In recent years, CubeSats have considerably extended their range of possible applications, from a low cost means to train students and young researchers in space related activities up to possible complementary solutions to larger missions. Increasingly popular, whereas CubeSats are still not a solution for all types of missions, they offer the possibility of performing ambitious scientific experiments. Especially worth considering is the possibility of performing Distributed Space Missions, in which CubeSat systems can be used to increase observation sampling rates and resolutions, as well as to perform tasks that a single satellite is unable to handle. The cost of access to space for traditional Earth Observation (EO) missions is still quite high. Efficient architecture design would allow reducing mission costs by employing CubeSat systems, while maintaining a level of performance that, for some applications, could be close to that provided by larger platforms, and decreasing the time needed to design and deploy a fully functional constellation. For these reasons many countries, including developing nations, agencies and organizations are looking to CubeSat platforms to access space cheaply with, potentially, tens of remote sensing satellites. During disaster management, real-time, fast and continuous information broadcast is a fundamental requirement. In this sense, a constellation of small satellites can considerably decrease the revisit time (defined as the time elapsed between two consecutive observations of the same point on Earth by a satellite) over remote areas, by increasing the number of spacecraft properly distributed in orbit. This allows collecting as much data as possible for the use by Disaster Management Centers. This paper describes the characteristics of a constellation of CubeSats built to enable access over the most remote regions of Brazil, supporting an integrated system for mitigating environmental disasters in an attempt to prevent the catastrophic effects of natural events such as heavy rains that cause flooding. In particular, the paper defines the number of CubeSats and the orbital planes required to minimize the revisit time, depending on the application that is the mission objective. Each CubeSat is equipped with the suitable payloads and possesses the autonomy and pointing capabilities needed to meet the mission requirements. Thanks to the orbital features of the constellation, this service could be exploited by other tropical countries. Coverage of other areas of the Earth might be provided by adjusting the number and in-orbit distribution of the spacecraft.

In order to simulate the conditions of the space environment at ground, the Laboratory of Application and Innovation in Aerospace Science (LAICA) of the University of Brasília (UnB) is developing a dedicated testbed aiming at reproducing nanosatellite attitude motion. The testbed is composed of an air bearing table and a Helmholtz cage. The air bearing table is a spacecraft simulator that can simulate frictionless conditions with three rotational degrees of freedom. Balancing the simulator is essential in order to make the gravitational torque negligible. The testbed 1 Silva, Approved on June 18th, 2018 is also equipped with a Helmholtz cage whose purpose is to recreate the Earth magnetic field conditions that spacecrafts encounter in orbit. The design and realization of this low-cost testbed is presented in this paper. A simple and efficient automated balancing algorithm based on the Least Squares Method (LSM) is proposed and validated by experiments. The performance of the proposed simulator is evaluated and compared with previous works.

No abstract

No abstract

Alves (2019). Helmholtz cage design and validation for nanosatellites HWIL testing. IEEE Transactions on Aerospace and Electronic Systems, 55 (6), p. 1.