S. Speretta
Please Note
59 records found
1
NovaMoon will enable sub-metre- to decimetre-level positioning in the south polar region, provide local differential corrections for lunar navigation users, and ensure an accurate and stable realisation of position and time for the lander. Through preliminary simulation studies, we show that the resulting multi-technique dataset significantly improves the lunar reference frame, the determination of lunar orientation and ephemerides, and the estimation of interior parameters such as tidal response, core properties, and dissipation.
NovaMoon will also provide the first long-duration physical realisation of a lunar time reference, enabling precise timing for lunar navigation users and contributing to the establishment of a future lunar timescale.
Beyond its primary goals, NovaMoon supports improved cartography, more accurate geolocation of surface features, and higher-resolution topography in the south polar region, contributing to safer and more precise landing and surface operations. Its multi-technique measurements also open new opportunities for fundamental physics, including enhanced tests of the Equivalence Principle, improved constraints on relativistic gravity, and increased sensitivity to deviations from classical gravitational models or potential variations in fundamental constants. ...
NovaMoon will enable sub-metre- to decimetre-level positioning in the south polar region, provide local differential corrections for lunar navigation users, and ensure an accurate and stable realisation of position and time for the lander. Through preliminary simulation studies, we show that the resulting multi-technique dataset significantly improves the lunar reference frame, the determination of lunar orientation and ephemerides, and the estimation of interior parameters such as tidal response, core properties, and dissipation.
NovaMoon will also provide the first long-duration physical realisation of a lunar time reference, enabling precise timing for lunar navigation users and contributing to the establishment of a future lunar timescale.
Beyond its primary goals, NovaMoon supports improved cartography, more accurate geolocation of surface features, and higher-resolution topography in the south polar region, contributing to safer and more precise landing and surface operations. Its multi-technique measurements also open new opportunities for fundamental physics, including enhanced tests of the Equivalence Principle, improved constraints on relativistic gravity, and increased sensitivity to deviations from classical gravitational models or potential variations in fundamental constants.
High-precision inter-satellite ranging is critical for formation flying, autonomous navigation, and scientific measurements in small-satellite missions. Laser communication terminals (LCTs) offer an opportunity to perform both data transfer and ranging, but their dual-use imposes stringent requirements on onboard clocks and timing electronics. This paper investigates the impact of clock-induced timing errors on two-way LCT-based ranging between CubeSats operating around the near-Earth asteroid 99942 Apophis. A methodology is developed to unify clock noise specifications provided in datasheets, generating realistic timing errors across microsecond-to-hour integration periods. Using high-fidelity orbital simulations, two orbital configurations—coplanar and non-coplanar—are analyzed to evaluate how relative satellite geometry influences the propagation of clock errors into range measurements, orbit determination, and the estimation of Apophis’ gravitational parameter. Results demonstrate that inter-satellite links (ISLs) can reduce orbit determination errors along directions weakly constrained by Earth-based Doppler—from 1–3 m to 0.1–0.3 m in coplanar formations, and even further in non-coplanar formations—corresponding to improvements of one to two orders of magnitude. Subsystem-level noise, such as detector jitter and time tagging, can still limit achievable precision, even with high-performance clocks. The methodology provides a framework applicable to a broad range of small-satellite missions, guiding the selection of clocks, formation geometry, and system design to optimize both navigation performance and science return.
It is of interest to better characterise the Gas-Surface Interactions (GSI) to improve drag coefficient modelling, which is, however, hindered by a lack of dedicated in-orbit experiments. We propose a new experiment to estimate the energy accommodation coefficient of the Diffuse Reflection with Incomplete Accommodation (DRIA) GSI model. The experiment consists of two small satellites with Global Navigation Satellite Systems (GNSS) receivers and attitude determination systems to derive atmospheric density observations from the positioning data. The experiment has two key features. The first is the satellites' close along-track formation flying, such that they should observe the same atmospheric density with a slight delay due to their along-track separation. Second, the satellites have controllable panels to modify their drag coefficients' response to GSI substantially. Hence, the satellites' atmospheric density observations will agree only when the DRIA model's energy accommodation coefficient is selected correctly. We demonstrate by simulation that the energy accommodation coefficient can be estimated at least once daily with a precision of 5-10% for satellites with decimeter-accuracy GNSS positioning. Given that GNSS receivers and attitude determination systems are common for small satellites currently in LEO, we conclude that there are plenty of opportunities to utilise existing data for the proposed experiment. Valuable byproducts would be atmospheric density observations that are relatively free of systematic errors. ...
It is of interest to better characterise the Gas-Surface Interactions (GSI) to improve drag coefficient modelling, which is, however, hindered by a lack of dedicated in-orbit experiments. We propose a new experiment to estimate the energy accommodation coefficient of the Diffuse Reflection with Incomplete Accommodation (DRIA) GSI model. The experiment consists of two small satellites with Global Navigation Satellite Systems (GNSS) receivers and attitude determination systems to derive atmospheric density observations from the positioning data. The experiment has two key features. The first is the satellites' close along-track formation flying, such that they should observe the same atmospheric density with a slight delay due to their along-track separation. Second, the satellites have controllable panels to modify their drag coefficients' response to GSI substantially. Hence, the satellites' atmospheric density observations will agree only when the DRIA model's energy accommodation coefficient is selected correctly. We demonstrate by simulation that the energy accommodation coefficient can be estimated at least once daily with a precision of 5-10% for satellites with decimeter-accuracy GNSS positioning. Given that GNSS receivers and attitude determination systems are common for small satellites currently in LEO, we conclude that there are plenty of opportunities to utilise existing data for the proposed experiment. Valuable byproducts would be atmospheric density observations that are relatively free of systematic errors.
The Dice Payload consists of a small chamber with five small aluminium dice of different colours, which will be used by primary school children. In collaboration with the LIS, a special mechanism has been designed to ‘roll the dice’ in microgravity and clamp them such that a picture of the numbers can be taken with the Earth as a backdrop. After the design, manufacturing, and assembly of the parts, the payload underwent a series of tests. These tests have included multiple 0g flight tests and a vibration test. Through the extensive testing, there have been iterative design changes to improve the payload’s overall performance and design.
The second payload of the Da Vinci Satellite is the BitFlip Payload. This novel payload recently has been tested in a proton accelerator facility at the Paul Scherrer Institute. This subsystem is a stack of PCB’s with SRAM that has been designed for high school students. High school students can send a picture of themselves to the satellite where the data will be stored on the SRAMs. Because of the radiation environment in LEO and the susceptibility of the memory, bitflips will occur. These changes in the information from a 1 to a 0 (or the other way around), will result in the information of the picture being changed. When the picture has been compressed using a compression algorithm such as GIF, JPEG, or PNG interesting effects can occur. Once the student will receive the altered picture, they will be able to compare it with the original and learn about space, radiation, compression algorithms, and electronics. ...
The Dice Payload consists of a small chamber with five small aluminium dice of different colours, which will be used by primary school children. In collaboration with the LIS, a special mechanism has been designed to ‘roll the dice’ in microgravity and clamp them such that a picture of the numbers can be taken with the Earth as a backdrop. After the design, manufacturing, and assembly of the parts, the payload underwent a series of tests. These tests have included multiple 0g flight tests and a vibration test. Through the extensive testing, there have been iterative design changes to improve the payload’s overall performance and design.
The second payload of the Da Vinci Satellite is the BitFlip Payload. This novel payload recently has been tested in a proton accelerator facility at the Paul Scherrer Institute. This subsystem is a stack of PCB’s with SRAM that has been designed for high school students. High school students can send a picture of themselves to the satellite where the data will be stored on the SRAMs. Because of the radiation environment in LEO and the susceptibility of the memory, bitflips will occur. These changes in the information from a 1 to a 0 (or the other way around), will result in the information of the picture being changed. When the picture has been compressed using a compression algorithm such as GIF, JPEG, or PNG interesting effects can occur. Once the student will receive the altered picture, they will be able to compare it with the original and learn about space, radiation, compression algorithms, and electronics.
This paper presents in detail the final outcome of the pre-Phase A design effort for the 16U4SBSP spacecraft. The trade-off studies conducted to select all sub-systems and components are presented and their final outcomes detailed and justified, together with the technical budgets and the main areas of attention for the spacecraft design. Particularly critical for the success of the mission are the choices related to: the power transmission payload (DC-RF converter, transmitting antenna and heat dissipation system); the ADCS subsystem and in particular the sensors required to provide sufficient accuracy in the knowledge of the 3-axis attitude (both absolute and relative to the other spacecraft in the swarm); the relative navigation system, based on inter-satellite link between the spacecraft in the swarm and on a beacon link to the receiving station on ground, for efficient beaming coordination; the main propulsion system for continuous formation flying control through the whole mission lifetime; the electric power system, based on orientable solar arrays by means of a SADA mechanism and a set of batteries with sufficient capacity for beaming the required amount of power while in eclipse conditions. ...
This paper presents in detail the final outcome of the pre-Phase A design effort for the 16U4SBSP spacecraft. The trade-off studies conducted to select all sub-systems and components are presented and their final outcomes detailed and justified, together with the technical budgets and the main areas of attention for the spacecraft design. Particularly critical for the success of the mission are the choices related to: the power transmission payload (DC-RF converter, transmitting antenna and heat dissipation system); the ADCS subsystem and in particular the sensors required to provide sufficient accuracy in the knowledge of the 3-axis attitude (both absolute and relative to the other spacecraft in the swarm); the relative navigation system, based on inter-satellite link between the spacecraft in the swarm and on a beacon link to the receiving station on ground, for efficient beaming coordination; the main propulsion system for continuous formation flying control through the whole mission lifetime; the electric power system, based on orientable solar arrays by means of a SADA mechanism and a set of batteries with sufficient capacity for beaming the required amount of power while in eclipse conditions.
This chapter provides an overview of the command and data handling system (CDHS) in small satellites and CubeSats. The chapter presents first analysis of radiation effects, specifically targeted at this subsystem, to justify components and architecture choices. Improvements in radiation testing strategies are also presented, specifically for small satellites. State-of-the-art components are then presented, providing an overview of the current market and the most common architectures. An overview of past and current missions is also presented, providing a clear mapping of the presented state-of-the-art components and architectures to guide future designs. High-level design considerations are also presented to help the reader follow some of the current trends in the sector. This chapter, overall, aims at presenting the most common approaches for the CDHS system and comparing this with traditional satellites, showing where the main differences lay with component selection and testing strategies being the fundamental points driving the architecture choices.