## 4 Materials and Methods for Designing Tether-Deployed Constellations
### Orbit Design
#### 4.2.1 Orbit Design Question 1: Single or Multiple Orbit Paths for Released Payloads  
When considering single or multiple orbit paths, this asks whether payloads are required to be deployed solely into identical orbits with their only variation being in true anomaly. If only a single payload orbit path is permitted, this requires the system to utilize asymmetrical payload deployment, which would require either an onboard propulsion system to repeatedly boost the deployer's orbit back to its initial configuration to recover from payload momentum exchanges, or utilize symmetrical deployment with matched payloads and counterweights. The benefits of this asymmetric method entail very particular orbits with identical geometries, but the drawbacks come with devoting less resources to payloads and more to propulsion or counterweights, which reduce payload capacity and increase the number of launches needed to complete the constellation.  
2.2 Orbit Design Question 2: Inclusion/Exclusion of Traditional Propulsion on Deployer for Asymmetric Release  
When considering asymmetric release deployment, it is necessary to determine if the deployer spacecraft will include traditional propulsion, such as chemical or electric propulsion systems. If traditional propulsion is not included on the deployer, it will be necessary to include some other form of propulsion, such as deploying a tethered counterweight. Each of these options are feasible, but not advantageous for the overall intentions of tethered constellation deployments. Traditional propulsion utilizes established technology and does not contribute to space debris, but requires more design effort and the usage of propellant. Using tethered counterweights is technologically simpler, but is a poor use of spacecraft mass and volume and also contributes to space debris. If possible, these deployment methods should be avoided, but they are technically feasible options.  
Figure 15: Basic SwingSat release orbits geometry.  
If the counterweights option were to be used with symmetrical releases, payloads would be released into either a prograde or retrograde release orbit, and counterweights released into the other. This particular approach is unfavorable, as it is not an efficient usage of overall mass and volume, which is critical for small satellites, and contributes to space debris. If this approach is required, it would be preferred to command the system to send payloads into prograde release orbits with the counterweights released into a  
Figure 16: MET-deployed constellation design flowchart.  
retrograde orbit small enough to put the weights on a re-entry trajectory for disposal to minimize space debris' contribution, potentially with a trajectory directly intersecting with the central planetary body. This approach with prograde-released payloads is shown in Figures 17 and 18, with options for circular or elliptical orbits, and similar graphics displaying retrograde-released payloads in Figures 19 and 20.  
Figure 17: Prograde concentric circular release trajectory (retrograde orbit hidden).  
Figure 18: Prograde concentric elliptical release trajectory (retrograde orbit hidden).