During the first semester of 2016/2017 course, some UPC SP members joined together for the first time, in order to develop an ambitious project for the Projects subject, officially imparted to all ESEIAAT aerospace engineering degrees students.
The aim of the project was to design a nanosatellite LEO constellation, capable of providing data relay services to other satellites. The following requirements were set by the team itself, having a competitive service in mind.
- Provide communication relay between two LEO nanosatellites with a latency lower than 1 minute.
- Provide communication relay between a LEO nanosatellite and the ground with a latency lower than 5 minutes.
- Back-up system prepared to handle up to two major failures in the system.
- A major failure can be defined as the loss of a client’s satellite coverage because of a failure in the network.
- Switch time after major failure happens, shall be below 6 hours.
- Each Satellite Node volume should be equal or lower than a 3U CubeSat, in order to keep the costs down.
- Each Node should be able to handle at least 25 Mbit/s of data rate.
Astrea’s team mainly focused on the following topics:
- Orbit Design of the constellation
- Space Segment Systems – Satellite Design
- Ground Segment Systems – Ground Station Design
- Communications Protocol Stack
- Launcher and Deployer Choice
- Life cycle Strategies and Operations
- Economic Feasibility Study
After three months of work, the team achieved to solve all of the previous points in a justified and competitive way. Details of the solutions can be found below.
The final orbit configuration will be:
The satellite nodes, on the other hand, will consist in 3-U Cubesats, achieving low-costs and high compatibility. Moreover, in order to achieve the requirements of data relay, each node has a very complex communication system, composed by four transceivers and nine antennas.
In order to provide all the necessary power needed to drive all the transceivers, a detailed Electric Power System (EPS) design has been done as well.
The amount and location of Ground Stations (GS) was not an easy decision since it is an entangled problem along the orbits configuration. A balance between the cost and meeting the requirements was followed in order to find the following options:
Eventually, just one GS in the Malvines, one in Scotland and one in Canada where chosen as the final candidates. Besides, a Mission Control Centre (MCC) was situated in Terrassa, Spain, in order to carry on the whole service operation. With this solution, redundancy is achieved as well as constant communication with the Space Segment.
Finally, many alternatives where considered for the launching services required to put the 189 satellites in orbit. After considering all of them, the best option taking into account cost, availability and capability was the Electron Rocket from Rocket Lab.
And the second stage:
The team: Joan Cebrián Galán, Pol Fontanes Molina, Lluís Foreman Campins, Roger Fraixedas Lucea, Óscar Fuentes Muñoz, Sílvia González García, Fernando Herrán Albelda, Boyan Kaloyanov Naydenov, Vícotr Martínez Viol, David Morata Carranza, Laura Pla Olea, Marina Ponsa Daza, Josep Puig Ruiz, Josep Maria Serra Moncunill, Sergi Tarroc Gil, Xavier Tió i Eva María Urbano González.