Hayabusa2 - mission and science results up to now

Hayabusa2 arrived at a C-type near Earth asteroid, (162173) Ryugu on 27 June 2018. We have carried out remote sensing observations, several descent operations, and releases of two small rovers and one lander within the year of 2018. Then in the year of 2019, the first touchdown operation was executed successfully in February, and the impactor experiment was done in April. We were able to observe the ejecta curtain and we have confirmed a crater created by the impactor. We have a lot of scientific data about Ryugu by the operations up to now and the natures of Ryugu have been revealed one after another

Rosetta Lander: Philae on comet 67P/Churyumov-Gerasimenko

Rosetta is a Cornerstone Mission of the ESA Horizon 2000 programme. In August 2014 it reached comet 67P/ Churyumov-Gerasimenko after a 10 year cruise. Both its nucleus and coma have been studied with its orbiter payload of eleven PI instruments, allowing the selection of a landing site for Philae. The landing on the comet nucleus successfully took place on November 12th, 2014. Philae touched the comet surface seven hours after ejection from the orbiter. After several bounces it came to rest and continued to send scientific data to Earth. All ten instruments of its payload have been operated at least once. Due to the fact that the Lander could not be anchored, the originally planned first scientific sequence had to be modified. Philae went into hibernation on November 15th, after its batteries ran out of energy. Re-activation of the Lander was expected for May/June 2015, when CG would be closer to the sun and, indeed, radio contact with the Lander was re-established on June 13th and for (so far) seven more occasions. Rosetta is an ESA mission with contributions from its member states and NASA. Rosetta's Philae lander is provided by a consortium le al contributions from Hungary,UK, Finland, Ireland and Austri

MASCOT: Communications With a Small Probe on Ryugu Asteroid

On October 3rd, 2018 and after a 4-year travel into space attached to the Japanese probe Hayabusa-2, the German French probe MASCOT, the size of a big shoebox, landed on the asteroid Ryugu. The objective was to study in-situ the structure of the asteroid. The article focuses on the communication subsystem of the mission providing a radiofrequency link between Hayabusa-2 and MASCOT. This subsystem, including the transceivers, the harness, the antennae and the onboard intelligence has been at the heart of a multinational team to provide the best conditions for MASCOT data to be transmitted. The first part of the article details the overall communication system architecture and validation before landing, including some validation operations during cruise. A second part presents the analysis of the communication system telemetry during the mission, from separation to the very end, giving an understanding of the mission events sequence

Rosetta Lander - Landing and operations on comet 67P/Churyumov-Gerasimenko

The Rosetta Lander Philae is part of the ESA Rosetta Mission which reached comet 67P/Churyumov–Gerasimenko after a 10 year cruise in August 2014. Since then, Rosetta has been studying both its nucleus and coma with instruments aboard the Orbiter. On November 12th, 2014 the Lander, Philae, was successfully delivered to the surface of the comet and operated for approximately 64 h after separation from the mother spacecraft. Since the active cold gas system aboard the Lander as well as the anchoring harpoons did not work, Philae bounced after the first touch-down at the planned landing site “Agilkia”. At the final landing site, “Abydos”, a modified First Scientific Sequence was performed. Due to the unexpectedly low illumination conditions and a lack of anchoring the sequence had to be adapted in order to minimize risk and maximize the scientific output. All ten instruments could be activated at least once, before Philae went into hibernation. In June 2015, the Lander contacted Rosetta again having survived successfully a long hibernation phase. This paper describes the Lander operations around separation, during descent and on the surface of the comet. We also address the partly successful attempts to re-establish contact with the Lander in June/July, when the internal temperature & power received were sufficient for Philae to become active again

The Philae Lander: Science planning and operations

Rosetta is an ambitious mission launched in March 2004 to study comet 67P/Churyumov–Gerasimenko. It is composed of a space probe (Rosetta) and the Philae Lander. The mission is a series of premieres: among others, first probe to escort a comet, first time a landing site is selected with short turnaround time, first time a lander has landed on a comet nucleus. In November 2014, once stabilized on the comet, Philae has performed its “First Science Sequence”. Philae’s aim was to perform detailed and innovative in-situ experi- ments on the comet’s surface to characterize the nucleus by performing mechanical, chemical and physical investigations on the comet surface. The main contribution to the Rosetta lander by the French space agency (CNES) is the Science Operation and Navigation Center (SONC) located in Toulouse. Among its tasks is the scheduling of the scientific activities of the 10 lander experiments and then to provide it to the Lander Control Center (LCC) located in DLR Cologne. The teams in charge of the Philae activity scheduling had to cope with considerable constraints in term of energy, data management, asynchronous processes and co-activities or exclusions between instruments. Moreover the comet itself, its environment and the landing conditions remained unknown until separation time. The landing site was selected once the operational sequence was already designed. This paper will explain the specific context of the Rosetta lander mission and all the constraints that the lander activity scheduling had to face to fulfill the scientific objectives specified for Philae. A specific tool was developed by CNES and used to design the complete sequence of activities on the comet with respect to all constraints. The baseline scenario for the lander operation will also be detailed as well as the sequence performed on the comet to highlight the difficulties and challenges that the operational team faced

Quick-look results for the surface/regolith mechanical properties of Ryugu based on MASCOT bouncing analyses

We present quick-look results and constraints on the mechanical properties of the regolith on asteroid 162173 Ryugu, based on expected data regarding the mechanical interactions by the lander MASCOT as well as data from MINERVA nano-landers and possibly from the first sampling touchdown by Hayabusa2. MASCOT is going to be deployed from an altitude of ~55 m and has a touch-down velocity of ~0.2 m/s. It is expected to bounce several times before coming to rest [3]. The descent trajectory and the larger bouncing arcs can be captured by optical imaging from the spacecraft (ONC [5]) giving constraints on MASCOT in-flight trajectories. Moreover, direct images of footprints as well as data from MASCOT’s magnetometer MASMAG [4] on bounce times (and possibly rotation rates or changes thereof), images by MASCOT’s camera MASCAM [2] during bouncing and their fusion with ONC images projected to the shape, and finally MASCAM images after rest offer a rich database that allows us to constrain Ryugu’s surface mechanical properties, with implications on the asteroid’s surface history. Variations of the radio-frequency signal all along MASCOT’s trajectory and day/night detection by MASCOT’s photoelectric cell sensors can also contribute to the analysis. The measured total linear energetic coefficient of restitution (CoR), i.e. the fraction of energy dissipated at each bounce, can be compared to the CoR values measured for the MASCOT structure bouncing against a hard wall [6] and soft-sphere DEM simulations of MASCOT landing on a bed of granular material [7,8]. Footprint images of the bounce imprints in loose granular material also constrain the granular frictional properties and the regolith depth. Preliminary conclusions on the mechanical properties of Ryugu’s surface material will be draw

MASCOT operations on Ryugu - focus on some specific tasks

Hayabusa2 is an asteroid sample return mission operated by the Japanese space agency, JAXA. It was launched in December 2014. In July 2018, the spacecraft has reached the mission target after a 4-year-long cruise. The objective is a C-type primordial asteroid called Ryugu, in search of organic and hydrated minerals that might give essential clues for the solar system formation. The small lander MASCOT (Mobile Asteroid surface SCOuT) carried aboard Hayabusa2 landed on the surface on the 3rd of October 2018 for reliminary in-situ investigations while the probe is aiming to study Ryugu on a global scale and to return samples to Earth. MASCOT was jointly developed by the German Aerospace Centre (DLR) and the Centre National d'Etudes Spatiales (CNES). It is equipped with a sensor suite consisting of four fully-fledged instruments. DLR was responsible for developing the MASCOT lander and ground segment, and was in charge of planning and conducting lander joint operations from MUSC. CNES supplied the hyperspectral IR spectrometer (MicrOmega, IAS Paris), antennae and power system, provided a support to operations and was in charge of the flight dynamics aspects of the mission. The 17 hours of on-asteroid operations exceeded expectations and the overall landing and operations were a huge success. Indeed, the characteristics of the Ryugu asteroid such as the shape and the gravity were known only after arrival of Hayabusa2 in July 2018 and the operating ccontext was very constrained but did not provide from fulfilling the objectives. This paper is a complement to the overall paper on MASCOT landing and first results. It will focus on several operational tasks such as communication and power subsystems assessments as well as flight dynamics computations needed in real time and for postprocessing

Variations of the surface characteristics of Ryugu returned samples

Abstract Hayabusa2 spacecraft successfully collected rock samples from the surface of C-type near-Earth asteroid 162173 Ryugu through two touchdowns and brought them back to Earth in 2020. At the Extraterrestrial Sample Curation Center in JAXA, we performed initial description of all samples to obtain fundamental information and prepare the database for sample allocation. We propose morphological classifications for the returned samples based on the initial description of 205 grains described in the first 6 months. The returned samples can be distinguished by four morphological characteristics: dark, glossy, bright, and white. According to coordinated study to provide an initial description and detailed investigation by scanning electron microscopy and X-ray diffraction analysis in this study, these features reflect the differences in the degree of space weathering and mineral assemblages. The degree of space weathering of the four studied grain types is heterogeneous: weak for A0042 (dark group) and C0041 (white group); moderate for C0094 (glossy); and severe for A0017 (bright). The white phase, which is the mineral characteristic of the white group grains, is identified as large carbonate minerals. This is the first effort to classify Ryugu returned samples into distinct categories. Based on these results, researchers can estimate sample characteristics only from the information on the JAXA curation public database. It will be an important reference for sample selection for further investigation. Graphical Abstrac