Stellaris: People of the Stars

by Robert E. Hampson

  A comparison might be made to other cases of medicine in austere environments, such as Antarctic bases and nuclear submarines. This comparison can be instructive, but there are limitations. In extreme cases, medical evacuations can take place from each of those settings, although this is quite challenging for Antarctica. The diagnostic equipment and medical supplies available on each site, while limited, are more plentiful than on a spacecraft. Perhaps of most concern, communication delay due to distance from Earth will preclude most forms of medical support from the ground, especially in an emergency. Thus, the crew will need to have the onboard resources to not only treat medical conditions, but also to diagnose and anticipate them, and to make complicated clinical decisions based on the latest information without contact with Earth.

  Information. Finally, crews will need access to a great amount and variety of information while on their journey: personnel, vehicle, and mission status, for example. Many complicated systems will need to be monitored and maintenance performed in a timely fashion. For all of this, an intuitive set of human-system interfaces will be needed. These will have to provide crews with necessary information that is easy to digest in a timely manner and that helps guide them to proper actions. Too much or too little information is not helpful and can lead to burnout or a dangerous lack of situational awareness. Anyone who has dealt with current information technology and tried to make sense of the seemingly haphazard information in an internet search, which is easy to obtain but difficult to process and understand, will know that this area still requires significant work.

  There remain other considerations, but this brief survey should give an idea of the range of concerns for humans on deep-space missions that are in the current planning stages. Countermeasures are in place or in development for each of these issues. We note just two here. Exercise is a very powerful and successful countermeasure and is in regular use on the ISS (approximately two hours per day per person). Not only are there obvious physiological benefits for bone, muscle, and cardiovascular fitness, but exercise provides a sense of well-being as a psychological countermeasure. “Runner’s high” is well known, but also the exercise schedule provides “protected time” during which other tasks are secondary, allowing a mental break. (Astronaut time is the single most valuable quantity during a spaceflight, and their time is often scheduled to the minute. This can lead to timeline pressure and constant stress.) Nutrition is the other main countermeasure now in place and it too has wide-ranging benefits. Again, not only are there obvious physiological benefits, but food provides something familiar and comforting in an environment that is largely devoid of the normal human pleasures. It is also a socializing aspect, which crews find to be very important when the demanding schedules on the ISS can inhibit regular social interactions.

  Note that in the area of psychological function, including teamwork, the countermeasures are not so highly developed. Education and awareness are perhaps the most useful current approaches. It is worth noting that one very important psychological countermeasure, however, will not be available to crews on Mars missions: the ability to speak to someone on Earth at any time about any issue. This includes family and friends, but also physicians and psychologists. The communication delay on a Mars mission will preclude most meaningful conversations of this nature.

  (More information on these risks and countermeasures can be obtained from the series of Evidence Reports that the NASA Human Research Program maintains on its web site: https://humanresearchroadmap.nasa.gov/evidence/)

  AUTONOMY

  Thus, we come to the issue of crew autonomy. This is not a major concern with missions to low-Earth orbit, where home is just a few hours away and there is constant communication with mission control. In an emergency, the crew knows it can get instant and expert assistance. For missions farther out into deep space, autonomy will be a critical issue for Mars and even more so for missions beyond that. The need for autonomy increases with distance and duration to the point where it will be almost beyond our current comprehension for missions in the next century that might settle and colonize other planets.

  The main feature of autonomy is that the crew must be able to function on its own under nominal and emergency operations. The ability to recover from the unexpected and maintain mission success is closely related to resilience. It would be nice, then, if resilience could be characterized and even measured, so that crews would know when it is being compromised. Let us consider how this might be done.

  THE WORST-CASE SCENARIO

  From the previous discussion, it would appear that things are under control for humans in missions to LEO and maybe even to the Moon and Mars. NASA’s ambitious but feasible plans call for the mitigation of each major risk described above through extensive research and proper mission design before undertaking a lunar or Martian journey. Consider, however, the following scenario on the way to Mars:

  There is a solar flare or coronal mass ejection—a solar particle event (SPE) that emits a storm of high-energy protons. There is an undetected microorganism hiding, deeply embedded, in the spacecraft water supply, or the food supply, or the air-filtration system. The spike in radiation induces a mutation in the microorganism. At the same time, for reasons not completely understood, the astronauts’ immune systems are undergoing alterations that make them less effective in fending off some pathogens. Also, at the same time, one person is on a course of antibiotics that has caused a significant change in his gut microbiome, which modulates many body functions. This has seriously depleted the on-board medical stores. As if this weren’t enough, the exercise equipment breaks. At first glance none of this is particularly troublesome because, as we know, each of the individual risks has been sufficiently mitigated: radiation, food supply, immune function, microbiome, medical supplies, and exercise countermeasures. So, there is no problem, right?

  Wrong. Two days later the entire crew is dead or debilitated to such an extent that the mission is compromised. What went wrong? The radiation spike induced a mutation, which impacted the nutritional status of the crew (food or water supply). The human immune system is altered in space, as are some pathogens, with some becoming more virulent and others less so. If a mutated organism invades a compromised immune system, the outcome is not likely to be pleasant. The gut microbiome—the many microorganisms that live in the intestinal tract—exhibits some alterations when in space, and medications like antibiotics can also have a devastating (hopefully temporary) effect on the quantity and diversity of these microorganisms. The microbiome has been implicated in a wide variety of physiological functions, including even cognitive status. Exercise, in maintaining general systemic health, could help overcome the changes in immune, microbiome, and cognitive function. When these events transpire together (and they might be related to each other, as for example a radiation event might adversely affect instrumentation that runs the exercise device), unanticipated consequences can ensue.

  Thus, a crazy interaction of factors has conspired to bring about a devastating outcome. But this is not as crazy as it sounds. Aviation and aerospace “mishaps” and incidents are rarely caused by a single precipitating factor; they are almost always the consequence of an interacting series of events. In our example, the interactions have not been understood, characterized, and tracked properly over the course of the mission. Early recognition of changes in these factors, and how they might be connected to each other, might have led to an early intervention to stave off the devastating result.

  How can we do this? How can we systematically track all the of the relevant factors and their interactions and predict when the overall system (mission) is approaching an undesired state from which recovery might not be possible? How can we use this knowledge, in other words, to increase mission resilience?

  A BETTER WAY

  Imagine now a situation in which the on-board computer contains a mathematical model of the main factors that can be measured and tracked over the course of a mission: environmental and physiological
parameters, interpersonal interactions, sleep quantity and quality, mood, exercise, and many others. Sensors for many of these quantities exist, as do “wearables” to make individual personal measurements continuously and nonintrusively; additional new sensors are being developed all the time. The mathematical model also contains information about expected interactions between parameters. For example, a change in CO2 level can be expected to have some specific effects on the crew, and that corresponds to an interaction or link between atmosphere and psychology, mood, depression, and team cohesion, in addition to performance on standard tasks. If CO2 level changes for some reason, the computer can compare the effects that actually occur to the expected effects. The actual effects might not be pleasant or desirable, but if they are at least understood, then the mission is still on track: The actual mission falls within the range of the model. If there are unexpected interactions, such as an unusual physiological response on the part of some of the crew to a change in CO2 level, then this can indicate that a crucial interaction has changed, and the underlying model of interactions is no longer accurate. If this happens with enough interactions, a problem might be in the offing. This is because, recall, it is unanticipated and little-understood interactions that lead to bad outcomes. (The model and algorithm described here are beyond the current state of the art. They might be based on complexity theory and network concepts, with AI and machine-learning components, some of which have yet to be developed.)

  With this sensor-model system in place on a spacecraft to assist the crew, now consider the following scenario. The level of CO2 goes up for reasons that can’t be helped (perhaps the scrubber is down and there is a need to conserve consumables and power). As expected from elevated CO2, two crewmembers get into arguments and have difficulty working together, but one other crewmember exhibits no change in behavior when she typically becomes irritable and sleeps longer. This is a change in interactions—in cause and effect. The cabin CO2 might still be within normal limits, and the individual crew behaviors might be within normal acceptable ranges. The interactions, however, tell a different and subtler story. Is the third person already maxed out with other stresses such that elevated CO2 no longer has much effect? Is there some other change in metabolism that has altered the response to CO2? Whatever the cause, this altered interaction should be tracked, and if similar unusual changes occur soon after, then some type of intervention might be needed to fend off an undesired developing situation. Perhaps the computer algorithm recommends a change in the schedule to separate the two who are fighting, and additional rest and relaxation for the third, and then monitors the situation to see if these changes improve crew conditions and interactions.

  Resilience and performance have now been enhanced. We have provided this crew the tools to be resilient and they have maintained mission resilience independent of mission control. This is a microcosm of what will be necessary on a much larger scale for the much more ambitious journeys of colonization.

  A NEW BREED OF COUNTERMEASURES

  Considerable thought and effort have gone into defining and developing countermeasures, as noted previously. There is a rigorous—if sometimes contentious—process for determining what areas need to be addressed and what the best countermeasures are. We can learn from this process in extrapolating to future missions what the major problems might be and how they might be mitigated.

  Consider a journey to an outer planet (or its moon), or even to another solar system, possibly taking several decades.

  If there is no artificial gravity (AG), then the physiological degradations can be substantial and dangerous—a serious concern once the crew reaches its destination. Given current knowledge and a set of reasonable conjectures on the design of such a mission (crew makeup, spacecraft capabilities), it is likely that crews would land in such a debilitated state that their very survival would be jeopardized. Consider first that on the ISS exercise is a major countermeasure for an array of deficits, but in current implementations requires approximately two hours a day. Let’s allow that sophisticated methods are developed to augment the potency of exercise, such as ketogenic diets, blood restriction, and muscle cooling. Even with these in place to reduce the actual exercise requirement, it is likely that compliance will be an issue. Further considering the psychological difficulties of such a journey, motivation will flag, and the drive to maintain health could in turn diminish.

  One has only to observe astronaut crews returning from ISS missions of six months to see the possible consequences of the problem. Even in these groups of elite, highly trained and motivated professionals, with excellent countermeasure compliance, there is need for assistance for the crew in leaving the spacecraft and making its way to the medical tent. The ability to walk in any meaningful way is impaired for hours to days, and full recovery can take weeks or months. This is the current best-case scenario. A possible solution to this is to allow the first planetary settlers a significant period of rest, recovery, and rehabilitation upon landing. The spacecraft would essentially become a rehab facility for physical therapy while the occupants once again learn to walk and maneuver in a gravity field and regain muscle strength and aerobic capacity. This is a reasonable approach but requires a much larger habitat on the surface than would be needed simply for landing a group of people.

  Even in this optimistic view, there are physiological issues such as loss of bone density and strength that will remain significant and dangerous. (Landing on a body with less than a one-gee field will ease these concerns since the likelihood of a fall, and the intensity of a fall, would be reduced and hence the possibility of breaking a bone would be reduced.) Added to this is the chronic shift of fluids to the upper body and head, which might not only induce vision problems as seen in some ISS astronauts, but could be causing low-level neural damage. The prospect of a large number of slightly demented individuals stumbling around on a new planet, tripping and breaking bones, is not one that most planners would find desirable or acceptable. They would be like the first settlers in a foreign land who encounter a bacterium or virus for which they have no natural immunity, only in this case the scythe is wielded by gravity and not by an organism.

  Artificial gravity is therefore a compelling option for such a journey (Young 1999; Clément and Bukley 2007). The longer the journey, the more compelling the case. When we consider journeys of decades or more, it is almost unconscionable not to consider AG as a requirement. Indeed, many of the practical issues that inhibit its ready acceptance in current planning should have been solved by the time these journeys of colonization become a reality. But AG is not a panacea, nor is it obvious how best to implement it. One appealing method entails constant linear acceleration of the spacecraft for half of the journey, and then constant deceleration (technically, acceleration in the other direction) for the other half of the journey. This creates a linear acceleration force, which is indistinguishable from gravity itself. The change from acceleration to deceleration at the halfway point would be quite an event. Other than that, this would be a benign method to produce some level of AG in the entire craft. The propulsion requirements for this are currently prohibitive. Better to think along more conventional lines: a rotating craft that produces centripetal force proportional to radius (distance from the axis of rotation) and to the square of the rate of rotation. Larger and faster spinning produces more AG.

  Rotation of an entire spacecraft in this manner is daunting. It also raises the question of what happens when the craft reaches its destination and rotation stops or the crew departs the rotating craft and experiences zero-gee for the first time, at exactly the time they must prepare for a challenging planetary descent. Perhaps there is a better way. Much thought has been given to alternate approaches, such as rotating just a part of the spacecraft. If the sleeping quarters are rotated, the crew will experience eight hours of AG each night, while enjoying the pleasures of zero-gee the rest of the time. A spacecraft might also contain a small exercise chamber in the form of a cycle ergometer
(exercise bicycle) that moves in a tight head-over-heels circle when pedaled, supplying exercise and providing AG at the same time. Each of these approaches has its problems, but some combination of them could almost certainly be made available to a large crew.