Extraterrestrial First Contact in Space Protocols

As we move into the outer Solar System and beyond, the possibility exists that we may encounter an extraterrestrial species engaged in similar exploration. How we approach first contact has been a theme of science fiction for many years (Murray Leinster’s 1945 story ‘First Contact’ is a classic treatment). In the essay below, Ken Wisian looks at how we can develop contact protocols to handle such a situation. A Major General in the US Air Force (now retired) with combat experience in Iraq, Afghanistan and the Balkans, Ken brings a perspective seasoned by command and a deep knowledge of military history to issues of confrontation and outcomes, building on our current rules of engagement to ask how we will manage an encounter with another civilization, one whose consequences would be momentous for our species.

By Ken Wisian Ph.D
Galactic Ventures LLC, Austin, Texas

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Abstract

How do two ships approach each other in a first contact setting? When it happens it will be a pivotal moment for human history. The slightest mistake or misperceived intention could cascade into violence. Therefore even future deep space robotic probes, let alone a true interstellar ship whether crewed by humans or AI, should incorporate courses of action for this possibility,

The development of first contact protocols is obviously rife with unknowns since we only have a one-planet historical data set build on; nevertheless we must proceed. The bulk of the thinking on first contact so far has focused on a remote contact via electromagnetic signal exchange (SETI) or finding non-sentient microbiota (aka Apollo post-mission quarantine), but what if we stumble upon another intelligence in space? Admittedly, this may not be the most likely course of action, but as we start to move deeper into space it is an increasing possibility. Through centuries of trial and error, protocols have been developed for military ship and aircraft encounters on Earth. These earth protocols provide as good a basis as we have for building extraterrestrial first contact protocols.

This paper will review human rules of encounter currently used and build a set of simple rules for a ship-to-ship encounter in space based on the assumption that there is no effective communication prior to or during the encounter.

1. Introduction

How do you approach a totally unknown entity in such a way as to not provoke a hostile reaction? This is not as easy a question as it might first appear. We are loaded with human-cultural preconceptions that are frequently subconscious. An example; smiling in humans is universally regarded as a friendly gesture, but in some primates and most species on earth (with a face that is) showing your teeth is a dominance/aggressive/threat gesture. And this difference here on earth exists between closely related species – who is to say how divergent the interpretation of gestures might be between species that evolved in different star systems? Another example is the white flag. Most industrialized states recognize it as a sign of surrender, some also would recognize its use to request parley, but it is far from universal in time or across cultures even today on earth. Thus nothing can be taken for granted and substantial on-the-spot sound judgement will be required.

Why worry about the vanishingly small chance of an unanticipated first contact? Risk management both in the military and civilian world considers not just the probability of an event, it also considers the potential consequences. In the case of a first contact, the odds of such an event are nearly vanishingly small, but they are cancelled out (and then some) by the off-the-chart potential impact of an encounter unintentionally entering an instantaneous, violent escalation spiral. Thus it is critically important that humans think through first contact in space before it happens.

Science fiction (SF) deals frequently with first contact scenarios. The volume of material is immense – far too much to even briefly review here. SF has explored, often quite well and with great “outside the box” thinking probably every conceivable scenario. So while there are no specific SF references here, the body of SF work informs all aspects of this paper.

We have a limited knowledge base from which to start and extrapolate general rules for first encounters, namely one technological species – homo-sapiens. This situation presents a danger that we must guard against as best we can; anthropomorphic bias. Given that potential bias, we will none the less start by looking at what humans do in the closest analog we currently have for first encounters; the meeting of unknown, neutral or potentially hostile ships and or aircraft. Through trial and (often fatal) error there are now well-defined rules of conduct for these situations (up to the level of international law).

The human-human contact experience is perhaps our best foundation upon which to build a set principles and protocols for a potential encounter in space. The envisioned scenario; two ships meeting in space rest on several assumptions.

Assumptions:

1. No effective telecommunication. There may be attempts to communicate via electromagnetic or other means, but understanding has not been achieved, thus we are without effective communication – “comm-out”.

2. Neither side is overtly hostile, but both are guardedly cautious.

3. At least one of the ships involved has “reasonable” maneuvering capability.

a. This will most likely be an “endpoint” encounter, in a solar system. An encounter in transit in deep interstellar space would likely mean neither ship has the ability to stop and/or maneuver in order to match vectors and effect a rendezvous.

Not a scenario assumption, but an important point is that these protocols apply just as well to Artificial Intelligence (AI) crewed ships as they do to human crewed ships. Also, ships is taken to include space stations or other similar outposts. Even probes without true AI can incorporate complex, branched Courses Of Action (COAs) for dealing with encounters. For instance, detection of radiation anywhere in a wide range of EM frequencies that does not correlate with known astronomical sources would be a target to slew all sensors to and report on. At that point, depending on level of sophistication, you enter COAs for determining artificiality etc.

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Image: Confronting the unknown. A still from Steven Spielberg’s Close Encounters of the Third Kind. Credit: EMI Films / Columbia Pictures.

2. Current human protocols

There are internationally accepted protocols for encounters between ships and correspondingly between aircraft. Some are based on international law and custom (Law of the Seas), some are rules by governing bodies (International Civil Aviation Organization). Similar laws and rules exist also within the boundaries of individual countries. Regardless of origin, they follow broadly similar, mostly common sense (at least to us nowadays) paths based on centuries of experience. Underlying much of this is an unwritten intent to minimize potential misunderstanding that could lead to violence. This point is critical for our purposes. It is difficult enough to minimize misunderstanding and escalation within our own species, it could be significantly more difficult to do the same when civilizations from different stars meet.

Much of the law and customs for ships at sea pertain to piracy or the right of a country to inspect a ship to ensure that it is conducting legal business (particularly in territorial waters). Even here though reasonable cause is required for more than a cursory inspection. The rules governing intercept of aircraft are more slanted towards the need to immediately protect a country from devastating attack that can result from a craft moving at or above supersonic speed and thus can lead much more quickly to lethal action.

In all air and sea cases there is a hierarchy of communication means used to establish meaningful dialog between ships from straightforward radio communication to flag and light signals up to and including weapons fire – the shot across the bow, so yes, even gunfire can be a form of communication. With aircraft there are no flags, but brief maneuvers (such as rocking wings) can be used for communication.

For ships at sea, there are rules for avoiding collision such as pass to the right (starboard). There is also a rule that the most maneuverable ship has primary responsibility to avoid collision. For example a functional ship at sea that comes upon a ship adrift, unable to maneuver, besides having a responsibility to help, is responsible to maneuver so to avoid collision. Correspondingly, the less maneuverable ship is obligated to maintain constant speed and heading or come to a stop. For aircraft meeting aircraft there is a similar most maneuverable has primary responsibility to avoid collision rule, so for instance a powered aircraft has responsibility to avoid a hot air balloon.

For military aircraft or ships meeting other military ships or aircraft there are additional guidelines that are critical for avoiding escalation. First is to avoid collision courses or aggressive maneuvers such as those designed to put one in a (better) shooting position. Right along with that are restrictions on pointing guns or (and this gets tricky) putting support systems such as radars into modes such as target track that are standard preparatories to firing weapons. Radar modes have become particularly problematic as technology has advanced; many weapon system no longer require a distinctive target tracking mode in order to shoot. Furthermore electromagnetic jamming during an intercept is a potentially hostile act. These rules unfortunately are not universally followed and not following them has resulted in very serious international incidents to the present day.

3. Excursion into past human civilizational first contacts

The past record of human civilization first contacts is a well-trodden area of history and will only briefly be covered as it pertains to extraterrestrial scenarios – the longer term consequences such as disease transfer and cultural domination will not be addressed. Less commonly studied though are the details and consequences of the actual first contact. The bottom line is that first encounters have often, though not always turned violent and in such cases the side with a major technological advantage usually wins. Commonly Western Europeans with well advanced gunpowder technology encountering stone or bronze/iron age technologies have won most violent encounters, but have sometimes been overcome bu numbers. The question of why encounters have turned violent and the cause is much more ambiguous – some encounters have been peaceful, but in many cases territoriality and xenophobia have been prompt causes for violence. Who can say for sure that any species encountered may not have these traits (even more markedly than humans)? Perhaps more disturbing, there are human cultures that consider war/killing a necessary prerequisite to full citizen status. Fortunately none of these cultures are dominant on earth today, but what if such a culture achieved an interstellar civilization?

4. Towards a protocol

The above review of human encounter situations and history gives us a good starting point for thinking about alien ship to ship encounters. First a few general principles to go with the assumptions already laid down at the beginning. These principles are distilled from the human contact procedures above which in turn are built upon millennia of experience.

Contact principles

  • 1. Be predictable
  • 2. Avoid any appearance of hostile intent
  • 3. Attempt communication

These seem straightforward, but #2 has many subtleties and #3 is a very complex subject which is beyond the scope or this paper or the expertise of the author.

The principles are in priority order; communicating is far less important than the closely related ideas of being predictable and not showing hostile intent. These principles are broadly applicable in human experience. For example besides applying at the level of international affairs, these are also appropriate at the level of individuals for an encounter with law enforcement around the world, driving a car, or encountering strangers on the street.

What has not been stated before is the underlying motivation for these principles and that is to avoid putting the other party into a position where they have to make a snap judgement about your intent. In human interactions between two wary parties ambiguity of intent is almost always interpreted in the most hostile way (unless the parties have a considerable experience base, which in a first contact they will not, that allows them to presume accidental ambiguity versus hostility). It is also important to note that for the foreseeable future, considering that we have only just become a spacefaring species, we are most likely to be the less technologically advanced of the two encountering civilizations and thus it becomes particularly important that we not precipitate any escalation that we are very likely to lose.

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Image: David Bowman (Keir Dullea) and a famous monolith, from Stanley Kubrick’s 2001: A Space Odyssey. Credit: Metro-Goldwyn-Mayer.

First, be predictable. Being predictable is taken to mean with respect to maneuvering primarily. If it is possible to determine that one ship has a decided maneuver advantage on the other, then rendezvous can be attempted with the ships adopting the convention of the most maneuverable ship takes primary responsibility for a safe rendezvous. In these cases gradual, deliberately slow maneuvers would be employed even if there is capability to rapidly affect course changes. With regards to maneuvers there are multiple COAs available. The simplest is to make no changes to what you are doing; if “coasting” – continue, if drive engines are engaged, continue at current setting. Alternatively, you might want to stop engines (this is not the same as stopping in space, which is probably not a practical thing to do (for that matter what frame of reference would you use to determine “stop”)). Regardless unless there is an overriding need (discussed shortly), maintain heading (in three dimensional terms – maintain vector).

What if one ship is approaching an orbital situation – remember that an encounter will most likely be at the endpoint of an interstellar journey. In such a case, in order to avoid catastrophe it might be necessary to start or continue maneuvers to achieve a safe, stable orbit, but this brings with it a slightly elevated risk misunderstanding. In this situation we would be forced to rely on the other parties’ ability to perceive the obvious need to conduct maneuvers. Note the potential for unintended consequences; for a ship that would need to “flip” end-to-end in order to reverse its engines and thrust, you would not want to “sweep” your thrust vector across the other ship and therefore place them in a position of having to decide if you are about to use you most destructive weapon (main drive) on them.

Secondly, avoid any appearance of hostile intent. This is a much more problematic issue than being predictable. The main problem with avoiding appearance of hostile intent is the perception problem. In any encounter between entities that do not share a common culture, there can be serious misinterpretations of intent and meaning, as exemplified by the smile and white flag examples earlier.

If a ship is equipped with weapons you would obviously not want to point them at the other ship. If practical stowing or deactivating them is good, but this then poses another question: would you want to have weapons that require time to activate completely deactivated, thus costing valuable time to spin up if things go bad?

Besides weapons, other non-destructive systems are used by the military; jammers and expendable decoys for example. These would obviously not want to be triggered (but what might be the difference between jamming and a high-powered attempt at communication?).

“But we are peaceful and will not be going armed into space” you say. Any conceivable ship will have technology/systems that are dual-use. The main drive of any self-powered interstellar ship will obviously be extremely high energy and could be used as a weapon of great range and destructive power, thus even a peaceful braking maneuver (with the drive off) that sweeps the business end of the drive towards the other ship, could prompt a swift reaction. Other systems that must be accounted for include communication systems; radios or lasers strong enough to communicate across interstellar distances could be very destructive at short range. So what is one to think when you see a high power laser move to point at you? Perhaps part of a communication protocol would be to only use low-power omnidirectional radio until good understanding is established. Shielding to protect ship and crew from radiation and or collisions has obvious military application – do you reduce its power, turn it off, or leave it in normal on mode? Can you? What if there is an active collision prevention system that destroys or pushes objects out of the way – that has major weapon potential. Is it safe to turn it off?

Tertiary considerations. Avoid looking like you are hiding (aircraft that turn off transponders are usually considered to have hostile or at least illegal intent). Turn on lights and anything else that makes you easily visible (but will this in turn blind any of the other ships sensors?). In your turn you will obviously use every sensor available to learn about the other ship, but passive sensors are probably best until goodwill is firmly established – an active radar scan may look like targeting to another party (just as targeting and search modes of radars are often indistinguishable in modern aircraft). A decoy, a probe, or a vessel containing materials to allow for communication and understanding, might be indistinguishable from a bomb, when launched from a ship.

Lastly, at what range do these actions need to start? As early as practical, probably at detection of the other ship. Your need to be predictable starts when they can see you and that is probably at least at the point when you can see them, if not much earlier.

5. Conclusion

What can be determined from the above discussion is that there are vast unknowns in any potential extraterrestrial encounter in space where effective communication is not established in advance. In these circumstances there are good principles to follow – be predictable, display no hostile intent, and attempt to establish communication, but the specific actions involve many gray areas where judgement, assumptions, or just plain hope, will be the guide. For any ship making an interstellar journey the scenarios must be “gamed” extensively in advance, but any COAs or checklist for an encounter should only be a guide/starting point. Flexibility, sound judgement and quick learning will be very important in these circumstances. The number one goal is to not put the other party in the position of having to make an instantaneous judgement about your intent.

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Toward a Space-based Anthropology

Cameron Smith is no stranger to these pages, having examined the role of evolution in human expansion into space (see Biological Evolution in Interstellar Human Migration), cultural changes on interstellar journeys (Human Universals and Cultural Evolution on Interstellar Voyages), as well as the composition of worldship crews (Optimal Worldship Populations). An anthropologist and prehistorian at Portland State University, Dr. Smith today offers up his thoughts on the emerging discipline he calls space anthropology. How do we adapt a field that has grown up around the origin and growth of our species to a far future in which humans may take our forms of culture and consciousness deep into the galaxy? What follows is the preface for Dr. Smith’s upcoming book Principles of Space Anthropology: Establishing an Evolutionary Science of Human Space Settlement, to be published by Springer later this year.

By Cameron M. Smith, PhD

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New Realms of Action Require New Domains of Expertise

In 1963, Siegfried J. Gerathewohl, NASA’s biotechnology chief, wrote the following passage early in his foundation text, Principles of Bioastronautics, outlining the need for this new field of study:

“Manned excursions into space require new types of vehicles, machines and hardware which were unknown in conventional flying. They will carry the traveler into such foreign environments as to pose serious problems of health and survival. The new field of medicine, which studies the human factors involved and the protective measures required, has been called space medicine. From its cooperation with modern technology, particularly with electronics, cybernetics, physics, and bionics, space biotechnology has branched out as a novel field of bioengineering.” [1:5-6]

At the time of that publication, less than ten people had been in space; the moon landings were yet vague plans, the robotic reconnaissance of our solar system was in its infancy and virtually nothing was known of human biology in space. Two generations later, space exploration and space sciences are at an historical apex of activity and rapid technical progress. Low Earth Orbit has been continuously occupied by at least one person, continuously, for over a quarter century, yielding thousands of scientific studies on space biology; Mars has been swarmed by robotic explorers seeking traces of life and mapping landscapes for human exploration and settlement; dozens of private companies and even individuals are re-inventing basic space exploration technologies with cheaper materials and methods than those of last century’s space age with the aim of lowering the cost of space access, and astronomy has entered a new age, with space-based technologies identifying multitudes of exoplanets now slated to be examined for traces of life with methods just coming on-line.

One significant outcome of these many efforts to better understand our stellar neighborhood will be the settlement of space by populations of humans and their domesticates. The ancient dream of setting off across space to explore and settle new lands—for freedom, exploration, economic advantage, the safeguarding of humanity by spreading out from the home planet, and a multitude of other motivations—appears more likely than ever, and its earliest steps are being taken now. For example, the SpaceX corporation was founded “…to revolutionize space technology, with the ultimate goal of enabling people to live on other planets” [2] and indeed in October 2016 Elon Musk is set to announce detailed Mars settlement plans. Such proposals involve not just individual people but populations, which have their own biological and behavioral (cultural) properties. In the same way that space exploration required Gerathewohl’s bioastronautics, space settlement planning requires a field of study to ensure that plans are designed and carried out informed by all we know of the adaptive tools and techniques of our species.

A New Branch of Anthropology

Traditionally, the study of humanity’s adaptations has been the domain of anthropology. Over the last century this field has capably documented our species’ remote origins, long and complicated evolution, and myriad manifestations in the present, but it has only occasionally (and then unsystematically) forayed into humanity’s distant future (e.g. see [3,4,5]). It is a premise of this book that that future should include the human settlement of environments beyond Earth, particularly for the purposes of safeguarding humanity’s apparently unique mode of consciousness, its hologenome and many of its domesticates, and the totality of human knowledge—accumulated over about 3,000 generations since the origins of behavioral modernity—by the method of establishing populations of humanity culturally and biologically independent of our home planet. I discuss arguments for space settlement in [5] and [6], but in the present book I focus on how the resources and expertise of anthropology may be deployed to assist in the goals of human space settlement.

While bioastronautics was established during the First Space Age (hereafter FSA) with tight focus on safeguarding the short-term health of individuals or small crews, today, plans include space settlement by communities, which raises many new issues; individual physiology is a different phenomenon than, say, population genetics, and individual psychology as short-term adaptation is different from cultural adaptation by reshaping cultural norms in accordance with new circumstances; I tabulate some other such differences below.

Chief Differences Between Space Exploration and Space Settlement Relating to Adaptation

Space ExplorationSpace Settlement
Goalsspecific, short-termgeneral, long-term
Group Sizesmall (crews)large (communities)
Social Organizationcommand hierarchycivil community
Essential Social Unitscrewsfamilies and communities
Adaptive Meanstechnological, individual behavior, and some reversible acclimatizationtechnological, cultural and biological adaptation
Adaptive Timescaleshort; weeks to monthslong; multigenerational

For these reasons a new field of study is required. In this book I propose, describe, and outline the scope of space anthropology or exoanthropology, and present some of my own results in this new discipline.

In the same way that Gerathewohl identified the need for his field in the quotation at the opening of this Preface, below I formally outline the need for space anthropology:

Space settlement will require novel biological and cultural adaptations to support populations of humans, on multigenerational timescales, in environments so far unfamiliar to our species even after 100,000 years of human cultural and biological adaptation to myriad Earth environments. The new field of anthropology that studies such adaptive efforts is space anthropology or exoanthropology, exo- referring to beyond Earth, in the same way it is used in the term exobiology.

Specifically, I propose space anthropology to have three main functions:

  • 1. To identify the biological and cultural adaptive suite of humanity globally and to date, resulting in a catalog of our species’ adaptive tools and capacities useful to space settlement planners.
  • 2. To evaluate the capacities of humanity’s various adaptive tools to adapt to reasonably forseeable space settlement plans, bettering the prospect of productive adaptations to new conditions, e.g. on Mars.
  • 3. To make recommendations, some broad and some specific, that would assist in human adaptation to environments beyond Earth, particularly based on evaluations of human adaptive capacities identified in functions 1 and 2.

The scope of exoanthropology, then, will be broad. I propose it as an applied form of anthropology with the specific goal of evaluating the adaptive capacities of our species, both biologically and culturally, so that they may be best deployed to assist in successful permanent space settlement. This will guide space settlement planning in a genuinely adaptive and evolutionarily-informed way, applying the lessons of billions of years of Earth life adaptation to what I consider to be the completely natural and expected dispersal of life throughout the solar system and beyond. This book, then, will thoroughly review the phenomenon of evolutionary adaptation, particularly among our species.

Human ‘adaptive tools’ are biological and cultural (which subsumes technology) [7]; an array of such adaptations so far recognized in the Earth’s cold, high altitude and hot regions are tabulated below as examples—these will be fully explored later in this book.

Some Human Adaptations to Earth Environments

BiomeLimiting FactorsBiological, Cultural and Technological Adaptations
Arctic / Cold*Extremely low temperatures for long periods

*Extreme light / dark seasonal cycles

*Low biological productivity
Biological
* increased Basal Metabolic Rate
* increased shivering, vasoconstriction and cold thermoregulation activity and efficiency
* compact, heat-retaining body stature

Cultural and Technological
* bilateral kinship = demographic flexibility
* clothing insulates but can prevent sweating
* semi-subterranean housing including igloo made of local, free, inexhaustible reosurce (snow)
* high fat diet yielding many calories and vitamins
* low tolerance of self-aggrandizement
* low tolerance of adolescent bravado
* high value of educating young
* social fission
* mobile, field-maintainable, reliable tools
* population control methods including voluntary suicide, infanticide
* high value on apprenticeship
* low tolerance for complaint: 'laugh don't cry'

High Altitude* Low oxygen pressures

* Nighttime cold stress

* Low biological productivity

* High neonatal mortality
Biological
* dense capillary beds shorten distance of oxygen transport
* larger placenta providing fetus with more blood-borne oxygen
* greater lung ventilation (capacity)

Cultural and Technological
* promotion of large families to offset high infertility
* use of coca leaves to promote vasoconstriction and caffeine-like alertness
* woolen clothing retains heat when wet
* trade connections with lowland populations
Arid / Hot* Low and uncertain rainfall

* High evaporation rate

* Low biological productivity
Biological
* tall, lean, heat-dumping body
* lowered body core temperature
* increased sweating efficiency
* lower urination rate
* increased vasodilation efficiency

Cultural & Technological
* flexible kinship & land tenure system = demographic flexibility matching shifting water resources
* intercourse taboo maintain sustainable population
* loose, flowing clothing blocks sunlight
* wide sandals block ground-reflected sunlight
* nakedness socially accepted during physical labor

In fulfilling Function 1, exoanthropology will survey humanity’s adaptations through time and across the globe, identifying patterns pertinent to space settlement planners. In fulfilling Function 2, it will review the adaptive competence of many of our species’ adaptive tools, allowing us to evaluate our readiness for space settlement and, where we find ourselves unready, suggest courses of action; it will also characterize forseeable space settlement conditions and limiting factors as needed. In fulfilling Function 3, recommendations for space settlement planners will be formulated, varying in specificity, based on the lessons identified in the surveys serving Functions 1 and 2. Finally, in fulfilling Function 4, directly actionable engineering and other design recommendations will be made, materially assisting in space settlement planning.

References to Author’s Preface

1. Gerathewohl, S. 1963. Principles of Bioastronautics. Prentice-Hall, New Jersey.

2. SpaceX website (accessed 14 April 2016): http://www.spacex.com/about.

3. Finney, B. and E. Jones (eds). 1985. Interstellar Migration and the Human Experience. Berkeley, University of California Press.

4. Finney, B. 1992. Space Migrations: Anthropology and the Humanization of Space. NASA SP-509: Space Resources, Volume 4: Social Concerns. Washington, D.C.

5. Smith, C.M. and E.T. Davies. 2012. Emigrating Beyond Earth: Human Adaptation and: Space Colonization. Springer, Berlin.

6. Smith, C.M. and E.T. Davies. 2005. The Extraterrestrial Adaptation. Spaceflight 47(12):46.

7. Morphy, H. and G. Harrison (eds). 1998. Human Adaptation. Oxford: Oxford University Press.

© 2016 by Cameron M. Smith, PhD

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Pluto: Unusual Interactions with the Solar Wind

David McComas (Princeton University) calls what his team of researchers have learned about the solar wind at Pluto ‘astonishing,’ adding “This is a type of interaction we’ve never seen before anywhere in our Solar System.” The reference is to data from the Solar Wind Around Pluto (SWAP) instrument that flew aboard New Horizons. McComas knows the instrument inside out, having led its design and development at the Southwest Research Institute.

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Image: The first analysis of Pluto’s interaction with the ubiquitous space plasma known as the solar wind found that Pluto has some unique and unexpected characteristics that are less like a comet and more like larger planets. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.

What startled McComas was that Pluto’s interactions with the solar wind are nowhere near what had been predicted. This stream of charged particles flowing outbound from the Sun can reach speeds of 500 kilometers per second and above, a ragged, bursting outrush that we may one day be able to capitalize on as a way to drive spacecraft. While planets act to divert the solar wind, comets slow it far more gently, an effect that researchers assumed they would find at Pluto.

Instead, Pluto’s complexities place it somewhere between planet and comet as its atmosphere copes with the solar wind. We learn in the paper from McComas and team that despite expectations, Pluto’s gravity is capable of holding electrically charged ions in its extended atmosphere. The dwarf planet has an ion tail extending ‘downwind’ to a distance of about 100 Pluto radii (120,000 kilometers). Earth has a similar ion tail, and Pluto’s is said to show ‘considerable structure.’

From the paper:

Initial studies of the solar wind interaction with Pluto’s atmosphere…, all assuming the absence of an intrinsic magnetic field, suggested that it would depend on whether the atmospheric escape flux is strong — producing a ‘comet-like’ interaction where the interaction region is dominated by ion pick-up and many times larger than the object — or weak — producing a ‘Mars-like’ interaction dominated by ionospheric currents with limited upstream pick-up and where the scale size is comparable to the object.

And Pluto, we learn, behaves more like its larger planetary cousins, as the image below suggests.

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Image: This figure shows the size scale of the interaction of Pluto (at lower left) with the solar wind. Scientists thought Pluto’s gravity would not be strong enough to hold heavy ions in its extended atmosphere, but Pluto, like Earth, has a long ion tail (red) loaded with heavy ions from the atmosphere. Pluto has a very thin “Plutopause” (purple), or the boundary of Pluto’s tail of heavy ion tail and the sheath of the shocked solar wind (blue) that presents an obstacle to its flow. Credit: American Geophysical Union.

The SWAP instrument was able to separate heavy ions of methane, which is the primary gas escaping the atmosphere, from the light hydrogen ions coming from the Sun. From it we also learn that Pluto has a thin ‘Plutopause,’ a boundary region where the heavy ion tail meets the solar wind along a sheath of particles. Moreover, the solar wind is not blocked until it reaches within about about 3000 kilometers of the dwarf planet — the paper calls this the ‘upstream standoff distance’ — a bit less than three Pluto radii.

As the paper notes, we’ll have a good deal of data from different parts of the Solar System to examine as we try to put Pluto into context:

While the small size of the interaction region relative to Pluto is reminiscent of Mars and Venus, we note that recent observations of the solar wind interaction with the relatively weakly out-gassing Comet 67P Churyumov-Gerasimenko by instruments on ESA’s Rosetta spacecraft show deflection of the solar wind with relatively modest decrease in speed. We anticipate interesting scientific discussions of the relative roles of atmospheric escape rate, solar wind flux, and IMF strength at Mars, Comet 67P and Pluto as the data from the MAVEN, Rosetta and New Horizons spacecraft are further analyzed.

And as McComas notes in this Princeton news release, “The range of interaction with the solar wind is quite diverse, and this gives some comparison to help us better understand the connections in and beyond our solar system. The SWAP data will … be reanalyzed … for many years to come as the community collectively grapples with Pluto’s unique solar wind interaction — one that is unlike that at any other body in the solar system.”

The paper is McComas et al., “Pluto’s Interaction with the Solar Wind,” accepted at the Journal of Geophysical Research: Space Physics (abstract / preprint).

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Beneath a Methane Sea

Back when Cassini was approaching Saturn and we all anticipated the arrival of the Huygens payload on the surface, speculation grew that rather than finding a solid surface, Huygens might ‘splash down’ in a hydrocarbon sea. I can remember art to that effect in various Internet venues of the time. In the event, Huygens came down on hard terrain, but since then Cassini’s continuing surveys have shown that seas and lakes do exist on the moon. Over 1.6 million square kilometers (about two percent of the surface of Titan) are covered in liquid.

Ligeia_Mare_article_mob

Image: Ligeia Mare, shown here in a false-colour image from the international Cassini mission, is the second largest known body of liquid on Saturn’s moon Titan. It measures roughly 420 km x 350 km and its shorelines extend for over 3,000 km. It is filled with liquid methane. The mosaic shown here is composed from synthetic aperture radar images from flybys between February 2006 and April 2007. Credit: NASA/JPL-Caltech/ASI/Cornell.

The liquid, of course, is not water but methane and ethane, existing in an atmosphere that is almost 95 percent nitrogen (with methane, small amounts of hydrogen and ethane making up the rest). Cassini has shown us three large seas near the north pole that are surrounded by numerous smaller lakes, while only a single lake has thus far been found in the southern hemisphere. New work on Cassini flyby data between 2007 and 2015 now confirms that Ligeia Mare, one of Titan’s largest seas, is made up primarily of liquid methane.

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Image: A radar image of Titan’s north polar regions (centre), with close ups of numerous lakes (left) and a large sea (right). The sea, Ligeia Mare, measures roughly 420 x 350 km and is the second largest known body of liquid hydrocarbons on Titan. Its shorelines extend for some 2000 km and many rivers can be seen draining into the sea. By contrast, the numerous lakes are typically less than 100 km across and have more rounded shapes with steep sides. Credit: NASA/JPL-Caltech/ASI/USGS; left and right: NASA/ESA. Acknowledgement: T. Cornet, ESA.

The finding is a bit surprising given that ethane is produced when sunlight breaks methane molecules apart. Thus expectations for Ligeia Mare involved primarily ethane. Alice Le Gall (Laboratoire Atmosphères, Milieux, Observations Spatiales and Université Versailles Saint-Quentin, France), who led the new study, comments on the finding:

“Either Ligeia Mare is replenished by fresh methane rainfall, or something is removing ethane from it. It is possible that the ethane ends up in the undersea crust, or that it somehow flows into the adjacent sea, Kraken Mare, but that will require further investigation.”

As this work progressed, Le Gall and team relied on a radio sounding experiment performed in 2013, described in this ESA news release. The radio sounding, led by Marco Mastrogiuseppe, detected seafloor echoes and was able to derive the depth of Ligeia Mare along Cassini’s track, which marked the first time we have ever detected the bottom of an off-Earth sea. The deepest depth recorded was 160 meters. Le Gall used the sounding data along with observations of thermal emissions from Ligeia Mare at microwave wavelengths in her work.

The result: The new paper reports that the researchers were able to separate the thermal emissions from the seafloor from those of the liquid sea. The seabed is found to be covered by what Le Gall calls “a sludge layer of organic-rich compounds.”

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Image: How different organic compounds make their way to the seas and lakes on Titan, the largest moon of Saturn. A recent study revealed that Ligeia Mare, one of Titan’s three seas, consists of pure methane and has a seabed covered by sludge of organic-rich material. Credit: ESA.

You can see the process at work in the image above. Nitrogen and methane in Titan’s atmosphere produce organic molecules, the heaviest of which fall to the surface. Reaching the sea through rain or one of Titan’s rivers, some are dissolved, while others sink to the ocean floor. We also find that the surface areas surrounding the lakes and seas are likely flooded with liquid hydrocarbons, based on the lack of temperature change between the sea and the shore.

The paper is Le Gall et al., “Composition, seasonal change, and bathymetry of Ligeia Mare, Titan, derived from its microwave thermal emission,” Journal of Geophysical Research: Planets, published online 25 February 2016 (abstract). Marco Mastrogiuseppe’s work on the depth of Ligeia Mare is described in “The bathymetry of a Titan sea,” Geophysical Research Letters, published online 4 March 2014 (abstract).

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Breakthrough Starshot: Mission to Alpha Centauri

Here on Centauri Dreams we often discuss interstellar flight in a long-term context. Will humans ever travel to another star? I’ve stated my view that if this happens, it will probably take several hundred years before we develop the necessary energy resources to make such a mission fit within the constraints of the world’s economy. This, of course, assumes the necessary technological development along the way — not only in propulsion but in closed-loop life support — to make such a mission scientifically plausible. I get a lot of pushback on that because nobody wants to wait that long. But overall, I’m an optimist. I think it will happen.

Let’s attack the question from another direction, though, and leave human passengers for a later date, as Yuri Milner’s Breakthrough Initiatives, aided by Stephen Hawking, is doing today in a New York news conference. What if we talk about unmanned missions? What if, in fact, the question is: How soon can we put a scientific payload past another star? Let’s not worry about decelerating — this will be a flyby mission. Let’s build it as soon as possible using every breakthrough technology we have at our disposal. How long would it take for that mission to be developed and flown?

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Milner, a philanthropist and investor who was an early backer of Facebook, Twitter, Spotify and numerous Chinese tech companies, tells me his goal is to ‘give back to physics’ in developing just such a mission. Part of that giving back is the $100 million he has already put forward to support SETI, a ten-year project that will produce more telescope time for SETI than any other. Milner is also the founder of the Breakthrough Prize, issuing awards in physics, life sciences and mathematics. But in many respects this third Breakthrough Initiative is the most daring of all.

Time for the Stars

Breakthrough Starshot is an instrumented flyby of Alpha Centauri with an exceedingly short time-frame, assuming research and development proceed apace. Milner is putting $100 million into the mission concept, an amount that dwarfs what any individual, corporation or government has ever put into interstellar research. A discipline that has largely been the domain of specialist conferences — and in the scheme of things, not many of those — now moves into a research enterprise with serious backing.

Could an Alpha Centauri flyby mission be developed and launched within a single generation? I think it’s quite a stretch, but it’s the best-case scenario Milner mentioned in a phone conversation over the weekend. He’s enough of a realist (with a first-rate physics background) to know that the challenges are immense. Even so, he sees no deal-breakers.

Let’s walk through the case and see why he finds reason for optimism. “There are major advances that we can now turn to as we develop this proof of concept,” Milner says. “Twenty years ago, none of these things would have been available to far-thinking scientists like Robert Forward. But now we can put them to use and test their possibilities.”

If you’re thinking of an interstellar mission in the near-term, there is really only one choice of propulsion: The beamed sail. Sails have the advantage of known physics, laboratory experiment and actual deployment in space. We could talk about fusion for some indefinite point in the future, but at present, we don’t know how to do fusion even in massive installations on Earth, much less in the tight confines of a spacecraft engine. Interstellar ramjets are a far-future unknown — they may act more effectively as braking devices than engines, according to recent research. Antimatter is nowhere near readiness for propulsion, either in production methods or storage. Chemical rockets fall victim to the mass/ratio problem and are useless for fast interstellar journeys.

That leaves us with sails carrying very small payloads. To cross the 4.37 light years to the Centauri A and B system, Breakthrough Starshot proposes small spacecraft, taking advantage of advances in nanotechnology to reduce payload size. Think Moore’s Law and the reductions in size and cost that have accompanied the vast increases in micro-chip power. “Moore’s Law,” says Milner, “tells us that now is the time.”

StarChip is the Breakthrough Initiatives’ name for a payload measured not in kilograms but grams, a wafer that carries everything you would expect in a fully functional probe. ‘What was once a 300 gram instrument is is now available at three grams,” Milner continues. “What was 100 grams is now 0.5 grams. This is the trend we are riding.”

The StarChip payload includes cameras, power supply, communications equipment, navigation capabilities and photon thrusters. And it would be thrown across the interstellar gulf at 20 percent of the speed of light by a sail that is itself a miniaturized version of the sails Robert Forward used to discuss. Forget the thousand-kilometer sail (much less the continent-sized sails of the science fiction dreamer Cordwainer Smith). Milner’s team believes we can now talk in terms of a laser-driven lightsail that is no more than 4 meters across. This is actually smaller than the first deployed sail craft, the Japanese IKAROS, which boasts a sail measuring 14 meters to the side.

Advances in metamaterials and additional research should be able to produce, Milner believes, a 4 meter sail whose own weight is tallied in grams, and whose materials allow fabrication at a thickness of a few hundred atoms. A sail that small makes its own statement: Clearly, it’s not going to be under the beam for long, which means we need to focus a great deal of light on it for a very brief time. Lasers are another technology that benefits from rising power and falling cost. The trick here will be to create ‘phased arrays’ of lasers that can scale up to the 100 gigawatt level. A phased array involves not one but a group of emitters whose effective radiation pattern is reinforced in the desired direction by adjusting the phase of the signals feeding the antennae.

This is classic Bob Forward thinking rotated according to the symmetries of our new era. Milner aims for a beamer technology that is modular and scalable. And it fits into a larger infrastructure. Breakthrough Initiatives talks about bringing a ‘Silicon Valley approach’ to the problem of interstellar flight. Build a StarChip that can eventually be mass-produced at no more than the cost of an iPhone. For the Alpha Centauri mission, whenever it flies, is itself a proof of concept that could lead to multiple destinations. And if the cost can be driven as low as Milner believes, then we can think in terms of redundancy, with StarChips sent in large numbers to return a full characterization of any destination system. Assemble the light beamer and, as the technology matures, the cost of each launch falls.

These are ideas that are at once familiar but also exotic, for while Forward talked about enormous power stations in close solar orbit to power up his banks of lasers (and a huge Fresnel lens in the outer system to focus the beam), Milner thinks we can build a ground-based beamer at kilometer scale right here on Earth. I was startled at the idea — surely efficiency favors a space-based installation — but Milner’s point is that he thinks we can begin to launch interstellar craft before we have the technology to build the kind of power station Forward envisioned. If you’re serious about a launch within a few decades (again, it’s a best case scenario, and a dramatic one), then you build an Earth-based beamer and use adaptive optics to cancel out atmospheric effects.

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Image: A wide-field view obtained with an Hasselblad 2000 FC camera by Claus Madsen (ESO), of a region around the Southern Cross, seen in the right of the image (Kodak Ektachrome 200, 70 min exposure time). Alpha Centauri is the bright yellowish star seen at the middle left, one of the “Pointers” to the star at the top of the Southern Cross. Although it appears here as a single ‘star,’ it is actually comprised of the G-class Centauri A, K-class Centauri B, and the M-dwarf Proxima Centauri. Credit: ESO/Claus Madsen. Original here.

All this will be subject to tightly focused research, which is what the $100 million is for, but what Milner hopes to see are nano craft delivered to orbit and then boosted on their way with a 30 minute laser ‘burn’ that, reaching 60,000 g’s, drives the sail to 20 percent of the speed of light. That makes for roughly a twenty year crossing to Alpha Centauri. With a craft this small, data return is highly problematic, and in fact I think it’s one of the biggest unanswered questions Breakthrough Starshot will have to face (well, this and the challenge of interstellar dust, and key questions related to sail design and the sail’s ability to stay on thee beam during acceleration). The sail is itself the antenna on a craft of this design, and Jim Benford told me in conversation that it will have to be shaped to one-micron precision. Even so, powering up the system to send imagery and data to Earth is going to be tricky. It will be fascinating to see what kind of solutions emerge as this research gets underway, and what alternative methods may be suggested.

Even so, and granting the cost reductions digital technology makes possible, Breakthrough Starshot embarks upon a multi-year research and engineering phase that will focus on building a mission infrastructure. Creating the actual mission will demand a budget comparable to the largest scientific experiments of our time. These are no small aspirations, but what drives them is something that interstellar studies have never had at their disposal: A dedicated, enthusiastic, well-funded effort with the participation of major scientists.

“We have an advisory board of twenty, including Freeman Dyson and other top scientists,” Milner added. “$100 million will be spent in coming years as we look toward concept verification. Multiple grants should flow from this, research and experiments. We need to complete the initial study and see if building a prototype, perhaps at a scale of 1/100, is then the next step.”

At the very least, we can expect the research behind this project to spin off numerous useful technologies, all of which should be applicable not only to star missions but to in-system exploration, along with, potentially, a kilometer-scale beamer that can double as a large telescope for astronomical observations. And while I doubt we can look at interstellar missions within the next few decades (I am open to being convinced otherwise), I believe that the timing for a fast flyby of Alpha Centauri will be considerably advanced by this work.

There is much to be said about all aspects of the Breakthrough Starshot concept, and as you would imagine, I’ll be covering this closely, beginning with a trip later this week to the Breakthrough Initiatives meeting in California. That meeting will have a large SETI component growing out of Milner’s prior commitment of another $100 million, which is already being translated into active observations at the Green Bank observatory in West Virginia. But as you can imagine, the Alpha Centauri mission will be under discussion as well as the research effort begins to be assembled. What spins out of this will keep us talking for a long time to come.

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