Sometimes the way we discover new things is by looking back, as witness the blue haze of Pluto. The image below comes, of course, from New Horizons, taken after the flyby and looking back in the direction of the Sun. Here we’re looking at a mosaic combining black and white LORRI images (Long Range Reconnaissance Imager) and enhancing them with lower-resolution color data from the Ralph/Multispectral Visible Imaging Camera (MVIC). The result, taken about 3.5 hours after closest approach, is in approximately true color.
Image: Pluto as seen by New Horizons from 200,000 kilometers after the flyby. The spectacular blue haze, extending to over 200 kilometers in altitude, is the result of sunlight acting on methane and other molecules in Pluto’s atmosphere to produce a photochemical haze. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.
Ultima Thule likewise yields more of its secrets as we look at data from beyond the closest encounter. New Horizons’ latest target produced departure imagery fleshing out our view of the object’s shape by showing us parts of the KBO that were not illuminated by the Sun during the approach. We learn that the two lobes of Ultima Thule are not spherical at all, but rather that the larger lobe is flattened into a pancake shape, while the New Horizons team sees in the smaller lobe a resemblance to a dented walnut. Here is a video rendering of the data.
Image: Mission scientists created this “departure movie” from 14 different images taken by the New Horizons Long Range Reconnaissance Imager (LORRI) shortly after the spacecraft flew past the Kuiper Belt object nicknamed Ultima Thule (officially named 2014 MU69) on Jan. 1, 2019. The central frame of this sequence was taken on Jan. 1 at 05:42:42 UT (12:42 a.m. EST), when New Horizons was 8,862 kilometers (5,494 miles) beyond Ultima Thule, some 6.6 billion kilometers (4.1 billion miles) from Earth. The object’s illuminated crescent is blurred in the individual frames because a relatively long exposure time was used during this rapid scan to boost the camera’s signal level – but the science team combined and processed the images to remove the blurring and sharpen the thin crescent. This is the farthest movie of any object in our Solar System ever made by any spacecraft. Credit: NASA/Johns Hopkins Applied Physics Laboratory/Southwest Research Institute/National Optical Astronomy Observatory.
“We’ve never seen something like this orbiting the Sun,” says mission PI Alan Stern, adding:
“We had an impression of Ultima Thule based on the limited number of images returned in the days around the flyby, but seeing more data has significantly changed our view. It would be closer to reality to say Ultima Thule’s shape is flatter, like a pancake. But more importantly, the new images are creating scientific puzzles about how such an object could even be formed.”
Image: New Horizons took this image of Ultima Thule on Jan. 1, 2019, when the NASA spacecraft was 8,862 kilometers (5,494 miles) beyond it. The image to the left is an “average” of ten images taken by the Long Range Reconnaissance Imager (LORRI); the sharper processed view is to the right. Credit: NASA/Johns Hopkins Applied Physics Laboratory/Southwest Research Institute/National Optical Astronomy Observatory.
Observing stars as they disappeared when Ultima Thule passed in front of them allowed scientists to further refine the shape. The illustration below shows the evolution of our understanding, as we’ve moved from the ‘snowman’ to the ‘pancake’ model.
“While the very nature of a fast flyby in some ways limits how well we can determine the true shape of Ultima Thule, the new results clearly show that Ultima and Thule are much flatter than originally believed, and much flatter than expected,” adds Hal Weaver, New Horizons project scientist from the Johns Hopkins Applied Physics Laboratory. “This will undoubtedly motivate new theories of planetesimal formation in the early solar system.”
Image: Scientists’ understanding of Ultima Thule has changed as they review additional data. The “old view” in this illustration is based on images taken within a day of New Horizons’ closest approach to the Kuiper Belt object on Jan. 1, 2019, suggesting that both “Ultima” (the larger section, or lobe) and “Thule” (the smaller) were nearly perfect spheres just barely touching each other. But as more data were analyzed, including several highly evocative crescent images taken nearly 10 minutes after closest approach, a “new view” of the object’s shape emerged. Ultima more closely resembles a “pancake,” and Thule a “dented walnut.” The bottom view is the team’s current best shape model for Ultima Thule, but still carries some uncertainty as an entire region was essentially hidden from view, and not illuminated by the Sun, during the New Horizons flyby. The dashed blue lines span the uncertainty in that hemisphere, which shows that Ultima Thule could be either flatter than, or not as flat as, depicted in this figure. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.
6th Interstellar Symposium and Interstellar Propulsion Workshop – TVIW 2019
In collaboration with the National Aeronautics and Space Administration (NASA), the Tennessee Valley Interstellar Workshop (TVIW) hereby invites participation in its 6th Interstellar Symposium and Interstellar Propulsion Workshop -hosted by Wichita State University (WSU) and Ad Astra Kansas Foundation – to be held from Sunday, November 10 through Friday, November 15, 2019, in Wichita, Kansas. The 2019 TVIW has the following elements:
The NASA Workshop on Interstellar Propulsion will focus solely on physics-based propulsion technologies that have the potential to meet the goal of launching an interstellar probe within the next century and achieving .1c transit velocity: Beamed Energy Propulsion, Fusion, and Antimatter.
At this meeting, the state-of-the-art of each will be examined, competing approaches to advancing the Technology Readiness Level (TRL) of each will be presented by advocates and assessed by non-advocates for synthesis into a workshop report to serve as the blueprint for possible future interstellar propulsion technology development.
The Interstellar Symposium will focus on all other aspects of interstellar travel excluding the advanced propulsion technologies to be covered in the NASA Workshop on Interstellar Propulsion, such as power, communications, system reliability/maintainability, psychology, crew health, anthropology, legal regimes and treaties, ethics, exoplanet science (possible destinations), and related research.
Working Tracks are collaborative, small group discussions around a set of interdisciplinary questions on an interstellar subject with the objective of producing “roadmaps” and/or publications to encourage further developments in the respective topics. This year we will be organizing the Working Tracks to follow selected plenary talks with focused discussions on the same topic.
Sagan Meetings. Carl Sagan famously employed this format for his 1971 conference at the Byurakan Observatory in old Soviet Armenia, which dealt with the Drake Equation. Each Sagan Meeting will invite five speakers to give a short presentation staking out a position on a particular question. These speakers will then form a panel to engage in a lively discussion with the audience on that topic.
Seminars are 3-hour presentations on a single subject, providing an in depth look at that subject. Seminars will be held on Sunday, November 10, 2019, with morning and afternoon sessions. The content must be acceptable to be counted as continuation education credit for those holding a Professional Engineer (PE) certificate.
Other Content includes, but is not limited to, posters, displays of art or models, demonstrations, panel discussions, interviews, or public outreach events.
Publications: Since TVIW serves as a critical incubator of ideas for the interstellar community, we intend to publish the work of TVIW 2019 in many outlets, including a complete workshop proceedings in book form.
No Paper, No Podium: If a written paper is not submitted by the final manuscript deadline, authors will not be permitted to present their work at the event. Papers should be original work that has not been previously published. Select papers may be submitted for professional publication, such as in the Journal of the British Interplanetary Society (JBIS).
Video and Archiving: All TVIW events may be captured on video or in still images for use on the TVIW website, in newsletters and social media. All presenters, speakers and selected participants will be asked to complete a Release Form that grants permission for TVIW to use this content as described.
Abstracts for presented papers/presentations at TVIW 2019 may be submitted to either of two categories:
1. NASA Workshop on Interstellar Propulsion
2. Interstellar Symposium
Topics for Working Tracks, Sagan Meetings, Seminars, and Other Content are NOT solicited at this time.
Abstracts for the NASA Workshop on Interstellar Propulsion must relate to one of the three propulsion technologies of interest (Beamed Energy Propulsion, Fusion, and Antimatter) and should include the aspects of recent research, an assessment of the technology’s Technology Readiness Level (TRL) using NASA’s definitions found here, and a discussion of critical technical issues to be resolved with realistic, near-term technical development milestones identified (including relevant performance metrics).
Abstracts for the Interstellar Symposium must related to one or more of the many other interstellar mission related topics, such as power, communications, system reliability/maintainability, psychology, crew health, anthropology, legal regimes and treaties, ethics, exoplanet science (possible destinations), and propulsion technologies not explicitly called for in the NASA Workshop on Interstellar Propulsion.
Abstracts due: July 30, 2019.
All abstracts must be submitted online here.
PRESENTING AUTHOR(S) – Please list ONLY the author(s) who will actually be in attendance and presenting at the conference. (first name, last name, degree –for example, Susan Smith, MD)
ADDITIONAL AUTHORS – List all authors here, including Presenting Author(s) – (first name, last name, degree(s) – for example, Mary Rockford, RN; Susan Smith, MD; John Jones, PhD)
ABBREVIATIONS within the body should be kept to a minimum and must be defined upon first use in the abstract by placing the abbreviation in parenthesis after the represented full word or phrase. Proprietary drug names and logos may NOT be used. Non-proprietary (generic) names should be used.
ABSTRACT LENGTH – The entire abstract, (EXCLUDING title, authors, presenting author’s institutional affiliation(s), city, state, and text), including any tables or figures should be a maximum of 350 words. It is your responsibility to verify compliance with the length requirement.
Abstract Structure – abstracts must include the following headings:
- Title – the presentation title
- Background – describes the research or initiative context
- Objective – describes the research or initiative objective
- Methods – describes research methodology used. For initiatives, describes the target population, program or curricular content, and evaluation method
- Results – summarizes findings in sufficient detail to support the conclusions
- TRL Assessment and Justification (NASA Propulsion Workshop only)
- Development Roadmap (NASA Propulsion Workshop only)
- Near-term technical milestones and performance metrics (NASA Propulsion Workshop only)
- Conclusions – states the conclusions drawn from results, including their applicability.
Questions and responses to this Call for Papers, Workshops and Participation should be directed to: email@example.com
For updates on the meeting, speakers, and logistics, please refer to the website: https://tviw.us/2019-symposium/
TVIW is incorporated in the State of Tennessee as a non-profit education organization. TVIW is a tax-exempt, 501(c)(3) educational, non-profit corporation by U.S. Internal Revenue Service. For U.S. tax purposes, all donations to TVIW are fully tax deductible (as allowed by your local laws).
Copyright © 2019 Tennessee Valley Interstellar Workshop, Inc. (TVIW), All rights reserved.
The search for technosignatures that could flag the presence of extraterrestrial cultures has accelerated in recent times with projects like Glimpsing Heat from Alien Technologies at Penn State and numerous papers. Or is the better term not ‘cultures’ but ‘societies,’ or ‘civilizations’? SETI’s funding challenges, at least from government agencies, point to the need for defining its terms in ways that NASA, for example, can live with. Nick Nielsen examines the question in today’s essay, probing the issue of terminology in relation to public support, and noting the ongoing effort to evaluate and revise how SETI is described. Nielsen, a frequent Centauri Dreams contributor and a member of the board of directors for Icarus Interstellar, is a prolific writer who tracks these and other space-related issues in Grand Strategy: The View from Oregon, and Grand Strategy Annex.
by J. N. Nielsen
Recently there have been some signs that NASA may consider a rapprochement with SETI and SETI scientists, after more than twenty years of a de facto NASA ban on funding SETI (cf. NASA Renews Interest in SETI by David Grinspoon). It’s not yet clear how far this rapprochement will extend, but NASA did lend its name to the NASA Technosignatures Workshop (NTW18) last September. The event webpage names the Lunar and Planetary Institute, Universities Space Research Association, and National Aeronautics and Space Administration as having provided “institutional support”; I do not know if this involved financial support from NASA. The recent NASA Technosignatures Workshop also resulted in a 70 page paper, “NASA and the Search for Technosignatures: A Report from the NASA Technosignatures Workshop.”
I have to wonder if the term “technosignatures” is ultimately more palatable than the acronym “SETI,” with the latter’s explicit reference to ETI (extraterrestrial intelligence). “Technosignatures” sounds tech-savvy and doesn’t explicitly invoke aliens, though the idea of aliens is still there implicitly as a presupposition. This may sound like an overly-subtle gloss on the situation, but it is still a significant consideration. It is conceivable that NASA eventually will consider funding projects that mention “technosignatures” while continuing to pass over any project that mentions “SETI.”
The need to re-brand SETI was discussed in ‘Search for Extraterrestrial Intelligence’ Needs a New Name, SETI Pioneer Says by Calla Cofield, primarily discussing the recent work of SETI notable Jill Tarter. The author attributes to Tarter the idea that the acronym “SETI,” and what it has come to signify, “…generates an incorrect perception of what scientists in this field are actually doing.” Tarter also discusses the need for terminology reform. The question of SETI terminology has come in for a lot of discussion lately. We have seen the explicit consideration of SETI terminology in Wright’s paper “Taxonomy and Jargon in SETI as an Interdisciplinary Field of Study” and in the collective effort “Recommendations from the Ad Hoc Committee on SETI Nomenclature” by Jason T. Wright, Sofia Sheikh, Iván Almár, Kathryn Denning, Steven Dick, and Jill Tarter.
I found myself rather annoyed by the second of the two papers named in the paragraph above (I will henceforth call it the “Recommendations paper”), because it failed to deal with the hard conceptual problems presented by the terminology commonly used, and the hardest problems are usually the most interesting problems once you buckle down and focus on them with a will to really understand what is going on. Usually one finds that vague and imprecise terms paper over a multitude of subtle meanings, easily conflated, and it is a lot of work—sometimes tedious work—to separate out all these threads and give a full accounting of the ideas that are the background of the natural language employed in a science before that science is fully formalized.
Early analytical philosophers had a word for this clarification that has sadly fallen out of use: explication; take a look at Chapter 1 of Carnap’s Logical Foundations of Probability, “On Explication,” for a detailed exposition of explication. Carnap’s conception of explication could provide a framework for thinking about the explication of concepts employed in SETI. It was disappointing to me that the Recommendations paper is a laundry list of terms to use and terms to avoid, but, in fairness to the authors, the remit of the ad hoc committee was, “…to recommend standardized definitions for terms,” and not a root-and-branch re-thinking of the conceptual foundations of the discipline (which is what I would have liked to have seen).
Of particular interest to me in the Recommendations paper was its treatment of “civilization”:
In a SETI context, e.g. (extraterrestrial or alien civilization) usually synonymous with technological species. Use with care.
Notes: The term civilization has imprecise popular meanings, but also particular scholarly meanings in relation to human history that are not generally what is meant by the term in a SETI context. Because of its ambiguity and anthropocentrism, the term is a suboptimal synonym for technological species, but it is nonetheless widely used in the literature. Society is a good alternative but not yet in common use.
It could be pointed out that “society” also has both imprecise popular meanings and particular scholarly meanings, so it is difficult to say how “society” is any better in this respect than “civilization.” I also question the idea that “technological species” is in any sense more precise or any less ambiguous than “civilization.”
The authors of the paper note that the use of “civilization” in SETI differs from its use in other scholarly contexts, but they don’t seem to be at all interested in why this is the case, or in finding some conception of civilization that is non-anthropocentric and is equally suitable for use in SETI and other sciences. This would be like someone saying that “BTU” is used to indicate energy in heating and “watt” is used to indicate energy in electricity, but that there is no need for any common conception of energy that might be an umbrella conception for BTU and watt (or calorie, or joule, etc.).
The same paper takes on the use of the term “advanced,” and while I agree that the term “advanced” is problematic, it is not problematic for the reasons cited in the paper. “Advanced” in isolation means nothing; it is a relational term. What would make sense is a formulation such as “x is more advanced than y.” With a little refinement we get, “x is a more advanced F than y.” Now, this latter formulation could be said to be in the same spirit as the recommendation in the paper of, “…simply specifying the scale or nature of the technology referenced.” I’m on board with this, as long as it is made clear that “advanced” is a relational term that is meaningless in isolation. What we find in most cases of using “advanced” in isolation is that the comparison is implicit; one of the virtues of formalizing any usage in a schema such as, “x is a more advanced F than y,” is that it forces us to make our assumptions explicit.
Clearly, however, the authors of the Recommendations paper mean to condemn, “…deprecated theories of human history which rank human societies from ‘primitive’ to ‘advanced’ based on ill-defined and ethnocentric measures.” No doubt the authors have the most virtuous motives for condemning what they see as ethnocentric measures to distinguish primitive from advanced civilizations, but—Alas!—science is unconcerned with the virtue of its practitioners, or the lack thereof. We could go a long way toward improving the situation by offering a precisely defined scale by which civilizations could be rank-ordered, but I doubt that this would quell the misgivings of those whose concern is addressing the grievances claimed to follow from ethnocentric bias. I will say no more at present regarding this.
In addition to his advocacy for SETI terminology reform, Jason Wright has also argued strongly that SETI is and ought to be a part of astrobiology (cf. “SETI is Part of Astrobiology”). Wright counters the official NASA line that, “Traditional SETI is not part of astrobiology,” by arguing that some of the most obvious signs of terrestrial habitability are Earth’s technosignatures. Wright also points out that NASA arbitrarily excludes technosignatures from “traditional SETI.” Obviously, to the extent that NASA’s exclusion is arbitrary, it is dissatisfying. Given that NASA has been deeply involved with astrobiology since its inception (cf. The Living Universe: NASA and the Development of Astrobiology by Steven J. Dick and James E. Strick, which discusses NASA’s involvement in astrobiology since the term was introduced), if SETI is part of astrobiology, and NASA was present at the foundations of astrobiology, then the case could be made that NASA’s astrobiology program should include SETI as an integral component, organically present ab initio. That is to say, SETI is not some foreign body that has become inexplicably lodged in astrobiology.
However, in a Twitter post, Jason Wright referenced two posts by Dr. Linda Billings, SETI: on the edge of astrobiology and Astrobiology and SETI: different evolutionary pathways, which argue against including SETI under the umbrella of astrobiology. These posts conclude, respectively, “The bottom line is that traditional SETI—using ground-based radio telescopes to listen for signals of extraterrestrial intelligent origin—falls outside the boundaries of NASA’s astrobiology program.” And, “…the history/evolution of exo/astrobiology more closely parallels the history/evolution of planetary protection. Exo/astrobiology and SETI evolved on very different, non-parallel tracks.” Thus the argument whether SETI ought to be considered a part of astrobiology has been made both in the affirmative and in the negative. It seems pretty weak to me to argue that SETI is intrinsically about ground-based observations, as SETI observations from space-based telescopes would be a great boost for the discipline, if only these resources were made available to SETI research. Wright deals with this weakness as one of the erroneous perceptions he identifies that has led to the exclusion of SETI from NASA’s astrobiology portfolio.
Much of this discussion is taking place because SETI is poorly funded, and if government monies were made available to SETI researchers, the discipline could pursue a more ambitious scientific research program. But because SETI has been largely frozen out of government funding through NASA, which would be its natural home (unless, like Billings, we see the National Science Foundation funded ground-based telescopes as the natural home of SETI), SETI funding efforts have taken creative forms. One of these creative ways of doing SETI science on the cheap has been projects that can be described as “parasitic,” “piggyback,” and “opportunistic.” This was taken up explicitly by Jill Tarter in 1984 in “Parasitic, Piggyback and Opportunistic SETI: It’s Cheap and It Just Might Work?”
A year prior, in 1983, the idea was already floated in “The Berkeley parasitic SETI program” by S. Bowyer, G. Zeitlin, J. Tarter, M. Lampton, and W. J. Welch. And since then we have seen, “The SERENDIP piggyback SETI project” by M. Lampton, S. Bowyer, D. Werthimer, C. Donnelly, and W. Herrick (1992) and “An Opportunistic Search for ExtraTerrestrial Intelligence (SETI) with the Murchison Widefield Array” by S. J. Tingay, C. Tremblay, A. Walsh, and R. Urquhart (2016). The latter paper characterizes their “opportunistic” SETI as follows:
“In this Letter, we present a first, and opportunistic, SETI pilot experiment with the MWA, in the frequency range 103–133 MHz, placing limits on narrow band radio emission toward 38 known planetary systems. The experiment is opportunistic in the sense that the observations were undertaken for a spectral line survey of the Galactic Plane that is ongoing; utility of the data for a SETI experiment was realised post-observation.”
There is a kind of subtle irony in SETI science having to operate parasitically on other projects deemed more fundable, or, at least, projects that would not draw the ire of politicians looking for a soft budgetary target to attack. Arguably, whatever public support that there is for space exploration (and however correct or mistaken it may be to connect space exploration with SETI), derives from the hope, perhaps even the titillating hope, of finding something “out there” that would mean that we are not alone.
I have often said that any excitement over things like exoplanet searches always turns on whether the planets are habitable, any excitement over whether the planet is habitable largely turns on whether we can ever determine whether or not these planets actually have life, any excitement over whether or not we can determine if these planets have life largely turns on whether that life could be intelligent, and any excitement over whether or not this life could be intelligent largely turns on whether we might possibly communicate with or travel to these intelligent beings. Space science, then, is to a large extent an artifact of our cosmic loneliness, and our desire to mitigate that cosmic loneliness.
I’ve read a few candid comments to this effect (I can’t remember the source), and I have no doubt that this is the case. In the same way that conservation biology has an easier time raising money to fight for charismatic megafauna, but has a much more difficult time raising money based on conservation efforts for unattractive animals or very small animals, so too space science efforts do better when they are related to some “sexy” space science topic like aliens?—?but this has to be done sotto voce, with a wink and a nudge, because NASA, to be taken seriously, must keep up the appearance of high seriousness. NASA’s budgetary choices are held hostage by the “giggle factor.”
In a sense, then, it is space science that is parasitic upon SETI and human spaceflight (which appeals as a source of national pride in accomplishment), which, when the latter dominated NASA and NASA’s budget, took the lion’s share of the money and left little for space science. In recent decades, the focus has been more on space science, and so it is SETI (rather than prestige) which is the unspoken background to what is going on explicitly in the foreground. While I care deeply about space science, and I know how much NASA’s space science programs have transformed our knowledge of the universe, few in the wider public share my sentiments, and they cannot be expected to so share these sentiments. But they can share an interest in the “charismatic megafauna” of astrobiology, which are the intelligent aliens that SETI is seeking.
If NASA can embrace technosignatures as a part of astrobiology, it may find a way to excite the interest of the public while maintaining its scientific respectability. And if that requires a shift in terminology, I suspect that SETI researchers will be ready to make that shift. An article by Lisa Grossman, It’s time to start taking the search for E.T. seriously, astronomers say: Some scientists are pushing for NASA to make looking for alien technology an official goal, notes that Jason Wright is part of a group of scientists who are actively seeking to have the search for technosignatures incorporated into NASA’s next Decadal Survey, which, if successful, would mean federal funding for SETI projects. Everyone is well aware that such funding would transform the discipline, and SETI advocates are now actively campaigning for the funding.
We can already see this transition to the language of technosignatures taking place. For example, if we take as a recent example the paper, “A search for technosignatures from TRAPPIST-1, LHS 1140, and 10 planetary systems in the Kepler field with the Green Bank Telescope at 1.15-1.73 GHz” by Pavlo Pinchuk, et al., we find that “technosignatures” are mentioned repeatedly throughout the text, “extraterrestrial” is mentioned ten times, “SETI” is mentioned a couple of times (as well as in the bibliography, in an internet address, and in a title), “civilization” is mentioned once, and “alien” appears nowhere in the document.
Any scientific discipline, as it evolves, eventually revises its terminology, as it usually begins with imprecise terms taken from ordinary language and eventually settles upon more formalized usages that are defined with scientific precision, and which become the accepted jargon of the discipline. There is scientific precision in spades to be found in SETI research papers. What is wanting in SETI (and in discussions of technosignatures, for that matter) is the conceptual framework within which these terms are formulated. SETI science is strong, but its concepts are often weak and ambiguous, as is evidenced by the recent concern with terminology. I have had this conceptual weakness on my mind for some time, and I hope to be able to write more about this as I clarify my own thoughts on the matter. Others seem to have noted this weakness as well. In a paper that has just come out by Jim Pass of the Astrosociology Research Institute, Exo-Astrosociology and the Search for Technosignatures, Pass notes:
“Unlike with the regard to discoveries associated with the search for biosignatures mostly in our Solar System, which have produced discoveries and insights of tangible value, the research associated with the search for technosignatures is less impressive.”
The charismatic megafauna of SETI—little green men, space aliens, Martians, and their kin—are emblematic of this conceptual weakness, and they could be made more respectable with a prolonged inquiry into and clarification of the conceptual framework within which we discuss the possibility of the emergent complexities we know on Earth—life, sentience, consciousness, intelligence, mind, technology, and civilization, inter alia — also existing elsewhere. If we have gotten the sequence of emergent complexities right, this sequence begins with biology, and so is initially an astrobiological inquiry. However, at some point it becomes an inquiry larger than astrobiology (or, if you prefer, an inquiry no longer narrowly contained within the boundaries of biological thought), and our conceptual framework must expand in order to accommodate this larger domain of inquiry. Explication, then, could play a crucial role in exorcising space aliens and replacing them with a theoretical construction more consonant with NASA’s demand for high seriousness.
Today we re-enter the realm of perspective-altering photographs, images that open new vistas in our early reconnaissance of the Solar System. Before October 7, 1959, we had little knowledge of the far side of the Moon, even though librations allowed the occasional glimpse at extremely low angles of a small part of it. The Soviet moon probe Luna 3 took the first photographs of the far side, and was followed by the much better imagery of Zond 3 in 1965. NASA’s Lunar Orbiter program would continue the mapping as the 1960s progressed.
Image: First glimpse. The view of the Moon’s far side from Luna 3.
The far side would swim into vivid focus, of course, when Apollo 8 and subsequent missions took astronauts to the Moon, but it was up to the China National Space Administration to make the first soft landing there on January 3 of this year (Ranger 4 had impacted on the far side in 1962, but without returning data before impact). Working in this environment demanded a relay satellite to support communications with the Chang’e 4 mission on the surface.
The Queqiao satellite handles signals from the surface and relays them to Earth, working with a satellite called Longjiang-2, from which the image below was downloaded on February 3. Remember, for most of human history, we had no idea what the far side of the Moon looked like. Now we’ve not only mapped it, but can see a view of Earth with the entire far side laid out before us.
Image: Downloaded at the Dwingeloo Radio Observatory in the Netherlands, this view from Longjiang-2 shows the Earth and the Moon’s far side. The contrast in color is reminiscent of Bill Anders’ famous shot from Apollo 8, though here we see the Moon in its entirety.
Another perspective changer is the fact that Longjiang-2 is equipped with an amateur radio transceiver that allows radio amateurs to downlink telemetry and relay messages through it, as well as commanding it to take and downlink images, as explained in this page at the Dwingeloo website. What an opportunity for space-minded amateurs. They can work Longjiang-2 (call sign BJ1SN) and join the amateur team at Dwingeloo itself (PI9CAM) to see images that, not all that long ago, would have seemed astonishing. For many of us, ‘astonishing’ still applies.
I can’t leave the far side without comparing the above to the animation below, a spectacular shot of of the Earth and Moon as seen by the DSCOVR satellite (Deep Space Climate Observatory).
Image: This animation features satellite images of the far side of the Moon, illuminated by the Sun, as it crosses between the DSCOVR spacecraft’s Earth Polychromatic Imaging Camera (EPIC) and telescope, and the Earth — 1.6 million km (1 million miles) away. The times of the images span from 3:50 p.m. to 8:45 p.m. EDT on July 16, 2015. The time of the New Moon was at 9:26 p.m. EDT on July 15. Credit: NASA/NOAA.
Another perspective enhancer is the view below from MARCO-B, nicknamed WALL-E. Along with MARCO-A (also known as EVE), the CubeSat made it to Mars in a seven-month journey that provided data on the InSight landing on November 26, 2018. The data were valuable because Mars orbiters could not observe the entire landing sequence and route information swiftly back to Earth. The MARCOs returned data at each stage of the InSight descent and landing in near-real time, also beaming back InSight’s first image.
And despite the failure of MARCO-A’s camera, MARCO-B succeeded in fine fashion with the memorable animation below.
Image: MARCO-B, one of the experimental Mars Cube One (MARCO) CubeSats, took the images shown in the animation above as it approached Mars from about 575,000 kilometers (357,300 miles) to 18,000 kilometers (11,200 miles) away, just before NASA’s InSight spacecraft landed on Mars on Nov. 26, 2018. MARCO-B flew by Mars with its twin, MARCO-A, to serve as communications relays for InSight as it touched down on the Red Planet. Nicknamed WALL-E, MARCO-B took these images on Sunday, Nov. 25 and Monday, Nov. 26, 2018. The bright point of light to the left is the corner of MARCO-B’s high gain antenna feed and to the right is the high gain antenna, which let the CubeSat communicate with Earth. In this animation, Mars is spinning on its axis from right to left. Credit: NASA/JPL-Caltech.
There have been no further transmissions from MARCO-B since the end of December, while we last heard from MARCO-A in early January. We have this from JPL:
The mission team has several theories for why they haven’t been able to contact the pair. WALL-E has a leaky thruster. Attitude-control issues could be causing them to wobble and lose the ability to send and receive commands. The brightness sensors that allow the CubeSats to stay pointed at the Sun and recharge their batteries could be another factor. The MarCOs are in orbit around the Sun and will only get farther away as February wears on. The farther they are, the more precisely they need to point their antennas to communicate with Earth.
This summer the two diminutive spacecraft will begin moving back toward the Sun. MARCO-A is, based on calculations of its trajectory, now more than 3.2 million kilometers beyond Mars, while MARCO-B is 1.6 million kilometers past the planet. Further attempts to communicate with the CubeSats will be made later this year, but it’s not known how long the batteries and other parts of the spacecraft will last. Whether we hear from either again or not, the MARCOs have pushed the paradigms of size and cost and pointed the way to future missions, perhaps one day involving solar sails and networking technologies taken all the way to the outer planets.
Figuring out the shape of things — where to place what we see in the sky in a 3-D representation — has always been challenging. We’re looking out at a disk of stars from well within it, and it wasn’t until the 1920s and the work of Edwin Hubble that we began to see there were other such disks, not nebulae at all but galaxies in their own right, some bigger than ours. Interestingly, Immanuel Kant had speculated about this as far back as 1755.
About our own galaxy, we still have much to learn, as I am once again reminded by a paper by authors from Macquarie University (Australia) and the Chinese Academy of Sciences. The Milky Way turns out to be not as flat as many depictions would have us believe. In fact, our galaxy shows distinct signs of warping, a spiral pattern that appears to be the result of torque produced by the Milky Way’s massive inner disk of closely packed stars.
In the outer regions of the galaxy’s neutral hydrogen disk, the warp becomes readily apparent. We wind up with a shape something like the one in this artist’s impression below:
Image: A slightly exaggerated impression of the real shape of our warped and twisted Milky Way. Credit: Xiaodian Chen (National Astronomical Observatories, Chinese Academy of Sciences).
The twisted spiral pattern is hardly unique to the Milky Way. In fact, about a dozen other galaxies are known to display such patterns.
Image: The galaxy ESO 510-G13 is an edge-on warped spiral galaxy. Similar to the Milky Way it has a pronounced warp in its gaseous disc and a less pronounced warp in its disc of stars. Credit: NASA/Space Telescope Science Institute.
Demonstrating a spiral pattern from within the galaxy under study is not easy, says lead author Xiaodian Chen (Chinese Academy of Sciences, Beijing):
“It is notoriously difficult to determine distances from the Sun to parts of the Milky Way’s outer gas disc without having a clear idea of what that disc actually looks like. However, we recently published a new catalogue of well-behaved variable stars known as classical Cepheids, for which very accurate distances can be determined with an error of only three to five per cent.”
Using Cepheid variables found in data from the Wide-field Infrared Survey Explorer (WISE) mission as well as a variety of optical surveys, the researchers set about producing a three-dimensional picture of the galaxy out to its farthest regions. Cepheid variables are helpful here because they vary in brightness, and their luminosity and pulsation period are directly linked. Observing a Cepheid variable’s pulsation period allows one to know its true luminosity. The distance to the star can then be calculated by comparing known luminosity to the brightness astronomers observe (hence the nickname ‘standard candles’ to describe such stars).
What the scientists found was that the 1339 Cepheids tracked the neutral hydrogen disk of the Milky Way, with an S-like spiral pattern apparent in each as we move toward the galaxy’s outer regions. From the paper:
…we establish a robust Galactic Disk model based on 1,339 classical Cepheids. We provide strong evidence that the warp’s line of nodes is not oriented in the Galactic Centre–Sun direction. Instead, it subtends a mean angle of 17.5° ± 1° (formal) ± 3° (systematic) and exhibits a leading spiral pattern. Our Galaxy thus follows Briggs’ rule for spiral galaxies, which suggests that the origin of the warp is associated with torques forced by the massive inner disk . The stellar disk traced by Cepheids follows the gas disk in terms of their amplitudes; the stellar disk extends to at least 20 kpc… This morphology provides a crucial, updated map for studies of the kinematics and archaeology of the Galactic Disk.
Image: The units ‘kpc’ (kiloparsecs) along the image’s three axes are used by astronomers to indicate distances on galaxy-wide scales. One kiloparsec is equivalent to about 3,262 light years. Credit: Chen et al.
The paper is Chen et al., “An intuitive 3D map of the Galactic warp’s precession traced by classical Cepheids,” Nature Astronomy 04 February 2019 (abstract). Thanks to Alex Tolley for useful information on this work.