The LuGRE project: a scientific opportunity to study GNSS signals at the Moon

The Lunar GNSS Receiver Experiment (LuGRE) is a joint NASA-Italian Space Agency (ASI) payload on the Firefly Blue Ghost Mission 1 with the goal to demonstrate GNSS-based positioning, navigation, and timing at the Moon. When launched, LuGRE will collect GPS and Galileo measurements in transit between Earth and the Moon, in lunar orbit, and on the lunar surface, and will conduct onboard and ground-based navigation experiments using the collected data. These investigations will be based on the observation of the data collected by a custom development performed by the company Qascom, based on the Qascom QN400-Space GNSS receiver. The receiver is able to provide, PVT solutions, the GNSS raw observables obtained by the real time operation, as well as snapshots of IF digital samples collected by the RF front-end at frequencies L1/E1 and L5/E5. These data will be the input for the different science investigations, that require then the development of proper analysis tools that will be the core of the ground segment during the mission. The current work done by the science team of NASA and ASI, which is supported by a research team at Politecnico di Torino, is planning the data acquisitions during the time windows dedicated to the LuGRE payload in the checkout, transit and surface mission phases

Characterization and Testing of the Passive Magnetic Attitude Control System for the 3U AstroBio CubeSat

AstroBio CubeSat is a mission funded by the Italian Space Agency aimed at validating novel lab-on-chip technology, that would enable the use of micro- and nanosatellites as autonomous orbiting laboratories for research in astrobiology. This 3U CubeSat is equipped with a passive magnetic attitude control system (PMACS), including permanent magnets and hysteresis strips, which allows for stabilizing the spacecraft with the longitudinal axis in the direction of the geomagnetic field vector. This work presents the process followed for the experimental characterization of the system, performed on the engineering unit of the satellite by using a Helmholtz cage facility and a spherical air-bearing to recreate environmental conditions similar to the ones experienced during the orbital motion. The hysteresis strips are characterized starting from the determination of the hysteresis loop, from which the energy dissipation per cycle and the apparent magnetic permeability are extracted. Tests performed by using the Helmholtz cage and the air-bearing facility allows for further investigating the damping torque produced by the PMACS and validating the abovementioned parameters. Numerical analysis is then used to select the number of permanent magnets which allows for achieving a pointing accuracy within an error of 10° within 24 h from the deployment. The analysis of the flight data supports the results obtained from the experimental test campaigns, confirming the effectiveness of the proposed methods and of the PMACS design

VADER: Probing the Dark Side of Dimorphos with LICIACube LUKE

The ASI cubesat LICIACube has been part of the first planetary defense mission DART, having among its scopes to complement the DRACO images to better constrain the Dimorphos shape. LICIACube had two different cameras, LEIA and LUKE, and to accomplish its goal, it exploited the unique possibility of acquiring images of the Dimorphos hemisphere not seen by DART from a vantage point of view, in both time and space. This work is indeed aimed at constraining the tridimensional shape of Dimorphos, starting from both LUKE images of the nonimpacted hemisphere of Dimorphos and the results obtained by DART looking at the impacted hemisphere. To this aim, we developed a semiautomatic Computer Vision algorithm, named VADER, able to identify objects of interest on the basis of physical characteristics, subsequently used as input to retrieve the shape of the ellipse projected in the LUKE images analyzed. Thanks to this shape, we then extracted information about the Dimorphos ellipsoid by applying a series of quantitative geometric considerations. Although the solution space coming from this analysis includes the triaxial ellipsoid found by using DART images, we cannot discard the possibility that Dimorphos has a more elongated shape, more similar to what is expected from previous theories and observations. The result of our work seems therefore to emphasize the unique value of the LICIACube mission and its images, making even clearer the need of having different points of view to accurately define the shape of an asteroid.This work was supported by the Italian Space Agency (ASI) within the LICIACube project (ASI-INAF agreement AC No. 2019-31-HH.0) and by the DART mission, NASA contract 80MSFC20D0004

The Dimorphos ejecta plume properties revealed by LICIACube

The Double Asteroid Redirection Test (DART) had an impact with Dimorphos (a satellite of the asteroid Didymos) on 26 September 20221. Ground-based observations showed that the Didymos system brightened by a factor of 8.3 after the impact because of ejecta, returning to the pre-impact brightness 23.7 days afterwards2. Hubble Space Telescope observations made from 15 minutes after impact to 18.5 days after, with a spatial resolution of 2.1 kilometres per pixel, showed a complex evolution of the ejecta3, consistent with other asteroid impact events. The momentum enhancement factor, determined using the measured binary period change4, ranges between 2.2 and 4.9, depending on the assumptions about the mass and density of Dimorphos5. Here we report observations from the LUKE and LEIA instruments on the LICIACube cube satellite, which was deployed 15 days in advance of the impact of DART. Data were taken from 71 seconds before the impact until 320 seconds afterwards. The ejecta plume was a cone with an aperture angle of 140 ± 4 degrees. The inner region of the plume was blue, becoming redder with increasing distance from Dimorphos. The ejecta plume exhibited a complex and inhomogeneous structure, characterized by filaments, dust grains and single or clustered boulders. The ejecta velocities ranged from a few tens of metres per second to about 500 metres per second.This work was supported by the Italian Space Agency (ASI) in the LICIACube project (ASI-INAF agreement AC no. 2019-31-HH.0) and by the DART mission, NASA contract 80MSFC20D0004. M.Z. acknowledges Caltech and the Jet Propulsion Laboratory for granting the University of Bologna a licence to an executable version of MONTE Project Edition software. M.Z. is grateful to D. Lubey, M. Smith, D. Mages, C. Hollenberg and S. Bhaskaran of NASA/JPL for the discussions and suggestions regarding the operational navigation of LICIACube. G.P. acknowledges financial support from the Centre national d’études spatiales (CNES, France). A.C.B. acknowledges funding by the NEO-MAPP project (grant agreement 870377, EC H2020-SPACE-2019) and by the Ministerio de Ciencia Innovación (PGC 2018) RTI2018-099464-B-I00. F.F. acknowledges funding from the Swiss National Science Foundation (SNSF) Ambizione (grant no. 193346). J.-Y.L. acknowledges the support from the NASA DART Participating Scientist Program (grant no. 80NSSC21K1131). S.D.R. and M.J. acknowledge support from the Swiss National Science Foundation (project no. 200021_207359)

Momentum transfer from the DART mission kinetic impact on asteroid Dimorphos

The NASA Double Asteroid Redirection Test (DART) mission performed a kinetic impact on asteroid Dimorphos, the satellite of the binary asteroid (65803) Didymos, at 23:14 UTC on 26 September 2022 as a planetary defence test1. DART was the first hypervelocity impact experiment on an asteroid at size and velocity scales relevant to planetary defence, intended to validate kinetic impact as a means of asteroid deflection. Here we report a determination of the momentum transferred to an asteroid by kinetic impact. On the basis of the change in the binary orbit period2, we find an instantaneous reduction in Dimorphos’s along-track orbital velocity component of 2.70 ± 0.10 mm s−1, indicating enhanced momentum transfer due to recoil from ejecta streams produced by the impact3,4. For a Dimorphos bulk density range of 1,500 to 3,300 kg m−3, we find that the expected value of the momentum enhancement factor, β, ranges between 2.2 and 4.9, depending on the mass of Dimorphos. If Dimorphos and Didymos are assumed to have equal densities of 2,400 kg m−3, β=3.61−0.25+0.19(1σ). These β values indicate that substantially more momentum was transferred to Dimorphos from the escaping impact ejecta than was incident with DART. Therefore, the DART kinetic impact was highly effective in deflecting the asteroid Dimorphos

Anticipated Geological Assessment of the (65803) Didymos–Dimorphos System, Target of the DART–LICIACube Mission

On 2022 September 26, the DART spacecraft will impact the surface of Dimorphos, the ∼160 m size satellite of the binary near-Earth asteroid (NEA) (65803) Didymos. What will be observed on the surfaces of both asteroids and at the DART impact site is largely unknown, beyond the details of Didymos revealed by previous Arecibo and Goldstone radar observations. We present here the expected DART and LICIACube observations of the Didymos system and discuss the planned mapping strategies. By searching similar geological features and processes identified on other NEAs, we constrain the impact conditions that DART might encounter at Dimorphos, assessing both the asteroid's surface and interior structure

Curl plasma antenna for SATcom navigation systems

Gaseous Plasma Antennas (GPAs) have been defined as devices that exploit weakly or fully ionised gas to transmit and receive electromagnetic (EM) waves. GPAs can offer several advantages over metal antennas: when the plasma is turned \u201con\u201d, they are (i) electronically reconfigurable with respect to frequency, and gain on time scales the order of microseconds to milliseconds, and (ii) transparent to incoming EM waves whose frequency is greater than the plasma frequency. When the plasma is turned "off", the GPA reverts to a dielectric tube with a very low radar cross-section. Thus, a GPA can potentially achieve frequency hopping electronically, rather than mechanically, and reduce co-site interferences when several antennas are placed in proximity. Moreover, the reduced interferences make GPAs suitable to be stacked into arrays that can steer the beam electronically by switching on and off the plasma array elements. The reconfiguration and beam-steering capabilities, together with the reduced interferences, make GPAs very appealing for Satellite Communication (SatCom), especially in navigation systems (i.e., systems that provide geolocation and time information). In navigation systems, the antenna pointing and tracking obtained electronically, rather than varying the orbital attitude of the satellite, can be crucial. Navigation systems, as for example the European Galileo, require improvements on the navigation antennas: this is confirmed by the growing demand to identify and implement antennas that can enhance the capability of the constellation by ensuring more robust GPS service especially in GPS-denied environments or in regions where service is inconsistent. GPS antennas are required (i) to cover the L frequency band (1-2 GHz), and (ii) to use Circular Polarization (CP). This work presents the preliminary results of a curl GPA that works in the L-band, specifically designed for SatCom navigation systems in the framework of the Italian Space Agency (ASI) project \u201cEPT.com - Enabling Plasma Technology towards Satellite Communications\u201d. The study here presented combines numerical and experimental approaches. A plasma experimental characterization provided the plasma parameters to estimate the antenna performances by means of full-wave numerical simulations. The numerical simulations considered in a first stage a simplified plasma curl plasma antenna and successively it included a more realistic design that comprises the equipment and the electrodes used to generate the plasma

Sardinia deep space antenna: Current program status and results

The Sardinia Deep Space Antenna (SDSA) of the Italian Space Agency has the purpose of providing tracking and communications services for deep space and lunar missions, and supporting radio science experiments. The SDSA shares with the Sardinia Radio Telescope (SRT) a part of the systems and infrastructure, but has its own specific equipment, a dedicated control center and operations. The SRT is a fully-steerable 64-m diameter parabolic radio telescope, capable of operating in the 0.3-116 GHz frequency range. The telescope is located about 35 km north of the town of Cagliari, on the island of Sardinia, Italy. This paper provides an overview of the SDSA program status and the results of some characteristic activities carried out in 2018, in particular related to the Entry, Descent and Landing phase of Insight and to the monitoring of the asteroid 2003-SD220

In-orbit Characterization of a Lab- on-Chip Payload with Integrated Thin-Film Photosensors for Chemiluminescent Immunoassays aboard the AstroBio CubeSat Mission

Preliminary results of the in-orbit characterization of an analytical payload based on a lab-on-chip device with integrated thin-film photosensors relying on chemiluminescence immunoassay is presented. The paper addresses the characterization of the main components of the analytical system based on data acquired during the AstroBio CubeSat mission launched aboard the Vega-C maiden flight in summer 2022. In particular, the performances of the on-chip thin-film sensors and the lab-on-chip front-end readout electronics are reported in detail confirming the suitability of the proposed technology for space application