Guillermo Ortega’s research while affiliated with European Space Agency and other places

CX-OLEV is a commercial mission aimed to extend the operational life of geostationary telecommunications satellites by supplying them propulsion, navigation and guidance services. Under SENER's contract and ESA's supervision, GMV designed the CX-OLEV ground guided rendez-vous (RV) approach. The starting point of the RV phase between CX-OLEV and the client is at 35km distance with an uncertainty of 2km. Dedicated ground tracking is performed to reduce the position uncertainty to 200m and therefore to command the closing to 1km distance. Fly around and final approach maneuvers complete the CX-OLEV RV approach along the client's zenith direction up to a relative distance of 7m. Two redundant optical cameras working in the 5m–2km range are selected as RV sensors. The RV camera images are sent to ground and processed to determine the relative position of the spacecraft. The flight dynamics system calculates, validates and transmits in near real time the RV maneuvers commands. The relative spiral motion of CX-OLEV around the telecommunication satellite is synchronized with the Sun-client-CXOLEV angle to guarantee a good illumination of the client but without shadowing the client satellite's solar panels. The complete RV is simulated in a dedicated environment to assess its feasibility.

Current and future Mars missions within ESA's AURORA programme rely heavily on flight simulations for system and mission design, and analysis. With the release of the ESA Mars Climate Database (EMCD) Version 4.1, an activity was initiated to interface this database with existing flight-simulation software packages, and to evaluate and use the output of this database. To evaluate the EMCD, a Beagle-2 like spacecraft and mission have been defined with three different candidate landing sites, to include areographical diversity in the simulations. To address the absolute influence of a selected climate database on trajectory simulations, NASA's Mars GRAM 2001 database as well as the previous version EMCD 3.1 have been used to generate comparison data. First, for each of the three landing sites and corresponding entry trajectories, a nominal simulation has been executed. In each case, a nominal dust profile has been selected and no gravity waves are considered. Second, a Monte-Carlo analysis has been performed to study the Impact of database use on selected performance indices. Differences between the results are discussed extensively. It has been concluded that the data obtained with each database should be considered carefully, due to the found discrepancies.

*† ‡ § This paper presents control studies performed in the frame the design, development, test, and evaluation of the GNC of a Mars Sample Return and a Mars Manned mission ascent vehicles. These activities were included in ESA Aurora exploratory program. This paper focuses on the analysis of a generic attitude control function covering the two Mars missions, and more precisely on the review and trade-off of envisaged control algorithms. Controllability analyses have been performed both for control command module and control means selection logic. Among the most promising control methods that could be considered for command module of an ascent vehicle we have benchmarked Eigenstructure Assignment, LQ methods and Multi-variable robust H∞ control. In the frame of 1st stage control design for Mars Ascent Vehicle, we have also made a trade off between various control selection logics that are: control via gimbaled engines, control via differential thrust of main engines or control via both differential thrust and gimbaled engines. The retained controller has been developed and we gathered here the main results obtained in the frame of MSR and Manned mission ascent vehicles.