Polifemo Device Business Plan

Spacecrafts continuously need for low cost and weight sensor easy to integrate in a plug-in approach and capable to improve platforms versatility while reducing integration time and complexity. This is particularly true for the new generation of small and micro satellites to be launched in constellation and formation. Controlling small satellites cooperation and protecting the space assets from debris are two important issues of current and future missions. The cost reduction and safety of space missions is a key issue for further expand European leadership in the Earth Observation and Communication sectors. The POLIFEMO (Panoramic Multifunctional Sensor for Small/Micro Satellite) is a unique solution for an integrated sensor capable to replace by one single unit the functions of Sun sensor, Earth sensor and Star tracker and, additionally, providing external situational awareness. POLIFEMO is based on an innovative lens with a very wide angle (with a hyper-hemispheric field of view) able to look at a field of view of 360 in azimuth (panoramic omnidirectional lens) and 270 in elevation (hyper-hemispheric capabilities), designed and patented by the Italian National Institute for Astrophysics (INAF). POLIFEMO, with that extremely high field of view and unique imaging detection capability, results in a small, low weight, low cost and reliable (no moving part, potentially failure point) space sensor. It is unique in the market of space sensors and suitable for many spaces and non-space missions (e.g., communication, weather, imaging, surveillance, deep space but also UAV/HAP). Progetti Speciali Italiani s.r.l., a SME active in developing microsatellite and space applications, has set up, during the phase 1 project, a very experienced team of engineering and commercial specialists for carrying on the proposed project. University of Napoli (Parthenope) is expert on developing satellites star trackers solutions. This paper reports a summary extracted from a more detailed BP (Doc: ECSME-PSI-POLIFEMO-BP-2016) which has been prepared within the EU-H2020 contract framework. The full BP is available on request

Fundamental physics and absolute positioning metrology with the MAGIA lunar orbiter

MAGIA is a mission approved by the Italian Space Agency (ASI) for Phase A study. Using a single large-diameter laser retroreflector, a large laser retroreflector array and an atomic clock onboard MAGIA we propose to perform several fundamental physics and absolute positioning metrology experiments: VESPUCCI, an improved test of the gravitational redshift in the Earth–Moon system predicted by General Relativity; MoonLIGHT-P, a precursor test of a second generation Lunar Laser Ranging (LLR) payload for precision gravity and lunar science measurements under development for NASA, ASI and robotic missions of the proposed International Lunar Network (ILN); Selenocenter (the center of mass of the Moon), the determination of the position of the Moon center of mass with respect to the International Terrestrial Reference Frame/System (ITRF/ITRS); this will be compared to the one from Apollo and Lunokhod retroreflectors on the surface; MapRef, the absolute referencing of MAGIA's lunar altimetry, gravity and geochemical maps with respect to the ITRF/ITRS. The absolute positioning of MAGIA will be achieved thanks to: (1) the laboratory characterization of the retroreflector performance at INFN-LNF; (2) the precision tracking by the International Laser Ranging Service (ILRS), which gives two fundamental contributions to the ITRF/ITRS, i.e. the metrological definition of the geocenter (the Earth center of mass) and of the scale of length; (3) the radio science and accelerometer payloads; (4) support by the ASI Space Geodesy Center in Matera, Italy. Future ILN geodetic nodes equipped with MoonLIGHT and the Apollo/Lunokhod retroreflectors will become the first realization of the International Moon Reference Frame (IMRF), the lunar analog of the ITRF

Lunar Gravitational-Wave Antenna

Monitoring of vibrational eigenmodes of an elastic body excited by gravitational waves was one of the first concepts proposed for the detection of gravitational waves. At laboratory scale, these experiments became known as resonant-bar detectors first developed by Joseph Weber in the 1960s. Due to the dimensions of these bars, the targeted signal frequencies were in the kHz range. Weber also pointed out that monitoring of vibrations of Earth or Moon could reveal gravitational waves in the mHz band. His Lunar Surface Gravimeter experiment deployed on the Moon by the Apollo 17 crew had a technical failure rendering the data useless. In this article, we revisit the idea and propose a Lunar Gravitational-Wave Antenna (LGWA). We find that LGWA could become an important partner observatory for joint observations with the space-borne, laser-interferometric detector LISA, and at the same time contribute an independent science case due to LGWA's unique features. Technical challenges need to be overcome for the deployment of the experiment, and development of inertial vibration sensor technology lays out a future path for this exciting detector concept.Comment: 29 pages, 17 figure

Performance characterization of a non-conventional star tracker based on a hyper-hemispherical panoramic camera

This paper aims at characterizing the attitude determination performance of a non-conventional star tracker based on a hyper-hemispheric panoramic camera designed as a multi-functional sensor for applications onboard small/micro-satellites. The peculiar features of the optical system allow imaging a field of view of 360° in azimuth and up to 135° in elevation (zenith), thus being able to observe an extremely wide portion of the celestial sphere, though at the expense of limited capabilities in terms of detector resolution and sensitivity. For this reason, each mode of the multi-functional sensor requires ad-hoc, original algorithmic solutions. In this respect, the star tracker mode relies on an innovative approach for star identification, based on template matching and image registration concepts inherited from the computer vision and robotic research community, combined with a standard solution to the Wahba's problem to determine the spacecraft attitude parameters during the lost-in-space condition. A numerical simulation environment is developed to realistically reproduce the star pattern imaged by the sensor including all the major sources of noise (e.g., outliers, hot pixels). Hence, the performance of the proposed approach is evaluated in terms of attitude determination accuracy and reliability over a wide set of attitude states characterized by a uniform distribution of the camera pointing in the celestial sphere. Also, this is done considering highly-variable settings in terms of sensor's specifications and algorithm's operational parameters

Hyper hemispheric lens applications in small and micro satellites

As well known, micro and nanosatellites are being proposed for a variety of space missions, due to the advantages offered in terms of flexibility, cost and development time-scales. They also allow the development of space missions based on distributed architectures, composed of a number of small platforms in coordinated flight. However, technological advancements are still needed to make micro and nanosatellite competitive with respect to larger platforms. In this paper, we explore the potentiality offered by hyper hemispheric lens for the development of miniaturized and multi-function sensors for use on board of micro satellites. Hyper hemispheric lens belong to the ultra-wide field-of-view optical objectives. Here a novel optics of this category is presented. Its field of view is 360° in azimuth (panoramic capabilities) and 135° for the off-boresight angle (hyper-hemispheric field). With such capabilities the lens may be exploited as a very-large field-of-view optics where moving parts can be avoided. This is of interest to space applications, in which devices with any moving part, representing a possible point of failure, shall be avoided or reduced to the minimum. A hyper hemispheric lens may, then, be adopted for electro optical devices in space satellite subsystems, such as star-, Sun- and Earth-sensors, or for monitoring the environment surrounding the satellite in the case of on-orbit servicing or active debris removal operations. Weight and cost budgets for small and micro satellites are also important parameters to determine their success. Hyper hemispheric lens may be kept quite compact in dimension and the need of a single imaging detector, for a so large field of view, strongly reduces costs. In this paper, we explore possible applications of a multi-purpose space device based on a hyper hemispheric lens on board of micro and nanosatellites

Drag and Attitude Control for the Next Generation Gravity Mission

The Next Generation Gravity Mission (NGGM), currently in a feasibility study phase as a candidate Mission of Opportunity for ESA-NASA cooperation in the frame of the Mass Change and Geo-Sciences International Constellation (MAGIC), is designed to monitor mass transport in the Earth system by its variable gravity signature with increased spatial and temporal resolution. The NGGM will be composed by a constellation of two pairs of satellites, each providing the measurement of two quantities from which the map of Earth’s gravity field will be obtained: the variation of the distance between two satellites of each pair, measured by a laser interferometer with nanometer precision; and the relative non-gravitational acceleration between the centers of mass of each satellite pair, measured by ultra-sensitive accelerometers. This article highlights the importance of the second “observable” in the reconstruction of the lower harmonics of Earth’s gravity field, by highlighting the tight control requirements in linear and angular accelerations and angular rates, and the expectable performances from the drag-free, attitude, and orbit control system (DFAOCS) obtained through an end-to-end (E2E) simulator. The errors resulting from different mission scenarios with varying levels of drag-free control and pointing accuracy are then presented, demonstrating that a high-performance accelerometer alone is not sufficient to achieve the measurement quality necessary to achieve the mission objectives, if the spacecraft does not provide to this sensor a suitable drag-free environment and a precise and stable pointing. The consequences of these different mission scenarios on the gravity field retrieval accuracy, especially for the lower spherical harmonic degrees, are computed in order to quantitatively justify the rationale for these capabilities on the NGGM spacecraft.Astrodynamics & Space Mission