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Research Containing: Technology demonstration

Assessment and control of spcaecraft charging risks on the International Space Station

by on 9 June 2015in Technology Development & Demonstration No comment

The International Space Station (ISS) operates in the F2 region of Earth's ionosphere, orbiting at altitudes ranging from 350 to 450 km at an inclination of 51.6 degrees. The relatively dense, cool F2 ionospheric plasma suppresses surface charging processes much of the time, and the flux of relativistic electrons is low enough to preclude deep dielectric charging processes. The most important spacecraft charging processes in the ISS orbital environment are: 1) ISS electrical power system interactions with the F2 plasma, 2) magnetic induction processes resulting from flight through the geomagnetic field and, 3) charging processes that result from interaction with auroral electrons at high latitude. Recently, the continuing review and evaluation of putative ISS charging hazards required by the ISS Program Office revealed that ISS charging could produce an electrical shock hazard to the ISS crew during extravehicular activity (EVA). ISS charging risks are being evaluated in an ongoing measurement and analysis campaign. The results of ISS charging measurements are combined with a recently developed model of ISS charging (the Plasma Interaction Model) and an exhaustive analysis of historical ionospheric variability data (ISS Ionospheric Specification) to evaluate ISS charging risks using Probabilistic Risk Assessment (PRA) methods. The PRA combines estimates of the frequency of occurrence and severity of the charging hazards with estimates of the reliability of various hazard controls systems, as required by NASA s safety and risk management programs, to enable design and selection of a hazard control approach that minimizes overall programmatic and personnel risk. The PRA provides a quantitative methodology for incorporating the results of the ISS charging measurement and analysis campaigns into the necessary hazard reports, EVA procedures, and ISS flight rules required for operating ISS in a safe and productive manner.

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SPHERES Operations aboard the ISS: Maturation of GN&C Algorithms in Microgravity

by on 9 June 2015in Technology Development & Demonstration No comment

The Synchronized Position Hold Engage Reorient Experimental Satellites (SPHERES) Program, at the MIT Space Systems Laboratory, provides research scientists with a facility to incrementally and iteratively mature estimation, control, autonomy, and artificial intelligence algorithms to advance the field of Distributed Satellite Systems. Operations aboard the ISS began in May 2006, with a total of five sessions completed by the end of 2006. These sessions achieved a wide range of successes including the demonstration of both formation flight and autonomous docking algorithms. The docking algorithms were developed incrementally throughout the five tests sessions, making heavy use of the reconfiguration and modularity features of the SPHERES design. The architecture for the docking algorithms is based on the development of smaller simple modules that implement: two estimation algorithms based on extended Kalman filters; mixer functions to convert forces and torques to thruster on/off commands; glideslope, phase-plane, and PID-type controllers; and fault detection and isolation algorithms. The modules were tested piecewise and assembled together to create increasingly complex docking maneuvers. The tests culminated with the successful demonstration of two SPHERES satellites performing cooperative docking to fixed targets, demonstrating the capabilities of safe docking maneuvers, and performing the first microgravity docking to a tumbling target.

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Stereo images from space

by on 9 June 2015in Technology Development & Demonstration No comment

The Erasmus Recording Binocular (ERB1) was the first fully digital stereo camera used on the International Space Station. One year after its first utilisation, the results and feedback collected with various audiences have convinced us to continue exploiting the outreach potential of such media, with its unique capability to bring space down to earth, to share the feeling of weightlessness and confinement with the viewers on earth. The production of stereo is progressing quickly but it still poses problems for the distribution of the media. The Erasmus Centre of the European Space Agency has experienced how difficult it is to master the full production and distribution chain of a stereo system. Efforts are also on the way to standardize the satellite broadcasting part of the distribution. A new stereo camera is being built, ERB2, to be launched to the International Space Station (ISS) in September 2008: it shall have 720p resolution, it shall be able to transmit its images to the ground in real-time allowing the production of live programs and it could possibly be used also outside the ISS, in support of Extra Vehicular Activities of the astronauts. These new features are quite challenging to achieve in the reduced power and mass budget available to space projects and we hope to inspire more designers to come up with ingenious ideas to built cameras capable to operate in the hash Low Earth Orbit environment: radiations, temperature, power consumption and thermal design are the challenges to be met. The intent of this paper is to share with the readers the experience collected so far in all aspects of the 3D video production chain and to increase awareness on the unique content that we are collecting: nice stereo images from space can be used by all actors in the stereo arena to gain consensus on this powerful media. With respect to last year we shall present the progress made in the following areas: a) the satellite broadcasting live of stereo content to D-Cinema's in Europe; b) the design challenges to fly the camera outside the ISS as opposed to ERB1 that was only meant to be used in the pressurized environment of the ISS; c) on-board stereo viewing on a stereo camera has been tackled in ERB1: trade offs between OLED and LCOS display technologies shall be presented; d) HD_SDI cameras versus USB2 or Firewire; e) the hardware compression ASIC solutions used to tackle the high data rate on-board; f) 3D geometry reconstruction: first attempts in reconstructing a computer model of the interior of the ISS starting form the stereo video available.

Related URLs:
http://dx.doi.org/10.1117/12.768982

Development of a thin film solar cell interconnect for the PowerSphere concept

by on 9 June 2015in Technology Development & Demonstration No comment

Progressive development of microsatellite technologies has resulted in increased demand for lightweight electrical power subsystems including solar arrays. The use of thin film photovoltaics has been recognized as a key solution to meet the power needs. The lightweight cells can generate sufficient power and still meet critical mass requirements. Commercially available solar cells produced on lightweight substrates are being studied as an option to fulfill the power needs. The commercially available solar cells are relatively inexpensive and have a high payoff potential. Commercially available thin film solar cells are primarily being produced for terrestrial applications. The need to convert the solar cell from a terrestrial to a space compatible application is the primary challenge. Solar cell contacts, grids and interconnects need to be designed to be atomic oxygen resistant and withstand rapid thermal cycling environments. A mechanically robust solar cell interconnect is also required in order to withstand handling during fabrication and survive during launch. The need to produce the solar cell interconnects has been identified as a primary goal of the PowerSphere program and is the topic of this paper. Details of the trade study leading to the final design involving the solar cell wrap around contact, flex blanket, welding process, and frame will be presented at the conference.

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http://www.sciencedirect.com/science/article/pii/S0921510704005161

The SPHERES Navigation System: from Early Development to On-Orbit Testing

by on 9 June 2015in Technology Development & Demonstration No comment

The MIT Space Systems Laboratory has developed the Synchronized Position Hold Engage and Reorient Experimental Satellites (SPHERES) facility for the testing of formation flight and autonomous docking algorithms inside the International Space Station (ISS), in NASA's reduced gravity aircraft and in a 1-g laboratory environment. To provide SPHERES with reliable and accurate position, velocity, attitude and angular rate estimation, an innovative state estimation system based on ultrasound transmission has been developed. An extended Kalman filter (EKF) processes time-of-flight data collectedby ultrasonic receivers, as well as angular rate measurements provided by gyroscopes, to compute the state estimates required by the satellites when maneuvering. To increase the robustness of the system, the EKF has been augmented with a fault detection capability that uses the filter innovation (residual) to diagnose measurement errors. Two versions of the algorithm were successfully implemented and used on the SPHERES facility onboard the ISS during a series of five test sessions, from May 2006 to November 2006. This paper describes both versions in detail, along with di culties encountered during the implementation on the hardware and their solution. Results from experiments performed in the ISS to validate the algorithms are also presented.

Related URLs:
http://dx.doi.org/10.2514/6.2007-6354

SPHERES interact—Human–machine interaction aboard the International Space Station

by on 9 June 2015in Technology Development & Demonstration No comment

The deployment of space robots for servicing and maintenance operations that are teleoperated from the ground is a valuable addition to existing autonomous systems, because it will provide flexibility and robustness in mission operations. In this connection, not only robotic manipulators are of great use, but also free-flying inspector satellites supporting the operations through additional feedback to the ground operator. The manual control of such an inspector satellite at a remote location is challenging, because navigation in three-dimensional space is unfamiliar and large time delays can occur in the communication channel. This paper shows a series of robotic experiments, in which free flyers are controlled by astronauts aboard the International Space Station (ISS). The Synchronized Position Hold Engage Reorient Experimental Satellites (SPHERES) were utilized to study several aspects of a remotely controlled inspector satellite. The focus in this case study is investigating different approaches to human–spacecraft interaction with varying levels of autonomy under zero-gravity conditions.

Related URLs:
http://dx.doi.org/10.1002/rob.21419

SPHERES Reconfigurable Control Allocation for Autonomous Assembly

by on 9 June 2015in Technology Development & Demonstration No comment

Current research on control allocation emphasizes reconfiguration for adapting to thruster failures. However, in the application of autonomous assembly, the reconfiguration is necessitated by changing physical properties. For the scenario of an assembler tug constructing a large space structure, every docking and undocking maneuver used for the tug to move an individual payload causes a large shift in the dynamics of the tug. Not only do the mass properties change, but so does the thruster configuration. Changes in the center of mass, mass, and inertia of the tug-payload system, causes changes in the equivalent force exerted by each thruster. This paper explores reconfigurable control allocation to adapt to changes in the mass properties. Specifically considered are changes to the center of mass and thruster configuration (number, location, and active thrusters). Results are presented from the implementation of a reconfigurable control allocation algorithm on the SPHERES (Synchronized Position Hold Engage Reorient Experimental Satellites) testbed aboard the International Space Station. Results demonstrate controllability for configurations with large center of mass shifts, varying number of thrusters, as well as maintaining performance from the baseline non-reconfigurable control allocation algorithm on SPHERES.

Related URLs:
http://dx.doi.org/10.2514/6.2008-7468

Advanced ISS Air Monitoring — The ANITA and ANITA2 Missions

by on 9 June 2015in Technology Development & Demonstration No comment

After 11 months of successful operation onboard the ISS US laboratory Destiny, the air quality monitors ANITA (Analyzing Interferometer for Ambient Air) was brought back to Earth on STS126 (ULF2). ANITA is a technology demonstrator flight experiment for continuous air quality monitoring inside the crewed cabin of the ISS with low detection limits and high time resolution. For the first time, the dynamics of the detected trace gas concentrations could be directly resolved by ANITA and correlated to gas events in the cabin. The system is the result of a long term ESA technology development programme initiated more than seventeen years ago. The ANITA mission was a cooperative project between ESA and NASA. ESA's responsibilities were the provision of the H/W, the data acquisition and the data evaluation. NASA was responsible for the launch, accommodation and operation onboard ISS, data download and the transportation of ANITA back to the Earth. ANITA was calibrated to detect and quantify 30 trace gases simultaneously with down to sub-ppm (parts per million) detection limits in addition to the always present background gases carbon dioxide and water vapour. The results of the mission are summarised in [ 1 ]. Further, with a specially developed gas bag hand pump system also gas analyses were performed on air samples from Node 1 of the Space Station. ANITA is a precursor for a permanent continuous trace gas monitoring system ANITA2 for ISS and future space vehicles. At the time of the conference the follow-on study on ANITA2 will have been initiated. This paper describes the measurement system, the lessons learned during the mission on ISS, and the planned follow-on activities. The work described has been performed under contract of the European Space Agency.

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ANITA Air Monitoring on the International Space Station Part 1: The Mission

by on 9 June 2015in Technology Development & Demonstration No comment

After the launch to the International Space Station with The Space Shuttle flight STS 118 13A.1 on August 9th 2007 and the accommodation in the US lab Destiny, the air quality monitor ANITA (Analyzing Interferometer for Ambient Air) has been successfully put into operation. ANITA is a technology demonstrator flight experiment being able to continuously monitor with high time resolution the air conditions within the crewed cabins of the ISS (International Space Station). The system has its origin in a long term ESA (European Space Agency) technology development program. The ANITA mission itself is an ESA-NASA cooperative project. ESA is responsible for the provision of the HW (Hardware), the data acquisition and data evaluation. NASA's responsibilities are launch, accommodation in the US Lab Destiny, operation and data download. The ANITA air analyser is designed to detect and quantify online and with high time resolution 30 trace gases simultaneously with down to sub-ppm (parts per million) detection limits in addition to the always present background gases carbon dioxide and water vapour. The air analyser thus monitors the trace gas dynamics of the spacecraft's atmosphere in providing continuous air monitoring as well as crew warning capability in case of malfunctions. Beside continuous measurements in the vicinity of the gas monitor, air samples from remote places in the International Space Station can be analyzed using gas bags and a hand pump. However, considering the experimental character of ANITA, the measurements are not on-line visible to the Crew. ANITA is an on-orbit test experiment and a precursor for a permanent continuous trace gas monitoring system on the ISS – ANITA II. It further represents a precursor system for future air monitoring in crewed vehicles being developed for the Human Space Exploration program. This is the first paper of two describing the measurement principle, the HW and the mission on the ISS. Finally, an outlook into the future highlights the potential of the ANITA technology for the Exploration program. The work described has been performed under contract of the European Space Agency.

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Mold species in dust from the International Space Station identified and quantified by mold-specific quantitative PCR

by on 9 June 2015in Technology Development & Demonstration No comment

Dust was collected over a period of several weeks in 2007 from HEPA filters in the U.S. Laboratory Module of the International Space Station (ISS). The dust was returned on the Space Shuttle Atlantis, mixed, sieved and the DNA was extracted. Using a DNA-based method called mold-specific quantitative PCR (MSQPCR), 39 molds were measured in the dust. Potential opportunistic pathogens Aspergillus flavus and Aspergillus niger and potential moderate toxin producers Penicillium chrysogenum and Penicillium brevicompactum were noteworthy. No cells of the potential opportunistic pathogens Aspergillus fumigatus, Aspergillus terreus, Fusarium solani or Candida albicans were detected.

Related URLs:
http://www.sciencedirect.com/science/article/pii/S0923250808000892