A set of tools was developed in the frame of ESA ac tivity (18191/04/NL) labelled RCET (Mars Rove... more A set of tools was developed in the frame of ESA ac tivity (18191/04/NL) labelled RCET (Mars Rover Chas sis Evaluation Tools) to support design, selection and optimisation of space exploration rovers. This acti vity was carried out jointly by Contraves Space as prime contractor, ETHZ, DLR, SSC and EADS Space Transportation. This paper describes the utilisation of the RCET in the contex t of a rover mission on Mars. The evaluation of the NASA MER and RCL-E rover chassis was done and the results are pr esented. This study includes wheel design optimisat ion on a particular soil, simulation of rover suspensions an d rover comparison based on normalisation rules. Wi th the experience gained in this study, a strategy for pre dicting locomotion performances was developed that allows an optimisation of both chassis configuration and moti on control. The facilities and methodology used in the frame of this activity for validating the tools is also briefly presented.
DOAJ (DOAJ: Directory of Open Access Journals), Nov 1, 2008
In this third of three short papers, I introduce some of the basic concepts of planetary rovers w... more In this third of three short papers, I introduce some of the basic concepts of planetary rovers with an emphasis on some specific challenging areas of research that are peculiar to planetary robotics and not usually associated with terrestrial mobile robotics. The style of these short papers is pedagogical and this paper stresses the issue of rover-terrain interaction as an important consideration. Soil-vehicle interaction originates from military vehicle research but may be regarded as part of the dynamical approach to mobile robotics. For hostile planetary surfaces, this is essential in order to design a robotic rover with sufficient tractive capability to traverse planetary surfaces.
We are developing a microwave investment casting process as a means of fabricating magnetron part... more We are developing a microwave investment casting process as a means of fabricating magnetron parts using lunar resources. Since a magnetron is the core part of a microwave oven, this work is the first step towards a self-replicating fabricator. Resources available on the moon are used wherever possible at each stage of the process, so this work also paves the way for development of an entire lunar infrastructure from a single seed fabrication unit. Magnetrons also have potential for other components of lunar and space infrastructure: they demonstrate the potential for vacuum tube electronics for rad-hard systems and could be used as microwave generators for solar power satellites. Our microwave investment casting process comprises four steps: 1) 3D printing of a 'positive' of the part, 2) encapsulation of the positive in a silicon carbide and calcium-aluminate based hydraulic cement mould, 3) removal of the positive, and 4) microwave casting, using either metal powders/solid charges, metal oxide with carbon as a reducing agent, or precursors to ferrite magnetic materials. 3D printing of the positives allows for flexibility in part shaping. The positive material is not of great consequence so long as it is water resistant - we have used positives of polylactic acid (PLA) and polyvinyl alcohol (PVA) (in spite of its water solubility), while spirulina positives were also used with early cement mixes. Positives are vibration set into the cement. After the cement cures, they are either burned out (spirulina, PLA) or dissolved in water (PVA). Powdered metal (or other material) is then poured into the cavity (which includes additional 'crucible' volume for shrinkage as required), and the filled mould is fired in a conventional home microwave oven. To date ingots of copper, iron, nickel, cobalt, and copper-nickel-iron have been successfully cast, with no apparent porosity, while attempts with aluminium, barium ferrite, and strontium ferrite have been unsuccessful. This has demonstrated the principle of casting metal magnetron parts in 3D print-formed moulds. This technology looks promising for application on the Moon in extending 3D printing beyond regolith processing to a wide range of in-situ sourced metals
This paper presents a novel artificial neural network approach for estimating regolith parameters... more This paper presents a novel artificial neural network approach for estimating regolith parameters and producing mobility metrics. We present an approach which acts as an enabling technology for all future rover missions. Regolith parameters in influence the performance of all ground rovers. Martian regolith is mostly sand; local variations in composition are unknown. Current approaches to regolith parameter estimation depend on stereo vision, laser measurements and kinematic models. The Canadian analogue micro rover, Kapvik, has an instrumented chassis to provide feedback information such as wheel load, wheel slip and wheel torque. The regolith parameters are estimated online during the rover's traverse. These estimated parameters are fed into a traction control system to improve the rover performance and reduce power consumption. A rover may create a mobility map based on metrics derived from the chassis measurements.
Water vapor plumes emanating from the geyser vents at Enceladus’s south pole area invite the poss... more Water vapor plumes emanating from the geyser vents at Enceladus’s south pole area invite the possibility of direct access to the subsurface liquid reservoir to acquire pristine biological material ...
57th International Astronautical Congress, Oct 2, 2006
SSTL has been studying the application of its highly successful Low Earth Orbit micro and mini-sa... more SSTL has been studying the application of its highly successful Low Earth Orbit micro and mini-satellites for lunar and planetary missions since 1996, through in-house funded design exercises and supported by ESA through Lunar and inner planet mission studies. Technical feasibility of a minisatellite lunar orbiter has been demonstrated. SSTL has since developed a range of improved subsystems and more advanced platforms, many of which have gained heritage in-orbit. These include the GMP-MiniSat platform with deployable solar arrays, accurate 3-axis stabilized attitude control, high resolution and wide field-of-view multispectral cameras and low cost bipropellant propulsion systems. Low cost launch options range from a Proton auxiliary payload launch direct to geostationary orbit, to prime passenger on a PSLV, to secondary payload alongside larger lunar missions. While SSTL is focused on low cost lunar orbiter development, it is jointly considering affordable means of conducting lunar landing, and ultimately sample return with the University of Surrey Space Centre. Lunar landing and sample return would demonstrate the applicability of low-cost small spacecraft technology to reduce the risk of high profile and barely affordable missions such as Mars Sample Return, by demonstrating key technologies, offering secondary science, and increased mission frequency to build enthusiastic public and political support. A parametric study for a lunar sample return mission from the south polar Aitken basin is highlighted, which has shown that a 15kg rover can in principle be landed on the lunar surface for a maximum surface stay of 150hours, subsequently returning a 200g sample to Earth, for a total launch mass from Earth orbit of less than 500kg, using a mixture of chemical and electric propulsion. This paper briefly considers the technology requirements and COTS technology availability for the separate mission stages, in order to establish how SSTL's low cost approach may be applicable to this challenging mission. This study is an ongoing area of research between SSTL and the University of Surrey Space centre.
International Conference on Robotics and Automation, Nov 28, 2006
A set of tools was developed in the frame of ESA activity [18191/04/NL] labelled RCET (Mars Rover... more A set of tools was developed in the frame of ESA activity [18191/04/NL] labelled RCET (Mars Rover Chassis Evaluation Tools) to support design, selection and optimisation of space exploration rovers. This activity was carried out jointly by Contraves Space as prime contractor, ETHZ, DLR, SSC and EADS Space Transportation. This paper describes the utilisation of the RCET in the context of a rover mission on Mars. The evaluation of the NASA MER and RCL-E rover chassis was done and the results are presented. This study includes wheel design optimisation on a particular soil, simulation of rover suspensions and rover comparison based on normalisation rules. With the experience gained in this study, a strategy for predicting locomotion performances was developed that allows an optimisation of both chassis configuration and motion control. The facilities and methodology used in the frame of this activity for validating the tools is also briefly presented.
The icy moon of the solar system signifies the most auspicious targets for astrobiological explor... more The icy moon of the solar system signifies the most auspicious targets for astrobiological exploration. Direct access to the geyser vents of Enceladus would be highly desirable to acquire pristine biological samples. Over the past few decades irrespective of multiple orbital and lander mission still relatively not much is known about the microbial presence and the biological composition. We have investigated the possibility of deploying penetrators to Enceladus to target the geyser vents to gain access to pristine or near-pristine subsurface samples. Penetrators are small missile type entry descent and landing vehicles that can carry modest scientific instruments capable of withstanding impact into the subsurface. The instrumentation used for any biochemical analysis on astrobiological bodies such as Enceladus should perform experiments with extreme precision and sensitivity such that it does not contaminate the sample and at the same time depict the results with high throughput. We have examined a subset of instruments that might be deployed on a penetrator based on current work in developing an astrobiological suite of a robotic instrument for Mars Rover deployment comprising a micro-assay and a nanopore instrument that works on extreme environments. For the microfluidics, we have explored to minimize the sample pre-processing required for the instruments and tested the microfluidic system which could perform experimentations that might detect life from the environmental sample collected from the Mars analogue sites. Here we describe a fully automated microfluidic device capable of performing end-to-end analyses of DNA/RNA preparation and sequencing by using microbial activity micro-assay (µ-MAMA) and oxford nanopore instruments. The system integrates an array of solenoid valves, peristaltic pumps and membrane filters for autonomous fluidic routing through the channels. The use of such an integrated device dramatically reduces the analysis time, reagent consumption, costs and overall mass of the subsystem. This miniaturized and sophisticated astrobiological instrument suite offers high potential for astrobiological prospecting in a highly challenging environment including Europa
International Journal of Astrobiology, Aug 1, 2022
In the early 1980s, Carl Sagan and Frank Tipler published a series of articles in the pages of th... more In the early 1980s, Carl Sagan and Frank Tipler published a series of articles in the pages of the Quarterly Journal of the Royal Astronomical Society on ETI that became a cause celebre at the time. Whilst reading for an MSc in Astronomy at the University of Sussex in the early 1990s, I expressed my interest in SETI as a staunch Saganite (influenced not only by the phenomenal Cosmos TV series, recently revamped by Neil de Grasse Tyson, but also by Sagan's preceding Royal Institution Christmas lecture series) to Professor John Barrow who introduced me to the relevant chapter in the book The Anthropic Cosmological Principle that he co-authored with Frank Tipler (I still recommend the entire book for its visionary scope). I immediately went to source material and was struck by the von Neumann or self-replicating probe concept under discussion (I shall use the latter term to avoid conflation with von Neumann machine which has a well-established meaning in computer engineering). This was my road to Damascus in converting me from ETI believer to skeptic (but by the power of scientific argument rather than any epiphany). Thence, I decided to pursue a PhD in space engineering specialising in space robotics (though my research project was rather more mundane than self-replicating probes). Yet, despite its foundational importance, the Sagan-Tipler debate is almost forgotten today despite the fact that it exposes the root-and-branch of the SETI venture. However, every now and then, there is still the occasional paper on self-replicating probes but they appear to be sidestream to the SETI programme. This special issue seeks to re-focus the self-replicating probe back into the SETI mainstream where it belongs. There are four papers in this special issue. Dobler's (2022) paper provides the ideal contextual discussion of the Fermi paradox that extant ETI are not here now. He suggests that any optimistic interpretation must accept that there must be a low probability of contact and that this state of affairs shall continue. He suggests that, although no one explanation can account for the Fermi paradox, perhaps a suite of explanations applicable to different categories of ETI are sufficient to cover the universality of the problem. And this will remain so. This is reminiscent of the "wedges" approach to combatting climate change (Pacala & Solow 2004). It does require that the explanatory wedges, even if they shift their weightings over time due to dynamic factors, must retain their universal coverage of non-contact. Nevertheless, from an instrumental viewpoint, this differs not from the assertion that ETI do not exist as Dobler (2022) points out. Only stable factors such as implausibility of interstellar travel are universal enough to account for the existence of ETI with the persistent lack of evidence. This dovetails neatly into Matloff's (2022) paper who addresses issues associated with the selfreplicating probes including propulsion for interstellar flight. He analyses several plausible options of increasingly technological sophistication. The use of gravity assists, be they unpowered or powered, is well-established but such methods yield extremely long interstellar transmit times ∼10 3-10 4 y/ly. Such probes would almost certainly be overtaken by more advanced probes within the next century. Various forms of nuclear propulsion were considered to improve performance and reduce flight times to ∼1000 y/ly. Propellantless sails were also considered to offer similar performance.
Most additive manufacturing (referred to as 3D printing henceforth) is applied to the creation of... more Most additive manufacturing (referred to as 3D printing henceforth) is applied to the creation of static structures. This severely restricts the scope of 3D printing techniques. To be sure, 3D printing can build structures in many different materials including plastics, metals and ceramics. This severely Nevertheless, monolithic structures are the rule of the day and the prospect of 3D-printed multi-material structures are still a research problem. In this paper, we look further to expanding the capabilities of 3D printing to manufacturing full mechatronic systems - specifically electric motor and their supporting electronics. We have taken preliminary steps towards this goal presented here - if fully successful, it will demonstrate that additive manufacturing constitutes a universal constructor in the von Neumann sense.
International Journal of Advanced Robotic Systems, Dec 1, 2005
Due to ultraviolet flux in the surface layers of most solar bodies, future astrobiological resear... more Due to ultraviolet flux in the surface layers of most solar bodies, future astrobiological research is increasingly seeking to conduct subsurface penetration and drilling to detect chemical signature for extant or extinct life. To address this issue, we present a micro-penetrator concept (mass < 10 kg) that is suited for extraterrestrial planetary deployment and in situ investigation of chemical and physical properties. The instrumentation in this concept is a bio-inspired drill to access material beneath sterile surface layer for biomarker detection. The proposed drill represents a novel concept of two-valve-reciprocating motion, inspired by the working mechanism of wood wasp ovipositors. It is lightweight (0.5 kg), driven at low power (3 W), and able to drill deep (1-2 m). Tests have shown that the reciprocating drill is feasible and has potential of improving drill efficiency without using any external force. The overall penetration system provides a small, light and energy efficient solution to in situ astrobiological studies, which is crucial for space engineering. Such a micro-penetrator can be used for exploration of terrestrial-type planets or other small bodies of the solar system with the minimum of modifications.
All space missions involve the control of mission operations from a ground station mediated throu... more All space missions involve the control of mission operations from a ground station mediated through a communications channel. Rover missions are no exception. For planetary missions, important constraints are imposed by the nature of the terrain, limited amount of energy available, limited computational resources, limited communication with human operators, and the nature of scientific targets and their location. Fully autonomous control through autonomous task planning is not yet conceivable nor, indeed, is it desirable—there will always be a need for human supervision.
Sustainability requires accessibility to material and energy resources with large reserves. We pr... more Sustainability requires accessibility to material and energy resources with large reserves. We propose that effectively inexhaustible reserves are available from the extraterrestrial environment (specifically, the Moon) and that they can be accessed at low cost. The key to low cost is in the realization of a self-replicating machine which amortises initial capital investment through exponential growth in productive capacity. This self-replicating machine must leverage itself from available lunar resources by expanding its population until sufficient productive capacity is attained to robotically construct solar power satellites to provision Earth with clean energy from space. We describe current work in developing the major parts of a self-replicating machine to enable leveraging of such extraterrestrial resources (energy and material) for a sustainable Earth.
International Journal of Advanced Robotic Systems, Sep 1, 2017
A classifier training methodology is presented for Kapvik, a micro-rover prototype. A simulated l... more A classifier training methodology is presented for Kapvik, a micro-rover prototype. A simulated light detection and ranging scan is divided into a grid, with each cell having a variety of characteristics (such as number of points, point variance and mean height) which act as inputs to classification algorithms. The training step avoids the need for time-consuming and error-prone manual classification through the use of a simulation that provides training inputs and target outputs. This simulation generates various terrains that could be encountered by a planetary rover, including untraversable ones, in a random fashion. A sensor model for a three-dimensional light detection and ranging is used with ray tracing to generate realistic noisy three-dimensional point clouds where all points that belong to untraversable terrain are labelled explicitly. A neural network classifier and its training algorithm are presented, and the results of its output as well as other popular classifiers show high accuracy on test data sets after training. The network is then tested on outdoor data to confirm it can accurately classify real-world light detection and ranging data. The results show the network is able to identify terrain correctly, falsely classifying just 4.74% of untraversable terrain.
A set of tools was developed in the frame of ESA ac tivity (18191/04/NL) labelled RCET (Mars Rove... more A set of tools was developed in the frame of ESA ac tivity (18191/04/NL) labelled RCET (Mars Rover Chas sis Evaluation Tools) to support design, selection and optimisation of space exploration rovers. This acti vity was carried out jointly by Contraves Space as prime contractor, ETHZ, DLR, SSC and EADS Space Transportation. This paper describes the utilisation of the RCET in the contex t of a rover mission on Mars. The evaluation of the NASA MER and RCL-E rover chassis was done and the results are pr esented. This study includes wheel design optimisat ion on a particular soil, simulation of rover suspensions an d rover comparison based on normalisation rules. Wi th the experience gained in this study, a strategy for pre dicting locomotion performances was developed that allows an optimisation of both chassis configuration and moti on control. The facilities and methodology used in the frame of this activity for validating the tools is also briefly presented.
DOAJ (DOAJ: Directory of Open Access Journals), Nov 1, 2008
In this third of three short papers, I introduce some of the basic concepts of planetary rovers w... more In this third of three short papers, I introduce some of the basic concepts of planetary rovers with an emphasis on some specific challenging areas of research that are peculiar to planetary robotics and not usually associated with terrestrial mobile robotics. The style of these short papers is pedagogical and this paper stresses the issue of rover-terrain interaction as an important consideration. Soil-vehicle interaction originates from military vehicle research but may be regarded as part of the dynamical approach to mobile robotics. For hostile planetary surfaces, this is essential in order to design a robotic rover with sufficient tractive capability to traverse planetary surfaces.
We are developing a microwave investment casting process as a means of fabricating magnetron part... more We are developing a microwave investment casting process as a means of fabricating magnetron parts using lunar resources. Since a magnetron is the core part of a microwave oven, this work is the first step towards a self-replicating fabricator. Resources available on the moon are used wherever possible at each stage of the process, so this work also paves the way for development of an entire lunar infrastructure from a single seed fabrication unit. Magnetrons also have potential for other components of lunar and space infrastructure: they demonstrate the potential for vacuum tube electronics for rad-hard systems and could be used as microwave generators for solar power satellites. Our microwave investment casting process comprises four steps: 1) 3D printing of a 'positive' of the part, 2) encapsulation of the positive in a silicon carbide and calcium-aluminate based hydraulic cement mould, 3) removal of the positive, and 4) microwave casting, using either metal powders/solid charges, metal oxide with carbon as a reducing agent, or precursors to ferrite magnetic materials. 3D printing of the positives allows for flexibility in part shaping. The positive material is not of great consequence so long as it is water resistant - we have used positives of polylactic acid (PLA) and polyvinyl alcohol (PVA) (in spite of its water solubility), while spirulina positives were also used with early cement mixes. Positives are vibration set into the cement. After the cement cures, they are either burned out (spirulina, PLA) or dissolved in water (PVA). Powdered metal (or other material) is then poured into the cavity (which includes additional 'crucible' volume for shrinkage as required), and the filled mould is fired in a conventional home microwave oven. To date ingots of copper, iron, nickel, cobalt, and copper-nickel-iron have been successfully cast, with no apparent porosity, while attempts with aluminium, barium ferrite, and strontium ferrite have been unsuccessful. This has demonstrated the principle of casting metal magnetron parts in 3D print-formed moulds. This technology looks promising for application on the Moon in extending 3D printing beyond regolith processing to a wide range of in-situ sourced metals
This paper presents a novel artificial neural network approach for estimating regolith parameters... more This paper presents a novel artificial neural network approach for estimating regolith parameters and producing mobility metrics. We present an approach which acts as an enabling technology for all future rover missions. Regolith parameters in influence the performance of all ground rovers. Martian regolith is mostly sand; local variations in composition are unknown. Current approaches to regolith parameter estimation depend on stereo vision, laser measurements and kinematic models. The Canadian analogue micro rover, Kapvik, has an instrumented chassis to provide feedback information such as wheel load, wheel slip and wheel torque. The regolith parameters are estimated online during the rover's traverse. These estimated parameters are fed into a traction control system to improve the rover performance and reduce power consumption. A rover may create a mobility map based on metrics derived from the chassis measurements.
Water vapor plumes emanating from the geyser vents at Enceladus’s south pole area invite the poss... more Water vapor plumes emanating from the geyser vents at Enceladus’s south pole area invite the possibility of direct access to the subsurface liquid reservoir to acquire pristine biological material ...
57th International Astronautical Congress, Oct 2, 2006
SSTL has been studying the application of its highly successful Low Earth Orbit micro and mini-sa... more SSTL has been studying the application of its highly successful Low Earth Orbit micro and mini-satellites for lunar and planetary missions since 1996, through in-house funded design exercises and supported by ESA through Lunar and inner planet mission studies. Technical feasibility of a minisatellite lunar orbiter has been demonstrated. SSTL has since developed a range of improved subsystems and more advanced platforms, many of which have gained heritage in-orbit. These include the GMP-MiniSat platform with deployable solar arrays, accurate 3-axis stabilized attitude control, high resolution and wide field-of-view multispectral cameras and low cost bipropellant propulsion systems. Low cost launch options range from a Proton auxiliary payload launch direct to geostationary orbit, to prime passenger on a PSLV, to secondary payload alongside larger lunar missions. While SSTL is focused on low cost lunar orbiter development, it is jointly considering affordable means of conducting lunar landing, and ultimately sample return with the University of Surrey Space Centre. Lunar landing and sample return would demonstrate the applicability of low-cost small spacecraft technology to reduce the risk of high profile and barely affordable missions such as Mars Sample Return, by demonstrating key technologies, offering secondary science, and increased mission frequency to build enthusiastic public and political support. A parametric study for a lunar sample return mission from the south polar Aitken basin is highlighted, which has shown that a 15kg rover can in principle be landed on the lunar surface for a maximum surface stay of 150hours, subsequently returning a 200g sample to Earth, for a total launch mass from Earth orbit of less than 500kg, using a mixture of chemical and electric propulsion. This paper briefly considers the technology requirements and COTS technology availability for the separate mission stages, in order to establish how SSTL's low cost approach may be applicable to this challenging mission. This study is an ongoing area of research between SSTL and the University of Surrey Space centre.
International Conference on Robotics and Automation, Nov 28, 2006
A set of tools was developed in the frame of ESA activity [18191/04/NL] labelled RCET (Mars Rover... more A set of tools was developed in the frame of ESA activity [18191/04/NL] labelled RCET (Mars Rover Chassis Evaluation Tools) to support design, selection and optimisation of space exploration rovers. This activity was carried out jointly by Contraves Space as prime contractor, ETHZ, DLR, SSC and EADS Space Transportation. This paper describes the utilisation of the RCET in the context of a rover mission on Mars. The evaluation of the NASA MER and RCL-E rover chassis was done and the results are presented. This study includes wheel design optimisation on a particular soil, simulation of rover suspensions and rover comparison based on normalisation rules. With the experience gained in this study, a strategy for predicting locomotion performances was developed that allows an optimisation of both chassis configuration and motion control. The facilities and methodology used in the frame of this activity for validating the tools is also briefly presented.
The icy moon of the solar system signifies the most auspicious targets for astrobiological explor... more The icy moon of the solar system signifies the most auspicious targets for astrobiological exploration. Direct access to the geyser vents of Enceladus would be highly desirable to acquire pristine biological samples. Over the past few decades irrespective of multiple orbital and lander mission still relatively not much is known about the microbial presence and the biological composition. We have investigated the possibility of deploying penetrators to Enceladus to target the geyser vents to gain access to pristine or near-pristine subsurface samples. Penetrators are small missile type entry descent and landing vehicles that can carry modest scientific instruments capable of withstanding impact into the subsurface. The instrumentation used for any biochemical analysis on astrobiological bodies such as Enceladus should perform experiments with extreme precision and sensitivity such that it does not contaminate the sample and at the same time depict the results with high throughput. We have examined a subset of instruments that might be deployed on a penetrator based on current work in developing an astrobiological suite of a robotic instrument for Mars Rover deployment comprising a micro-assay and a nanopore instrument that works on extreme environments. For the microfluidics, we have explored to minimize the sample pre-processing required for the instruments and tested the microfluidic system which could perform experimentations that might detect life from the environmental sample collected from the Mars analogue sites. Here we describe a fully automated microfluidic device capable of performing end-to-end analyses of DNA/RNA preparation and sequencing by using microbial activity micro-assay (µ-MAMA) and oxford nanopore instruments. The system integrates an array of solenoid valves, peristaltic pumps and membrane filters for autonomous fluidic routing through the channels. The use of such an integrated device dramatically reduces the analysis time, reagent consumption, costs and overall mass of the subsystem. This miniaturized and sophisticated astrobiological instrument suite offers high potential for astrobiological prospecting in a highly challenging environment including Europa
International Journal of Astrobiology, Aug 1, 2022
In the early 1980s, Carl Sagan and Frank Tipler published a series of articles in the pages of th... more In the early 1980s, Carl Sagan and Frank Tipler published a series of articles in the pages of the Quarterly Journal of the Royal Astronomical Society on ETI that became a cause celebre at the time. Whilst reading for an MSc in Astronomy at the University of Sussex in the early 1990s, I expressed my interest in SETI as a staunch Saganite (influenced not only by the phenomenal Cosmos TV series, recently revamped by Neil de Grasse Tyson, but also by Sagan's preceding Royal Institution Christmas lecture series) to Professor John Barrow who introduced me to the relevant chapter in the book The Anthropic Cosmological Principle that he co-authored with Frank Tipler (I still recommend the entire book for its visionary scope). I immediately went to source material and was struck by the von Neumann or self-replicating probe concept under discussion (I shall use the latter term to avoid conflation with von Neumann machine which has a well-established meaning in computer engineering). This was my road to Damascus in converting me from ETI believer to skeptic (but by the power of scientific argument rather than any epiphany). Thence, I decided to pursue a PhD in space engineering specialising in space robotics (though my research project was rather more mundane than self-replicating probes). Yet, despite its foundational importance, the Sagan-Tipler debate is almost forgotten today despite the fact that it exposes the root-and-branch of the SETI venture. However, every now and then, there is still the occasional paper on self-replicating probes but they appear to be sidestream to the SETI programme. This special issue seeks to re-focus the self-replicating probe back into the SETI mainstream where it belongs. There are four papers in this special issue. Dobler's (2022) paper provides the ideal contextual discussion of the Fermi paradox that extant ETI are not here now. He suggests that any optimistic interpretation must accept that there must be a low probability of contact and that this state of affairs shall continue. He suggests that, although no one explanation can account for the Fermi paradox, perhaps a suite of explanations applicable to different categories of ETI are sufficient to cover the universality of the problem. And this will remain so. This is reminiscent of the "wedges" approach to combatting climate change (Pacala & Solow 2004). It does require that the explanatory wedges, even if they shift their weightings over time due to dynamic factors, must retain their universal coverage of non-contact. Nevertheless, from an instrumental viewpoint, this differs not from the assertion that ETI do not exist as Dobler (2022) points out. Only stable factors such as implausibility of interstellar travel are universal enough to account for the existence of ETI with the persistent lack of evidence. This dovetails neatly into Matloff's (2022) paper who addresses issues associated with the selfreplicating probes including propulsion for interstellar flight. He analyses several plausible options of increasingly technological sophistication. The use of gravity assists, be they unpowered or powered, is well-established but such methods yield extremely long interstellar transmit times ∼10 3-10 4 y/ly. Such probes would almost certainly be overtaken by more advanced probes within the next century. Various forms of nuclear propulsion were considered to improve performance and reduce flight times to ∼1000 y/ly. Propellantless sails were also considered to offer similar performance.
Most additive manufacturing (referred to as 3D printing henceforth) is applied to the creation of... more Most additive manufacturing (referred to as 3D printing henceforth) is applied to the creation of static structures. This severely restricts the scope of 3D printing techniques. To be sure, 3D printing can build structures in many different materials including plastics, metals and ceramics. This severely Nevertheless, monolithic structures are the rule of the day and the prospect of 3D-printed multi-material structures are still a research problem. In this paper, we look further to expanding the capabilities of 3D printing to manufacturing full mechatronic systems - specifically electric motor and their supporting electronics. We have taken preliminary steps towards this goal presented here - if fully successful, it will demonstrate that additive manufacturing constitutes a universal constructor in the von Neumann sense.
International Journal of Advanced Robotic Systems, Dec 1, 2005
Due to ultraviolet flux in the surface layers of most solar bodies, future astrobiological resear... more Due to ultraviolet flux in the surface layers of most solar bodies, future astrobiological research is increasingly seeking to conduct subsurface penetration and drilling to detect chemical signature for extant or extinct life. To address this issue, we present a micro-penetrator concept (mass < 10 kg) that is suited for extraterrestrial planetary deployment and in situ investigation of chemical and physical properties. The instrumentation in this concept is a bio-inspired drill to access material beneath sterile surface layer for biomarker detection. The proposed drill represents a novel concept of two-valve-reciprocating motion, inspired by the working mechanism of wood wasp ovipositors. It is lightweight (0.5 kg), driven at low power (3 W), and able to drill deep (1-2 m). Tests have shown that the reciprocating drill is feasible and has potential of improving drill efficiency without using any external force. The overall penetration system provides a small, light and energy efficient solution to in situ astrobiological studies, which is crucial for space engineering. Such a micro-penetrator can be used for exploration of terrestrial-type planets or other small bodies of the solar system with the minimum of modifications.
All space missions involve the control of mission operations from a ground station mediated throu... more All space missions involve the control of mission operations from a ground station mediated through a communications channel. Rover missions are no exception. For planetary missions, important constraints are imposed by the nature of the terrain, limited amount of energy available, limited computational resources, limited communication with human operators, and the nature of scientific targets and their location. Fully autonomous control through autonomous task planning is not yet conceivable nor, indeed, is it desirable—there will always be a need for human supervision.
Sustainability requires accessibility to material and energy resources with large reserves. We pr... more Sustainability requires accessibility to material and energy resources with large reserves. We propose that effectively inexhaustible reserves are available from the extraterrestrial environment (specifically, the Moon) and that they can be accessed at low cost. The key to low cost is in the realization of a self-replicating machine which amortises initial capital investment through exponential growth in productive capacity. This self-replicating machine must leverage itself from available lunar resources by expanding its population until sufficient productive capacity is attained to robotically construct solar power satellites to provision Earth with clean energy from space. We describe current work in developing the major parts of a self-replicating machine to enable leveraging of such extraterrestrial resources (energy and material) for a sustainable Earth.
International Journal of Advanced Robotic Systems, Sep 1, 2017
A classifier training methodology is presented for Kapvik, a micro-rover prototype. A simulated l... more A classifier training methodology is presented for Kapvik, a micro-rover prototype. A simulated light detection and ranging scan is divided into a grid, with each cell having a variety of characteristics (such as number of points, point variance and mean height) which act as inputs to classification algorithms. The training step avoids the need for time-consuming and error-prone manual classification through the use of a simulation that provides training inputs and target outputs. This simulation generates various terrains that could be encountered by a planetary rover, including untraversable ones, in a random fashion. A sensor model for a three-dimensional light detection and ranging is used with ray tracing to generate realistic noisy three-dimensional point clouds where all points that belong to untraversable terrain are labelled explicitly. A neural network classifier and its training algorithm are presented, and the results of its output as well as other popular classifiers show high accuracy on test data sets after training. The network is then tested on outdoor data to confirm it can accurately classify real-world light detection and ranging data. The results show the network is able to identify terrain correctly, falsely classifying just 4.74% of untraversable terrain.
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Papers by Alex Ellery