Beyond Earth (ATWG) - Chapter 31 - A Magnificent Challenge by Richard E. Eckelkamp

From The Space Library

Jump to: navigation, search

Chapter 31

A Magnificent Challenge

By Richard E. Eckelkamp

We as a nation and as a world have been presented by the U.S President a magnificent new vision - a challenge in space exploration to return to the moon and continue to the beyond. (1) Positive visions and challenges are inherently good for a people, just as for individuals. "Without a vision, the people perish." (2) Without challenges, individuals and mankind stagnate, vegetate, and turn inward to pursue little of value.

This new space visionary challenge is quite significant and significantly difficult. What at first might seem almost blasé and not worth one's while, quickly becomes a massive and ambitious endeavor when the hood is opened for detailed observation. The challenge, however, is not so much financial as it is human and technical.

On the human front, our traditional space industry, both governmental and corporate, crawls inefficiently through present and toward future projects with a highly-viscous, heavy-organizational inertial, an inertia inherited from the "early days" projects like War World II aircraft, early missile programs, the atomic bomb project, and Apollo. In these projects the emphasis had been on quick decisive results with cost not being a primary driver. Humans were desperate for these items. "Decent" human existence was judged to be at stake.

Strangely enough, this time around with the President's challenge, "decent" human existence is again at stake. The enemy this time is our own internal failures to be flexible, to be adaptive to needed changes and innovations, and to employ common sense design and execution of cost-efficient and meaningful programs. As with any vision, the "meaningfulness" part is supra important and necessary. There must be a significant reason "why?" for a project in order for that project to take hold in the heart and mind of both individuals and society.

For the earlier U.S. projects mentioned, the "whys?" were grounded in fear. For this present exploration challenge there is no discernable, immanent fear. Worries over future meteoric collisions, solar burnout, environmental disaster, or some possible interplanetary alien invasion either generate only brief mental acknowledgement or, in the last case, minimal credence. Considerations that society's lack of clear purpose or direction towards substantive endeavors usually results in decay seldom enter the human consciousness, much less rise to be a driving force.

If not fear, then, faith and or hope seem logical alternate motivators. Subtracting out the fear factor from Apollo reveals that hope was also present in the hearts of mankind. We all wanted to make some positive progress that would be oriented towards improving the future of all on this planet, rather than bashing each other to bits in new, "exciting" ways. The spiritual side of us felt good during Apollo.

What about now? What can stir our hearts to support and work these new space endeavors? The answers so far are dribbling in a few pieces at a time, not yet enough to be able to spin one or more inspiring tapestries. Our special opportunity is to search for and provide some of the pieces. I, for one, judge that a strong component is the meaningful and noble work that space quests can provide. For example, we have enough unprocessed data from previous space projects to provide interesting work for whole nations of people of all ages: vintaged seniors, middle-aged adults, students, even those of elementary age. There also exist forward tasks of many magnitudes that could be farmed out to all who are willing to participate in Earth's space work. These and other candidates will eventually be assayed for inclusion in a solid vision for the future. Without such a vision our technical efforts, impressive as they might be, will falter.

On the technical front, the challenges to accomplish the exploration vision are just as significant as on the aforementioned human front! Substantial, but achievable, advances are needed in robotics. This chapter will focus mostly on robotic needs. Also treated in summary fashion are command and control, communications, navigation, advanced life support, radiation protection, and space suits. Though not treated in this chapter, advances are also required in planetary surface and in-space construction, planetary mobility, thermal control, field medical equipment and techniques, science data and specimen gathering and processing, equipment maintenance, off-Earth societal and residential infrastructures, and education, cultural, and religious support. There are assured more than on this list.

Robotics

One of the greater exploration challenge areas is in the field of robotics. The President in announcing the space vision placed strong emphasis on the use of robots. The ratio of robotic tasks to human tasks should probably be 1.0 or greater. This will require many advances in robotics and in human-robotic cooperative operations. To date, use of robots and automated machines in space has consisted mostly only of mobile data gathering in free space or on planetary surfaces or the remote control of single mechanical arms to perform simple tasks. Translated, this means that we have a long way to go before robots can play a major role in exploration activities.

Though the robotic challenge is great, there is great expectation of success. Terrestrial use of robots has and is flourishing. Beginning with imaginative anthropomorphic constructs in movies and other entertainment centers, proceeding to tele-operated single and multiple arms and hands extending man's reach into environments too dangerous for humans to tread, then to programmed arm/hands performing repetitious assembly tasks, and now to a myriad of robots and automated machines performing a like myriad of scientific, military, and personal assistance tasks. We employ flying drones to perform reconnaissance and soon active military operations. In a Saturn car factory six robots assemble a car in three hours. There are robot dogs for companionship and entertainment. There are automated home vacuum cleaners and lawn mowers. There are smart prosthetic human limbs. And the laboratories across the planet are rich with developments, a number of which will come to the market place to meet eagerly-waiting organizational and personal consumers.

With all this progress in earthy robotics, why is exploration robotics such a challenge? The answer consists of several hard facts: the environment, the human-less factor, and the human factor. First, extraterrestrial efforts whether in free space or on heavenly body surfaces are conducted in harsh environments. Outside the comforting cocoon of Earth, survival, whether it be for carbon-based living entities or silicon and metallic-based mechanisms, is far from certain. High and low temperatures are extreme. Lighting conditions are glaring or dimmed. Atmospheric pressure is absent, near-absent, or too great. Gravitational and similar force effects are much different than those on Earth, where our bodies grew up and where our machinery was built.

We are making some strides in building robots and automated machines that can work in space. Successful photo and scientific data gatherers have been sent to our moon and all but one of our known planets save Pluto, other moons, and recently to asteroids. Table 31.1 lists successful mission suites from multiple countries.3 Added to this list should be a host of unspecified military reconnaissance craft.

Table 31.1 Successful Robotic Planetary Mission Suites


Besides the successful missions listed in Table 31-1, there exist a larger number of attempts that failed. For example, of all the spacecraft launched towards Mars from 1960 through 1999, over half failed before achieving their objectives. Of thirty-two attempts, six failed during launch and seventeen after launch. Nine achieved their objectives.(4) Please realize that this record should not be a source of discouragement. Such is the nature of space endeavors.

The successes do attest to our ability to operate complex machines in the harsh space environment. In other instances, however, the environment has won. In 1967, The USSR Venera 4 spacecraft entering Venus became inoperable before it reached the surface due to the severe high-pressured and acidic atmosphere. The USSR Mars 4 landing craft hardware and software were no match for the Martian dust storms in 1971. Contact with the US Mars Surveyor Polar Lander was lost as it entered the Martian atmosphere in 1999. We have more than enough lessons on the challenge of building automated machines for such environments.

The human-less or human missing factor of difficulty is quite interesting. Our best results in building things and in accomplishing activities come when we humans can be present to modify, to adjust, to compensate, to replan, to rethink. Many of our automated failures have been accompanied by the "Oh, no!" moans as we watched our projects go awry from afar. We humans could not in these instances be present close enough to the craft to prevent or fix the problems. Had we been there, our ingenuity might have saved the day. Thus the human-less challenge factor of fielding space machines becomes evident. Many of these robotic devices must in large part be operated without humans in the loop. Despite intense and talented design efforts, conditions, unforeseen or discounted, sometimes bite us hard as our machines fail.

Theoretically these latter shortcomings can be minimized radically. We have plenty of experience in real space life. We have developed useful techniques such as contingency analysis, component redundancy, fault identification software, and automated reconfiguration. Still to be developed are methods to repair robots in the field. Each problem associated with building and operating space robots is solvable. Success lies in applying significant effort to the problems, one at a time.

Since the challenges associated with the off-earth environment and the remoteness of human intervention are solvable, what else remains to hamper a flourishing robotic exploration program? A minor problem is a latent fear of robots, concerns that they might run amuck or "take over", and a worry that they might rob man of his livelihood. These issues do need to be addressed and are solvable with proper designs.

The main challenge, however, is the human factor of getting organized to define the specific robots needed and to develop them in an integrated cooperative program spread across multiple companies and space centers while minimizing development and operation costs. This human or organization factor is achievable with concentrated and unified effort. Historical examples of the kind of organization and drive required include the Manhattan World War Two atomic bomb project and the Apollo lunar landing program. During these two projects substantial new managerial efforts were invented to get the end results. The leaders of these programs built a carefully choreographed set of development assignments, tests, contingency analyses, and new paradigms to achieve gigantic results.

Our task now is to formulate and execute a similar choreograph. We must weld a considerable number of our individual university, space center, and private company robotic experiments and programs into an integrated effort, add pieces that are yet to be done, and build an efficient system of exploration robots.

Figure 31.1 (5) illustrates a logical pathway to developing such a robotic exploration system. One derives objectives based on the vision. The objectives are used to design missions. The missions are used to determine what types of robots are needed. In some instances, candidate robotic concepts must be tested either in earth-based or space-based facilities. Parallel to this thread of activity, two others can be performed. We can formulate design principles for space robots consistent with the exploration environment, with sound engineering practices, and with the objectives of flexible and cost-time efficient operations. We can also glean design and operational information from our past successes and failures with space and terrestrial robots.

Figure 31.1 Pathway to an Integrated Exploration Robotic System


Where are we now in the pathway to integrated robotics illustrated in Figure 31.1? Work is currently progressing well in defining program objectives and missions. (6) (7) (8). There are, of course, plenty of questions to be answered. For example, associated with lunar objectives as a class:

1) Do we build lunar base(s)

A) to serve only as a temporary proving ground for interplanetary efforts,

B) or also to accomplish permanent moon-based endeavors?

2) Which scenario do we use for human-robotic time task partitioning:


Scenario A

  • (1) Robots go first to build the infrastructure
  • (2) Humans come later and

a) work alone

b) work with robotic help, or

Scenario B

  • (1) Humans go first with robotic assistants
  • (2) Human go alone and work forever without robotic assistants
  • (3) Humans go first alone and acquire robotic assistance later?

Questions at lower levels must also be answered before robots can be designed. For example in the mission category a few questions are:

  • permanent base versus mobile base versus wandering "pack mule" prospectors?
  • prospecting for ice?, valuable ores? in highlands or mares?
  • roads versus hopping versus. flying vs. all terrain vehicles?
  • power transmission via wire or emf? * navigation via beacon or/and satellites?

Eventually decisions will have to made on how to use robots on the moon and beyond in: * surveying and reconnaissance

  • power generation, transmission, and storage
  • fuel and water generation, transmission, and storage
  • environmental control
  • communications and navigation infrastructure buildup
  • dirt manipulation
  • human and materials transportation
  • mining
  • building materials production
  • construction of buildings, roads, landing port, and science/industrial facilities, and maintenance including that of robots

One task that can be done now is to develop robotic design principles, since these are independent of most aspects of specific mission definitions. Some principles developed so far include:

1) redundancy - use either one more-massive and expensive large-capacity robot plus a similar backup to do the job or use several smaller less expensive and robots who together could do the job in the same time or the same job in a longer time in the presence of failures? (The answer may vary with each specific task.)

2) interoperability - use components of robotics in multiple machines, both robotic & non-robotic, e.g., power supplies, computers, limbs, end effectors, wiring harnesses, ...

3) market choice - use commercial-off-the-shelf hardware, software, and standards - e.g., web-based packet communications, standard interfaces (e.g., USB, Firewire, data and mechanical connection), and commonly-available components and subunits

4) standardization - develop and use new international robotic standards

5) generalized workers - build robots that can perform a variety of tasks

6) alterability - to be able to re-program and or physically reconfigure robots to perform new tasks or recover from unplanned events or failures

7) controllability - provide autonomous operations with override capability and provide for various levels of tele-robotic control

Some of the more important specific challenging work items to be performed to produce successful exploration robots include:

1) Build robots that can work in space environment - Most developed robots work only in the Earth's environment. Space robots built to date include the Shuttle SRMS and Station SSRMS arms and many successful interplanetary orbiter, probes, and landers.

2) Minimize the time latency effects inherent in controlling space robots from Earth control. - Round trip signal path and processing times vary from a few seconds for the moon to many minutes for Mars and beyond. Potential compensation methods include use of automated scripts, on board autonomy, and robot movement anticipatory algorithms.

3) Be able to conduct surface robotic operations at lunar noon - The high temperature and albedo within several earth-length days of lunar noon cause heat rejection problems and preclude many types of optical navigation and some types of optical perception techniques.

4) Be able to conduct surface robotic operations during Martian blowing dust times - How much of this can be achieved is unknown.

5) Make further advances in robotic perception and "cognition" -

6) Develop secure and redundant command paths to robots - It is essential that our exploration robots not be high jacked or "control-jacked" by enemies or fools.

7) Repair robots in the "space field" - It is impracticable to bring robots back to earth for most repairs since the lunar one-way trip is days and is months or more from Mars and beyond.

8) Human-Robot coordination - How does one coordinate operationally remote multiple robots and humans working together in a confined area on the lunar/planetary surface or outside in-transit vehicles?

There are often many developmental subtasks contained in each of aforementioned work areas. For example, subtasks under perception and "cognition" advances include:

1) Translating the input of visual, auditory, and tactile sensory inputs into rapid "recognition" of objects by robotic software

2) Physical path planning in presence of many multiple types of constraints

3) Logical layering of hierarchical control mechanisms, i.e., building simple behaviors and task skills into complex behaviors and specific tasks involving multiple skills [ single joint movement ...basic skill (grasp) ... tasks with multiple skills ( go fetch panel)]

4) Transformation of high-level commands to a sequence of skills including constraints checking and intelligent reaction to these constraints

5) Inter -robot information and skill transfer

6) Operating in the environment of non-cooperative agents (e.g., robots avoiding interference with the actions of other robots and with carbon-based units)

7) Self-starting actions based on perceived needs (within constraints)

There also exist some non-technical challenges associated with building and using exploration robots. These latter challenges can be as strong a barrier to overcome as are the technical ones. On the human front, on both the individual and on the organizational level, there exists some fear of robots and of automation in general. The more common of these fears are associated with potential job loss and potential physical harm from robots. These fears can and should be answered. For example, automation and the increasing use of robots produce about as many jobs as are displaced. These new jobs are in the design and construction of robots and automated tools and in new areas of accomplishment that have not been able to be worked due to excess manpower has been required to because there has been little or no automation.

Today, many of our more advanced robots are, with some exceptions, being designed and built in austere, low-organizational-overhead environments of small companies. This seems a good trend. Innovative robotic research projects and products often come from this type of environment. The type of robots coming out are myriad, as are the target markets for these robots. It is a similar trend for robotic work being performed at universities and space centers.

What is needed to have successful, time- and cost-efficient robots systems in space exploration is to built and execute an integrated, thoughtful plan of attack. To accomplish this great work we must evolve our current sets of robotic activities scattered among individual space centers, private companies, universities, and, in other countries into an integrated endeavor to propel robotics into the Exploration Era. For the sake of success we must do this.

An integrated Exploration Robotics System is our goal. This Exploration Robotics System can be built in stages as mission needs unfold. In fact the system, much like a living person, will continue to grow and to develop, and to refine new capabilities. Stasis will not be achieved in this robotic system, anymore than stasis will be achieved in exploration endeavors in general. Exploration and change are parts of our future. The possible roads and choices are endless.

Command and Control

Ranking as one of the two most significant exploration technical and managerial challenges is a major overhaul of the command and control infrastructure and its use to conduct space operations. For a detailed analysis of the problems and potential solutions to solve the problems, see chapter 25 of this book. In summary, our challenge is to build an efficient, cost effective exploration infrastructure, to coordinate exploration robots and human crews from multiple earth sites to accomplish science and exploration objectives, and to maximize the self-sufficiency of the lunar/planetary exploration teams while preserving exploration and science activity participation by Earth-based personnel when needed or logical to do so.

The command and control area includes the computer timing and execution processes, both manual and automatic, of exploration activities, the communication, procedural, software, and control process methods employed, and the partitioning of control functionality between astronauts and equipment in the space field and Earth-based controllers and control centers. Much detail on requirements, measures of success, and methods to achieve efficient command and control is given in Chapter 25.

Because of the long distances involved, efficiency and safety concerns dictate heavy use of automation and robots working in cooperation with humans to accomplish exploration objectives, a significant number of technological advances are needed. Required are:

  • Order of magnitude faster computers,
  • Large distributed data bases,
  • 100 megabit per second space communication links,
  • Web-based or similar space network,
  • Inter-control center voice, data, and video connectivity,
  • Exploration Vehicle autonomous navigation,
  • Advances in ground-based robotic control, and
  • Advances in autonomous fault management for equipment.

Many interesting new operational techniques need to be developed. For example, how does one coordinate operationally remote multiple robots and humans working together in a confined area on the lunar/planetary surface or outside in-transit space vehicles?

As stated strongly in Chapter 25, much hard work is required to establish a new paradigm for operations for the Exploration Era. Those agencies, countries, and, companies who fail to do so will find themselves spectators watching the innovators explore and profit from space.

Communications

Space communications for the Exploration Era presents marvelous opportunities to establish unprecedented richness in possible space missions as well as to improve mankind's earthly existence through better and faster information flow and global capabilities development. This is a continuation of mutual benefits between celestial and planetary efforts that has been occurring since the late 1950s. We have gone from local low-power crystal radios and underwater limited cable communications traffic to continuously available intercontinental color television and trading information over the internet while one is bicycling though cascades or walking on the surface of Antarctica. As we have been impressed continually by communication advances and we will be more so during the Exploration Era.

In the Exploration Era the types, number, and of communications links will need to be multiplied by at least two orders of magnitude. Modern operational concepts require significant bandwidths and multipoint communication capabilities. The exploration communications architecture has requirements for an adaptable, high-rate communication backbone infrastructure with access links to space and ground networks, with inter-spacecraft communication links, and with close range wireless proximity links. The human and robotic endeavors will require a communication infrastructure that supports bi-directional, multiple video, voice, and Internet-like data transfers and will enable simultaneous communications among local work site personnel and equipment, planetary bases, orbiting facilities and Earth-based control centers. When feasible, planetary orbital satellites will be deployed to aid in both communications and navigation. (9) (10)

Communications must occur among multiple spacecraft, multiple planets and moons, multiple exploration-faring humans and robot. Arenas of communication need include:

1. Local In-Space Communications - provides communications for EVA crew personnel and equipment outside of a traversing spacecraft.

a. Provides two-way voice, video and data communications while on EVA outside a traversing spacecraft: i. among EVA personnel, ii. between EVA personnel and the spacecraft, iii. between EVA personnel and detached or docking equipment, and iv. between detached or docking equipment and the spacecraft.

b. Communications with surface bases with Earth are relayed through the spacecraft,

c. Provides situational awareness for EVA personnel

d. Enables EVA crews to execute procedures using up-to-date textual and graphical data.

e. Enables crew to monitor and control detached or docking equipment

f. Enables automatic docking

g. Allows spacecraft and ground/planetary personnel to monitor EVA procedures and operational status.

The bandwidths required to achieve the needed communications (11) among EVA crewman, the spacecraft and robots are one megabit per second (MBS) in data plus compressed, scalable high-density television. For automatic docking equipment a 0.2 MBS data link is needed.

Necessary technological developments can begin with personal surveillance devices and prototype three dimensional high definition prototypes. Low mass cameras, antennas, and transmitter/receiver devices need to be built. The surveillance market seems to be heading in the required direction. Current space communication methods need to be upgraded to use multi-point techniques and to provide expanded bandwidth needed for operational efficiencies.

2. Lunar and Planetary Surface Communications - provides communications among elements at local surface worksites, planetary bases, and home planet facilities. Provided are voice, video, and data communications among personnel and equipment at a worksite on surface of the moon (or Mars/other similar body) including EVA personnel, robots, rovers, fixed equipment, local transports, surface habitats, and home planet (Earth) facilities. Types include:

a. two-way voice and live high-resolution, compressible video from each EVA crew person and each robot to the planetary surface base and to Earth (can be relayed through surface base),

b. two-way voice and live video among EVA personnel, and

c. two-way data/command transfer among EVA personnel and local robots. The bandwidth provided needs to be of sufficient width to send instructional photographs, data/command, and videos from the surface base to each EVA person. The local work site area is defined as a range that extends approximately 1 kilometer from the center of the work site or permanent base.

The bandwidths required to achieve the needed communications are in Table 31.2. The first number in each cell is the bandwidth in MBS and the second number is the video resolution required

Table 31.2 Lunar and Planetary Surface Communication Requirements

Using these capabilities EVA crew will able to execute procedures using up-to-date textual and visual information sent by elements external to the site. EVA crews can perform coordinated tasks via information exchange with each other and can monitor and control robots, rovers, and equipment platforms.

3. Surface and near-surface mobile communications - provides voice, video and data communications among vehicles moving along the surface, vehicles in suborbital transport or reconnaissance, surface elements, and home planet facilities. This capability allows traversing vehicles and crew to:

a. receive procedures, maps, systems' data from surface bases and home planet facilities,

b. perform coordinated tasks via exchange information exchange with each other, and

c. have full command and control of robotic rovers, platforms, and stationary equipment. The bandwidths required to achieve the needed communications are in Table 31.3.

Significant communication capabilities between the moon and the earth must be replaced. The equipment used in during Apollo is old, doesn't use current protocols, isn't not web-compatible, and to a significant extent inoperative13. In the 40 plus years since Apollo, communications technologies have improved dramatically. The ability to transfer megabits of information on Earth is near trivial. In space for the Exploration Era 100 megabitper-second links are needed. Our current capability, however, lies at one megabit per second (11). Technological developments required also include some ability to provide communications over the horizon perhaps by surface beacon or satellites, either of which will need to support navigation requirements.

Table 31-3 Surface and Near-surface Mobile Communication Requirements

It is judged that all that with focused efforts and funding, all the aforementioned exploration communications equipment and infrastructure can be built using existing earth-based developing and marketed technologies. The challenge lies in combining all the individual required kinds of communication links into a comprehensive system of integrated capabilities that are compatible with existing earth-based communications, uses common hardware with them and is both expandable and upgraded by nature.

Navigation

Whereas nautical navigation often uses the stars to determine ship and airplane locations on the surface or in the air of the Earth, celestial navigation uses the stars and other equipment to determine where and how fast Earth's spaceships have progressed towards the stars themselves. From the inception of space flight, considerable amounts of under-the-hood effort have gone into the endeavors, part art and part science, labeled as space or celestial navigation. Its task is to determine vehicular position and velocity, thus enabling automated guidance schemes to perform thrusting maneuvers to propel the spacecraft to the desired location. Throughout the history of space accomplishments, navigation techniques using specially developed navigation sensors and software algorithms have been used to take our spacecrafts to are near all of the planets in our solar system save Pluto, to fly by, orbit, or land on asteroids and copious moons, even to achieve pinpoint landings on our own moon, to rendezvous spacecraft, to propel spacecraft out of the solar system, and to traverse the lunar and Martian surfaces in unmanned and, in the Apollo program manned, surface vehicles.

In the Exploration Era, navigation will need to expand its breadth and techniques to provide needed services to many types of space and surface vehicles going to many destinations. (10) Local in-space navigation will provide relative navigation information for EVA crew personnel and equipment outside of a traversing spacecraft. Information provided includes attitude, relative position and velocity, relative range and range rate and any other needed relative navigation parameters for:

  • EVA personnel relative to the spacecraft,
  • Detached and docking equipment relative to the spacecraft,
  • EVA personnel relative to detached equipment, and
  • EVA personnel relative to each other.

The information provided will allow EVA personnel to estimate traverse times, provides the needed elements to enable capture or rescue of crew or items that have drifted away accidentally, and enable the automatic docking of co-orbiting equipment. Examples of equipment needing navigation are miniature flying camera systems, automated tool carts, equipment carriers, and robotic crew assistants. The required one sigma relative accuracies for EVA crew or non docking equipment are 2 meters in position, 0.2 meters/sec in velocity, and 1.5 degrees in attitude. (10) For docking equipment docking the accuracies need to be 2 centimeters, 1 centimeter/sec, and 1 degree.

Though space relative navigation systems have not been developed for multiple users, the algorithms and navigation hardware changes are achievable by building on previous efforts by the U.S. and Russia. Encouraging the development of items such as optical LED devices, optical shape and color algorithms, and multi-element local traffic control algorithms is advisable.

Lunar and planetary surface and near-surface navigation consists of navigation tasks performed at local surface worksites, on vehicles moving along the surface, on suborbital transports, and on overhead reconnaissance vehicles. Local worksite surface navigation provides position, velocity, bearing, and other navigational parameters for personnel and equipment on the surface of the moon (or Mars/other similar body) relative to a local rectangular or similar site grid. The local work site area defined as a range of approximately 1 kilometer from the center of the work site or permanent base. Work site personnel and equipment include, but are not limited to, EVA personnel, robots, rovers, surveyed navigational beacons or landmarks, fixed equipment, specimen locations, and local transports. This capability enables situational awareness for the personnel and autonomous equipment and provides the location of the other equipment or personnel with respect to each other and to the work site or the permanent base. One application, for example, is the ability of EVA personnel or robots to return to locations where previous specimens have been gathered.

The required one sigma position accuracies, relative to the local grid for fixed equipment, such as recharging stations is 10 meters for mobile equipment and 20 meters for personnel, For specimen locations, excavation sites and navigation beacons the requirement is 5 centimeters. In addition, the local site grid must be matched to local overhead photography within 3 meters (1 sigma) and the local site grid must be tied to an inertial coordinate system within an accuracy of 100 meters. Though some of these requirements are stringent, the techniques developed during Apollo, Martian, and more recent lunar programs along with current advances in terrestrial hardware and software are a good starting point for the required moderate development of surface and near-surface exploration navigation systems that can achieve these accuracies. . Surface beacons or equivalent and, probably orbital navigation satellites need to be developed, as well as small, low power navigation sets that can be worn by personnel and robots and sensor reflectors and transponders that can be affixed to mobile and stationery equipment.

Surface and near-surface mobile navigation provides both relative and inertial navigational information for personnel and equipment traversing the moon or Mars/other similar body. The range of operation extends outward from the main surface base to distances defined by remote work sites, eventually on the order of several thousand kilometers. Personnel and vehicles include but are not limited to pressurized crew transports, unpressurized equipment movers, suborbital transports, aerial reconnaissance vehicles, mobile rovers and robots, and EVA personnel. Provided are both relative position, velocity, bearing, and other navigation parameters with respect to a planet-wide surface grid, as well as absolute position, velocity, and other navigation parameters in an inertial coordinate system frame.

Traversing relative navigation enables personnel and surface mobile equipment in transit to find their way to remote work sites and to return to a permanent base using some of the same equipment and techniques used for local worksite navigation. Both the traversing inertial navigational system and the relative navigational systems enable suborbital or other transports to land close enough to designated sites to accomplish mission objectives safely. The inertial navigation capability allows over-flying or orbiting vehicles to perform required overhead surveys of remote worksites

The required one sigma position accuracies of in-transit surface moving vehicles and personnel are:

100 meters with respect to the planetary surface grid (relative nav) and 350 meters with respect to an inertial coordinate frame (inertial nav). For sub-orbital transports landing at a surface site and for overhead reconnaissance vehicles, the accuracies one sigma must be 100 meters in position with respect to the site surface grid (relative nav) and 350 meters in position and .35 meters/sec in velocity inertially.

Realtime lunar inertial navigation is quite challenging due to the anomalous gravity field. There is a strong need due to efficiency of operations and autonomy considerations that dictate the need to develop inertial navigation sensors not dependent upon earth-based equipment and personnel. Satellites, beacons, and optical sensors are good technical candidates.

Finally, a more efficient navigation system architecture needs to be developed for spacecraft traveling to and from planetary surfaces, for Earth and planetary orbits, and for deep space destinations. Our current system is quite manual and quite old. New trackers and other sensors and new navigation techniques and algorithms are needed that will enable smooth traffic control of many vehicles without the use of a large workforce.

Advanced Life Support

When one goes on an extended backpacking trip in the wilderness, one must take along all that is needed for survival. This includes shelter, clothing, food, water, and other necessary equipment. The amount one takes depends on what is available in that wilderness. If there is no or little chance of food and water replenished, then one must take a supply adequate for the journey duration. The longer the trip, the more one must take. Thus it is in space. Up until now most of our space adventures have lasted several weeks or less. We have taken all the food, water, and air needed for the duration. In the case of our space stations, we have relied on periodic resupply from our mother planet.

For our planned future planetary outposts, remote space platforms, and longer space flights, however, this complete reliance on resupply is not tenable. Excepting the resources perhaps discovered on distant worlds, e.g., water on the moon or Mars, most, if not all, life-sustaining consumables must be recycled in a closed-loop fashion. This applies to air, water, and food. Almost from the inception of manned spaceflight, both the U.S and Russia have advanced, tested, and fielded to space some technologies to this end. But these efforts have not been enough, nor have they been designed to work in an integral fashion. A working, comprehensive, and integrated advanced life support system needs to be developed if we are to become truly a space-faring society. As with any similar endeavor, the technologies developed will provide quite useful terrestrial applications. The required Exploration Era environment system would:

1. Close the loop entirely for water

a. Water in all forms would be recycled - that contained in the human transport craft, habitats and spacesuits as well as in hydrous materials, waste water, and other waste products (urine, etc.),

b. The amount of water would be a constant. No extra would be needed form Earth.

2. close the loop entirely for air,

a. Oxygen would be produced from plants and manmade devices.

b. Carbon dioxide would be removed by plants and manmade devices.

c. Contaminants and pathogens would be removed by systems that employ no non-replenishable consumables.

3. Close the loop to a high degree for food,

a. Grow or raise as much food as practicable.

b. Supplement with thermo stabilized-irradiated and freeze-dried foods.

4. Close the loop to a high degree on solid and gaseous wastes,

a. Recycle plant and animal wastes to compost and fuel.

b. Recover fuel gases.

c. Incinerate solids for energy production, if healthy to do so.

d. Compact or convert remaining solids for building materials.

e. Have a super-small ("thimble-sized") trash container for the remainder. All of the elements of such a system are possible using current and approaching technologies (15,16). All are elements of this system are quite necessary to enable long and distant space missions, to provide a safe, good quality lifestyle for humans traveling and working in space, and to prevent contamination of solar system heavenly bodies, including Earth.

There has been considerable progress made in some of the above areas. (17) Water recycling technologies such as vapor compression and rotating distillation processes, organic and inorganic filtration, adsorption / ion exchange beds, catalytic oxidation, ultraviolet sterilization, and the use of microbial check valves has brought water purification to a state near ready for deployment. Air cleaning technologies are also fairly well developed. Devices such as the International Space Station's Solid Polymer Electrolyte Oxygen Generation Assembly and the regenerative 4-bed molecular sieve process (that also provides for water recovery), solid amine absorbent beds (under study) plus the demonstrated use of plants for carbon dioxide absorption (doubles as a food source) holds great promise that we are moderately near to closing the loop on air.

The growing of plants for fresh food, as well as air will certainly contribute to crew health and performance.(15) Likewise the raising of fish such as the space-efficient tilapia would be cheered by spacefarers. How much fresh food can be provided depends on the nature of the vehicles, missions, and crew quarters. The amount possible is expected to increase as the exploration program progresses. Further development needs to occur on in-space plant production, when desired crop densities are twenty times that in open air home planet fields. This development includes the reduction of input energy required (mostly lighting), the increase in the varieties of crops used, and increasing plant resistance to diseases, as well as recovery from disease infestations.

Closing the solid loop will take more effort than will the others loops. Compact composting and energy extraction on the small scales that will be required for exploration need to be developed. The overall philosophy of throwaway or disposable objects, just as in our modern terrestrial life, needs to be transformed to one of conversion and second use, third use, fourth use, etc.

Finally, much advancement needs to be made to produce an integrated advanced life support system that is controlled for the most part automatically without human intervention. Today the various closed loop components are not integrated, are controlled manually, and require a lot of crew intervention. For example, one earlier envisioned system, designed by logical extensions from Russian and U.S. flight and experimental experiences would require 1.75 persons working one eight hour shift daily just to maintain and perform routine tasks associated with running the system. Not included are repairs.

All of this said, the developments needed to bring an integrated closed loop life support system to deployment status are quite achievable with moderate effort. If such a system is not developed, we will have a very limited and unfulfilling exploration program.

Radiation Protection

The most serious of Exploration Era challenges is the need to protect people from radiation once they leave the safety of Earth's environment, including its Van Allen radiation belt. Potentially lethal barrages of event radiation can and have occurred. Thank the Lord that no such events occurred while the astronauts of Apollo were out on lunar surface EVAs 19,20. Even the continual normal background radiation has its cumulative harmful effects on the human body. It is imperative that both exploration vehicles and habitats, as well as associated crew time-lines, be designed to minimize human susceptibility to radiation.

The goal of radiation protection is to enable astronauts to live and work safely in the space environment, one that does include significant radiation. To the extent possible the safety will be achieved by stopping the radiation via shielding. Only secondarily, should the safety be achieved by limiting the astronaut career lifetime exposure to the danger.

Space faring humans must deal with four types of radiation: that radiation trapped in Earth's Van Allen belt formed by the interaction of our planet's magnetic field with continuous solar wind particles, galactic high energy cosmic radiation, occasional and often deadly special energetic solar particle events, and secondary radiation formed by the interaction between incoming radiation and shielding (17, 21). The second type of radiation is peculiar to spacecraft in low Earth orbit. The remaining types dominate above low Earth orbit, even out to the planets and beyond. All types of radiation exposure need to be limited because they can produce damage to the central nervous system, degenerative tissue disease (cataracts, heart disease, etc.), acute radiation sickness any of which can easily lead to a shorter life.

Astronauts have been classified as radiation workers and, monitoring their radiation exposure has been a key requirement for spaceflight since Project Mercury 19. The minimum radiation protection required is stated as the lowest acceptable maximum astronaut career time in the space environment. One current candidate set of exposure limits for career space time is three 180-day missions in low Earth orbit, six 90-day lunar missions, or one 1000day mission to Mars. These mission limits are not valid if a large special energetic solar particle event would occur. Such an event of sufficient magnitude could severely decrease or end an astronaut's in-space career. Therefore, it is very important that all possible feasible steps be taken to lessen the danger. Astronauts on the moon or other planetary surface will have to live in shielded quarters, probably underground. Traversing spacecraft whether making the several day back-an- forth trips to the moon or making the many-months trips associated with Mars will have to be shielded. Astronauts will need to minimize their exposure in outdoor areas and must wear shielded spacesuits.

There is hope. Lighter, more effective shielding materials are being developed (e.g., polyethemides et al) that produce less secondary radioactive particles (21). Smaller, lighter, and closer-to-full-spectrum radiation dosimeters are being manufactured. Advances are being made in the prediction of energetic solar particle events. Experimental genetic DNA repair of radiation damage are being sought in laboratories. Judicious adherence to the principle of minimizing human exposure to radiation via shielding, the use of surrogate robots to perform outside tasks, and the use of faster spaceships give the best protection. With vigilance, the careful design of operational scenarios, and a continual focused development of specific pertinent technological items, men and women should be able to flourish in space.

Space Suits

Working, even existing in space requires humans to have extensive bodily protection. For many tasks the humans can work in relatively large constructed cocoons capable of keeping the body within the necessary narrow limits of temperature, pressure, atmospheric, and luminosity needed for survival. The cocoons can be space ships, enclosed planetary rovers, or surface habitats. Within these, humans can exist without extra epidural apparatus.

However, when man ventures out of the cocoon into the harsh environment of free space or onto extraterrestrial surfaces, he must wear a spacesuit. Space suits exist today. They were derived initially from suits worn by high altitude aviators and were evolved by both the Russian and U.S. space programs for use for a few hours during extravehicular excursions in earth orbit , lunar transit, and on the lunar surface. These suites are used for short work sessions, need replenishing before reuse, expend consumables, and work within narrow temperature ranges. For the Exploration Era activities suits that overcome some of these limitations need to be built. More that one suit will probably need to be developed. For example, the environment on the surface of the moon is quite different from the surface of Mars. And there are other environments in which we will wish to function, such as the deep cold of asteroid work.

The greatest challenge for the lunar suit is cooling. (18) First there is no known way for humans to work on the lunar surface within several "earth-days" of lunar noon. No space suit built or currently conceivable can overcome the intense heat of lunar midday. Apollo surface EVAs were accomplished at low sun angles. This is a serious and mission limiting problem. There is no known solution. For now, man's outside activities on the lunar surface will need to be restricted to locations near the shadows of topographical features or be restricted to lunar early mornings and late afternoons when the sun angle is 50 degrees or lower. This same temperature mission limit probably applies to robots.

How to cool the lunar suit is also a challenge. The Apollo suit sublimated water to free space. It was an effective technique, but such a technique cannot be used for extended lunar stays. Water is much too scarce to use in this way. Techniques being considered include the use of closed-loop phase change substances or using cryogenic oxygen as an expendable.

Additional suit challenges to be worked include: (15) (18)

  • extending suit use time - the limit for EVA time is 5 to 8 hours for the lunar surface and 3 to 4 hours for the Martian surface(due to stronger gravity), based of carrying weight,
  • CO2 control - the LiOH canisters of current suits must give way to consumable-less closed-looped systems such as solid amine absorbent beds,
  • dust - a major problem on both the lunar and Martian surfaces. It was estimated that dust alone might limit suit use to three outings based on Apollo crew experience reports.
  • lower pressure suits to decrease pre-breathing time, and
  • reduced-thickness gloves - necessary for better work dexterity. This item will need continual development as better materials are introduced.

All of the above challenges can be met. The toughest, the mission-limiting challenge of lunar cooling, needs intense work.

Summary

This chapter has listed the more important technological challenges in seven major systems that must be worked and solved before much space exploration can be done. These challenges will not go away. They must be faced before mankind can become truly space faring. Those organizations that delay the start of meeting these challenges delay their own trek into space. These work items, along with additional ones in other systems, may be grouped together and be labeled as part of our magnificent challenge. Come join us in working this great endeavor.

References

  • (1) George W. Bush, "New Vision for Space Exploration", January 14, 2004
  • (2) Proverbs 29:18
  • (3) Calvin J. Hamilton, Visions of the Solar System, 1996-2005
  • (4) Jim Plaxco, "Mars Space Missions", Astronomical Society of Long Beach website
  • (5) Richard E. Eckelkamp, "Space Robot Laborers", September 13, 2004, Aerospace and Technology Description of Human and Robotic Surface Activities", NASA/TP-2003-212053, July, 2003Working Group conference
  • (6) Michael B. Duke, Stephen J. Hoffman, Kelly J. Snook," Lunar Surface Reference Missions: A
  • (7) Owen K. Garriott, Michael D. Griffin et al., " Extending Human Presence into the Solar System, An Independent Study for the Planetary Society on the Strategy for the Proposed U.S. Space Exploration Policy, July, 2004.
  • (8) NASA's Exploration Architecture, September 19, 2005, NASA website http://www.nasa.gov/pdf/1133654main_ESAS_charts.pdf
  • (9) Robert Spearing and Michael Regan, "Space Communications Capability Roadmap Interim Review", presented to the National Science Foundation, March 24, 2005
  • (10) June Zakrasjek and Richard E. Eckelkamp, "Human Exploration Systems and Mobility Capability Roadmap Progress Review: Capability 9.2 Mobility", presented to the National Science Foundation, March 29, 2005
  • (11) Conversations with Orin L. Schmidt, Communications and Tracking, Johnson Space Center, January through April, 2005
  • (12) Compressed High Density Television
  • (13) Conversations with Thomas E Ohnesorge, Advanced Operations Development, Johnson Space Center, March through October, 2005
  • (14) Conversations with Ellen M. Braden and Emil R. Schiesser, Aeroscience and Flight Mechanics, Johnson Space Center, January through October, 2005
  • (15) Al Boehm and Dennis Grounds, "Human Health & Support Systems Capability Roadmap Progress Review", presented to The National Science Foundation, March 17, 2005
  • (16) Crew and Thermal Systems, JSC, "Advanced Life Support Requirements Document", JSC-38571C, February, 2003
  • (17) Bruce E. Duffield, "Advanced Life Support Technologies List, Lockheed Martin memo HDID-2G42-1130 to Crew and Thermal Systems, JSC, June 24, 1999
  • (18) Conversations with Michael N. Rouen, Crew and Thermal Systems, Johnson Space Center, February through December, 2005
  • (19) "Experiment Description for: Radiation Protection and Instrumentation (AP003)", Life Sciences Data Archive @ Johnson Space Center, Houston, Texas, Spaceflight Radiation Health Program at JSC
  • (20) E. V. Benton, Editor, "Space Radiation", Nuclear Tracks and Radiation Measurements, Vol. 20 No. 1, Pergamon Press New York, January, 1992
  • (21) Nassar Barghouty, "Space Radiation: Understanding & Meeting the Challenge for Exploration", September 13, 2004 meeting of the Aerospace and Technology Working Group

About the Author

Extracted from the book Beyond Earth - The Future of Humans in Space edited by Bob Krone ©2006 Apogee Books ISBN 978-1-894959-41-4

Buy This Book Click here

Retrieved from "http://www.thespacelibrary.com/mediawiki/index.php/Beyond_Earth_%28ATWG%29_-_Chapter_31_-_A_Magnificent_Challenge_by_Richard_E._Eckelkamp"