Probabilistic assessments of asteroid impact risks: problematic

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Credit: pinterest.com

At the Kluge Center of the Library of Congress’s recent “ScholarFest” event, a person in the audience asked astrobiologist David Grinspoon if Earth was due for an extinction-scale asteroid impact. Grinspoon replied that impacts are non-probabalistic events. Just because an extinction-scale impact event hasn’t happened lately doesn’t mean that one will happen soon.

Grinspoon is right on. Yet the community of scientists who work on finding, tracking, and characterizing near-Earth asteroids and identifying those that might pose a risk of impacting with Earth remain deeply wedded to their mathematical methods of calculating impact risks, which – not necessarily intentionally – can convey an impression of regularity where none is proven.

This commitment to probabilistic risk assessment was evident at the so-called “first international workshop on potentially hazardous asteroid assessment,” held July 7-9 at NASA’s Ames Research Center (ARC). The workshop was organized by a new ARC research group, supported by NASA’s Near Earth Object Observations Program (one of two NASA science programs that funds my work), that is studying the physics of asteroid impacts with Earth. A video recording of the workshop is archived here. This was a workshop for expert-to-expert communication. My commentary here is not intended as a critique of participants’ abilities to communicate across the expert-non-expert boundary. I’m simply raising some points that you all can “talk among yourselves” about.

The purpose of the workshop was to advance understanding of potentially hazardous asteroids (PHAs) through modeling of their atmospheric entry/breakup, risk assessments of surface impact (land and tsunami), and characterization of pre-entry properties, toward “developing reliable predictive and assessment tools enabling decision makers to take appropriate mitigation action in the event of pending PHA strike.”

Workshop participants were asked to address these questions: What are the likely physical characteristics for different classes of potentially hazardous asteroids (PHAs) and how can they be measured? What is the dependence of surface damage on PHA size and impact trajectory? What is the range of damage effects and potential for casualties from impacts (both land and tsunami)?

ARC’s David Morrison said characterizing asteroid impact risks in terms of human deaths per year is “a good way to communicate with decision makers.” (I disagree.) He also said “it is prudent to assess the nature of the threat” by means of statistical analyses. (It may be prudent to do so among experts, but such assessments are not necessarily meaningful to non-experts – such as decision makers.)

Elizabeth Pate-Cornell, Jason Reinhardt, and Matthew Daniel of Stanford University’s Engineering Risk Research Group presented interesting material at the workshop that, in my humble opinion, is strictly for discussion among fellow experts. When Steinhardt started talking about such things as “backcasting” and “recency bias,” he lost me.

Steinhardt said risk=probability + consequences. Risk communication expert Peter Sandman says risk=hazard + outrage. Steinhardt’s conception of risk is mathematical. Sandman’s is psycho-social. Steinhardt said, “We can quantify asteroid risk.” (I’m not convinced. Well, I can accept that perhaps statisticians can quantify this risk to their own satisfaction. But I don’t believe such quantifications will be widely meaningful to people who don’t live by the numbers.) Matthew Daniel commented, “uncertainty quantification can be hard to interpret.” (Amen.)

I’m not criticizing the work of this group, which is top-notch.* I am commenting on the value of probabilistic risk assessment in communicating with decision makers about “actionable” risks.

After hearing presentations on an array of approaches to modeling asteroid entry and breakup, Peter Brown of Western University (Toronto) said experts now need to compare and validate these various models. Mark Boslough of Sandia National Laboratory said he’s skeptical that any amount of data on fragmentation generated by computer models will enable accurate predictions of how actual impacting objects will break up (presumably because every impact is unique?).

My colleague Leviticus Lewis of the Federal Emergency Management Agency sent a message to workshop participants when he said, “There will be no formulas in my presentation.” (Most people got the message, I think, based on questions and comments afterward.) He explained how the U.S. national incident management system works, and he explained what disaster planners and emergency responders will need to know about predicted impacts. (Al Harris later commented that Lewis had “told scientists what they need to know.”)

When the experts, and the media, talk about asteroid impact risks, they tend to speculate about “what if” an impact occurs over New York, or Los Angeles, or maybe Paris (in the U.S., at least, they don’t tend to speculate about the world’s most populous cities, such as Delhi, Mexico City, or Sao Paulo….). Somebody at the workshop wondered, “What if something explodes over the Vatican?” I often wonder why – if asteroid impacts with Earth are randomly distributed (see the bolide-impact map released last year) – the experts tend to focus on big cities when most of the world’s surface is covered by water or unpopulated/sparsely populated land. Maybe it’s due to concerns about injuries and fatalities? Then again, I’m not a mathematician, so maybe I’m missing something.

I’m not convinced of the existence of widespread public concern over when the next catastrophic asteroid impact with Earth will occur. I am convinced of the media’s attention to this subject. Impending doom is a popular topic, in fiction and nonfiction media. (If you want to worry about impending doom, read Kathryn Schultz’s story, “The really big one,” in the July 20 issue of The New Yorker. It’s not about asteroid impacts.)

As I told a reporter recently, I don’t worry about the next asteroid impact with Earth. I worry about my neighbor’s tilting hemlock tree falling on my house during the next derecho.

* See Jason C. Steinhardt, Matthew Daniel, and M. Elizabeth Pate-Cornell, “Probabilistic Analysis of Asteroid Impact Risk Mitigation Programs,” Probabilistic Safety Assessment and Management (PSAM) 12, June 2014, Honolulu, Hawaii.

Why space colonies?

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Credit: wikipedia.org

My opinion piece in the August issue of Scientific American about the rhetoric of human space flight has drawn some attention – positive, from friends and colleagues, and nasty, from a couple of (male) people.

As I noted in a March 27 blog post, for more than a decade I have been engaged in an ongoing project of research, analysis, and critique of the ideology of space exploration, in particular its embrace of the frontier metaphor and the idea of manifest destiny. As a U.S. citizen, I am especially interested in how and why this ideology has long been embedded in U.S. space policy and whether and how it serves the public interest. Scientific American’s publication of my piece has clearly stimulated discussion on this topic, which was my goal in writing about it.

As I stated in a July 20 blog post, “The idea of establishing a permanent and expanding human presence in space makes me queasy.” I will continue to engage in analysis and critique of the ideology and the rhetoric of human space flight, space settlement, space mining, and so on, as I am not at all convinced that colonizing other planetary bodies is for the benefit of humankind. How will this benefit the millions of refugees displaced by wars, especially the traumatized children? How will this benefit the people of nations attempting to deal with a history of colonization and dictatorship? How will this help children in this country, and elsewhere, who are undernourished and under-educated?

I’d like to say a few words about titles. They’re intended to draw attention. Why publish a piece if you don’t want people to read it? I submitted my piece to Scientific American under the title, “The rhetoric of the space frontier: turn-on or turn-off?” The first edit of the piece came back to me with this title: “How archaic beliefs about manifest destiny corrupt American rhetoric on human spaceflight is corrupted.” The print version of the piece has this title: “Space cowboys: How jingoism corrupts American rhetoric on human spaceflight.” The online version has this title: “The inexcusable jingoism of American spaceflight rhetoric: how jingoism corrupts American rhetoric on human spaceflight.” (I should note that it was a pleasure to work with the editors of the magazine, who gave me an opportunity to review and approve all changes.)

This piece drew me my first piece of hate mail – here’s a sample, without the four-letter words: “I wonder why this group of people that you discriminate against wants to move to mars [sic]? Maybe its [sic] because of the far left, politically correct bullshit going on in this country. I know that you live in a liberal bubble and do not realize that white males are the reason for 90% of inventions ever happened [sic]. How come the French do not like space? cause of the white American male of course! get the hell out of here.”

Another blogger has criticized my piece as an attack on the Space Frontier Foundation – of which the blogger is a member. My essay is a critique of the old-school rhetoric of human space flight, and the Space Frontier Foundation is one of several dependable sources of this rhetoric. A careful reading of the piece will make that clear.

(For the record, I do not identify as a “liberal.” I identify as a left-leaning democrat.)

As part of my ongoing analysis and critique of the ideology of human space flight, I am looking further into the history of economic neoliberalism, which lies at the heart of U.S. space policy. In his book, A Brief History of Neoliberalism (Oxford University Press, 2005), David Harvey observes that “neoliberalism has…become hegemonic as a mode of discourse” in the global political economy…. It has pervasive effects on ways of thought to the point where it has become incorporated into the common-sense way many of us interpret, live in, and understand the world…. The process of neoliberalization” – deregulation, privatization, and withdrawal of the state from many areas of social provision – “has, however, entailed much ‘creative destruction’…of prior institutional frameworks and powers….”

Just a reminder – the Space Frontier Foundation’s “credo” states: “Our purpose is to unleash the power of free enterprise and lead a united humanity permanently into the Solar System.” Its “frontier enabling test” is this: “Our definition of a “frontier enabling” technology or policy is one which has as its effect the acceleration of the creation of low cost access to the space frontier for private citizens and companies, enables or accelerates our use of space resources, and/or accelerates the rate at which wealth can be generated in space. In other words, is the project or policy going to provide a return on the national investment, if we define “return” to be the economically sustainable human habitation of space?”

I’ll also remind readers of President Obama’s April 15, 2010, speech at NASA’s Kennedy Space Center, in which he said, “Our goal is the capacity for people to work and learn and operate and live safely beyond the Earth for extended periods of time, ultimately in ways that are more sustainable and even indefinite. And in fulfilling this task, we will not only extend humanity’s reach in space — we will strengthen America’s leadership here on Earth…. Leading the world to space helped America achieve new heights of prosperity here on Earth, while demonstrating the power of a free and open society to harness the ingenuity of its people…. If we fail to press forward in the pursuit of discovery, we are ceding our future and we are ceding that essential element of the American character.”

If you have any doubts about the persistence of the old-school ideology of space exploration, see NASA Administrator Charlie Bolden’s remarks to the President’s Council of Advisors on Science and Technology (PCAST) earlier this month (thanks to Michael Henry of the American Institute of Physics for reporting on this meeting). AS AIP reported, “Bolden articulated the nation’s rationale for a mission to Mars by appealing to American values, heritage, and history. The United States, he argued, is about exploration and expansion through the colonization of new places. Said Bolden: ‘We are going farther into the solar system, except this time we’re going to stay. This is not about sending a man to a body and bringing them safely back to Earth. This is about moving humanity farther into the solar system and establishing a foothold where we can remain time in memorial….Through the history of humanity, we’ve always been confronted with crossing the next river, or crossing the next mountain, or going beyond something…. It is the story of the journey West, you know, of the early pilgrims and other people landing on the shores of the United States, but then just not being satisfied and continually moving west and exploring, and so, we’re now trying to get off this planet and farther out’.”

Garrett Reisman, director of crew operations at SpaceX, told PCAST, “Mars, as Charlie [Bolden] mentioned, is the ultimate goal of the agency, [and] also is the ultimate goal of our company. Really, the company [SpaceX] was founded to make humans a multi-planetary species.”

In the June 1 issue of The New Yorker, Elizabeth Kolbert wrote about the idea of colonizing Mars (“Project Exodus”). In a letter to the editor published in the July 20 issue, John Huxhold comments on the article: “Humans are ill suited to space travel, which is why it is so expensive to keep astronauts healthy and safe. As the success of the Mars rovers demonstrates, sending machines to places and environments in our solar system that humans can’t reach is more than enough to satisfy our thrill of discovery…. We should not supplant the real environmental imperative to preserve the earth with the fantasy of colonizing other planets.”

As to many of the key people driving this idea of colonizing outer space – the multimillionaires and billionaires of Silicon Valley, and elsewhere – they are a special breed. In another letter to the editor of The New Yorker, Tony Robinson comments on a story in the May 18 issue of the magazine about Silicon Valley venture capitalist Marc Andreesen: “The V.C.s of Silicon Valley are…the financial engineers of the vast capital flows that are transforming the way the economy operates. But these people are not investing in the wheel, the internal-combustion engine, or the telephone. Playing roulette with other people’s money and, on occasion, hitting it big with a Web portal, a software platform, or a cell-phone app is not exactly ‘changing the world,’ in the traditional sense.”

I agree with Mr. Huxhold and Mr. Robinson.

Exoplanets everywhere, but not another Earth

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Credit: exoworld.info

Astrobiologist David Grinspoon has wisely observed that scientists will never find “another Earth” because every planet is unique. Yet the search for “another Earth” continues.

Today NASA announced that scientists have “confirmed the first near-Earth-size planet in the ‘habitable zone’ around a sun-like star,” 1400 light years away.

In a July 20 media alert about today’s announcement, NASA had said “astronomers are on the cusp of finding something people have dreamed about for thousands of years — another Earth.”

“The newly discovered Kepler-452b” – which NASA characterizes as a “bigger, older cousin to Earth” – “is the smallest planet to date discovered orbiting in the habitable zone — the area around a star where liquid water could pool on the surface of an orbiting planet — of a G2-type star, like our sun,” says the agency.

This discovery was the result of analyses of data collected NASA’s Kepler extrasolar-planet-searching space telescope and follow-up ground-based-observations.

In a media teleconference today about the discovery of Kepler-452b, NASA Associate Administrator for Science John Grunsfeld described this planet as the closest object to Earth 2.0 found thus far in the Kepler dataset.

According to today’s NASA press release, “Kepler-452b is 60 percent larger in diameter than Earth and is considered a super-Earth-size planet. While its mass and composition are not yet determined, previous research suggests that planets the size of Kepler-452b have a good chance of being rocky [emphasis added]…. While Kepler-452b is larger than Earth, its 385-day orbit is only 5 percent longer. The planet is 5 percent farther from its parent star Kepler-452b than Earth is from the Sun. Kepler-452b is 6 billion years old, 1.5 billion years older than our sun, has the same temperature, and is 20 percent brighter and has a diameter 10 percent larger…. This discovery and the introduction of 11 other new small habitable zone candidate planets mark another milestone in the journey to finding another ‘Earth’.””

During Q&A with reporters, Kepler scientists Jon Jenkins of NASA and Jeff Coughlin of the SETI Institute added a lot of qualifiers and caveats to their report on Kepler-452b. Jenkins said the discoverers of Kepler-452b worked with a planetary geologist to come up with a reasonable description of what the planet might be like. They think it’s probably rocky, but they can’t say for sure. (See above.) One reporter asked how they came up with a description of the planet “given that you have so little information about it.” Jenkins said there’s a “slightly better than even chance” it’s rocky.

Another reporter asked how the six billion year age of the host star and its planet is known. Jenkins said the age is an estimate based on models of stellar evolution. For stars like Kepler-452b’s hot star, age is less certain than other details about them. For this planetary system, the age estimate is six billion plus or minus two billion years.

Another reporter asked the scientists to explain “why this one [planet] in particular today stands out as the closest cousin yet” to Earth. Another asked if this planet is “the most likely to support life” discovered thus far. Jenkins replied that it’s the one most like Earth discovered thus far. Another asked how scientists know the mass of the planet. Jenkins said, “I don’t expect we’ll ever have a mass measurement” of Kepler-452b. The planet’s too small to enable direct measurements of its mass. We have an estimate of five Earth masses, based on the masses and distribution of other known exoplanets.

(According to a press release about Kepler-452b from the McDonald Observatory at the University of Texas, “Kepler data provide the ratio of a potential planet’s size to the star’s size, but not the actual size of either.” It also notes that, “at around 1.5 times the Earth’s radius there seems to be a transition going on from predominantly rocky planets to planets that contain more volatiles – ices…which would make [Kepler-452b] a mini-ice giant…we don’t know if it’s a big rocky planet or if it’s a mini-Neptune.”)

Coughlin noted that scientists are just starting to make estimates of the types of planets in our galaxy. Right now it’s estimated that 15-25 percent of sunlike stars have planets. “The most common planets are small rocky planets like Earth…. Planets like Earth do appear to be quite common.”

Questions to NASA on Twitter were all over the place – for example:

  • Is there life on this planet?
    • (“Planetary habitability is complicated,” according to exoplanet scientist Rory Barnes. See my blog post of July 1 for some thoughts from the experts on looking for signs of life on other planets.)
  • What is its atmosphere like? Is there methane?
  • Does the planet have plate tectonics?
  • Does it have moons?
  • Does it have water?
  • How long would it take to travel to this planet?
    • (Kepler-452b is 1400 light years from Earth. Light travels at 300,000 kilometers (186,000 miles) per second. One light year=approximately 9 trillion kilometers (about 6 trillion miles). According To Wikipedia, NASA’s New Horizons spacecraft to Pluto traveled to its target at “58,536 km/h (36,373 mph), making it the fastest spacecraft to ever leave Earth orbit.” How long would it take a spacecraft traveling at 58,536 km an hour to travel 1400 light years? Do the math.)
  • Is there a good possibility of finding a habitable planet that is within traveling distance using current technology? (See above.)
  • Are SETI scientists pointing their telescopes to this planet to listen for radio signals of technological origin?

(I don’t know if anybody at NASA actually answers all of these questions.)

I came away from today’s Kepler teleconference feeling as though scientists were tantalizing people with “news” of a “near-twin” of Earth, only to reveal that most of what’s “known” about this planet is educated guesses. Questions on Twitter indicated to me that people don’t have a very good grasp of cosmic scales or exoplanet detection methods or the space community’s current scientific and technical capabilities, among other things. I feel sad about that. I know that most scientists work hard to explain the work they do, and it’s difficult to avoid talking down or talking over non-experts. We science communication people have a lot of work to do.

Billionaires for SETI

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Credit: pokerstars.com

This morning’s news features reports on yesterday’s announcement in London of a $100 million private investment in the search for extraterrestrial intelligence (SETI). Yesterday I counted five press releases in my mailbox about this announcement.

From the Breakthrough Prize Foundation (or is it the Breakthrough Initiatives? See below): “Yuri Milner and Stephen Hawking Announce $100 Million Breakthrough Initiative to Dramatically Accelerate Search for Intelligent Life in the Universe.”

From the University of California, Berkeley: “The Breakthrough Prize Foundation and its founder, internet investor Yuri Milner, have signed a contract with the University of California, Berkeley, to lead a major escalation in…SETI.”

From the National Radio Astronomy Observatory: “The National Science Foundation’s Green Bank Telescope (GBT) will join in the most powerful, comprehensive, and intensive scientific search ever for signs of intelligent life in the universe.”

From the CSIRO Australia Telescope National Facility: “The Breakthrough Prize Foundation has signed a multi-million dollar agreement with CSIRO [Commonwealth Scientific and Industrial Research Organization] to use the organization’s 64-m Parkes radio telescope in eastern Australia to search for extraterrestrial intelligence.”

From the University of California Observatories at the University of California, Santa Cruz: “Lick Observatory’s Automated Planet Finder (APF) Telescope above San Jose, California, will undertake a new deep and broad search for optical laser transmissions from nearby civilizations, if any exist.”

Breakthrough Initiatives unveiled two SETI “initiatives” yesterday: Breakthrough Listen and Breakthrough Message. Breakthrough Listen “includes a survey of the 1,000,000 closest stars to Earth. It scans the center of our galaxy and the entire galactic plane. Beyond the Milky Way, it listens for messages from the 100 closest galaxies to ours. The instruments used” – the Green Bank Telescope in West Virginia, the Parkes Telescope in Australia, and the Automated Planet Finder at Lick Observatory in California – “are 50 times more sensitive than existing telescopes dedicated to [SETI]. The radio surveys cover 10 times more of the sky than previous programs. They also cover at least 5 times more of the radio spectrum – and do it 100 times faster… We are also carrying out the deepest and broadest ever search for optical laser transmissions. These spectroscopic searches are 1000 times more effective at finding laser signals than ordinary visible light surveys… The initiative will span 10 years and commit a total of $100,000,000.”

The Breakthrough Message initiative will offer $1 million in prizes for “messages that could be read by an advanced civilization.” This project “aims to encourage debate about how and what to communicate with possible intelligent beings beyond earth. It takes the form of an international competition…. The message must be in digital format, and should be representative of humanity and planet Earth…. For the moment we have no plan to send these messages. The program is a way to learn about the possibilities and constraints associated with interstellar correspondence. To encourage global discussion on the ethical and philosophical issues of sending messages into space, we pledge not to transmit any message until there has been a wide-ranging debate at high levels of science and politics on the risks and rewards of contacting advanced civilizations.”

For a Silicon Valley outfit with billions and billions of dollars to blow, this Breakthrough group has a rather messy web presence. Yesterday’s SETI announcement is found at breakthroughinitiatives.org, a site that provides a link to breakthroughprize.org. There is no mention of the SETI announcement on the “news” page of breakthroughprize.org. There is no link to or mention of breakthroughinitiatives.org on breakthroughprize.org. On breakthroughinitiatives.org, Pete Worden is listed as chairman of the Breakthrough Prize Foundation. On breakthroughprize.org, Cornelia Bargmann* is listed as chair of the foundation’s board on life sciences. Is Pete Worden chairman of the foundation, or chairman of the board of directors of the foundation? If the latter, who are the other members of the board? What exactly is the relationship between the foundation and the initiatives?

Other members of the foundation’s board on life sciences, according to the foundation’s web site, are Mark Zuckerberg (net worth, $34.8 billion), Anne Wojcicki ($22.8 billion), Jack Ma ($22.2 billion), and Yuri Milner ($3.4 billion).

Speaking of Pete Worden, he apparently had opportunities to schmooze with Breakthrough’s billionaires while he was director of NASA’s Ames Research Center. The Breakthrough Prize Foundation held its 2014 and 2015 Breakthrough Prize ceremonies at NASA’s Hangar One in Mountain View.

In November 2014, a Google subsidiary called Planetary Ventures LLC signed a 60-year lease with NASA signed a 60-year lease with NASA worth $1.16 billion for Hangar One.

According to the Breakthrough Prize Foundation, its 2014 prize ceremony took place on December 12, 2013, at Hangar 1. “The event was produced by Vanity Fair and Don Mischer Productions…. The ceremony started with a video message from Stephen Hawking and was hosted by Kevin Spacey. From Hollywood, Glenn Close, Rob Lowe, Michael C. Hall and Anna Kendrick presented awards alongside Google’s Larry Page [net worth $29.2 billion] and Wikipedia founder Jimmy Wales, as well as Breakthrough Prize founding sponsors Sergey Brin [net worth $29.7 billion], Anne Wojcicki, Mark Zuckerberg and Yuri Milner.”

The 2015 prize ceremony, on November 9, 2014, featured “host Seth MacFarlane…actors Kate Beckinsale, Cameron Diaz, Benedict Cumberbatch, Jon Hamm and Eddie Redmayne, who presented the Breakthrough Prizes alongside Silicon Valley’s Dick Costolo [net worth $300 million], Laurene Jobs [$19.5 billion], Elon Musk [$14.1 billion], Anne Wojcicki, Sergey Brin, Mark Zuckerberg and Yuri Milner…. The ceremony opened with a video message from Stephen Hawking and closed with a tribute to Carl Sagan and his vision of the Pale Blue Dot.”

In my blog post of July 16, I reported on some recent talks by SETI scientists, who still rely on a rationale for their work that rests on a pile of arguable assumptions. (Also see this paper.) I’ll stick by my conclusion that SETI is a bit of a boutique enterprise, and private rather than government funding is appropriate.

And, oh, by the way, if you’re puzzling over why your retirement savings look so scrawny, see above.

*Bargmann is a neurobiologist at Rockefeller University who, according to Wikipedia, is “known for her work on the behavior in the C. elegans, particularly olfaction in the worm.” She received the $3 million 2013 Breakthrough Prize in Life Sciences and the $1 million 2012 Kavli Prize in Neuroscience.

Here we go again: “trillion dollar” asteroids

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Credit: goldcopreciousmetals.com

In this morning’s news feeds I saw a few headlines about a “trillion dollar baby” asteroid – for example, this Forbes story, “’Trillion dollar baby’ asteroid has wannabe space miners salivating.”

According to Forbes, the near-Earth asteroid 2011 UW158, which made a so-called “close approach” to Earth yesterday – passing by at a distance of about 1.5 million miles – “is believed to be worth more than the entire economy of Japan.”

Who believes it? Chris Lewicki, president of Planetary Resources, who has claimed that 2011 UW158 contains $5 trillion worth of platinum.

The Slooh Community Observatory did a live Webcast about the fly-by, promoting it as an “asteroid mining show” about “The $5 trillion asteroid.” Headlines followed (mercifully, only a few). The live event included a recorded interview with Lewicki about asteroid mining.

According to Slooh host Eric Edelman, charting the course of 2011 UW158 is “very intriguing not just because of how close it gets to us but because of the dollar amount it could potentially be worth…. Nicknamed the five-trillion-dollar asteroid, it could contain between $300 billion and $5.4 trillion worth of platinum.”

Edelman asked Slooh astronomer Bob Berman, if I had an asteroid and I wanted to know what it’s worth, could I figure that out? “Yes, spectroscopically,” Berman said. “This is why Planetary Resources isn’t just hot air.”

In his interview with Lewicki (recorded July 17), Berman asked, you said a few years ago that 2011 UW158 contained $5 trillion of platinum – “how did you come up with that number?”

Lewicki didn’t answer the question. What he said is this: “Our near-term interest is the carbonaceous asteroids…. We’re not as interested in [2011 UW158] as we were.” Now Planetary Resources is interested in water, for use in space. “In a perfected industry, where space resources are part of our sphere of influence, we can use platinum for what it’s best at without worrying about the price tag.”

Berman responded, “That is so cool.”

“We haven’t made a change from platinum to water,” Lewicki said. The Planetary Resources “roadmap” calls for starting with water, to supply crews in space and to use as rocket-fuel feedstock. Platinum will be harder to mine, he said.

Planetary Resources owns Asterank, a Web site that “calculates” the dollar value of asteroids. According to Asterank, “Scientists know very little about the composition of asteroids. Most data used in our calculations come from the JPL’s Small Body Database and the Minor Planet Center. The overwhelming majority of asteroids have no spectral classification and are missing other important data attributes. Without full information it is impossible to fully estimate the true value of an asteroid or the cost of mining it.” This is correct.

However, Asterank goes ahead and assigns dollar values to individual asteroids. It says it “applies accurate, up-to-date information from world markets and scientific papers. To ensure realistic estimates, data from meteorites on Earth and known reference asteroids heavily influence our calculations.”

Asterank claims it infers an asteroid’s composition from its spectra. Those inferences, “in conjunction with current market prices, determine potential value. Accessibility estimates are based primarily on delta-v, but…also incorporate orbital characteristics such as perihelion, aphelion, eccentricity, and period. Profit and ROI calculations are a combination of accessibility and value. The formula strikes a balance between high value and high distance and energy expenditure. Mining costs are factored in as a flat percentage of potential value.”

Sounds like fancy guesswork to me.

I’ve shared my thoughts about asteroid mining on this blog before. The rationale for asteroid mining offered by Lewicki and other advocates is that it will be necessary to support the human settlement of space. The idea of establishing a permanent and expanding human presence in space makes me queasy. I’d be more deeply disturbed by the idea of exploiting extraterrestrial resources for profit than I actually am if I believed it could ever be affordable.

SETI: still not making sense

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Allen Telescope Array, credit: startalkradio.net

 

At the Astrobiology Science Conference (AbSciCon) in Chicago last month, I heard several talks by scientists involved in the search for evidence of extraterrestrial intelligent life (SETI). Listening to these talks was like being in a parallel universe to the AbSciCon universe.

Many talks I heard at AbSciCon convinced me that the rationale for search for evidence of microbial life in our solar system is strengthening, while the SETI talks I heard led me to think the rationale underlying their arguments to continue the search remains weak, at best (see my posts on the so-called “Drake equation” and prospects for life on exoplanets). See what you think.

Andrew Siemion of the Berkeley SETI Research Center, University of California-Berkeley, advocated using the Square Kilometer Array (SKA) for SETI, claiming it will be “primed” for the search. (The SKA is to be built in South Africa. Construction is scheduled to begin in 2018.) Siemion claimed that SETI surveys – campaigns using radio telescopes to search for radio signals of extraterrestrial technological (that is, intelligent) origin – are not “anthropocentrically biased…making no assumptions about locations, habitable zones, etc.”

Okay. But the overall SETI endeavor is anthropocentrically biased. Deeply. The SETI endeavor rests on a number of assumptions – for example, that terrestrial biology is “universal,” that intelligent life is an inevitable result of biological evolution, that extraterrestrial intelligence would be like human intelligence, that extraterrestrial intelligent life would develop the same sorts of technology that humans have…. These assumptions have no solid basis in science. They are speculations.

(FYI, Siemion was on the witness list for a now-postponed June hearing before the House Science, Space, and Technology Committee on astrobiology.)

In checking its web site, I found that in 2011 the Berkeley SETI Research Center began a search for ETI at the Green Bank Telescope (GBT) in West Virginia, targeting 86 exoplanet candidates detected by the Kepler Space Telescope. According to the Center, “the 86 candidates chosen for the GBT SETI search are those in the ‘Habitable Zone,’ that is, they are just the right distance from their parent star for liquid water to exist on their surface.”

Results? The Center reports that its “analyses have generated a few ‘hits,’ but all are undoubtedly examples of terrestrial radio frequency interference (RFI). … Why are these signals interesting? We know these signals are interference, but look similar to what we think might be produced from an extraterrestrial technology. They are narrow in frequency, much narrower than would be produced by any known astrophysical phenomena, and they drift in frequency with time, as we would expect because of the doppler effect imposed by the relative motion of the transmitter and the receiving radio telescope. Even though these signals are interference, detecting events with similar characteristics to what we expect from ET is a good indication that the first steps of our detection algorithms are working properly.”

(No comment.)

Next, I heard Gerry Harp, director of the Center for SETI Research at the SETI Institute, argued for a change in approach to searching for ETI signals. He said 50 years of SETI have focused on looking for radio signals in the so-called “water hole,” 1.4-1.7 gigahertz (GHz) on the electromagnetic spectrum.

(The rationale for searching for signals in this range is that since life on Earth requires water, life elsewhere requires water, and intelligent life elsewhere would send signals in this range so that we would recognize them as a signal from life elsewhere.)

This half-century of searching, Harp said, has shown that the water hole is dry. “Stick a fork in it, it’s done.” It’s time for SETI to look for signals in the rest of the so-called terrestrial microwave window, from 1-10 GHz. The water hole accounts for only 3 percent of the microwave window, and that 3 percent is subject to a lot of radio frequency interference (RFI).

(According to the SETI Institute, “For interstellar communication, a particular range of radio frequencies, “microwaves” from 1 GHz to 10 GHz, are particularly good choices.  At lower frequencies our galaxy emits prodigious amounts of radio waves creating a loud background of noise.  At higher frequencies the Earth’s atmosphere, and presumably the atmosphere of other Earth-like planets, absorbs and emits broad ranges of radio frequencies.  The result is a quiet ‘Microwave Window’ through which efficient radio communication is possible.”)

“If we find a signal, Harp noted, “we have a protocol” for what to do.

(I have a question: Precisely who is “we?” As far as I know, “we” is a small group of people who have been working on a protocol at International Astronautical Federation and International Academy of Astronautics meetings. Emphasis on small.)

Katy Wimberley, an intern at the SETI Institute, reported on her examination of a database of 10 years worth of SETI searching using the Allen Telescope Array. She claimed her research disproves that ETI signals would be distinguishable from RFI and other “noise.” If ETI signals are in the database, then we have to come up with another way to identify them.”

(I must note again that the assumption here is that ETI signals are available to find. The other way to interpret Wimberly’s results is that 10 years of ATA searching has not found any ETI signals.)

I heard Doug Vakoch, director of interstellar message composition at the SETI Institute, present a rationale for “active SETI” – sending powerful, information-rich radio signals out into the galaxy in hopes that “someone” might receive them.

(The assumption here – in addition to the assumptions I’ve already pointed out – is that if “someone” receives our signal, that someone will understand it and care about it.)

The SETI community should pursue active SETI, Vakoch said, to diversify its approach, since 50 years of listening has turned up nothing.

Finally, I heard retired State Department official Michael Michaud say that searching for evidence of extraterrestrial microbial life is not so interesting as searching for evidence of extraterrestrial intelligent life because non-intelligent alien life can’t grant us wisdom or threaten us.

Some members of the SETI community have been advocating for NASA to resume funding SETI. I worked with NASA’s former SETI program from 1988 to 1993 on communication and advocacy planning. I recall that during that time, I argued that SETI leaders needed to articulate a scientific rationale for their program – something that they had not, but ultimately did, put down on paper. It was not enough to save the program from budget cutting. And today, budget limits mean that funding for SETI remains outside the boundaries of NASA’s science portfolio. It’s a bit of a boutique enterprise, and private funding is appropriate.

Searching for extraterrestrial life: it’s complicated

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Last month I spent four intensive days at the 2015 Astrobiology Science Conference in Chicago. Among many messages I took home from this meeting is that searching for evidence of extraterrestrial life is complicated. As in difficult, challenging, frustrating, time-consuming….

Nonetheless, the growing community of scientists engaged in this endeavor are becoming more and more convinced that, ultimately, the search will be successful. As to how long it will take to find incontrovertible evidence that life exists somewhere other than Earth, few astrobiologists are willing to venture a guess – such a prediction would be, indeed, nothing more.

I’ve been going to AbSciCons for more than 10 years. The first AbSciCon I attended had no concurrent sessions. I could listen to every single talk on the agenda. This year, AbSciCon featured no less than five concurrent sessions each day plus multiple plenaries, two massive poster sessions (150 posters per), lunchtime meetings, and other special events.

The theme of this year’s conference, which drew 750 registrants, was “habitability, habitable worlds, and life.” A press conference held during the conference featured astrobiologists who are engaged in cutting-edge research into the habitability of extrasolar planets, icy planetary bodies, and planetary subsurfaces.

I can’t offer a summary of the conference, as at any given time I was missing four out of five concurrent sessions. What I can offer is a list of interesting questions and statements I heard there that provide a taste of what astrobiology is about today (I note sources where I remember them):

  • Big Questions:
    • How can we distinguish between biosignatures and abiosignatures?
    • What is “habitable”? What is a “habitable zone”? How do we define the habitable zone of a planetary system?
    • What was the relative abundance of carbon from exogenous and accreted materials on the early Earth?
    • “What does a planet do to let life get there? What exactly is the problem that life solves?” (Everett Shock, Arizona State University)
  • Origin and evolution of life:
    • When did life cross “the Darwinian threshold” from communal to individual evolution?
    • It seems more sensible to think about life beginning inside a planetary body, eventually working its way to the surface and adapting to the use of light. (Everett Shock, Arizona State University).
    • Research shows that atmospheric oxygen on Earth was low prior to the Great Oxidation Event 2.45 billion years ago. Research also shows that local and global “whiffs” of oxygen appeared in the atmosphere before that event, 3 billion years ago. If oxygen was being produced on Earth 3 billion years ago, then why did the Great Oxidation Event not occur until 2.45 billion years ago? (Jim Kasting, Penn State)
  • Carbon and life:
    • How does terrestrial carbon processing inform us about extraterrestrial habitable worlds?
    • Carbon is the backbone of life. But it might be impossible to explain how carbon in a planet participates in the prebiotic chemistry that eventually led to life on Earth. (Michael Callahan, NASA Goddard Space Flight Center).
    • Carbon itself doesn’t lead to life. It’s the interaction of carbon with its environment that leads to life. (Andrew Steele, Carnegie Institution for Science)
  • Exoplanet habitability:
    • At AbSciCon 2012, no global climate models for extrasolar planets were presented. At AbSciCon 2015, six models were presented. These models “are proving to be a very useful tool” in studying exoplanet habitability. (Rory Barnes, U. Washington).
    • A tidally locked planet, close to its star with one side always facing it, is not necessarily inhabitable. (Ibid.)
    • The early evolution of M dwarf stars may desiccate planets in their habitable zones. (Ibid.)
    • Astrobiology needs more geophysicists. We need to know what goes on inside planets as they evolve. (Ibid.)
    • The mass of a star can be just as important to planetary habitability as its luminosity is. (Ibid.)
    • “Planetary habitability is complicated.” (Ibid.)
    • Direct imaging of an exoplanet requires angular separation of star and planet and suppression of the star’s light. “We don’t have it yet for terrestrial planets.” (Vikki Meadows, U. Washington)
    • Transit transmission is a technique for looking through an exoplanet’s atmosphere (but not for observing its surface). The James Webb Space Telescope will provide the first opportunities for transit transmission observations of exoplanets. (Ibid.)
    • What global climate models are most useful to the study of exoplanet habitability?
    • Small, common stars with planets usually have multiple planets – so should the search for habitable exoplanets focus on these multiple-planet systems? (Aowama Shields, UCLA)
    • It is not logical to assume that Earthlike planets are most likely to be habitable. (Rene Heller, McMaster University)
  • Life detection:
    • Heat + pressure + time can create abiotic organic materials that are similiar in physical appearance, elemental composition, and molecular characteristics to biotic materials. So when we’re looking for fossil evidence of life – on Earth or elsewhere – we have to be really careful to distinguish between the two. (Abigail Allwood, Jet Propulsion Laboratory)
    • “The biggest lesson I’ve learned” is that “context is key” to identifying true biosignatures in the terrestrial rock record. If a potential biosignature were to be identified in a returned Mars sample, interpreting that evidence properly would require a lot of contextual evidence. (Ibid.)
    • “Habitability is the potential but not the proof for life.” (Murthy Gudipati, Jet Propulsion Laboratory)
    • We know that (on Earth) microbes can live in ice. We know little about how microbes affect ice structure. We know that ice is abundant in the solar system. (Britney Schmidt, Georgia Tech)
    • “We’re biased by what we know about life on Earth…. How much fun it is” to put aside those biases and think about other possibilities for life. (Jen Eigenbrode, NASA Goddard Space Flight Center)
    • “I leave this meeting thinking that all of Mars is habitable.” (Ibid.)

 

 

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