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Research Outside CODER

Dynamics Analysis and GNC Design of Flexible Systems for Space Debris Active Removal 
Location:
Politecnico di Milano, Dipartimento di Scienze e Tecnologie Aerospaziali, Italy
Investigator:
Riccardo Benvenuto, Samuele Salvi, Michele Lavagna
Duration:
2014-2015

Active debris removal is one of current hot spots in space research, necessary for space exploitation durability. Different techniques have been proposed for this challenging task, among them the use of throw-nets and tow-tethers seems promising: that opens new challenges for Guidance Navigation and Control (GNC) design, especially whenever flexible connections are involved. Via numerical simulations using a multi-body dynamics simulation tool developed at Politecnico di Milano – Department of Aerospace Science and Technology, this paper shows that tethered-net systems are a promising technology to capture and remove space debris and discusses the main difficulties that are likely to take place during capture and disposal phases, particularly from a GNC point of view.


Optimal Guidance Trajectories for a Nanosat Docking with a Non-Cooperative Resident Space Object
Location:
Embry Riddle Aeronautical University
Investigator:
Bogdan Udrea

There has been an increasing interest in on-orbit autonomous servicing and repair of satellites as well as controlled active debris removal (ADR) in the space industry recently. One of the most challenging tasks for servicing/repair as well as for ADR is the rendezvous and docking with a non-cooperative tumbling resident space object (RSO). This paper presents a propellant optimal maneuver profile for a servicing spacecraft to perform proximity operations and eventually dock with a non-cooperative target. The strategy is to find an optimal trajectory which will guide the servicing spacecraft to approach the tumbling satellite such that the two vehicles will eventually have no relative motion. Therefore, a subsequent docking or capture operation can be safely performed. The research described here elaborates on the previous work that studied the minimum-control-effort for a 3-D docking to a tumbling object considering a full six-degree-of-freedom model of both chaser and target. The current work expands the scope by adding new set of linearized equations of motion that capture the effect of the J2 geopotential disturbance force.
 


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Protecting the GEO environment: policies and practices
Location:
NASA JSC
Investigator:
Nicholas L. Johnson
Duration:
1999

The geosynchronous orbital regime has long been recognized as a unique space resource, dictating special measures to ensure its continuing use for future generations. During the past 20 yr a variety of national and international policies have been developed to preserve this environment. A review of current practices involving the deployment and disposal of geosynchronous spacecraft, associated upper stages and apogee kick motors, and geosynchronous orbit transfer objects indicates both positive and negative trends. Most spacecraft operators are indeed performing end-of-mission maneuvers, but the boost altitudes normally fall short of policy guidelines. Russia, a major operator in geosynchronous orbit, maneuvers only 1 in 3 spacecraft out of the region, while China has never retired a spacecraft above GEO. The viability of voluntary protection measures for this regime depends upon the responsible actions of the aerospace community as a whole.


Small Satellites and Their Regulation
Location:
Pelton Consulting International
Investigator:
Jakhu, Ram S., Pelton, Joseph N.
Duration:
2014

Since the launch of UoSat-1 of the University of Surrey (United Kingdom) in 1981, small satellites proved regularly to be useful, beneficial, and cost-effective tools. Typical tasks cover education and workforce development, technology demonstration, verification and validation, scientific and engineering research as well as commercial applications. Today the launch masses range over almost three orders of magnitude starting at less than a kilogram up to a few hundred kilograms, with budgets of less than US$ 100.00 and up to millions within very short timeframes of sometimes less than two years. Therefore each category of small satellites provides specific challenges in design, development and operations.

Small satellites offer great potentials to gain responsive, low-cost access to space within a short timeframe for institutions, companies, regions and countries beyond the traditional big players in the space arena. For these reasons (particularly the low cost of construction, launch and operation), small (micro, cube or nano) satellites are being preferred by students and educational institutions, amateur radio operators, small and developing countries, international aid agencies and most recently by defense agencies and satellite operators who are examining deployment of constellation clusters instead of conventional application satellites. In some cases these new capabilities are being deployed as hosted payloads on larger satellites. The advent of hosted payloads as a significant part of the satellite industry represents a key new topic that this book will address.

The number of small satellites—of various types--is increasing fast as their benefits are being realized. This short and unique interdisciplinary book, covering both technical and regulatory aspects, examines all the different types of applications and reasons for small as well as exploring technical and operational innovations that are being introduced. It also examines the new technical standards, removal techniques or other methods that might help to address current problems and the regulatory issues and procedures to ameliorate problems associated with small satellites, especially mounting levels of orbital debris and noncompliance with radio frequency and national licensing requirements, liabilities, export controls and so on.


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