The lower thermosphere (between 100 and 250 km) is badly known due to the scarcity
of operating satellites in this region. Nevertheless, it is very relevant for the study of
Earth-Sun relations, satellite re-entry forecasting, and climate change, among other
disciplines.
We propose the analysis of a swarm of femtosatellites to directly analyze the
thermosphere by means of a MEMS accelerometer onboard each satellite. The goal is
to use the deceleration caused by drag to determine the local density, thus drawing a
map of the thermosphere on multiple locations.
The shape of the satellites will be spherical (with a diameter of 5 or 10 cm), thus
simplifying the measurement of drag. The mass distribution will be that of a spherical
top (then, no attitude control), or will have the center of mass separated from the
geometric center (thus providing aerodynamic stability).
Each satellite will also count with a MEMS GNSS receiver that will provide precise
location and time-tagging to the measurements. A small onboard computer, mass
storage system, radio transmitter, and primary battery will form the bus of the satellite.
The goal of this Master Thesis is to develop a self-consistent mission analysis of the
mission, with special interest in comparing the properties of the non-stabilized and
aerodynamically stabilized satellites.
The main objectives must be:
Σ Design and analysis of the optimal orbit for these satellites. Of particular interest
is the study of the different alternatives for orbital injection and dissemination.
Σ Analysis of orbital decay using DRAMA. Evaluation of the risk for third-party
satellites posed by a large swarm. Proposals for decreasing this risk.
Σ Data gathering strategy.
Σ Sources of noise for the accelerometer, both instrumental and environmental.
Σ Communication strategy. Determination of the link budget, proposal for ground
station typology and location.
Σ Energy budget. Analysis of mission’s life limitations due to the endurance of the
battery.
Σ Alternative scenarios for mission success. Identify and evaluate scenarios in
which the mission cannot be accomplished in the planned way. For example,
analyze possible mission procedures should the accelerometer fail.
This project is undertaken in collaboration with Prof. Igor Belokonov, Inter-University
Department of Space Research, Samara University (Russia).
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