Calathus: A sample-return mission to Ceres

Ceres, as revealed by NASA's Dawn spacecraft, is an ancient, crater-saturated body dominated by low-albedo clays. Yet, localised sites display a bright, carbonate mineralogy that may be as young as 2 Myr. The largest of these bright regions (faculae) are found in the 92 km Occator Crater, and would have formed by the eruption of alkaline brines from a subsurface reservoir of fluids. The internal structure and surface chemistry suggest that Ceres is an extant host for a number of the known prerequisites for terrestrial biota, and as such, represents an accessible insight into a potentially habitable “ocean world”. In this paper, the case and the means for a return mission to Ceres are outlined, presenting the Calathus mission to return to Earth a sample of the Occator Crater faculae for high-precision laboratory analyses. Calathus consists of an orbiter and a lander with an ascent module: the orbiter is equipped with a high-resolution camera, a thermal imager, and a radar; the lander contains a sampling arm, a camera, and an on-board gas chromatograph mass spectrometer; and the ascent module contains vessels for four cerean samples, collectively amounting to a maximum 40 g. Upon return to Earth, the samples would be characterised via high-precision analyses to understand the salt and organic composition of the Occator faculae, and from there to assess both the habitability and the evolution of a relict ocean world from the dawn of the Solar System.The attached document is the authors’ final accepted version of the journal article provided here with a Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) Creative Commons Licence. You are advised to consult the publisher’s version if you wish to cite from it.

Instrumentutveckling av Jovian Neutrals Analyzer (JNA) och simulerade observationer

This thesis deals with the development of the Jovian Neutrals Analyzer (JNA) for the Jupiter ICy moons Explorer (JUICE) mission to Jupiter, planned to launch in 2023. Jupiter, the largest planet in the Solar System, orbits the Sun at five times the distance from the Earth to the Sun, accompanied by dozens of moons, rings, and the largest object in the SolarSystem: the Jovian magnetosphere. Born of the interaction betweenthe solar wind and Jupiter’s strong magnetic field, the Jovian magneto-sphere is host to a number of unique, complex phenomena, includingthe creation of a sheet of energetic particles orbiting the giant planetand interacting with its four largest moons: Io, Europa, Ganymede, and Callisto. A better understanding of Jupiter’s magnetosphere and its interaction with its four largest moons is one of the main objectives of the JUICE mission. To achieve this goal, JUICE is equipped with the Particle Environment Package (PEP), comprised of six particle sensors, including JNA. By measuring low-energy Energetic Neutral Atoms (ENAs) in the range from 10 eV to 3.3 keV, JNA will image the plasma co-located with the orbit of Io, and reveal ion precipitation patterns at the surface of Jupiter’s icy moons. JNA improves on its predecessors (CENA on Chandrayaan-1 and ENA on BepiColombo) by featuring a higher angular resolution, with a 150◦ field-of-view divided into 11 pixels. JNA is also more resistant to radiation, a necessary improvement to be able to make measurements in the harsh radiation environment expected in the Jovian system. To measure ENAs in the low-energy range, JNA uses a charged particle deflector to remove ambient ions; a charge conversion surface to ionize incoming neutral particles, which are then energy-analyzed by an electrostatic wave system; and a Time-of-Flight cell to derive the mass of the original particle. In this work, we report on how JNA was designed, developed, and calibrated. We show the first results of JNA’s calibration campaign, and compare them to its expected performance. Finally, to facilitate the interpretation of JNA data at Jupiter, we estimate ENA fluxes expected at Ganymede and use our results to simulate JNA observations.Various pagination. Chapter 6 appended article not included in pdf. </p

Instrumentutveckling av Jovian Neutrals Analyzer (JNA) och simulerade observationer

This thesis deals with the development of the Jovian Neutrals Analyzer (JNA) for the Jupiter ICy moons Explorer (JUICE) mission to Jupiter, planned to launch in 2023. Jupiter, the largest planet in the Solar System, orbits the Sun at five times the distance from the Earth to the Sun, accompanied by dozens of moons, rings, and the largest object in the SolarSystem: the Jovian magnetosphere. Born of the interaction betweenthe solar wind and Jupiter’s strong magnetic field, the Jovian magneto-sphere is host to a number of unique, complex phenomena, includingthe creation of a sheet of energetic particles orbiting the giant planetand interacting with its four largest moons: Io, Europa, Ganymede, and Callisto. A better understanding of Jupiter’s magnetosphere and its interaction with its four largest moons is one of the main objectives of the JUICE mission. To achieve this goal, JUICE is equipped with the Particle Environment Package (PEP), comprised of six particle sensors, including JNA. By measuring low-energy Energetic Neutral Atoms (ENAs) in the range from 10 eV to 3.3 keV, JNA will image the plasma co-located with the orbit of Io, and reveal ion precipitation patterns at the surface of Jupiter’s icy moons. JNA improves on its predecessors (CENA on Chandrayaan-1 and ENA on BepiColombo) by featuring a higher angular resolution, with a 150◦ field-of-view divided into 11 pixels. JNA is also more resistant to radiation, a necessary improvement to be able to make measurements in the harsh radiation environment expected in the Jovian system. To measure ENAs in the low-energy range, JNA uses a charged particle deflector to remove ambient ions; a charge conversion surface to ionize incoming neutral particles, which are then energy-analyzed by an electrostatic wave system; and a Time-of-Flight cell to derive the mass of the original particle. In this work, we report on how JNA was designed, developed, and calibrated. We show the first results of JNA’s calibration campaign, and compare them to its expected performance. Finally, to facilitate the interpretation of JNA data at Jupiter, we estimate ENA fluxes expected at Ganymede and use our results to simulate JNA observations.Various pagination. Chapter 6 appended article not included in pdf. </p

Evolution of the signal induced by ChemCam on Mars as a function of focus

ChemCam, mounted on the mast of the Mars Science Laboratory (MSL) rover, uses Laser-Induced Breakdown Spectroscopy (LIBS) to perform remote-sensing science on Mars. ChemCam’s telescope is used to simultaneously focus the laser on martian rocks up to 7 meters away from the rover and collect the light emitted as the plasma plume created on the target cools down. The light is then transmitted to three spectrometers located in the body of the rover, providing spectra from which the composition of the samples is inferred on the ground. Context images of the sampled targets are captured by the Remote Micro Imager (RMI) that completes the instrument. A hardware failure that occurred a bit more than two years into the mission caused the ChemCam instrument to lose its original autofocus ability. This resulted in a degraded performance mode for several months while the ChemCam team developed a new autofocus algorithm based on the RMI images. During this period of degraded performance, several observations with different focus conditions were made on each target.  This unusual set of data provides the opportunity to study the influence of less-than-optimal focus conditions on the LIBS signal created on the target and analyzed by ChemCam. To this purpose, we look at both raw ChemCam spectra and  post-processed products used for scientific analysis to investigate how the quality of the focus influences the LIBS signal and the quantitative predictions of the composition of the observed targets