ExoMars 2016 Schiaparelli Module Trajectory and Atmospheric Profiles Reconstruction

Abstract

On 19 th October 2016 Schiaparelli module of the ExoMars 2016 mission flew through the Mars atmosphere. After successful entry and descent under parachute, the module failed the last part of the descent and crashed on the Mars surface. Nevertheless the data transmitted in real-time by Schiaparelli during the entry and descent, together with the entry state vector as initial condition, have been used to reconstruct both the trajectory and the profiles of atmospheric density, pressure and temperature along the traversed path. The available data-set is only a small subset of the whole data acquired by Schiaparelli, with a limited data rate (8 kbps) and a large gap during the entry because of the plasma blackout on the communications. This paper presents the work done by the AMELIA (Atmospheric Mars Entry and Landing Investigations and Analysis) team in the exploitation of the available inertial and radar data. First a reference trajectory is derived by direct integration of the inertial measurements and a strategy to overcome the entry data gap is proposed. First-order covariance analysis is used to estimate the uncertainties on all the derived parameters. Then a refined trajectory is computed incorporating the measurements provided by the on-board radar altimeter.

ExoMars Atmospheric Mars Entry and Landing Investigations and Analysis (AMELIA)

“…Then at a later time, the outcome of the Schiaparelli flight anomaly investigation was officially presented (T. Tolker-Nielsen, 2017) and the results of the analysis published (e.g. Portigliotti et al 2017, Bonetti et al 2018 as were the results of the AMELIA reconstructions (Aboudan et al 2018).…”

“…Despite the ultimate failure of Schiaparelli in its landing phase, sufficient EDL data were returned in order to reconstruct the trajectory and attitude of the EDM and to retrieve atmospheric profiles over the altitude range from 121 km to 4 km above the surface (Aboudan et al 2018), even if at lower resolution, with a significant gap in the middle atmosphere and with higher uncertainty ranges than those that would have been achievable had the full Schiaparelli data-set been recovered after landing, as was originally planned. The EDL instrumentation included Guidance, Navigation and Control (GNC) equipment: one Miniaturized Inertial Measurement Unit (MIMU) containing three gyroscopes and three accelerometers, a sun sensor (SDS) located on the back shield for attitude determination prior to atmospheric entry, a Radar Doppler Altimeter (RDA), for altitude determination in the lowest 6-3 km of the atmosphere, and three pairs of landing accelerometers (for axial and tangential accelerations) to monitor Mars landing.…”

MARSWRF Prediction of Entry Descent Landing Profiles: Applications to Mars Exploration

“…Even though in most cases this was due to electronic/software issues, schedule constraints or human error and hence not directly related to uncertainties in the atmospheric conditions (e.g., Bitten et al, ; Sauser et al, ), a better understanding of the atmospheric variability/uncertainty may help to exclude some landing sites/seasons as well as open up more EDL options. The most recent example is the Schiaparelli Entry Demonstrator Module (EDM) that crashed landed in October 2016 (Aboudan et al, ). The EDL stage takes less than 10 min and occurs after a long journey to the planet (for Mars the trip takes at least 6 months).…”

“…Model forecasts can also be combined with observational data to produce a reanalysis dataset, our best guess of the actual state of the atmosphere (e.g., Dee et al, ). While on Earth there is a good understanding of the near‐surface winds and density profiles due to the large number of available measurements, on Mars there have only been to date six surface weather stations—Viking Landers 1 and 2 (Chamberlain et al, ), Pathfinder (Seiff et al, ), Phoenix (Taylor et al, ), Mars Science Laboratory (MSL) Curiosity rover (Gómez‐Elvira et al, ) and the Interior Exploration using Seismic Investigations, Geodesy and Heat Transport ( InSight ) lander (Banfield et al, ), and eight EDL profiles at different sites and seasons—Viking Landers 1 and 2 (Seiff & Kirk, ), Pathfinder (Magalhães, ), Phoenix (Dickinson, ), Mars Exploration Rovers (MER) Opportunity and Spirit (Withers & Murphy, ), MSL Curiosity rover (Holstein‐Rathlou et al, ), and Schiaparelli EDM (Aboudan et al, ). This makes it even more challenging to have an accurate prediction of the atmospheric conditions, which in turn are needed to design the EDL phase as well as to determine the size of the landing ellipse.…”

“…Despite all the challenges inherent to the EDL, it provides a once‐per‐mission chance to retrieve vertical profiles of variables such as density, pressure, and temperature at very high vertical and horizontal resolution, especially in the lower atmosphere, making it scientifically valuable even in comparison with those estimated from orbital assets such as the Mars Global Surveyor (MGS) Thermal Emission Spectrometer (TES) and the Mars Reconnaissance Orbiter Mars Climate Sounder (Holstein‐Rathlou et al, ). As explained in detail in Aboudan et al (), the atmospheric acceleration that is measured during the descent is directly related to the atmospheric density through the drag equation, which allows its retrieval. Given the density profile, the pressure can be derived from the hydrostatic balance.…”