Dextre: Improving maintenance operations on the International Space Station

The Special Purpose Dexterous Manipulator (SPDM), known as “Dextre”, is currently slated to launch in February 2008 for deployment on the International Space Station (ISS) as the final component of Canada's Mobile Servicing System (MSS). Dextre's primary role on the Space Station is to perform repair and replacement (R&R) maintenance tasks on robotically compatible hardware such as Orbital Replaceable Units (ORUs), thereby eventually easing the burden on the ISS crew.This burden on the on-orbit crew translates practically into crew time being a limited resource on the ISS, and as such, finding ways to assist the crew in performing their tasks or offloading the crew completely when appropriate is a bonus to the ISS program. This is already accomplished very effectively by commanding as many non-critical robotics tasks as possible, such as powering up and free-space maneuvering of the Space Station Remote Manipulator System (SSRMS), known as “Canadarm2”, from the Ground.Thus, beyond its primary role, and based on an increasing clarity regarding the challenges of external maintenance on the ISS, Dextre is being considered for use in a number of ways with the objective of improving ISS operations while reducing and optimizing the use of crew time through the use of ground control for various tasks, pre-positioning hardware, acting as a temporary storage platform to break an Extra Vehicular Activity (EVA) day into manageable timelines, and extending the physical reach and range of the Canadarm2.This paper discusses the planned activities and operations for Dextre an rationale for how these will help optimize the use of crew resources on the ISS.     

Canada and the International Space Station program: overview and status

The twelve months since IAF 2000 have been perhaps the most exciting, challenging and rewarding months for Canada since the beginning of our participation in the International Space Station program in 1984. The highlight was the successful launch, on-orbit check out, and the first operational use of Canadarm2, the Space Station Remote Manipulator System, between April and July 2001. The anomalies encountered and the solutions found to achieve this success are described in the paper. The paper describes, also, the substantial progress that has been made, during the twelve months since IAF 2000, by Canada as it continues to complete work on all flight-elements of its contribution to the International Space Station and as we transition into real-time Space Station operations support and Canadian utilization. Canada's contribution to the International Space Station is the Mobile Servicing System (MSS), the external robotic system that is key to the successful assembly of the Space Station, the maintenance of its external systems, astronaut EVA support, and the servicing of external science payloads. The MSS ground segment that supports MSS operations, training, sustaining engineering, and logistics activities is reaching maturity. The MSS Engineering Support Center and the MSS Sustaining Engineering Facility are providing real-time support for on-orbit operations, and a Canadian Payloads Telescience Operations Center is now in place. Mission Controllers, astronauts and cosmonauts from all Space Station Partners continue to receive training at the Canadian Space Agency. The Remote Multi Purpose Room, one element of the MSS Operations Complex, will be ready to assume backroom support in 2002. Canada has completed work on identifying its Space Station utilization activities for the period 2000 through 2004. Also during the past twelve months the CSA drafted and is proceeding with the approval of a Canadian Space Station Commercialization Policy. Canadian astronauts have now participated in three ISS assembly missions--Julie Payette on STS-96, Marc Garneau on STS-97, and Chris Hadfield on STS-100 in April 2001 during which he performed Canada's first EVA and the successful installation of the Space Station Remote Manipulator System.     

Analytical and semi-analytical inverse kinematics of SSRMS-type manipulators with single joint locked failure

Redundant space manipulators, including Space Station Remote Manipulator System (SSRMS), Special Purpose Dexterous Manipulator (SPDM) and European Robotic Arm (ERA), have been playing important roles in the construction and maintenance of International Space Station (ISS). They all have 7 revolute joints arranged in similar configurations, and are referred to as SSRMS-type manipulators.     

Identification and status of design improvements to the NASA Shuttle EMU for International Space Station application

To meet the significant increase in EVA demand to support assembly and operations of the International Space Station (ISS), NASA and industry have improved the current Shuttle Extravehicular Mobility Unit (EMU), or "space suit", configuration to meet the unique and specific requirements of an orbital-based system. The current Shuttle EMU was designed to be maintained and serviced on the ground between frequent Shuttle flights. ISS will require the EMUs to meet increased EVAs out of the Shuttle Orbiter and to remain on orbit for up to 180 days without need for regular return to Earth for scheduled maintenance or refurbishment. Ongoing Shuttle EMU improvements have increased reliability, operational life and performance while minimizing ground and on-orbit maintenance cost and expendable inventory. Modifications to both the anthropomorphic mobility elements of the Space Suit Assembly (SSA) as well as to the Primary Life Support System (PLSS) are identified and discussed. This paper also addresses the status of on-going Shuttle EMU improvements and summarizes the approach for increasing interoperability of the U.S. and Russian space suits to be utilized aboard the ISS.     

The Special Purpose Dexterous Manipulator (SPDM) Systems Engineering Effort – A successful exercise in cheaper,faster and (hopefully) better systems engineering

The Special Purpose Dexterous Manipulator (SPDM) is the latest Space Robot developed by the Canadian Space Agency (CSA) and McDonald Detwiller Space and Advanced Robotics (MD Robotics, previously Spar Aerospace) for the International Space Station (ISS). The SPDM has presented its designers with a number of new challenges in performing the Systems Engineering effort required for a complex robotic system:(1) The SPDM initial design was started and attained various levels of maturity for various components under the Space Station Freedom environment, then the Program was stopped and finally restarted under the harsher environment in which the International Space Station is being built.(2) The SPDM is the first space robot to utilize previously developed and space certified robotic components, as well as components with high-commonality to the previously developed ones (electronics, S/W).(3) New requirements levied by the Customer during the negotiations leading to the Program re-start necessitated significant architectural changes versus the SPDM configuration `frozen' when the Program was shut down.(4) The SPDM is the first robotic system of this complexity that is being built under a Firm Fixed Price contract, with the commonality assumptions as one of the cost drivers.This combination of components of various pedigree, coupled with the constraints imposed by an FFP contract have been addressed by the designers through the definition of a novel approach to integrated Systems and Design Engineering.     

Ground and on-orbit command and data handling architectures for the Active Rack Isolation System microgravity flight experiment

The Active Rack Isolation System [ARIS] International Space Station [ISS] Characterization Experiment, or ARIS-ICE for short, is a long duration microgravity characterization experiment aboard the ISS. The objective of the experiment is to fully characterize active microgravity performance of the first ARIS rack deployed on the ISS. Efficient ground and on-orbit command and data handling [C&DH] segments are the crux in achieving the challenging objectives of the mission. The objective of the paper is to provide an overview of the C&DH architectures developed for ARIS-ICE, with the view that these architectures may serve as a model for future ISS microgravity payloads. Both ground and on-orbit segments, and their interaction with corresponding ISS C&DH systems are presented. The heart of the on-orbit segment is the ARIS-ICE Payload On-orbit Processor, ARIS-ICE POP for short. The POP manages communication with the ISS C&DH system and other ISS subsystems and payloads, enables automation of test/data collection sequences, and provides a wide range of utilities such as efficient file downlinks/uplinks, data post-processing, data compression and data storage. The hardware and software architecture of the POP is presented and it is shown that the built-in functionality helps to dramatically streamline the efficiency of on-orbit operations. The ground segment has at its heart special ARIS-ICE Ground Support Equipment [GSE] software developed for the experiment. The software enables efficient command and file uplinks, and reconstruction and display of science telemetry packets. The GSE software architecture is discussed along with its interactions with ISS ground C&DH elements. A test sequence example is used to demonstrate the interplay between the ground and on-orbit segments.     

Ground based ISS payload microgravity disturbance assessments

In order to verify that the International Space Station (ISS) payload facility racks do not disturb the microgravity environment of neighboring facility racks and that the facility science operations are not compromised, a testing and analytical verification process must be followed. Currently no facility racks have taken this process from start to finish. The authors are participants in implementing this process for the NASA Glenn Research Center (GRC) Fluids and Combustion Facility (FCF). To address the testing part of the verification process, the Microgravity Emissions Laboratory (MEL) was developed at GRC. The MEL is a 6 degree of freedom inertial measurement system capable of characterizing inertial response forces (emissions) of components, sub-rack payloads, or rack-level payloads down to 10(-7) g's. The inertial force output data, generated from the steady state or transient operations of the test articles, are utilized in analytical simulations to predict the on-orbit vibratory environment at specific science or rack interface locations. Once the facility payload rack and disturbers are properly modeled an assessment can be made as to whether required microgravity levels are achieved. The modeling is utilized to develop microgravity predictions which lead to the development of microgravity sensitive ISS experiment operations once on-orbit. The on-orbit measurements will be verified by use of the NASA GRC Space Acceleration Measurement System (SAMS). The major topics to be addressed in this paper are: (1) Microgravity Requirements, (2) Microgravity Disturbers, (3) MEL Testing, (4) Disturbance Control, (5) Microgravity Control Process, and (6) On-Orbit Predictions and Verification.     

Hardware/software integration & verification for the mobile servicing system of the international space station

The system architecture of the Mobile Service System (MSS) forms an integral part of the architecture of the International Space Station (ISS) in which elements interact through data components controlled by their respective element software. Tne element developers produce software components which, subsequent to being validated on their respective elements, are integrated and verified in test environments which are representative of the integrated MSS/ISS system. This is the classical method for integration and verification. If program software requirements are, for various reasons, slow to finalize, the software development process starts later than anticipated, and following the classical development/verification processes, could put the scheduled software deliveries at risk. A new approach to development and verification is needed which must encompass the entire software program from component unit software to fully integrated system software. This paper describes the approach which was taken to perform system hardware/software integration and verification with software components which were essentially incomplete, but were developed in a phased fashion, having mutually compatible functionality. The paper describes the MSS and ISS system architecture, the various software components and an overview of the original integration and verification plan. The paper will then describe the new integration approach which was developed, and discuss the evolution of the various software components in terms of functionality and their phased integration into a system. The paper will conclude by providing a summary of the results of the integration and verification activities, and demonstrate how delivery schedules for the integrated system software were met.     

Human and robotic repair of a solar array wing during ISS assembly mission 10A

With the installation of a new module and the relocation of three other modules, including multiple hand-offs from the station arm (SSRMS) to the shuttle arm (SRMS), International Space Station (ISS) assembly mission 10A/STS-120 was anticipated to be one of the most complicated ISS assembly missions ever attempted. The assembly operations became even more complex when a solar array wing (SAW) on the relocated Port-6 (P6) truss segment ripped while being extended. Repairing the torn SAW became the single most important objective for the remainder of STS-120, with future ISS assembly missions threatened by reduced power generation capacity if the SAW could not be repaired. Precise coordination between the space shuttle and ISS robotics teams led to an operational concept that combined the capabilities of the SRMS and SSRMS robotic systems in ways far beyond their original design capacities. Benefits of consistent standards for ISS robotic interfaces have been previously identified, but the advantages of having two such versatile and compatible robotic systems have never been quite so spectacular. This paper describes the role of robotics in the emergency SAW repair and highlights how versatility within space robotics systems can allow operations far beyond the intended design scenarios.     

Human and robotic repair of a solar array wing during ISS assembly mission 10A

With the installation of a new module and the relocation of three other modules, including multiple hand-offs from the station arm (SSRMS) to the shuttle arm (SRMS), International Space Station (ISS) assembly mission 10A/STS-120 was anticipated to be one of the most complicated ISS assembly missions ever attempted. The assembly operations became even more complex when a solar array wing (SAW) on the relocated Port-6 (P6) truss segment ripped while being extended. Repairing the torn SAW became the single most important objective for the remainder of STS-120, with future ISS assembly missions threatened by reduced power generation capacity if the SAW could not be repaired. Precise coordination between the space shuttle and ISS robotics teams led to an operational concept that combined the capabilities of the SRMS and SSRMS robotic systems in ways far beyond their original design capacities. Benefits of consistent standards for ISS robotic interfaces have been previously identified, but the advantages of having two such versatile and compatible robotic systems have never been quite so spectacular. This paper describes the role of robotics in the emergency SAW repair and highlights how versatility within space robotics systems can allow operations far beyond the intended design scenarios.     

EVA worksite analysis—Use of computer analysis for EVA operations development and execution

To sustain the rate of extravehicular activity (EVA) required to assemble and maintain the International Space Station, we must enhance our ability to plan, train for, and execute EVAs. An underlying analysis capability has been developed to ensure EVA access to all external worksites as a starting point for ground training, to generate information needed for on-orbit training, and to react quickly to develop contingency EVA plans, techniques, and procedures. This paper describes the use of computer-based EVA worksite analysis techniques for EVA worksite design. EVA worksite analysis has been used to design 80% of EVA worksites on the U.S. portion of the International Space Station. With the launch of the first U.S. element of the station, EVA worksite analysis is being developed further to support real-time analysis of unplanned EVA operations. This paper describes this development and deployment of EVA worksite analysis for International Space Station (ISS) mission support.     

International space station: : Ready to fly

The International Space Station (ISS) is no longer a paper program, focused on design, development and planning. It is an operational program, with hardware soon to be launched and ground systems in place. Additional modules, components and elements are now under construction in almost all of the 16 ISS International Partner and Participant countries, with metal being bent, software being written, and testing ongoing. Crew members for the first four crews are in training in the U.S. and Russia, with the first crew launching in mid 1999. Mission control centers are fully functioning in Houston and Moscow, with operations centers in St. Hubert, Darmstadt, Tsukuba, Turino, and Huntsville going on line as they are required.

The International Space Station, as the largest international civil program in history, features unprecedented technical, managerial, and international complexity. Seven international partners and participants encompassing 15 countries are involved in the ISS. Each partner is contributing and will be operating separate pieces of hardware, to be integrated on-orbit into a single orbital station. Mission control centers, launch vehicles, astronauts/cosmonauts, and support services will be provided by partners across the globe, but must function in a coordinated, integrated fashion. This paper will review the accomplishments of the ISS Program and each of the Partners and Participants over the past year, focusing on completed milestones and hardware. It will also give a status report on the development of the remainder of the ISS modules and components by each Partner and Participant, and discuss upcoming challenges.     

The International Space Station human life sciences experiment implementation process.

The selection, definition, and development phases of a Life Sciences flight research experiment has been consistent throughout the past decade. The implementation process, however, has changed significantly within the past two years. This change is driven primarily by the shift from highly integrated, dedicated research missions on platforms with well defined processes to self contained experiments with stand alone operations on platforms which are being concurrently designed. For experiments manifested on the International Space Station (ISS) and/or on short duration missions, the more modular, streamlined, and independent the individual experiment is, the more likely it is to be successfully implemented before the ISS assembly is completed. During the assembly phase of the ISS, science operations are lower in priority than the construction of the station. After the station has been completed, it is expected that more resources will be available to perform research. The complexity of implementing investigations increases with the logistics needed to perform the experiment. Examples of logistics issues include- hardware unique to the experiment; large up and down mass and volume needs; access to crew and hardware during the ascent or descent phases; maintenance of hardware and supplies with a limited shelf life,- baseline data collection schedules with lengthy sessions or sessions close to the launch or landing; onboard stowage availability, particularly cold stowage; and extensive training where highly proficient skills must be maintained. As the ISS processes become better defined, experiment implementation will meet new challenges due to distributed management, on-orbit resource sharing, and adjustments to crew availability pre- and post-increment.     

Preparing EMU for Space Station

In today's fiscally constrained environment, it can be expected that systems designed for one space program will increasingly be used to support other programs. The example of the U.S. extravehicular mobility unit (EMU), designed for use with the Space Shuttle, and now part of the baseline for the International Space Station (ISS) program, illustrates the adaption process. Certifying the Shuttle's EMU for use aboard ISS requires addressing three fundamental issues: Identifying new ISS requirements to be imposed on the EMU. Extending Shuttle's EMU on-orbit service interval to meet ISS's longer missions. Certifying Shuttle's EMU to meet new environments unique to ISS. Upon completion of the certification process, Shuttle's EMU will meet all requirements for supporting both the Shuttle and ISS program. This paper discusses the processes for addressing these issues and progress to date in achieving resolution.     

Research progress and accomplishments on International Space Station

The first research payloads reached the International Space Station (ISS) more than two years ago, with research operating continuously since March 2001. Seven research racks are currently on-orbit, with three more arriving soon to expand science capabilities. Through the first five expeditions, 60 unique NASA-managed investigations from 11 nations have been supported, many continuing into later missions. More than 90,000 experiment hours have been completed, and more than 1,000 hours of crew time have been dedicated to research, numbers that grow daily. The multidisciplinary program includes research in life sciences, physical sciences, biotechnology, Earth sciences, technology demonstrations as well as commercial endeavors and educational activities. The Payload Operations and Integration Center monitors the onboard activities around the clock, working with numerous Principal Investigators and Payload Developers at their remote sites. Future years will see expansion of the station with research modules provided by the European Space Agency and Japan, which will be outfitted with additional research racks.     

The European Astronaut Centre prepares for International Space Station operations

The European Space Agency (ESA) contribution to the International Space Station (ISS) goes much beyond the delivery of hardware like the Columbus Laboratory, its payloads and the Automated Transfer Vehicles. ESA Astronauts will be members of the ISS crew. ESA, according to its commitments as ISS international partner, will be responsible to provide training on its elements and payloads to all ISS crewmembers and medical support for ESA astronauts. The European Astronaut Centre (EAC) in Cologne has developed over more than a decade into the centre of expertise for manned space activities within ESA by contributing to a number of important co-operative spaceflight missions. This role will be significantly extended for ISS manned operations. Apart from its support to ESA astronauts and their onboard operations, EAC will have a key role in training all ISS astronauts on ESA elements and payloads. The medical support of ISS crew, in particular of ESA astronauts has already started. This paper provides an overview on status and further plans in building up this homebase function for ESA astronauts and on the preparation towards Training Readiness for ISS crew training at EAC, Cologne. Copyright 2001 by the European Space Agency. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. Released to IAF/IAA/AIAA to publish in all forms.     

Space station MMOD shielding

This paper describes the International Space Station (ISS) micro-meteoroid orbital debris (MMOD) impact shielding including the requirements for protection as well as technical approaches to meeting the requirements. Current activities in providing MMOD protection for ISS are described, including efforts to augment MMOD protection by adding shields on-orbit. Another activity is to observe MMOD impact damage on ISS elements and returned hardware, and to compare the observed damage with predicted damage using Bumper code risk assessment software. A conclusion of this paper is that ISS will be protected adequately from MMOD impact after completing augmentation of ISS shielding for service module, and after improving MMOD protection for Soyuz and Progress vehicles. Another conclusion is that impact damage observed to the ISS mini-pressurized logistics module matches the distribution of impacts predicted by Bumper code.     

Adaptive environmental control for optimal results during plant microgravity experiments

The SVET Space Greenhouse (SG)--the first and the only automated plant growth facility onboard the MIR Space Station in the period 1990-2000 was developed on a Russian-Bulgarian Project in the 80s. The aim was to study plant growth under microgravity in order to include plants as a link of future Biological Life Support Systems for the long-term manned space missions. An American developed Gas Exchange Measurement System (GEMS) was added to the existing SVET SG equipment in 1995 to monitor more environmental and physiological parameters. A lot of long-duration plant flight experiments were carried out in the SVET+GEMS. They led to significant results in the Fundamental Gravitational Biology field--second-generation wheat seeds were produced in the conditions of microgravity. The new International Space Station (ISS) will provide a perfect opportunity for conducting full life cycle plant experiments in microgravity, including measurement of more vital plant parameters, during the next 15-20 years. Nowadays plant growth facilities for scientific research based on the SVET SG functional principles are developed for the ISS by different countries (Russia, USA, Italy, Japan, etc.). A new Concept for an advanced SVET-3 Space Greenhouse for the ISS, based on the Bulgarian experience and "know-how" is described. The absolute and differential plant chamber air parameters and some plant physiological parameters are measured and processed in real time. Using the transpiration and photosynthesis measurement data the Control Unit evaluates the plant status and performs adaptive environmental control in order to provide the most favorable conditions for plant growth at every stage of plant development in experiments. A conceptual block-diagram of the SVET-3 SG is presented.     

Open for business: a new approach to commercialisation of the International Space Station

The International Space Station (ISS) is the result of collaboration between 15 countries [Inter-Governmental Agreement (IGA) between the Governments of Canada, the United States of America, Japan, Russia and ESA member States, concerning co-operation on the civil International Space Station, 1998]. Originally planned as a scientific facility, a shift in policy of the partners has recently occurred towards commercialisation of the Station. This article is a response to this policy shift. Based on a report prepared by a Master of Space Studies class at ISU, it set outs to identify the major constraints in which the potential commercial user must operate and proposes solutions for both commercial user and the partner space agencies to facilitate this commercialisation process. At a time when spacefaring nations face reduced fiscal resources and increasing pressure from their constituencies to justify the huge costs of the ISS, commercialising utilisation seems a logical solution. Clearly, successful commercialisation can help recover some of the development and operating costs of the ISS. The structure of the article is divided into two main parts. The first part proposes new solutions to existing constraint to ISS commercialisation in areas of policy, law, technology and business. Its conclusions are integrated and unified into A New Approach towards ISS commercialisation. This approach is then applied in part two to two case studies: the International Space Satellite Servicing Station (I4S) and protein crystallisation. The article then concludes with a recommended approach to the future of ISS commercialisation.