Applying autonomy to distributed satellite systems: Trends, challenges, and future prospects

While monolithic satellite missions still pose significant advantages in terms of accuracy and operations, novel distributed architectures are promising improved flexibility, responsiveness, and adaptability to structural and functional changes. Large satellite swarms, opportunistic satellite networks or heterogeneous constellations hybridizing small-spacecraft nodes with highperformance satellites are becoming feasible and advantageous alternatives requiring the adoption of new operation paradigms that enhance their autonomy. While autonomy is a notion that is gaining acceptance in monolithic satellite missions, it can also be deemed an integral characteristic in Distributed Satellite Systems (DSS). In this context, this paper focuses on the motivations for system-level autonomy in DSS and justifies its need as an enabler of system qualities. Autonomy is also presented as a necessary feature to bring new distributed Earth observation functions (which require coordination and collaboration mechanisms) and to allow for novel structural functions (e.g., opportunistic coalitions, exchange of resources, or in-orbit data services). Mission Planning and Scheduling (MPS) frameworks are then presented as a key component to implement autonomous operations in satellite missions. An exhaustive knowledge classification explores the design aspects of MPS for DSS, and conceptually groups them into: components and organizational paradigms; problem modeling and representation; optimization techniques and metaheuristics; execution and runtime characteristics and the notions of tasks, resources, and constraints. This paper concludes by proposing future strands of work devoted to study the trade-offs of autonomy in large-scale, highly dynamic and heterogeneous networks through frameworks that consider some of the limitations of small spacecraft technologies.Postprint (author's final draft

Flexible, High-Speed, Small Satellite Production

Planet’s first mission is to image the entire land mass of the Earth every day in an effort to make global change visible, accessible, and actionable. To do this, Planet designs and builds highly capable Earth-imaging satellites and today operates the largest Earth-imaging fleet in history. To support this mission, Planet had to develop an adaptable concurrent product development cycle associated with a unique assembly and manufacturing line to support the quick production and delivery of satellites. This paper introduces how Planet achieved that objective by building multiple spacecraft design iterations concurrently and how Planet orchestrates a production line for speed, flexibility, and high throughput of satellite delivery in just over a few weeks

Quantifying Potential Energy Efficiency Gain in Green Cellular Wireless Networks

Conventional cellular wireless networks were designed with the purpose of providing high throughput for the user and high capacity for the service provider, without any provisions of energy efficiency. As a result, these networks have an enormous Carbon footprint. In this paper, we describe the sources of the inefficiencies in such networks. First we present results of the studies on how much Carbon footprint such networks generate. We also discuss how much more mobile traffic is expected to increase so that this Carbon footprint will even increase tremendously more. We then discuss specific sources of inefficiency and potential sources of improvement at the physical layer as well as at higher layers of the communication protocol hierarchy. In particular, considering that most of the energy inefficiency in cellular wireless networks is at the base stations, we discuss multi-tier networks and point to the potential of exploiting mobility patterns in order to use base station energy judiciously. We then investigate potential methods to reduce this inefficiency and quantify their individual contributions. By a consideration of the combination of all potential gains, we conclude that an improvement in energy consumption in cellular wireless networks by two orders of magnitude, or even more, is possible.Comment: arXiv admin note: text overlap with arXiv:1210.843

Space-Based Countermeasure for Hypersonic Glide Vehicle

The purpose of this thesis is to investigate the effectiveness of a space-based laser weapon system for countering a hypersonic glide vehicle. Hypersonic glide vehicles are an emerging type of weapon system which combine the range of ballistic missiles with the maneuverability of cruise missiles. These systems pose a unique threat to military assets not only for their expanded capabilities but also for the lack of an effective defensive countermeasure. Space-based laser weapon systems may offer a solution to this problem. The dynamics of a space-based laser system defending against a hypersonic glide vehicle are modeled first. The governing equations of motion for the space orbital mechanics and the atmospheric flight mechanics of the two objects, assuming point mass three degree of freedom conditions, are defined. Several variables in the engagement model are allowed to vary including initial conditions for true anomaly and right ascension of the ascending node for the space-based laser system and the velocity ratio, angle of attack, and heading about the ground target for the hypersonic glide vehicle. The motion of each object is propagated from the initial condition forward in time from which the relative motion and lasing along the line of sight are analyzed. A predetermined intercept range for the laser is then compared against the flight path of the hypersonic glide vehicle to determine when a successful intercept of the hypersonic glide vehicle occurs. Finally, the solution set for the intercept of the hypersonic glide vehicle by the laser is examined. Results reveal usable solution sets do exist where a space-based laser system could defensively counter a hypersonic glide vehicle attacking a specific ground target

Orbital Debris Quarterly News

The Indian spacecraft Microsat-R (International Designator 2019-006A, U.S. Strategic Command [USSTRATCOM] Space Surveillance Network [SSN] catalog number 43947), launched on 24 January 2019, was intentionally destroyed in a test of a ground-based, direct-ascent Anti-Satellite (ASAT) weapon system at 0640 GMT on 27 March 2019. At the time of breakup the 740 kg spacecraft was in an approximately 294 x 265 km altitude, 96.63 orbit. A total of 101 debris have entered the public satellite catalog (through object 2019-006DF), of which 49 fragments remain on-orbit as of 15 July 2019. However, over 400 fragments were initially tracked by SSN sensors and cataloging is complicated by the low altitude of the event and the concomitant rapid orbital decay. A Gabbard plot of this debris cloud is presented in the figure on page 2. A Centaur V Single-Engine Centaur (SEC) rocket variant (International Designator 2018-079B, SSN number 43652) fragmented in early April 2019. At the time of the event the stage was in an approximately 35,092 x 8526 km altitude, 12.2 orbit. This Centaur V upper stage is associated with the launch of the USA 288, or Advanced Extremely High Frequency 4 (AEHF 4), spacecraft from the (U.S.) Air Force Eastern Test Range on 17 October 2018. The cause of the event is unknown. No debris have entered the catalog at this time, but the ODQN will provide updates should they become publicly available

ESMD Space Grant Faculty Project

No abstract availabl

IMPLEMENTATION OF A STATE-OF-THE-ART GNSS RECEIVER AUTONOMOUS INTEGRITY MONITORING TECHNIQUE

This thesis implements a state-of-the-art solution separation advanced RAIM (ARAIM) algorithm as it is written as reported in the literature. Specifically, a GNSS fault detection and exclusion algorithm for a multi-constellation GNSS was implemented in software and tested against simulated data. RAIM algorithms have been created in many forms over the last couple of decades and are still in development today. The position solution results produced by this ARAIM algorithm were compared to that of a snapshot weighted least squares (WLS) solution in which failed satellites are removed before processing and an WLS solution with no corrections applied. In addition, the difference in position solution between ARAIM and the simulation truth was compared to the ARAIM reported horizontal and vertical protection limits, as well as, the position performance criteria. This thesis also investigates the performance of the exclusion method and how it affects the performance of the overall ARAIM algorithm. The algorithm implemented and tested in this thesis will be used as a basis of comparison for on-going research into robust GNSS processing techniques