by Paul Gilster | Jun 23, 2014 | Uncategorized |
Adam Crowl first appeared in Centauri Dreams not long after I opened the site to comments about nine years ago. His insights immediately caught my eye and challenged my thinking. I have always admired auto-didacts, and Adam is an outstanding example: “I don’t work in this field nor did I especially train in it,” he writes. “I did physics/maths/engineering study but my astrophysics, astrodynamics, planetology and interstellar propulsion knowledge is self-taught.” The list of books in the various disciplines — as well as science fiction — by which he did this will, I hope, become a future Centauri Dreams article. Adam writes the Crowlspace blog, is active in Project Icarus, the re-design of the 1970’s Project Daedalus fusion starship now in progress at Icarus Interstellar, and is a frequent participant on this site, often pointing me to papers I would otherwise have missed. The one he discusses today is, typically for Adam, a true mind-bender.
by Adam Crowl
The long-term fate of Life in this Universe is rarely contemplated. A few landmark studies, by Freeman Dyson, then Fred Adams, Peter Bodenheimer & Greg Laughlin, have looked into Deepest Time, long after Matter itself fails and the Void becomes unstable. How far can biological Life extend into the Long Dark? A study by Robin Spivey extends Life’s tenure, in neutrino-annihilation warmed Ocean Planets, to 1025 years – and Beyond. That’s 100 times longer than the 1023 years we’ve reported here previously and some 1,000 trillion times longer than the time the Universe has presently existed. If the current Age of the Universe was a clock tick – a second -, then those 1025 years would be 20 million years.
Spivey discusses his new finding here: Planetary Heating by Neutrinos: Long-Term Habitats for Aquatic Life if Dark Energy Decays Favourably [Open Access article]. Outer-shell electrons of 56Fe (iron) inside the cores of Ocean-Planets become ‘catalyzers’ of Inverse Photo-Neutrino Process (IPP) reactions, annihilating neutrinos and creating a steady heat-flow sufficient to warm the planet at ~0.1 W/m2. This Figure, published in the paper, illustrates the flow:
Perhaps coincidentally, the inexorable processing of stellar materials in Type Ia Supernovae leads to a chemical mixture which makes Earth-like planets. Each Type Ia Supernova masses about 1.4 Solar Masses, or about half a million Earths, with the ejecta debris being mostly iron, then oxygen and silicon. Earth-stuff. Thus the ‘ashes’ of stars can produce a multitude of Ocean Planets.
To quote Spivey:
Observations have determined that the ejecta of a typical SNIa are, by mass, 18% oxygen, 15% silicon, 13% iron, and 49% nickel (almost all in the unstable form 56Ni which decays radioactively to 56Fe), along with smaller amounts of carbon, calcium, sulphur and magnesium. Elements emerge from SNIa in strata, with the lightest occupying the outermost layers. This provides the oxygen-rich outermost shell with the best opportunities for reacting with hydrogen in the interstellar medium, resulting in the formation of water molecules. On cooling to temperatures found in deep space, ice XI is obtained, whose ferroelectric self-aggregation may be relevant to comet formation [38-40]. The bombardment of protoplanets with comets would be important to the formation of oceanic planets, deferring the delivery of water to their surfaces.
Notice that the iron component is 62% by mass, thus the very large core in the illustration. Quoting Spivey again:
Based on the composition of type Ia supernova ejecta, a hypothetical oceanic planet of one Earth-mass is projected to consist of a large iron core of radius ~4240 km surrounded by a silicate mantle of thickness ~1300 km through which heat would be transported by advection. External to this inner mantle would be an outer mantle of ice consisting of strongly convective ice VI and VII phases of combined depth ~320 km. A liquid ocean ~50 km in depth covered by a solid crust of ice Ih upwards of 50 m in thickness would overlie the hot ice mantles.
Spivey’s new paper focuses on how the supply of neutrinos can be maintained at the right density to keep planets warm for the maximum amount of time. He posits several, as yet, unobserved processes – the decay of dark energy into neutrinos in less than ~70 billion years and the accelerated decay of black holes, also preferably into neutrinos. Other researchers have posited the existence of ‘sterile’ neutrinos, which Spivey shows improves the characteristics of the neutrino halo surrounding a Galaxy cluster, enabling planets to be warmed in a life-friendly manner in a sphere of 400 thousand light-years radius.
The existence of Dark Matter itself has been called into question by physicists, such as Mordechai Milgrom, who think the evidence for invisible Dark Matter can be equally well explained by modifying Newtonian Gravity to have a minimum gravitational acceleration. This Modification of Newtonian Dynamics (MOND) theory neatly explains the structure of galaxies, but hasn’t been as successful on a cosmological scale. Intriguingly if Galactic haloes are made of sterile neutrinos, then MOND and Dark Matter physics are equivalent in outcomes: Reconciliation of MOND and Dark Matter theory with giant ‘Neutrino Stars’ forming around each large Galaxy. Spivey suggests that a key research priority is determining the properties of neutrinos, to confirm the IPP heating mechanism. Such neutrino studies are important for refining the Standard Model of particle physics – and possibly discovering new physics, such as the masses of the various neutrinos, something not predicted by the Standard Model.
Spivey’s most audacious suggestion is the strategy that Life should adopt in the next few aeons to extend its lifespan. Unfortunately for Life in this Galaxy, our local Group of Galaxies is insufficiently massive to form a large enough neutrino ‘star’ before Dark Energy spreads galaxies too far apart. To survive, Life in our Local Group needs to emigrate to the Virgo Super-Cluster. Although our Milky Way is heading towards Virgo at ~200 km/s, cosmic acceleration, from Dark Energy, is presently pushing us away from Virgo at ~1,000 km/s. Thus we need to launch towards Virgo faster than the Dark Energy pushing us away. Yet the reward is 10 trillion trillion years of Habitable planetary environments, which may well be worth intergalactic migration.
Spivey suggests using antimatter rockets to launch modest payloads. Essentially small Life-seeds, like those proposed by Michael Mautner to seed Life in our own Galaxy, but launched on intergalactic journeys of a hundred or more billennia. Whether the cosmic-ray flux between the Galaxies can be endured for geological epochs is presently unknown and while I wouldn’t rule it out, it seems unlikely at best. A good reference, available online, is still Martyn Fogg’s “The Feasibility of Intergalactic Colonisation and its Relevance to SETI”, which suggests how a mere 5 million year intergalactic voyage might be survived by a bio-nanotech seed-ship.
But we’ve discussed other options in these pages previously. In theory a tight white-dwarf/planet pair can be flung out of the Galactic Core at ~0.05c, which would mean a 2 billion year journey across every 100 million light-years. A white-dwarf habitable zone is good for 8 billion years or so, enough to cross ~400 million light-years. It’d be a ‘starship’ in truth on the Grandest Scale. Perhaps other Intelligences have begun their preparations earlier than us and we should look for very high-velocity stars leaving the Milky Way and Andromeda’s M31. Over the next aeon we might observe many, many stars flinging towards Virgo from the nearby Galactic Core black-holes.
by Paul Gilster | Jun 20, 2014 | Uncategorized
Heath Rezabek continues his experiment in possible futures, science fiction with a collaborative bent exploring the archives that may one day preserve the story of our world and the sometimes mysterious processes that may bring them into being.
by Heath Rezabek
This is the fifth installment in a continuing series of speculative fiction here on Centauri Dreams. Feedback from prior installments helps shape the themes and direction of subsequent entries, but the purpose and focus of these pieces is to explore a timeline (or timelines) in which comprehensive, resilient archives of Earth’s biological, scientific, and cultural record — deep archives for deep time — are developed through unexpected means.
Woven Light (I) – Vessel Haven https://centauri-dreams.org/?p=29669
Woven Light (II) – Adamantine https://centauri-dreams.org/?p=29897
Woven Light (III) – Augmented Dreamstate https://centauri-dreams.org/?p=30128
Woven Light (IV) – Proteaa https://centauri-dreams.org/?p=30352
Woven Light (V) – Lesson Arcs
– – – – –
In my last installment, we launched the Centauri Dreams Vessel Survey, beginning community curation of a core booklist embodying Centauri Dreams‘ themes and influences. I discussed my work with the Long Now Foundation, showcasing their work and discussing my pending trip to be present for the opening of The Interval. We will return to both of these topics in a future installment. This week, however, I’ll continue the speculative fiction arc of Woven Light here on Centauri Dreams.
2013 was a tremendous year of change and evolution for the Vessel project; in the span of that year, the Vessel proposal moved from being a conference presentation to a published proceedings paper. After joining Icarus Interstellar to help organize the first Starship Congress, the Vessel project was summarized and presented at the event. A monograph version of that session should ultimately find its way to the JBIS special issue on SC2013.
At that conference, I met Paul Gilster, and introduced him to Nick Nielsen: There began a collaboration which continues today. Perhaps the biggest advancement of all, for me, was the opportunity to serve as an Intern with the Long Now Foundation as they began the community curation process for their Manual for Civilization collection. Although this Internship is drawing to a close, the effort has planted seeds that will continue to sprout for years to come.
With clarity can sometimes come a contradictory confusion. Even as progress on the Vessel proposal assured me that this effort had much in store, I soon discovered a large complication: To make progress on the practical proposal — the Vessel Open Framework, a specification document which could help pave the way for a unified approach to very long term archives — I realized I would need time and a team. Neither of these things are easily secured. My time remains split between these efforts and my livelihood.
Sometimes, however, help comes in unexpected forms. In this case, my conflicted feelings on how to proceed with the Vessel proposal led to a rediscovery of fiction as a vehicle for evoking and envisioning possibilities that remain unreachable in reality. My work on the Woven Light story arc continues, and if anything, is picking up steam.
Likewise, with this realization has come another shift in my perspective. While I continue to feel that a practical proposal for scalable, widespread archival efforts of all kinds is necessary, I have also come to realize that equally important is the collective role of storytellers as living archives of potent possibilities. One path forwards with Woven Light is to create a kind of fiction which can be approached from many directions, including by those inspired enough by it to try their hand at its themes and scenarios themselves.
Should humanity fail in its task in the short term, and Vessel Archives (or their like) not be constructed or created in time to forestall scattered cultural collapse or stagnation, it becomes crucially important that the stories with which humanity is left retain a trace of incentive towards rebuilding. Some would say that our advancements will soon outpace our challenges. Others would say that cases of permanent stagnation and flawed realization are already underway, in nations around the world which struggle against tides of poverty or political despair.
Where, then, is the wellspring of inspiration needed to renew a belief in the possible? Even as I continue to work at the Vessel proposal as a practical deliverable, I am working more and more on a way of storytelling which above all else plants seeds of potential in the gaps between what we can foresee and what we collectively doubt is possible.
It was a surprise, in writing, to find Thea Ramer revising the first sections of Woven Light in response to the entreaty that her robots and starships were never going to make it far in the fictional world of her present-day (an alternate-timeline 1990s), which was in turn a response to the overarching suspicion of previous comments. The resurgent myth which emerged at that point is going somewhere — Vaachez descends into the bazaar in search of a guide and map to even deeper passages, and not all in the storyline is as it seems.
As we move forwards, the number of timelines at work may begin to collapse and merge a bit — and other, unexpected ones may open up. With silence in the comments, I forge ahead sounding out the way based on the echoes already at work in the world of the story. Always, of course, comment is welcomed — it’s no longer expected: All of us, perhaps, are in unexplored territory.
One thing I do foresee is that the Vessel Open Framework will begin to unfold again, from within the world of the fiction. I take as an inspiration the experience I had in 1991 when, well after the original TV series of Star Trek: The Next Generation had ended, I encountered the ST:TNG Technical Manual, by Sternbach and Okuda. Though this kind of metafictional resource had been published before, something about the depth of thought and description in this work inspired me towards a new kind of fiction, one in which the only limits are those of our own vision, deduction, and imagination. [1]
I am thankful in the extreme to Paul Gilster, for his constant encouragement and support of this effort, a form of serialized fiction perhaps not seen before on Centauri Dreams, but now belonging thoroughly to it. I am grateful for his patience as I work my way towards a myth of possible futures that somehow includes as many possibilities as we can foresee, and asks us as readers to choose between them. Which will we accept or reject? Which will we create through our vision, or our blind spots?
Even for me, there is only one way to know, and that is to follow the work where it goes.
[1] Okuda, M and Sternbach, R. Star Trek: The Next Generation Technical Manual (Pocket Books, 1991).
– – – – –
[Image 1 – ‘Manuscript: The Tracer Guild Book 1 by Thea Ramer.’ Adaptation of photography CC BY-SA Cory Doctorow ]
1994. Thea Ramer continues her work on a novel that will be called The Tracer Guild. It will be her only published work, and will reflect but a sliver of the world she is to sketch out between now and its publication in December, 1996. These two years will be spent, for her, in a frenzy of creation, drawing upon notes she has been reworking for several years already.
The Tracer Guild — planned as the first of a series — goes so confidently astray as to float the working titles of six more planned volumes. It enjoys a brief period of uptake, before becoming overwhelmed by the market. After its publication, exhausted and bemused, Thea will put aside the work, only to return many years later, by another route entirely. And she will go through many changes.
For one, she will determine to pick up her scientific pursuits again, and return to academia. This will ultimately result in her team’s development of hologlyphic syntax, and from its hologlyphic origins, the synthetic mind called Avatamsaka.
For another, she will bear a son. His name will be Aben.
– – – – –
[Image 2 – ‘CU Boulder: Resilience, Remembrance, and the Future of Humanity Symposium 2024.’ Adaptation of photography CC BY-SA devnulled 2010 ]
2023. Aben Ramer returns to Denver from the Playa, prepared to dedicate his energy to a community knowledge and resiliency center, and grassroots version of specification document known as the Vessel Open Framework. The next year, a chance meeting at a conference at CU-Boulder introduces him to Professor of Computational Psychology, Dr, Jota Kaasura.
Resilience, Remembrance, and the Future of Humanity. Symposium 2024.
Lunch Keynote: From Active Imagination to Synthetic Minds: Preserving Ancestral Symbology through Jungian Design Discovery in a Computational Matrix.
After the talk, by the side of the stage as the audience mills towards afternoon, Aben reaches the presenter. Records show him young and eager, an anxious spark in his eyes. Recovered from video, this transcript remains:
Ramer: Doctor — Dr. Kaasura, I wanted to thank you. I’d never thought about it quite that way — the synthesis […unclear…] meaning through visualization — thanks for painting the picture. Oh — I’m Aben.
Kaasura: Yes, thank you. Call me Jota. I appreciated your question, ah.., Aben.
Ramer: Thanks. Ok, well so, you also mentioned that your team was seeking volunteers for the Thematic Sampling phase of input. I’ve practiced Active Imagination before, just a little, and I’d love to participate. I’m in Denver, so getting to CU’s not a problem.
Kaasura: Ah! You have? Well, excellent! It’ll be a bit yet as we gather applications. Here’s the lab’s card. We can certainly explore the possibilities. We’ll take your application and history, and we’ll go from there.
Ramer: Great. Great!
Kaasura: Out of curiosity, how did you run across Active Imagination?
Ramer: My mother used to use it for creative inspiration. She was a writer, years back — she’s actually in AI research as well, now — holography, holographic syntax. Dr. Thea Ramer?
Kaasura (brightening): Ah! Yes, yes, I know her work. Small world! She’s — didn’t she break some new ground, so to speak, in New York last year?
Ramer: Well, yes, that’s — yeah, I guess it was a breakthrough, really. But after what happened, she’s actually on sabbatical now. She says she’s not sure if she’ll return to it. I’m not quite clear on why. But she’s writing it up, so there’s time. She’s here, in fact! Well, not here-here. She was’t up for the conference, too soon she says. But she’s staying with me in Denver. We’re going through her old fiction, her drafts, trying to catalog.
Kaasura: (…) Interesting. Yes, you know, I’d actually love the chance to speak with her, if the chance comes up. Holographic syntax holds great promise. It’d be a shame for her to let it go. I mean, work goes on, always, of course, but sometimes there’s a spark, and it’s always worth perking up when that’s so. Something worth doing, there.
Ramer: Yeah. I’ll tell her. She’ll appreciate it. Maybe we can set something up. I mean she’s right here, really… Too near for a miss, right?
Kaasura: Right. Right. Good way to put it! Well, there’s my card — I do have to go, but we’ll look forward to —
Ramer: Absolutely. Thank you. I really appreciate what you’re doing, and especially why you’re doing it. Thanks for sharing that.
Kaasura: Well, thanks for such an interesting question. The unexpected ones are the best, aren’t they?
Ramer: I’ll bet they are. Great. See you soon!
Kaasura: Yes. See you soon.
– – – – –
[Image 3 – ‘Proteaa: Dyson Eggs, Living Archives’ (Detail) Heath Rezabek. Adaptation of photography CC BY-SA Wikimedia. ]
Timeframe Unknown. A reflective, refractive sphere, brimming with a maelstrom of living matter, drifts through endless night, tracing the edge of gravity’s embrace. Though utterly alone, it is not lonely, as the Protean cells which form its very quanta are entangled with many other such vessels, peer civilizations spiraling in affinity. True entanglement is a strange thing. Most of these entangled peers are smaller than itself. Most do not share the same origin. Most do not share the same gravity (which means locality, or galaxy), or space, or time.
Some, though not all, have sails; and all such sails stream ancient light.
At least one of these bears passengers, deep in stasis, living — ponderously, glacially, but metabolically living — archives.
At least one of these living archives bears the name of Ramer.
And each Ramer contains the rest.
How did this come to be?
– – – – –
[Image 4 – ‘Pendulum: Lesson Arc’. Adaptation of photography CC BY John Morgan 2013. ]
It was possible to become lost in here.
This much was well known, and all were taught the telltale signs of probability sickness early on. Vaarea Ramer did well in her lesson arcs, the small worlds adrift in fog on which she had learned to discern Realia from its echoes and shadows and subcreations.
She tracked the arc of the pendulum, swinging, swinging above an ancient pool, reflecting a blinding blue sky with each pass. Ancient, it seemed. Swinging, she felt. It was easy, seeing such a simple scene, to believe it grounded and absolute.
But she stood upon a sort of observation deck, and between her and the pool lay a gap too wide to leap, filled with fog. And beside her stood her family’s Mentor, Tuavaadha, nodding behind her veil.
~Yes, Vaarea. The pendulum would stop in time, if we waited here long enough. But there is much more to do, and even I might become bored waiting so long as that.~
Vaarea lifted her eyes, scanning the clouds for signs of anything but stasis. Her thoughts felt like a sound she heard, unspeaking, though she was the one projecting. She was used to this by now. ~What else is there to do?~
~After the Pendulum Pool comes the Grotto; at least for you. And all of your line, stretching back and back, have found it more interesting a place to be.~ Tuavaadha smiled, she knew without seeing.
And of course, she knew that she was being nudged, poked and tested, gently but inevitably. Vaarea felt a familiar irritation, which resolved itself in its familiar way into a motion of the hand. Lifting from her sash a small shard of smooth stone, she rubbed it twice with her thumb, and felt its weight shift to signal that a beacon had been placed. She’d be back, she was sure.
~As sure as your father. As sure as your son.~ Tuavaadha strode forwards, holding out her palm. A Mentor’s palm seems as wide as night, when it’s open, thought Vaarea.
She placed the stone there, and waited for the blink. But this time was different. To her right, out of eyeshot, she felt something shift and slide, and turned to see a panel of the observation platform falling away. Underneath, familiar lines of woven light interlaced and parted, indexing the scene and retracing the Voronoi frame around them.
~What about the Grotto?~ she quested, following Tuavaadha below.
~We’ll get there, impatience. We just can’t from here.~
Vaa stopped, furrowed. ~Since when can’t we get to one pattern from another?~
~Since the time it was woven that way, which means everfore.~
They were moving now, wisdom bodies flowing past the index lattice, passing pods where her peers slept and drifted, suspended in the weave.
~How far, then?~
~Not far.~
~A different lattice?~
~A different loom.~
A different loom! Now surely there was no reason they couldn’t trace a thread from one pattern to any other while remaining in the same loom. Unless by design, but why?
~Security, for one part,~ rang Tuavaadha. ~But only one part. There is something to the journey, sometimes. Something worth doing. You should know this better than most, being spun as you have from the thread of all Ramers.~
The Ghemaai were not prone to resentment, but an ancestor of Vaarea’s might have felt something sharper at the reminder that great choices had been made for her, long before her, which as far as she knew she could not unchoose. But she knew that she was also here, and alive, and flowing starwards with them all, in a way she could not be had different choices been made. And she had her vows, and they were resilient.
~So what is this, then? This Grotto we can’t reach from anywhere?~
~Anywhere else~ adjusted Tuavaadha. ~The Grotto is a family weave. ~ They were passing, now, lightflows that would have led them off towards the flowing cores, or the gathering cores, or the sinking cores; but none of these did they follow.
Tuavaadha said nothing, but smiled beneath the quiet; and Vaarea followed. So they went, in silence, weighing the memory of her shardstone, lacing it between her fingers as their footfalls silenced the deck.
Up ahead, in time, they reached a branching, and another, and a last; and there Tuavaadha stopped, as she had many times before, and waited for Vaarea to read the weave before them. It was old, but always the first time it felt fresh to new eyes. In time, Tuavaadha knew, familiarity would bring a kind of slow sorrow more like joy, keen enough to earn a name. But this time was new time.
Vaarea blinked, reaching out to touch the woven pattern of this tale. There at its center was something she’d heard of, but never seen. A cubic lattice the size of her fist was held tilted and sunken in the center of a circular plateau. Leading out from it, threads spun and raveled, and shoots reached up from loamy soil, sheltering the small camp arrayed there. This close to the fabric, she could see that the lattice stood in for a fire.
Vaarea had learned of shelterfires not two lessons prior, and shivered at the glacial cold she thought they’d left behind in a liminal valley beset by frozen seas. Around this fire sat and stood a dozen, maybe fewer, maybe more; a handful huddled – but against what cold she couldn’t see.
These grassy trees seemed city walls for them, golden green and thriving. And their tips brushed at a dusted, starry sky.
She knew better than to trace too long the lines between these diamonds, but she couldn’t help seeing the similarity – a kinship she’d never noticed in these tapestries before – between the lattice at the heart of this little shelterfire, and the splaying array of stardust beyond these trampers’ reach.
These trampers, she guessed, had tramped the path to this pattern here and now. Why so huddled? Why so intent upon the fire, if not for warmth? It shimmered and billowed, a tiny curtain, golden and ghostly above embers.
She wished she could see one in Realia. She wished she could see one patterned here and now.
~But you can, Vaarea Ramer. And you always will be able.~
So reaching out, she brushed it gently with one fingertip. And sometimes, in such places, the slightest touch is enough.
– – –
[Image 5 – ‘Woven Fire’. Adaptation of photography CC BY-SA Mathias Erhart 2009. ]
Aben Ramer sat before the fire, stirring its coals. “I am old, now… But once I was young, like you, and you as well,” he began.
Young eyes looked up, in awe at their elder. They had heard this beginning before, many times; always – every time – it ran on from there differently than the time before. And always – every time – it ran on like a new stream down the same mountain.
As old Aben Ramer spoke, the children gazed and rested, their eyes sifting firelight, and then lost themselves in patterns ever changing, never changed, woven of golden light; and in through its murmuring cracks could be glimpsed the most ancient of archives, finding itself revealed again, deciphered again, read out and comprehended, voiceless and booming.
Up reached Old Ramer’s arms,
and as tall as the shoots far above them he seemed;
and as full seemed the sky as their hearts and their eyes;
and the stars seemed as close as the sparks which there met them;
and as sure seemed the song of Old Ramer as morning.
And in the morning, the children awoke from dreams of a dragonfly in the night, flowing starwards, wings like sails unfurling, ringed about with an arcing bowl of starlight. And among them was a girl, whose name was a new one; they just called her V.
– – –
Vaarea, stunned, hours or years later, stood just as she had before the weave, finger fading from the cubic lattice turned to fire before her. Tuavaadha smiled. ~This place – can I come here?~
~Of course; any time. All you need to do is seek it, awake or asleep, and remember that you’re seeking.~ Tuavaadha paused. ~But it helps to have some methods. In the Grotto, you will learn them.~
~That wasn’t the Grotto?~
~It was, reflected. But emulators are for studies; this place is for dreaming. We can go there tomorrow. Tonight, your assignment is just to ponder one thing, while you rest and you wait.~
Vaarea looked up, still not fully present.
~?~
~The fire: Where did it come from? Where is it going? What does it preserve? What does it destroy? Is memory stored there? And if not there, then where?~
Vaarea looked at the lattice, shimmering softly, woven into this meshwork, and closed her eyes to recall true flame, true flame unseen but everthere. She furrowed; she sighed; she looked to her Mentor for more.
~These seem like different questions, but they are not. They are conjoined. Why? For matter–
–is slumbering light~ Vaarea concluded.
Tuavaadha nodded contentedly, as any Mentor would. ~Now rest.~
– – – – –
[Image 6 – ‘Edits’. CC BY-SA Heath Rezabek 2014. ]
Thea Ramer, digging through old boxes, finds a fraying printout from long before. Old habits: Reading through it, although the time for revision is long gone, she watches herself scratch through a few words, and watches her outbreath as she does so.
If there had been a reason, these crew in theory could have navigated the actual physical spaceframe of Saudade IV.
She writes above:
She writes below:
Thea Reamer closes her eyes, old threads of a story unwinding; and in a blink, she’s far away.
Time shifts and adapts, enfolding again all around her.
by Paul Gilster | Jun 18, 2014 | Outer Solar System |
Once New Horizons has performed its flyby of Pluto/Charon and, let’s hope, its reconnaissance of a Kuiper Belt object (KBO), what comes next in our exploration of the outer Solar System? Pushing further out, Innovative Interstellar Explorer grew out of a NASA ‘Vision Mission’ study and has been developed at Johns Hopkins University Applied Physics Laboratory by Ralph McNutt and team. Boosted by a Jupiter gravity assist, IIE would explore the interstellar medium some 200 AU and further from the Sun, using a plutonium-fueled 1 kW electric radioisotope power supply.
And then there’s Claudio Maccone’s FOCAL mission, which would target the Sun’s gravitational focus beginning at 550 AU, continuing well past 1000 AU for observations exploiting gravitational lensing effects. FOCAL has been the subject of intense study — Maccone’s 2009 book Deep Space Flight and Communications grew out of this decades-long work — and with both IIE and FOCAL we have the prospect of making observations of the medium through which any future interstellar mission would pass, having exited the heliosphere inflated by the solar wind from the Sun.
But there is much to do in the region between the gas giants, with their astrobiologically interesting targets Europa and Enceladus and the seductive Titan, and the inner edge of the Kuiper Belt. Here we are in the domain of the ice giants last visited by the Voyagers in the 1980s. A new paper from Diego Turrini (Institute for Space Astrophysics and Planetology INAF-IAPS, Italy) and colleagues makes the scientific case for a mission to Neptune and Uranus, to be flown by two identical spacecraft. The ESA-funded mission would have a launch date of 2034.
Image: Neptune as captured by Voyager 2 in 1989. Credit: NASA/JPL.
I want to focus on Turrini and team’s discussion of planet formation this morning, because this is where the scientific payoff for a return to Uranus and Neptune is the most profound. The rising tide of exoplanet research is uncovering more and more planetary systems showing us that the old view of planet formation as an orderly process producing stable, well-spaced systems is incorrect. Systems around other stars are not necessarily patterned on what we see in the Solar System. In fact, it is we who seem to be the outliers, confronting a cosmos that produces a bewildering array of planetary configurations in which migration surely plays a major role.
Thus the ‘Jumping Jupiters’ mechanism that involves close gravitational encounters that occur after the original circumstellar disk has dispersed. In our Solar System, our changing views have led to the ‘Nice Model,’ which involves our own jumping Jupiter scenario, one tied to the era known as the Late Heavy Bombardment. Here we have a series of encounters between the giant planets, with interactions with what the paper calls a ‘massive primordial trans-Neptunian region.’ The end result is to take giant planets once closer to each other and to move Jupiter inward while migrating Saturn, Uranus and Neptune outward. The paper describes this scenario:
The importance of the Nice Model lies in the fact that it strongly supports the idea that the giant planets did not form where we see them today or, in other words, that what we observe today is not necessarily a reflection of the Solar System as it was immediately after the end of its formation process. Particularly interesting in the context of the study of Uranus and Neptune is that, in about half the cases considered in the Nice Model scenario, the ice giants swapped their orbits (Tsiganis et al. 2005). The success of the Nice Model in explaining several features of the Solar System opened the road to more extreme scenarios, also based on the Jumping Jupiters mechanism, either postulating the existence of a now lost fifth giant planet (Nesvorny et al. 2011) or postulating an earlier phase of migration and chaotic evolution more violent and extreme than the one described in the Nice Model (Walsh et al. 2011).
Mixing of the solid materials that make up the primordial Solar System would have occurred, with both inward and outward fluxes of ejected material affecting the composition of primordial planetesimals. When we look at the satellites of the gas giants today, we may be seeing material that was originally extracted by these processes from the inner Solar System and incorporated in their systems.
Uranus and Neptune would have been strongly affected by these events, with a giant impact involving Uranus that explains its sideways rotation. And we can see other evidence in the capture of Triton by Neptune, Triton being a moon that orbits in the opposite direction to its host planet. The paper continues:
…our view of the processes of planetary formation and of the evolution of the Solar System has greatly changed across the last twenty years but most of the new ideas are in the process of growing to full maturity or need new observational data to test them against. The comparative study of Uranus and Neptune and their satellite systems will allow to address the problems still open, as the ice giants were the most affected from the violent processes that sculpted the early Solar System and yet they are the least explored and more mysterious of the giant planets.
Turrini and team also make the case that based on data from the Kepler mission, about one star in every five should have a Neptune-class planet, but the only up-close data we have on this class of planet comes from the Voyager 2 flybys of Uranus and Neptune performed in the 1980s. Here the authors have to pause, for Kepler’s candidates have short orbital periods because of the nature of Kepler’s operations. Kepler can only detect ‘warm’ or ‘hot Neptunes,’ whose composition and dynamics will differ from the ice giants in our own Solar System. Even so, characterizing our ice giants is something we can do with existing space technologies, and it can offer up templates for interpreting the data returned from future exoplanet observations.
From observation of the satellite systems around the ice giants to study of planetary interiors, there is much to investigate in the outer Solar System. The ODINUS mission described in the paper would put a spacecraft into orbit around both Neptune and Uranus, an ambitious goal that would allow measurements with the same set of instruments in both systems, as well as studies of the interplanetary medium from different angular positions during cruise. The ESA’s Senior Survey Committee has already stated that exploration of the ice giants “appears to be a timely milestone, fully appropriate for an L class mission,” assuming financial support emerges.
There is no question we are going to get payloads back to Uranus and Neptune at some point, and the Turrini paper makes a strong case for the scientific validity of the effort in helping us understand our own system’s violent past and the results of our planet-hunting observations in other systems. The comparatively well studied Jupiter and Saturn are composed mainly of hydrogen and helium, while Neptune and Uranus are dominated by water, ammonia and methane along with metals and silicates, with hydrogen and helium making up a scant 25 percent. We obviously have much to learn about such planetary formation outcomes.
The paper is Turrini et al., “The Scientific Case for a Mission to the Ice Giant Planets with Twin Spacecraft to Unveil the History of our Solar System,” submitted to Planetary and Space Science (preprint).
