Page images

materials and objects acquisition, handling, and assembly must also be further developed; robots doing construction work in Earth orbit or on the lunar surface will need manipulative and locomotion devices to perform the necessary transport and handling operations.


C. Future Applications

In space applications, robots may take on many forms. None looks like the popular science fiction conception of a mechanical man. Their appearance follows strictly functional lines, satisfying the requirements of the mission objectives to be accomplished. The discussion which follows briefly presents mission categories, mission objectives, and system characteristics pertinent to space robot and automation technology. Estimates of technology development efforts to automate system functions are given in Table 4-1.

1. Space Exploration

Space exploration robots may be exploring space from Earth orbit as orbiting telescopes, or they may be planetary flyby and/or orbiting spacecraft like the Mariner and Pioneer families. They may be stationary landers with or without manipulators like the Surveyor and the Viking spacecraft, or they may be wheeled like the Lunakhod and the proposed Mars rovers. Others may be penetrators, flyers, or balloons, and some may bring science samples back to Earth (Figures 4-1 4-3). All can acquire scientific and engineering data

Figure 4-2. Mars surface robot will operate for 2 years and travel about 1000 km performing experiments automatically and sending the scientific information back to Earth.


Figure 4-1. Galileo spacecraft navigates between Jupiter and Galilean satellites in rendering. After sending a probe into the jovian atmosphere, the robot spacecraft will perform complex maneuvers at various inclinations with repeated close encounters with the satellites.

Figure 4-3. Artist's concept of a Mars surface scientific processing and sample return facility. Airplanes transport samples into the vicinity of the processing station. Tethered small rovers then bring the samples to the station for appropriate analysis and return to Earth.

[blocks in formation]

Table 4-1. Estimates of the technology development efforts to
automate system functions

[ocr errors]
[ocr errors]
[ocr errors]










using their sensors, process the data with their computers, plan and make decisions, and send some of the data back to Earth. Some robots are, in addition, able to propel themselves safely to different places and to use actuators, manipulators, and tools to acquire samples, prepare them, experiment in situ with them, or bring them back to Earth.

Exploratory robots are required to send back most of the collected scientific data, unless they become repetitive. The unknown space environment accessible to the sensors is translated into a different, still uninterpreted environment, in the form of computer data banks on Earth. These data banks are then accessible for scientific investigation long after the space mission is over.

Projections into the future lead one to speculate on the possibility of highly autonomous exploratory robots in space. Such exploratory robots would communicate to Earth only when contacted or when a significant event occurs and requires immediate attention on Earth. Otherwise, they would collect the data, make appropriate decisions, archive them, and store them onboard. The robots would serve as a data bank, and their computers would be remotely operated by accessing and programming them from Earth whenever the communication link to the robot spacecraft is open. Scientists would be able to interact with the robot by remote terminal. Indeed, the concept of distributed computer systems, presently under investigation in many places, could provide to each instrument its own microcomputer, and scientists could communicate with their respective instruments. They could perform special data processing onboard and request the data to be communicated to them in the form desired. Alternatively, they could retrieve particular segments of raw data and perform the required manipulations in their own facilities on Earth.

Prime elements in this link between scientists and distant exploratory robots would be large antenna relay stations in geosynchronous orbit. These stations would also provide data handling and archiving services, especially for inaccessible exploratory robots, e.g., those leaving the solar system.

2. Global Services

Global service robots orbit the Earth. They differ from exploratory robots primarily in the intended application of the collected data. They collect data for public service use on soil conditions, sea states, global crop conditions, weather, geology, disasters, etc. These robots generally acquire and process an immense amount of data. However, only a fraction of the data is of interest to the ultimate user. At the same time, the user often likes to have the information shortly after it has been obtained by the spacecraft. For instance, the value of weather

information is short-lived except for possible historical reasons. The value of information of disasters such as forest fires is of comparably short duration. The demand for high-volume onboard data processing and pertinent automated information extraction is therefore great.

The usual purpose of global service robots is to collect time-dependent data in the Earth's environment, whose static properties are well-known. The data are used to determine specific patterns or classes of characteristics and translate these into useful information. For instance, for Landsat and Seasat (Figure 4-4), the data are currently sent to the ground, where they are processed, reduced, annotated, analyzed, and distributed to the user. This process requires up to 3 months for a fully processed satellite image and costs several thousand dollars. The image must then be interpreted by the receiver; i.e., the information must still be extracted by the

[merged small][graphic]

Figure 4-4. Seasat. The oceanographic satellite's high-data-rate Synthetic Aperture Radar imaging device has provided data on ocean waves, coastal regions, and sea ice.

Present developments in artificial intelligence, machine intelligence, and robotics suggest that, in the future, the groundbased data processing and information extraction functions will be performed onboard the robot spacecraft. Only the useful information would be sent to the ground and distributed to the users, while most of the collected data could be discarded immediately. This would require the robot to be able to decide what data must be retained and how they were to be processed to provide the user with the desired information. For instance, the robot could have a large number of pattern classification templates stored in its memory or introduced by a user with a particular purpose in mind. These templates would represent the characteristics of objects and/or features. of interest. The computer would compare the scanned patterns with those stored in its memory. As soon as something of interest appeared, it would examine it with higher resolution, comparing it to a progressively narrower class of templates until recognition had been established to a sufficient degree of confidence. The robot would then contact the appropriate ground station and report its findings and, if required, provide the user with an annotated printout or image. The user would be able to interact with the robot, indeed with his particular instrument, by remote terminal much the same as with a central computer and, depending on intermediate results, modify subsequent processing.

For space exploration and global services, the groundbased mission operations can become extremely complex. A recent example of a planetary exploration mission, and perhaps the most complex to date, is Viking. At times there were several hundred people involved in science data analysis, mission planning, spacecraft monitoring, command sequence generation, data archiving, data distribution, and simulation. Although for earlier space missions sequencing had been determined in advance, on Viking this was done adaptively during the mission. The operational system was designed so that major changes in the mission needed to be defined about 16 days before the spacecraft activity. Minor changes could be made as late as 12 hours before sending a command. The turnaround time of about 16 days and the number of people involved contributes, of course, to sharply increased operational costs. The Viking operations costs (Figure 3-1) are for a 3-month mission. The planned Mars surface rover mission is expected to last 2 years, covering many new sites on the Martian surface. Considering that this mission would be more complex and eight times as long, ground operations would have to be at least ten times as efficient to stay within, or close to, the same relative costs as for Viking.

During the Viking mission, about 75,000 reels of image data tapes were collected and stored in many separate locations. The images are now identifiable only by the time when and the location where they were taken. No indication regard

ing image information content is provided, and the user will have to scan catalogs of pictures to find what he or she wants. For such reasons, it is expected that most of the data will not be used again.

The ground operations for Earth orbital missions suffer from problems similar to those of planetary missions. The overall data stream is usually much higher for Earth orbital missions, images are still very costly, and they take up to several months to reach the user.

These considerations strongly suggest that technology must be developed so that most ground operation activities can be performed as close as possible to the sensors where the data is collected, namely by the robot in space. However, examining the various ground operations in detail, we conclude that most of those that must remain on the ground could also be automated with advanced machine intelligence techniques. The expected benefits derived from this would be a cost reduction for ground operations of at least an order of magnitude and up to three orders of magnitude for user-ready image information.

3. Utilization of Space Systems

Space industrialization requires a broader spectrum of robotics and automation capabilities than those identified for space exploration and global services. The multitude of systems and widely varying activities envisioned in space until the end of this century will require the development of space robot and automation technology on a broad scale. It is here that robot and automation technology will have its greatest economic impact. The systems under consideration range from large antennas and processing and manufacturing stations in Earth orbit to lunar bases, to manned space stations, to satellite power systems of up to 100 km2. These systems are not matched in size by anything on Earth. Their construction and subsequent maintenance will require technologies not yet in use for similar operations on Earth.

Space processing requires a sophisticated technology. First it must be developed and perfected, and then it must be transferred into the commercial arena. Basic types of processes currently envisioned include solidification of melts without convection or sedimentation, processing of molten samples without containers, diffusion in liquids and vapors, and electrophoretic separation of biological substances. It is expected. that specialized automated instrumentation will be developed for remote control once the particulars of these processes are worked out and the pressure of commercial requirements becomes noticeable.

Large-area systems such as large space antennas, satellite power systems, and space stations require large-scale and complex construction facilities in space (Figures 4-5 and 4-6). Relatively small systems, up to 100 m in extent, may be deployable and can be transported into orbit with one Shuttle load. For intermediate systems of several hundred meters in extent, it becomes practical to shuttle the structural elements into space and assemble them on site (Figure 4-7).

Very large systems require heavy-lift launch vehicles which will bring bulk material to a construction platform (Figure 4-8), where the structural components are manufactured using specialized automated machines.

The structural elements can be handled by teleoperated or self-actuating cranes and manipulators which bring the components into place and join them (Figure 4-9). Free-flying robots will transport the structural entities between the Shuttle or the fabrication site and their final destination and connect them. These operations require a sophisticated general-purpose

[graphic][ocr errors]

Figure 4-5. Large space systems require robot and automation technology for fabrication, assembly, and construction in space.

Figure 4-7. Construction of a space station. Bulk material is brought by the Shuttle. Structural elements are fabricated at the construction facility and then assembled by remotely controlled manipulators.


Figure 4-6. Large space antennas are erected with the help of a space-based construction platform. The Shuttle brings the structural elements to the platform, where automatic manipulator modules under remote control perform the assembly.

Figure 4-8. Complex construction facility in space with automatic beam builders, cranes, manipulators, etc., is served by the Shuttle.

« PreviousContinue »