engineering technologies has enabled the launching into orbit of vast numbers of relatively small satellites, each of which can be monitored and controlled individually. The major player in the satellite industry is Spacex, which has launched thousands of their Starlink satellites. Below is a look at the rocket used to send up their satellites.

One of the issues associated with the increased number of satellites is the potential for them to crash into each other. To address this, contemporary satellites have the capability of orbit adjustment. Satellite operators monitor for collisions and modify the orbit accordingly with appropriate engine thrust. In this assignment, you will be writing computer programs to query a database of known satellites. This process can be used in a real-world scenario to assess the likelihood of a collision. For this purpose, you will have access to a database provided by the Union of Concerned Scientists at: Union of Concerned Scientists

Satellite Orbital Trajectories

Figure 2(a) shows some satellites in orbit about Earth. The satellites orbiting the Earth are in elliptical orbits (and a circular orbit is a special case of an ellipse). For this reason, the geometry of an ellipse is very useful for computing information about satellite orbits, such as the time taken to complete the orbit and the speed of the satellite at points along its orbit. The basic geometry of an ellipse is shown in Figure 2(b). An ellipse is characterised by the lengths of its major and minor axes and its focus points. In an orbital mechanics sense, the satellite only orbits one of the focus points; the Earth is the focal point. We will need to compute some basic orbital parameters in this assignment. The images in Figure 2 provide a visual reference for our calculations. There are two important points on the orbit, and they are given special names: (1) the apogee is the point where the satellite is furthest from Earth; and (2) the perigee is the point where the satellite is closest to Earth. In this assignment, the data about a satellite's orbit will be given in terms of altitudes at apogee and perigee. 

Figure 2:Elliptical orbits. (a) depiction of satellites in various orbits about Earth; (b) geometry of an ellipse. Source: UCS Satellite Database User's Manual [1]. 

Let's now look at some properties of actual satellites in orbit above the Earth. The properties include those related to the satellite itself and the orbit it occupies. Table 1 shows data for a small selection of satellites. Sky Muster 1 — an NBN satellite — and Starlink-1009 are both communications satellites, but the differences between them show the evolving nature of communications satellites technology. Sky Muster 1 is an example of a single large piece of infrastructure (6440 kg) that sits in geosynchronous orbit so that it permanently services a portion of the Earth (ie. Australia). By contrast, Starlink-1009 has a mass of 227 kg and occupies a low Earth orbit. It moves around the Earth in about 1.5 hours but is part of a much larger constellation, and collectively the constellation can service all regions of the Earth's surface.