Achieving Human Presence in Space Exploration

Transcription

1 FORUM Achieving Human Presence in Space Exploration Abstract One of the primary goals of human spaceflight has been putting human cognition on other worlds. This is at the heart of the premise of what we call space exploration. But Earth-controlled telerobotic facilities can now bring human senses to other worlds and, in that respect, the historical premise of exploration, of boots on the ground, no longer clearly applies. We have ways of achieving remote presence that we never used to have. But the distances over which this must be achieved, by humans based on the Earth, is such that the speed of light seriously handicaps their awareness and cognition. The highest quality telepresence can be achieved not only by having people on site, but also by having people close, and it is that requirement that truly mandates human spaceflight. In terms of cost, safety, and survival, getting people close is easier than getting people all the way there. It is suggested here that to the extent that space exploration is best accomplished by achieving a sense of real human off-earth presence, that presence can be best achieved by optimally combining human spaceflight to mitigate latency, with telerobotics, to keep those humans secure. This is culturally a new perspective on exploration. 1 Introduction: Exploration and Presence The popular premise of space exploration has been strongly based on historical templates. These templates figure space explorers as humans who put their boots on celestial rocks, ideally planting flags as they do so. This premise was manifested by the Apollo astronauts, who brought human insight and awareness to the surface of the Moon, reaping huge geopolitical gain in the process. Forty years ago, our lack of technical sophistication was such that bringing human insight and awareness to the Moon had to be done in exactly that way. Of course, the congressional premise for space exploration is as much Presence, Vol. 22, No. 4, Fall 2013, doi: /pres_a_00160 ª 2013 by the Massachusetts Institute of Technology about putting jobs in congressional districts as about putting feet on otherworldly rocks. But our telerobotic technologies have evolved dramatically since then, and this historically based premise is no longer binding. We send rovers to Mars that, controlled by humans on Earth, scout and investigate much as a human would do in situ, with mobility, vision, and some measure of dexterity. Of course, we send satellites across the solar system that bring our eyes, as well as some senses humans do not even have, to faraway venues. The contemporary nature of space exploration is therefore no longer entirely clear (Lester Robinson, 2009). NASA nevertheless chooses to use the word exploration explicitly for human space flight. Interestingly, congressional authorizing legislation for the agency never refers to the importance of boots on otherworldly rocks, but repeatedly refers instead to the importance of human presence in space. The last NASA authorization act (P.L ; NASA, 2010), pronounces that The long term goal of the human space flight and exploration efforts of NASA shall be to expand permanent human presence beyond low-earth orbit and to do so, where practical, in a manner involving international partners. Authorization bills now wending their way through Congress say much the same thing. While it is likely that congressional intent is to put humans in boots at exploration sites, those words are not the ones that appear in federal legislation. The congressional emphasis on human presence instead of human boots on the ground cuts to the heart of the premise of how space exploration might be viewed. That is a premise not necessarily consistent with the historical template for exploration, and is one that human spaceflight advocates are therefore not entirely comfortable with. Dan Lester Department of Astronomy University of Texas at Austin Austin, Texas Lester 345

2 346 PRESENCE: VOLUME 22, NUMBER 4 The presence community should be paying some attention to this, because when Congress starts using the phrase human presence to authorize a $17B agency, the phrase takes on some importance. The attainment of human presence in space has two important dimensions. One is technical, likely involving putting humans on rockets, and the other is cultural, involving the historical template for exploration that we are culturally wedded to. The purpose of this brief Forum article is to refresh the issue in this community whose perceptions of telepresence and second-order mediated experience are more sophisticated than that of the space exploration community. 2 The Promise of Telepresence for Space Exploration Human spaceflight is hard, expensive, and dangerous, and to the extent that our species needs to explore, such challenges on emplacing human presence are understandable. But we have reached a level of technological refinement that putting boots on the ground may not be the only way to explore. If colonization and settlement were the goals of space exploration, boots on the ground would be of primary interest. But colonization and settlement of outer space is in no way, right now, considered an established need of our nation by our legislative bodies. Thirty years ago, Marvin Minsky mused about the importance of telepresence for space exploration (Minsky, 1980). Somewhat later, Minsky formally proposed to NASA that a space station could be entirely remotely controlled from the Earth (Minsky, 1990). These ideas were exciting and innovative, but in addition to being technologically handicapped at the time, were considered threatening to the deeply ingrained premise that true exploration was something heroic that looked like Columbus or Lewis and Clark. Those threats remain even today. Of course, at that time, our telepresence capabilities were just in their infancy. But we now find ourselves with vastly improved communication systems, and sensor packages that offer imaging at least as good as human vision. Our robotic dexterous manipulation capabilities, even offering some measure of haptics, have advanced to the point that we now routinely do telerobotic surgery and remote control of deep undersea construction and maintenance. In fact, the telerobotic dexterity and mobility we now have in many respects exceeds that of a space-suited human. You would not want to be operated on by a surgeon wearing a space suit. It should be understood that space science is routinely done telerobotically, although the tasks are done largely autonomously, with supervision by controllers on the Earth. In the case of planetary telerobotics, such as the Mars rovers, the latencies in such supervision are limited by the speed of light to 4 10 min, and by operational protocols to many hours. Scientists do not have what we could call hands-on, real-time access to planetary venues that would constitute telepresence at those sites. Why is such access of value? A thought experiment might be to consider a field geologist on the Earth, handicapped by such control latency. Every rock that he or she picks up or moves aside, every turn to view it from different angles, every surface scratch, every core sample, every step across the surface, is the result of a series of perceptions and individual controlled motions that each is delayed. The price of latency for such complex work is enormous, and a real sense of presence on site is therefore scientifically enabling. The Mars Exploration Rover Principal Investigator, Steve Squyres, has said that a human on Mars could do in a minute what those rovers could do in a day (Squyres, 2005). That operational discrepancy is in many respects the result of communication latency to those rovers from the Earth. We can say that we have a measure of telepresence on these rovers, but with the large latency, the quality of that telepresence is very poor. In view of the tasks that a telepresent human would do on another planet, the architecture of that needed telepresence can be defined. The human would want highdefinition imaging to view the situation there, with a camera that could be moved as a human head could be moved. We have such imagers right now. A human would want mobility, to explore different places. Wheeled vehicles offer that capability, although perhaps not for climbing. A human would want dexterity with a fidelity comparable to a human hand and arm. That is more difficult, but the technological status of that capability is wellrepresented by contemporary telerobotic surgery, in

3 Lester 347 which a remote surgeon can have dexterity that is far better, at least, than a human in a space suit would have. Modern telerobotic dexterity, also represented by prosthetic limb teleoperation, and even explosive ordnance disposal robots (EODs), demonstrates the dexterity that can now be achieved by a human in a space suit. This is what at least scientific telepresence would look like. 3 Humans Versus Robots, or Humans Through Robots? In the last decade or two, the space exploration community has seen a humans-versus-robots argument develop, where mainly scientists point to the accomplishments of robots, and question the need for human spaceflight at all. The counterargument by human space flight advocates is that of course humans are more insightful than robots and, besides, who fixes the robots? This argument has engendered fierce tirades between these camps, but has come to the point that the argument is tired and stale, and can be considered a false dichotomy (Launius McCurdy, 2007). It is now generally accepted, perhaps just in the interest of making peace between these camps, that some combination of humans and robots is in the greater interest of advancing our understanding of outer space. What an optimal partnership or combination actually looks like is not well defined, however. While fully autonomous robots are still far from being able to duplicate the cognitive performance of a human, it is evident that the rapid advances in telerobotic technology have made remote human surrogates far more capable than they used to be. Those advances will only continue. It can be assumed that eventually such human surrogates will match the senses, dexterousness, and mobility of a human body. This would allow a human to embed his or her presence, avatar-like, at a site that may be inhospitable to his or her human body. 4 The Price of Latency, and Cognitive Horizons Space exploration has a caveat that makes it poorly matched to terrestrial telerobotic pursuits. That caveat is latency. Space is a big place, and the communication delays from the Earth to where presence is emplaced can be large. The operational price of latency has been well studied see, for example, Sheridan and Ferrell (1963), Held and Durlach (1991), and Sheridan (1993). For Mars, the speed of light limits the two-way latency to 8 40 min, depending on the orbital location of that planet. In fact, because of ground station availability and planning overhead, commands and data are exchanged with the Mars rovers Spirit, Opportunity, and Curiosity on a timescale of more like a day. Even for the Moon, the light-time limited latency is 2.6 s. For the Moon, the sense of presence that is achievable is limited, and for Mars, it is downright poor. The recipe for the highest quality presence requires two-way latencies that are smaller than the human reaction time, in order for the interaction to be considered real time. The relevant human reaction time can be taken to be an eye-hand reaction time, on the order of 200 ms. This recipe then dictates a limiting distance, which is 200 ms times the speed of light (and divided by two to account for bidirectionality). That distance, of about 30,000 km, is what we call the cognitive horizon, because at distances closer than this we can, in principle, have a highly cognitive sense of presence, but at distances farther away, cognition is necessarily handicapped (Lester Thronson, 2011). This is not a hard limit, of course, but just a distance at which cognitive awareness starts to change. Of course, the Moon is a factor of six beyond the cognitive horizon, and Mars is factors of thousands beyond it. The International Space Station, about 400 km over the surface of the Earth, is well within that distance. But low-latency telerobotics on the surface of the Earth controlled from Station (or on the Station controlled from Earth) are achievable mainly just during relatively brief and infrequent ISS overpasses of ground stations, rather than with the high bandwidth, but relatively large latency, TDRSS satellite system that is used for ISS data communication. More to the point, we already know how to put people up there in low- Earth orbit. We do it all the time. The Earth is physically small enough that the challenge of latency in telerobotics is largely borne by space

4 348 PRESENCE: VOLUME 22, NUMBER 4 exploration. In fact, NASA and other leading space agencies have outstanding expertise at high-latency telerobotics. But they have rather little expertise, compared with the multitude of applications in the commercial and defense world, in low-latency telerobotics and highquality telepresence. NASA science, for example, has virtually no such expertise. One would like to believe that those considering low-latency teleoperation for space exploration would acknowledge this fact, and with regard to at least human factors and task planning, would reach out to those with some real operational, if not technical, experience to offer. 5 On-Orbit Telerobotics and Surface Telepresence For distant worlds, the challenge of latency in telerobotic control from the Earth is inviolable. But new thinking has refreshed the potential of telerobotic control on planetary surfaces with high-quality human presence. For while human spaceflight is hard, expensive, and dangerous, human spaceflight down onto planetary surfaces is more so. Safe descent into a gravity well is critically dependent on perfect control of propulsion, perhaps aerodynamics. Operations in such a gravity well are likely to be compromised by day night cycles and airborne or levitated dust. The prospect of on-orbit telerobotics, where astronauts in orbit over a planetary surface control telerobots down below, is therefore exciting. With a wellchosen orbit, those astronauts can have such control for extended periods of time, can operate telerobots stationed at multiple sites all over the hemisphere below, staying within the cognitive horizon as they do. This would be done using life support and orbit control strategies already worked out on the International Space Station. The strategy is not exactly new. Fred Singer, in the 1970s, considered sending humans to the Martian moon Deimos where, among other things, they could control a dozen telerobots across the surface of Mars, about 20,000 km below (Singer, 1984, 2000). Soon after that, Marvin Minsky, in insightful musings about telepresence noted above, concluded more generally, I think the best way to explore the planets is to have people in orbiting spacecraft to operate telerobots on the surface (Minsky, 1980, p. 48). Minsky claimed inspiration from the science fiction short story Waldo by Robert Heinlein, whose title character rested comfortably in zero-g while he operated telerobots down in the oppressive gravity on the surface of the Earth. The strategy was advanced more formally in the Stafford Report, America at the Threshold, whose drafting committee was convened by Vice President Dan Quayle in 1991 to assess the Space Exploration Initiative (Stafford Commission, 1991). Here the idea was called telescience. But in spite of these creative viewpoints, and in spite of rapidly developing telerobotic capabilities, the idea of space accomplishment by boots on rocks remained sacred and unchallengeable. Such telerobots would, after all, change the practical definition of an astronaut (Mindell, 2009). Several efforts involving the International Space Station have since exercised on-orbit telepresence for lunar and planetary exploration in some detail. What would humans do with their telepresence on planetary surfaces? Pretty much everything they would do if they were down there themselves (Lester, 2012). Except they could spread that presence over large areas, and exercise their presence on time scales that would be vastly longer than a space suit could support an astronaut going for a walk. Their avatars would carry with them a sense of sight that would far outperform human eyes, in both resolution and spectral discrimination, and have dexterity, at least in manipulative precision, that could outperform gloved human hands. With a properly chosen orbit, their spacecraft could remain in continual sunlight, simplifying power and thermal constraints. The potential of on-orbit telerobotics to put human presence in places where we would never want to put humans is nothing short of stunning. We can envision a human presence on the 8008F surface of Venus, turning this way and that, stepping to the edge of outcrops and reaching out to pick up and inspect samples. We can envision human presence diving in the frigid methane lakes of the Saturnian moon Titan. Telepresence applied to space exploration can vastly increase the number of potential destinations for human presence, as opposed to human bodies, in space. This is not to say that we should not send humans to the surfaces of the Moon and planets. The idea of colonization and settlement is still attractive to many, and the

5 Lester 349 soft power that comes with such an accomplishment has geopolitical value. But to the extent that putting humans on planetary surfaces is presently unaffordable, on-orbit telerobotics and telepresence could be a near-term approach to putting human bodies in these places. The remarkable logical conclusion here, in view of dramatic developments in telerobotics and opportunities for telepresence, is nothing short of a two-word rationale for human spaceflight getting close. For with these developments, what separates us from high-quality human cognition and a real sense of presence in space is latency. Human spaceflight is how we remove that latency. To the extent that colonization and settlement become established goals, it really requires that humans go all the way there. But as noted above, those are goals that have not yet been recognized as national priorities. 6 Moving Human Cognition The goal of human presence, with the extraordinary developments in teleoperation, shows space exploration in a new light. Those who research and develop theory about the concept of presence should be aware of what appears to the human spaceflight community as an inconvenient truth about exploration. This is that exploration derived from human presence may well not need humans in situ, although it probably needs humans close by. To humans exploring space by telepresence, there is nothing simulated or virtual about the task. It is simply about relaying human cognition from one venue, which may be relatively inhospitable, to another nearby, which is more hospitable. Historical explorers had no such ability, and our newfound capability offers a completely new cultural perspective on exploration. In order to take advantage of the opportunities that telepresence offers, we have to look beyond historical definitions of exploration. Telepresence in space exploration is about much more than technology, but about overcoming dated preconceptions of what exploration actually entails. Acknowledgments The potential importance of telepresence to space exploration has been recently refreshed in collaboration and conversation with a number of colleagues. I want to thank in particular Kip Hodges, Cameron Ower, Kurt Klaus, Harley Thronson, Mark Craig, David Portree, Jim Garvin, George Schmidt, and Leonard David. References Held, R., Durlach, N. (1991). Telepresence, time delay, and adaptation. In S. Ellis (Ed.)., Pictoral communication in virtual and real environments (pp ). London: Taylor Francis. Launius, R. D., McCurdy, H. E. (2007) Robots and humans in space flight: Technology, evolution, and interplanetary travel. Technology in Society, 29(3), Lester, D. (2012). Putting human awareness and cognition on other worlds. Space Times, 51(5), 4 7. Lester, D., Robinson, M. (2009). Visions of exploration. Space Policy, 25(4), Lester, D., Thronson, H. (2011). Human space exploration and human spaceflight: Latency and the cognitive scale of the universe. Space Policy, 27(2), Mindell, D. (2009). The end of the cult of the astronaut. IEEE Spectrum, 46(6), Minsky, M. (1980). Telepresence. OMNI, 6, Minsky, M. (1990). Proposal for a remotely manned space station. In G. Landis (Ed.), Vision-21: Space travel for the next millennium, NASA Conference Publication 10059, pp National Aeronautics and Space Administration Authorization Act of 2010, Pub. L. No , 92 U.S.C (2010). Sheridan, T. (1993). Space teleoperation through time delay: Review and prognosis. IEEE Transactions on Robotics and Automation, 9(5), Sheridan, T., Ferrell, W. (1963). Remote manipulative control with transmission delay. IEEE Transactions on Human Factors in Electronics, 4(1), Singer, S. F. (1984). The PH-D proposal: A manned mission to Phobos and Deimos. In P. Boston (Ed.), The case for Mars (pp ). San Diego, CA: Univelt. Singer, S. F. (2000). To Mars by way of its moons. Scientific American, 282(3), Squyres, S. (2005). Roving Mars: Spirit, Opportunity, and the exploration of the red planet. New York: Hyperion Books. Stafford Commission. (1991). America at the threshold Report of the synthesis group on America s space exploration initiative. PDF.