The JAXA Hayabusa 2 spacecraft is rapidly approaching its rendezvous target, C-type asteroid Ryugu. On-board is the Mobile Asteroid Surface Scout (MASCOT), developed by the German Aerospace Center (DLR) with major contributions by the French space agency (CNES) [1]. MASCOT will be ejected towards the surface of Ryugu in October 2018 to land around noon local time. Its mission is expected to last about two asteroid days and nights, depending on the on-board battery performance. Ryugu is of the rare spectral type Cg, with reflective properties of both the C and G-type asteroids [2]. MASCOT will provide the first close-up view of the regolith of a C-type asteroid. For this purpose it carries a variety of instruments, one of which is a wide-field camera with a CMOS detector and an LED array of 4 different colors [3]. The camera will support both the missions of Hayabusa 2 and MASCOT by characterizing the physical and scattering properties of the regolith at high spatial resolution, providing the ground truth for the remote observations by the Hayabusa 2 instruments, and providing context and guidance for the Hayabusa 2 sampling effort. Several mission phases can be distinguished, during each of which the camera will acquire data. Images taken during the descent will reveal the surface at increasingly higher resolution. After landing, MASCOT's attempts to upright itself will be documented. During the first asteroid day, the camera will acquire images at regular intervals, to study the reflective properties of the surface at different solar illumination angles. At night, several sets of images will be acquired at different times to deal with the challenging thermal environment. Naturally, the LEDs will be employed at night to provide illumination of the surface, but will also be used during the day to illuminate any terrain in the shadows. We describe the camera imaging plans for each of the mission phases in detail and present an overview of

We study a seasonally recurrent cyclone and related cloud phenomena observed on Mars at L-s similar to 120 degrees, latitude similar to 60 degrees N, and longitude 90 degrees W from images obtained with cameras in different spacecraft between 1995 and 2018. A remarkable double cyclone formed in 2012 and we present a detailed study of its dynamics using images from Mars Express and Mars Reconnaissance Orbiter obtained between 6 June and 9 July. A double cyclone was also observed in 2006 and 2008. In other Martian years the primary cyclone showed an annular cloud morphology with a large water ice cloud observed eastward of it. The cyclones have a size of similar to 600-800km with a cloud-free core of a radius similar to 100-300km. Tangential velocities measured from cloud tracking in 2012 images are similar to 5-20m/s(-1) at 10-km altitude and double cyclone moved eastward with a velocity of 4m/s(-1) during its lifetime of one month. The vortices grow in the morning hours, but with the increasing insolation as the sol progresses, a part of the clouds evaporate, the winds weaken, and the vortices lose coherence. This phenomenon forms under high-temperature gradients in a region with a large north-south topographic slope and has been recurrent each Martian year between 1995 and 2018. We argue the interest of studying its changing properties each Martian year in order to explore their possible relationship to the state of the Martian atmosphere at L-s similar to 120 degrees. Plain Language Summary We study a remarkable annular vortex observed some years to be formed by two coupled cyclones that grow every Martian northern summer at the same longitude and latitude of the planet. Each vortex has a size of 700km and its center is a cloud-free area with a radius of about 200km. The vortex is formed by water ice clouds at about 10-km altitude where the winds blow with speeds of 5 to 20m/s. The clouds grow in the morning hours and sublimate as the vortex weakens with increasing insolation. Dynamical models show that the vortex forms in a region with a large north-south terrain slope that combines with north-south temperature gradient. The study mainly uses images taken in 2012, but a survey shows that the vortex recurrently forms every Martian year between 1995 and 2018. This vortex system can be used as a proxy, studying its variability, to characterize the state of the atmosphere at the time of its formation.

Schmitz, A. Koncz, R. Jaumann, H. Hoffmann, D. Jobs, J. Kachlicki, H. Michaelis, S. Mottola, B. Pforte, S. Schroeder, R. Terzer, F. Trauthan, M. Tschentscher, S. Weisse, T.-M. Ho, J. Biele, S. Ulamec, B. Broll, A. Kruselburger, L. Perez-Prieto. DLR, Institute of Planetary Research, Berlin, Germany, Nicole.Schmitz@dlr.de, DLR, Institute of Space Systems, Bremen, Germany, DLR-MUSC, Linder Höhe, Cologne, Germany, Airbus DS, Germany.

JANUS (Jovis Amorum Ac Natorum Undique Scrutator) is a high-resolution visible camera designed for the ESA space mission JUICE (Jupiter Icy moons Explorer). The main scientific goal of JANUS is to observe the surface of the Jupiter satellites Ganymede and Europa in order to characterize their physical and geological properties. During the design phases, we have proposed two possible optical configurations: a Three Mirror Anastigmat (TMA) and a Ritchey-Chretien (RC) both matching the performance requirements. Here we describe the two optical solutions and compare their performance both in terms of achieved optical quality, sensitivity to misalignment and stray light performances.

The High Resolution Stereo Camera (HRSC) of ESA׳s Mars Express is designed to map and investigate the topography of Mars. The camera, in particular its Super Resolution Channel (SRC), also obtains images of Phobos and Deimos on a regular basis. As HRSC is a push broom scanning instrument with nine CCD line detectors mounted in parallel, its unique feature is the ability to obtain along-track stereo images and four colors during a single orbital pass. The sub-pixel accuracy of 3D points derived from stereo analysis allows producing DTMs with grid size of up to 50m and height accuracy on the order of one image ground pixel and better, as well as corresponding orthoimages. Such data products have been produced systematically for approximately 40% of the surface of Mars so far, while global shape models and a near-global orthoimage mosaic could be produced for Phobos. HRSC is also unique because it bridges between laser altimetry and topography data derived from other stereo imaging instruments, and provides geodetic reference data and geological context to a variety of non-stereo datasets. This paper, in addition to an overview of the status and evolution of the experiment, provides a review of relevant methods applied for 3D reconstruction and mapping, and respective achievements. We will also review the methodology of specific approaches to science analysis based on joint analysis of DTM and orthoimage information, or benefitting from high accuracy of co-registration between multiple datasets, such as studies using multi-temporal or multi-angular observations, from the fields of geomorphology, structural geology, compositional mapping, and atmospheric science. Related exemplary results from analysis of HRSC data will be discussed. After 10 years of operation, HRSC covered about 70% of the surface by panchromatic images at 10–20m/pixel, and about 97% at better than 100m/pixel. As the areas with contiguous coverage by stereo data are increasingly abundant, we also present original data related to the analysis of image blocks and address methodology aspects of newly established procedures for the generation of multi-orbit DTMs and image mosaics. The current results suggest that multi-orbit DTMs with grid spacing of 50m can be feasible for large parts of the surface, as well as brightness-adjusted image mosaics with co-registration accuracy of adjacent strips on the order of one pixel, and at the highest image resolution available. These characteristics are demonstrated by regional multi-orbit data products covering the MC-11 (East) quadrangle of Mars, representing the first prototype of a new HRSC data product level.

The capability to orient Mars Express makes it possible to implement a great diversity of observations modes, in particular nadir and limb (fig 1). During day and night limb's observations, 4 out of 7 MEX instruments (the spectrometers: SPICAM[1], OMEGA [2], PFS [3] and the high-resolution camera HRSC [4]) work together to provide spectra (.12 µm to 45 µm) of the Martian atmosphere (dust and clouds detached layers, day and night emissions), at each altitude step, with the associated image.. Fig 1 : Mars Express pointing modes relevant for limb observations by remote sensing instruments. Until now, the data reduction of observations of the limb from each Mars Express instrument had been done separately. Examples of the potential of each data set are given in Figures 2,3,4,5). We present here a database which makes it possible to retrieve the limb observations from different Mars Express instruments relevant for a given location and time frame. The limb database is now accessible to the scientific community via the ESA/PSA website (www.rssd.esa.int/PSA). Fig 2: detached layer observed by HRSC

Aims. From April 2008 to August 2011 Mars Express carried out 74 Phobos flybys at distances between 669 and 5579 kin. Images taken with the Super Resolution Channel (SRC) were used to determine the spacecraft-centered right ascension and declination of this Martian moon.Methods. Image positions of Phobos were measured using the limb-fit and control-point measurement techniques. Camera pointing and pointing drift were controlled by means of background star observations that were compared to corresponding positions from reference catalogs. Blurred and noisy images were restored by applying an image-based point spread function in a Richardson-Lucy deconvolution.Results. Here, we report on a set of 158 Phobos astrometric observations with estimated accuracies between 0.224 and 3.405 km circular w.r.t. the line of sight to the satellite. Control point measurements yield slightly more accurate results than the limb fit ones. Our observations are in good agreement with the current Phobos ephemerides by the jet Propulsion Laboratory (JPL) and the Royal Observatory of Belgium (ROB) with mean offsets of up to 335 m. Our data can be used for the maintenance and update of these models.

The JUICE (JUpiter ICy moons Explorer) satellite of the European Space Agency (ESA) is dedicated to the detailed study of Jupiter and its moons. Among the whole instrument suite, JANUS (Jovis, Amorum ac Natorum Undique Scrutator) is the camera system of JUICE designed for imaging at visible wavelengths. It will conduct an in-depth study of Ganymede, Callisto and Europa, and explore most of the Jovian system and Jupiter itself, performing, in the case of Ganymede, a global mapping of the satellite with a resolution of 400 m/px. The optical design chosen to meet the scientific goals of JANUS is a three mirror anastigmatic system in an off-axis configuration. To ensure that the achieved contrast is high enough to observe the features on the surface of the satellites, we also performed a preliminary stray light analysis of the telescope. We provide here a short description of the optical design and we present the procedure adopted to evaluate the stray-light expected during the mapping phase of the surface of Ganymede. We also use the results obtained from the first run of simulations to optimize the baffle design.

This review summarizes the use of High Resolution Stereo Camera (HRSC) data as an instrumental tool and its application in the analysis of geological processes and landforms on Mars during the last 10 years of operation. High-resolution digital elevations models on a local to regional scale are the unique strength of the HRSC instrument. The analysis of these data products enabled quantifying geological processes such as effusion rates of lava flows, tectonic deformation, discharge of water in channels, formation timescales of deltas, geometry of sedimentary deposits as well as estimating the age of geological units by crater size–frequency distribution measurements. Both the quantification of geological processes and the age determination allow constraining the evolution of Martian geologic activity in space and time. A second major contribution of HRSC is the discovery of episodicity in the intensity of geological processes on Mars. This has been revealed by comparative age dating of volcanic, fluvial, glacial, and lacustrine deposits.Volcanic processes on Mars have been active over more than 4Gyr, with peak phases in all three geologic epochs, generally ceasing towards the Amazonian. Fluvial and lacustrine activity phases spread a time span from Noachian until Amazonian times, but detailed studies show that they have been interrupted by multiple and long lasting phases of quiescence. Also glacial activity shows discrete phases of enhanced intensity that may correlate with periods of increased spin-axis obliquity. The episodicity of geological processes like volcanism, erosion, and glaciation on Mars reflects close correlation between surface processes and endogenic activity as well as orbit variations and changing climate condition.

After more than 10 years of operation, the High Resolution Stereo Camera (HRSC) of ESA’s Mars Express mission covered about 70% of the surface by panchromatic images at 10-20 m/pixel, and about 98% at better than 100 m/pixel. As the areas with contiguous coverage by stereo data are increasingly abundant, the HRSC team has recently started a coordinated effort for the systematic mapping of Mars by multi-orbit digital elevation models (DTMs) and image mosaics, using the complete HRSC mission data record. The new global mapping program is based on the USGS MC-30 quadrangle scheme, where quadrangles are split into eastern and western parts to limit data volumes. We present the DTM and orthoimage mosaic (grid spacing of 50 m and 12.5 m, respectively) for the first half-tile, MC-11E (Eastern Oxia Palus), and highlight their use for characterizing the landing site areas of ESA’s ExoMars landing mission to be launched in 2018.

NASA’s PHOENIX spacecraft has successfully landed on Mars on 25 May 2008. ESA supported the event by recording signals from PHOENIX by the Mars EXPRESS spacecraft using its lander communication subsystem. Following numerical simulations of the probe entry plume emission, two Mars EXPRESS instruments, namely the High Resolution and Stereo Camera (HRSC) and the Ultraviolet and Infrared Spectrometer (SPICAM), were switched on in to observe the emission associated with the atmospheric entry. No positive detection was reported unfortunately. This article reports on the simulations, the planning, and the results. The non-detection by the UV spectrometer was due to a wrong instrument setting. Result for the camera is tentatively explained by the level of emission in the visible range. Lessons learned are given in the conclusions: the entry probe trajectory should be communicated as soon as possible to all interested parties, within the boundary conditions of confidentiality obviously. It is important to plan some redundancy to prevent incorrect instrument operations. A multi-instrument multi-spacecraft campaign should be encouraged by all means. Since detection of such faint signal is challenging, the integration time must be properly matched to the event duration. Payload operational (exclusion) rules should be discussed in an open way, to check whether the prudence of such measures is procedural or physical. The numerical simulations discussed in this paper have been focused on IR radiation in the lower density flow wake, using a DSMC/line-by-line method. These could be complemented with other numerical approaches more focused in the VUV–visible region in the high-pressure bow-shock region, using continuum Navier–Stokes fluid methods, which would yield information on the contribution to the emission spectrum from minor flow species such as CN, C2 and C.

Due to the strong evidence for aqueous processes at or near the surface, Mars is the most Earth-like body in the Solar System. After 10 years of ESA’s Mars Express orbiting the planet its High Resolution Stereo Camera (HRSC) covered about 90 % of the surface in stereo and color with resolutions up to 10 m/pixel [1]. Digital elevation models of up to 50 m grid spacing, generated from all suitable datasets of the stereo coverage, currently cover about 40 % of the surface [2]. The geomorphological analysis of surface features, observed by the HRSC indicate major surface modifications by endogenic and exogenic processes on all scales. Endogenic landforms (e.g., tectonic rifts, small basaltic shield volcanoes) were found to be very similar to their equivalents on Earth [1,3,4,5,6,7], suggesting that no unique processes are required to explain their formation. Volcanism may have been active up to the very recent past or even to the present, putting important constraints on thermal evolution models [6,7]. The analysis of diverse landforms produced by aqueous processes revealed that surface water activity was likely episodic, but ranged in age from very ancient to very recent [1,8-16]. Particularly important is prominent glaciation and periglacial features at several latitudes, including mountain glaciers [17-21]. The identification of aqueous alteration minerals and their geological context has enabled a better understanding of paleoenvironmental conditions and pedogenetic processes [23-25]. Dark dunes contain volcanic material and are evidence for the significantly dynamic surface environment, characterized by widespread erosion, transport, and redeposition [26]. Since basically all geologic interpretations of extraterrestrial features require profound knowledge of the Earth as key reference, studies of terrestrial analogues are mandatory in planetary geology. Field work in Antarctica, Svalbard and Iceland [5,6,21,22,27] provided a basis for the analysis of periglacial and volcanic processes, respectively.

We review the previous exploration of Phobos and Deimos by spacecraft. The first close-up images of Phobos and Deimos were obtained by the Mariner 9 spacecraft in 1971, followed by much image data from the two Viking orbiters at the end of the 70s, which formed the basis for early Phobos and Deimos shape and dynamic models. The Soviet Phobos 2 spacecraft came within 100km of landing on Phobos in 1988. Mars Global Surveyor (1996–2006) and Mars Reconnaissance Orbiter (since 2005) made close-up observations of Phobos on several occasions. Mars Express (since 2003) in its highly elliptical orbit is currently the only spacecraft to make regular Phobos encounters and has returned large volumes of science data for this satellite. Landers and rovers on the ground (Viking Landers, Mars Pathfinder, MER rovers, MSL rover) frequently made observations of Phobos, Deimos and their transits across the solar disk.

JANUS (Jovis, Amorum ac Natorum Undique Scrutator) is the visible camera selected for the ESA JUICE mission to the Jupiter system. Resources constraints, S/C characteristics, mission design, environment and the great variability of observing conditions for several targets put stringent constraints on instrument architecture. In addition to the usual requirements for a planetary mission, the problem of mass and power consumption is particularly stringent due to the long-lasting cruising and operations at large distance from the Sun.JANUS design shall cope with a wide range of targets, from Jupiter atmosphere, to solid satellite surfaces, exosphere, rings, and lightning, all to be observed in several color and narrow-band filters. All targets shall be tracked during the mission and in some specific cases the DTM will be derived from stereo imaging. Mission design allows a quite long time range for observations in Jupiter system, with orbits around Jupiter and multiple fly-bys of satellites for 2.5 years, followed by about 6 months in orbit around Ganymede, at surface distances variable from 104 to few hundreds km.Our concept was based on a single optical channel, which was fine-tuned to cover all scientific objectives based on low to high-resolution imaging. A catoptric telescope with excellent optical quality is coupled with a rectangular detector, avoiding any scanning mechanism.In this paper the present JANUS design and its foreseen scientific capabilities are discussed.

The JANUS (Jovis, Amorum ac Natorum Undique Scrutator) will be the on board camera of the ESA JUICE satellite dedicated to the study of Jupiter and its moons, in particular Ganymede and Europa. This optical channel will provide surface maps with plate scale of 15 microrad/pixel with both narrow and broad band filters in the spectral range between 0.35 and 1.05 micrometers over a Field of View 1.72 × 1.29 degrees2. The current optical design is based on TMA design, with on-axis pupil and off-axis field of view. The optical stop is located at the secondary mirror providing an effective collecting area of 7854 mm2 (100 mm entrance pupil diameter) and allowing a simple internal baffling for first order straylight rejection. The nominal optical performances are almost limited by the diffraction and assure a nominal MTF better than 63% all over the whole Field of View. We describe here the optical design of the camera adopted as baseline together with the trade-off that has led us to this solution.

This abstract presents a review of the mesospheric cloud observations performed with OMEGA/MEx, accompanied by HRSC/MEx, and the modeling efforts that permit us today to draw a clearer picture of the formation of the exotic mesospheric CO2 clouds.

HAYABUSA-2. N. Schmitz, A. Koncz, R. Jaumann, H. Hoffmann, D. Jobs, J. Kachlicki, H. Michaelis, S. Mottola, B. Pforte, S. Schroeder, R. Terzer, F. Trauthan, M. Tschentscher, S. Weisse, T.-M. Ho, J. Biele, S. Ulamec, B. Broll, A. Kruselburger, L. Perez-Prieto DLR, Institute of Planetary Research, Berlin, Germany, Nicole.Schmitz@dlr.de, DLR, Institute of Space Systems, Bremen, Germany, DLR-MUSC, Linder Hohe, Cologne, Germany, Astrium GmbH, Germany.

The Mars Express mission was launched in June 2003 and was inserted into orbit around Mars in December 2003. Its main objective is to study the Mars' subsurface, surface, atmosphere and interaction with the solar wind. A secondary objective is to study the martian moons, in particular the largest one Phobos, thanks to a near polar and elliptical orbit which allows the spacecraft to perform close flybys about every five months. The Mars Express data not only consist of high-resolution 3D color images, but also astrometric images, spectra from 0.18 to 20μm, radar echoes, Doppler signals from gravity experiments, and ion data. A new view of the moons has emerged from this data set, favoring now the idea that they are not captured asteroids, but rather the result of a re-accretion following a major impact on Mars. This unique set of data is available in the ESA Planetary Science Archive (PSA) and mirror imaged in the NASA Planetary Data System (PDS). This paper presents an overview of the Mars Express Phobos flybys, the specificities of their operations and the scientific achievements.