UNISAT-7: A Flexible IOD Platform with Orbital Maneuvering Capabilities

New Space technology for Small Satellites has greatly advanced in the past five years. These progresses shall match with a swift integration and testing phase, to be readily marketable, therefore IOD missions are essential to expedite project outcomes. GAUSS has started working on Small Satellites since 1990s, with its first satellite, UNISAT, launched in 2000. In 2013, UNISAT-5 was the first platform to accomplish in-orbit-release of third-party satellites, with UNISAT-6 following in less than one year. UNISAT-7 is the latest addition to the UNISAT series: a 32kg microsatellite designed and manufactured by GAUSS Srl (a spin-off company of Scuola di Ingegneria Aerospaziale, Sapienza University of Roma), built from scratch thanks to the extensive experience gained with past missions. Launch is scheduled in in Q1 2021. It is the most complex mission ever flown by GAUSS, and it includes several original GAUSS subsystems developed for Earth Observation, sat-to-ground optical links, navigation, power, RF, and Smallsat in-orbit-deployments. All these subsystems are tested in orbit in specific IOD missions. Moreover, UNISAT-7 integrates a precise ADCS solution and a newly developed low-thrust, electric propulsion system named REGULUS, from Italian Company Technology for Propulsion and Innovation (T4i), which will allow the satellite to modify its final orbit, as well as to execute housekeeping maneuvers for drag compensation. REGULUS is a propulsive unit based on MEPT (Magnetically Enhanced Plasma Thruster) technology developed inside the propulsion laboratory of the University of Padua. T4i, born as a Spin-off of the University of Padua, industrialized this technology in order to make it fly. REGULUS is T4i very first product that has ever flown into space. Its envelope is 1.5 U of volume, it is equipped with solid iodine propellant and its main features are a thrust level of 0.55 mN and Isp of 550 s at 50 W of input power, and wet mass of 2.5 kg at 3000 Ns of Itot. REGULUS is designed to serve nanosatellite platforms from 6U to 24U and CubeSat carriers. The integration took place in GAUSS white chamber in Rome in late 2020 and the launch is scheduled in March 2021 from Baikonur as a secondary payload of Soyuz-2-1a/Fregat. Performances of REGULUS propulsion system are evaluated after the initial commissioning of UNISAT-7. This key IOD mission paves the way to next UNISAT programs, where GAUSS microsatellites will be able to execute orbital maneuvers before any single CubeSat deployment, in order to efficiently shape customized constellations by using UNISATs as autonomous vehicles for in-orbit-deployment. Provide an informative abstract of no more than 500 words. The abstract should stand alone as a summary of the paper, not as an introduction (i.e., no numerical references). Type the abstract across both columns and fully justified

A low-cost earth-moon-mars mission using a microsatellite platform

The paper presents the preliminary results of a space exploration mission designed by GAUSS Srl, aiming at performing, for the first time ever, the exploration of the Moon and Mars using a microsatellite platform. Microsatellites offer advantages over larger “traditional” spacecraft, such as reduced development time and cost, but they also set several challenges when considering space exploration missions. In fact, their limited volume and mass directly translates into strict power and thrusting constraints, and traditional maneuvers required by interplanetary transfers are often impractical. A solution to this issue is proposed in this paper and consists in taking advantage of the chaotic behavior in multi-body systems to transfer a microsatellite of the UNISAT class from the Earth, to the Moon and then to Mars. The mission is compatible with available rideshares in which the microsatellite is deployed along a highly eccentric orbit around the Earth, whose apogee crosses the orbit of the Moon. From the mentioned deployment conditions, a lunar capture is established, injecting the microsatellite into a chaotic orbit governed by the combined gravitational forces of the Sun, Earth and Moon. If the Keplerian energy at capture is adequately selected, the perturbations acting in the Sun-Earth-Moon system can lead the spacecraft to experience a gravity assist by the Moon and, eventually, by the Earth, at a time when the relative position of the Earth and Mars is suitable to allow a transfer between the two planets. Consequently, the microsatellite is transferred and captured at Mars, where two 3U CubeSats are deployed. The overall mission architecture and design techniques are discussed and verified by means of numerical analyses. A selection of on-board systems currently on the market and compatible with the resulting mission profile is proposed. The availability of launch opportunities and the need for on-ground services necessary to support the mission is investigated. All these elements are finally examined to outline a risk management plan and to define a suitable budget for the mission, showing that deep space exploration using microsatellites is a real option for current space programs

Characterization of a flux-pinning interface for the control of nanosatellites in very close proximity

In this work, we propose a system ensuring autonomous station-keeping of a prescribed configuration of two, or more satellites, in very close proximity, which is realized equipping one satellite with a type-II high temperature superconductor and the other one with a magnet. It is known that the interaction between two magnets can generate either a repulsive or an attractive force, differently a type-II superconductor and a magnet can show an interaction based on the flux-pinning effect and are therefore named a flux-pinning interface (FPI). The force exchanged by the FPI switches from attractive to repulsive as the two devices approach, therefore it allows binding the relative motion of the satellites while ensuring collision avoidance. To establish the flux-pinning effect, the superconductor must be cooled-down below its critical temperature, a process that can be performed by a passive thermal control system. The magnetic characterization of the type-II superconductor, in a sample of granular ceramic YBCO, is performed using a vibrating sample magnetometer. Once characterized the high temperature superconductor, a model of the FPI is and an extension of the Hill-Clohessy-Wiltshire equations is developed. Analysis on the dynamics on the problem allows identifying new equilibrium conditions existing for the FPI and some cases of interest are investigated numerically

UNISAT-7: A Small Satellite with Big Potential

More than twenty years have passed since the launch of the first UNISAT, a microsat-class spacecraft designed entirely by students of the GAUSS lab of the Scuola di Ingegneria Aerospaziale in Rome, when Small Satellites were deemed just a toy by the aerospace industry. The latest iteration in this fortunate series is UNISAT-7, a 32kg octagonal-shaped micro-sat, designed and manufactured by GAUSS Srl, scheduled to be launched in Q1 2021 by a Soyuz-Fregat launch vehicle. The four main topics over which UNISAT-7 was built upon, are: Heritage, Technology, Research and Radioamateur. The mission is based on the successful idea of acting both as an in-orbit deployer of third-party satellites and as a flexible in-orbit demonstrator for space technology, while maintaining open access for radioamateurs worldwide. UNISAT-7, developed thanks to the vast experience earned with past missions, continues in the footsteps of its predecessors, UNISAT-5 (2013) and UNISAT-6 (2014), which released a total of 12 nano- and pico-sats, with a turnaround of less than two years. UNISAT-7 will release two CubeSats and three PocketQubes, among which are custom-sized platforms. The satellite, developed using lean-satellite methodologies, integrates payloads and GAUSS-designed subsystems that will be tested in orbit, to boost the capacity of next UNISAT platforms: a fine ADCS system and a low-thrust, electric propulsion system named REGULUS, from Italian Company T4i, which will allow the satellite to modify orbit height, as well as to execute housekeeping maneuvers for drag compensation. This will open endless possibilities for future UNISATs to release satellites based on a desired constellation architecture, enhance life-time expectancy in low-altitude orbits or command an accelerated de-orbit phase. UNISAT-7 will act as in-orbit demonstrator for original GAUSS technology: two Earth Observation payloads, on-board computers, RF transceivers and switches, GNSS navigation, high-power EPS units, sat-to-ground optical links and upgraded electronics for automated in-orbit deployments. GAUSS electronics are manufactured using COTS components, with the aim to lower manufacturing costs while assuring operational reliability. All subsystems were tested for vibration and TVAC, some of them while active. The satellite will also test third-party technology, such as equipment in the framework of NB-IOT research, and it will perform joint operations with GAUSS Observatory for Space Debris “CastelGAUSS” for light-curve detection on different commanded attitudes. UNISAT-7 spacecraft will be employed to test the space segment of the upgraded GAUSS UNISAT bus, which will pave the way for future UNISAT programs