European Student Moon Orbiter Research Articles

Contingency and recovery options for the European Student Moon Orbiter

This paper presents an overview of the analysis performed on the lunar orbit and some of the possible contingencies for the European Student Moon Orbiter (ESMO). Originally scheduled for launch in 2014 –2015 as a piggyback payload, it was the only ESA planned mission to the Moon. By way of a weak stability boundary transfer, ESMO is inserted into an orbit around the Moon. Propellant use is at a premium, so the operational orbit is selected to be highly eccentric. In addition, an optimization is presented to achieve an orbit that is stable for 6 months without requiring orbit maintenance. A parameter study is undertaken to study the sensitivity of the lunar orbit insertion. A database of transfer solutions across 2014 and 2015 is used to study the relation between the robustness of weak capture and the planetary geometry at lunar arrival. A number of example recovery scenarios, where the orbit insertion maneuver partially or completely fails, are also considered.

Attitude Dynamics of ESMO Satellite: Mass Expulsion Torques and Propellant Slosh Model

The European Student Moon Orbiter (ESMO) was the first European student mission to the Moon and the fourth mission within ESA (European Space Agency) Education Satellite Programme. The purpose of this mission was to place the spacecraft on a polar orbit around the Moon, return new data by acquiring surface images of the Moon South Pole and test new technologies.

Navigating to the Moon along low-energy transfers

This paper presents a navigation strategy to fly to the Moon along a Weak Stability Boundary transfer trajectory. A particular strategy is devised to ensure capture into an uncontrolled relatively stable orbit at the Moon. Both uncertainty in the orbit determination process and in the control of the thrust vector are included in the navigation analysis. The orbit determination process is based on the definition of an optimal filtering technique that is able to meet accuracy requirements at an acceptable computational cost. Three sequential filtering techniques are analysed: an extended Kalman filter, an unscented Kalman filter and a Kalman filter based on high order expansions. The analysis shows that only the unscented Kalman filter meets the accuracy requirements at an acceptable computational cost. This paper demonstrates lunar weak capture for all trajectories within a capture corridor defined by all the trajectories in the neighbourhood of the nominal one, in state space. A minimum Δv strategy is presented to extend the lifetime of the spacecraft around the Moon. The orbit determination and navigation strategies are applied to the case of the European Student Moon Orbiter.

Orbit determination and control for the European Student Moon Orbiter

This paper presents the preliminary navigation and orbit determination analyses for the European Student Moon Orbiter. The severe constraint on the total mission Δv and the all-day piggy-back launch requirement imposed by the limited available budget, led to the choice of using a low-energy transfer, more specifically a Weak Stability Boundary one, with a capture into an elliptic orbit around the Moon. A particular navigation strategy was devised to ensure capture and fulfil the requirement for the uncontrolled orbit stability at the Moon. This paper presents a simulation of the orbit determination process, based on an extended Kalman filter, and the navigation strategy applied to the baseline transfer of the 2011–2012 window. The navigation strategy optimally allocates multiple Trajectory Correction Manoeuvres to target a so-called capture corridor. The capture corridor is defined, at each point along the transfer, by back-propagating the set of perturbed states at the Moon that provides an acceptable lifetime of the lunar orbit.

Modelling of the Moon orbiter for the ESA project ESMO

AbstractThis paper presents the simulator developed for the European Student Moon Orbiter (ESMO) project, which is planned to be the first European student mission to the Moon. During the ESMO project, student teams, supported by faculty staff, will produce a complete spacecraft from scratch. Its mission will be to fly towards the Moon, enter the Moon's orbit and execute scientific experiments while orbiting around the Moon. A Functional Engineering Simulator (FES) was produced as a part of the ESMO project and will allow the project teams to model the spacecraft's functions and performance at various stages of the mission and simulate the space environment. This paper focuses on the spacecraft's orbit and attitude propagation model. Finally, the overview of the FES simulator is presented along with the preliminary results produced with the simulator.

Remote sensing of the Moon's subsurface with multifrequency microwave radiometers: A numerical study

Within the renewed interest in the study of the Moon, in 2006 the European Space Agency approved a feasibility study for the European Student Moon Orbiter (ESMO) mission. In order to accomplish the ESMO mission objectives, a Microwave Radiometric Sounder (MiWaRS) was selected as a possible payload for flight on the ESMO satellite. This work summarizes the results of a numerical analysis of MiWaRS sounding capabilities. An (inhomogeneous) multilayer model of the microwave emission from the Moon's subsurface is presented, focusing the attention on the Moon's morphological, thermal, and dielectric properties. These properties have been determined and parameterized after a thorough investigation of available measurements and models. To this end, a radiative transfer numerical model, neglecting volume scattering, is coupled with a nonlinear thermal equation to simulate the microwave emission of the Moon's subsurface. Numerical simulations between L and Ka bands are performed to investigate the capability of MiWaRS to sound the characteristics of the Moon's regolith subsurface and detect the presence of rocks and ice under the near‐surface regolith layer. Under these forward model assumptions, results show that the Moon's brightness temperature response allows the detection of discontinuities within regolith media down to 2 and 5 m depth when channels at 3 and 1 GHz are used, respectively. Lunar near‐surface temperature may be also estimated within an accuracy less than a few kelvins. The discrimination of ice from rock by MiWaRS is hardly practicable and is limited to the presence of ice in the upper layers (with a depth less than 20 cm) beneath the lunar crust.

The European Student Moon Orbiter (ESMO): A lunar mission for education, outreach and science

ESMO is the fourth mission within ESA's Education Satellite Programme and builds upon the experience gained with SSETI Express (a micro-satellite launched into LEO in 2005), the YES2 tether experiment (launched into LEO on the Foton-M3 mission in 2007) and the European Student Earth Orbiter (a micro-satellite planned for launch in 2011/2012). The ESMO project is performed in order to attract and train the next generation of lunar and planetary engineers and scientists. The 250 kg ESMO mini-spacecraft is designed to be launched into geostationary transfer orbit (GTO) as a secondary payload in the 2012/2013 timeframe. An onboard liquid bi-propellant propulsion system will be used to transfer the spacecraft from its initial GTO to the operational lunar orbit via the Sun–Earth L1 Lagrange point over a period of 3 months. A miniaturised payload consisting of a narrow angle camera for optical imaging of the surface, and a subsatellite for global gravity field mapping would perform measurements over a period of 6 months. Alternative payloads under consideration include a biological experiment, and a passive microwave radiometer. The paper presents the scientific, educational and technical aspects of the ESMO project, including a description of the payload, the spacecraft design and mission profile.

European Student Moon Orbiter solar electric propulsion subsystem architecture: An all-electric spacecraft

This paper presents the results of the Phase A study for the solar electric propulsion subsystem selected for the ESA European Student Moon Orbiter spacecraft, performed at QinetiQ under ESA funding. To minimise mass, a so-called “all electric” approach is adopted based around the re-use of a flight-spare GOCE T5 gridded ion engine and the introduction of hollow cathode thrusters (HCTs) for attitude control functions. Three different subsystem architectures are considered and analysed with reference to the mass, cost, risk and level of integration between the HCTs and the T5. The favoured system architecture that best meets the various requirements adopts a shared tank and gas flow controller between the HCTs and the T5, with power being supplied from two dedicated power processing units. The possibility of reducing the propellant requirement by using an engine gimbal mechanism is also presented. The study also demonstrates how an increase in the T5 specific impulse to higher values than used on GOCE does not offer substantial system-level mass savings in this particular case.

En route to the Moon using GNSS signals

Lunar exploration introduces higher requirements in terms of performances, flexibility and cost for all spacecraft subsystems. As for the navigation, the success of GPS in providing autonomous on board orbit determination in Low Earth Orbit environment calls for a possible extension to Earth-to-Moon missions. This paper, referring to the upcoming European Student Moon Orbiter mission concept, investigates such a possibility, considering present and foreseen available GNSS signals. Carrier-to-noise levels achievable during different phases of the mission are evaluated and compared with the thresholds of current satellite navigation hardware receivers. Moreover, possible application of emerging software receivers’ techniques, able to cope with weak signals, is discussed.

Power system design of ESMO

The European Student Moon Orbiter (ESMO) spacecraft is a student-built mini satellite being designed for a mission to the Moon. Designing and launching mini satellites are becoming a current trend in the space sector since they provide an economic way to perform innovative scientific experiments and in-flight demonstration of novel space technologies. The generation, storage, control, and distribution of the electrical power in a mini satellite represents unique challenges to the power engineer since the mass and volume restrictions are very stringent. Regardless of these problems, every subsystem and payload equipment must be operated within their specified voltage band whenever they required to be turned on. This paper presents the preliminary design of a lightweight, compact, and reliable power system for ESMO that can generate 720 W. Some of the key components of the EPS include ultra triple-junction (UTJ) GaAs solar cells controlled by maximum power point trackers, and high efficiency Li-ion secondary batteries recharged in parallel.

On the design of low‐thrust transfers through L1 for the ESMO mission

AbstractThe following paper summarises the mission analysis studies performed for the phase A of the solar electric propulsion option of the European Student Moon Orbiter (ESMO) mission. ESMO is scheduled to be launched in 2011, as an auxiliary payload on board an Ariane 5. Hence the lack of influence on the launch date. Two methods were devised to assess efficiently wide launch windows for the Earth‐Moon transfer, they are presented below. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)