Finding Earth 2.0

In honor of Carl Sagan’s birthday, I figured I’d write a few thoughts I had about a fascinatingly unique conference I attended in the Bay Area last week. It was called “Finding Earth 2.0,” and it was organized by 100 Year Starship, a group partially funded by NASA and the Defense Advanced Research Projects Agency (DARPA) to plan for interstellar travel within the next century.

A potential spacecraft called Icarus Pathfinder would be powered by electric propulsion engines called VASIMR, taking it out to 1,000 times the distance between the Earth and Sun. (Credit: NBC News)

A potential spacecraft called Icarus Pathfinder would be powered by electric propulsion engines called VASIMR, taking it out to 1,000 times the distance between the Earth and Sun. (Credit: NBC News)

Like you might imagine such an organization, the conference speakers and attendees appeared rather eclectic, including astronomers and planetary physicists and science journalists—whom I’m usually hanging out with—as well as aerospace engineers, science fiction writers, business people, teachers, space enthusiasts, and many others. But everyone displayed an active interest in exploring the distant universe and imagining what our future might be like.

Dr. Mae Jemison, the first woman of color in space, heads the 100 Year Starship, and she gave a plenary talk. She pointed to many motivations people have for finding another Earth, including conundrums and challenges our planet and species face, such as limited resources, overpopulation, and our own behavior—perhaps a reference to climate change or nuclear weapons. I think we have many other compelling reasons for interstellar space exploration, but I’ve written about that here before.

I also saw many interesting perspectives and presentations about hunting for planets beyond the solar system, called exoplanets, including habitable ones or even inhabited ones. Dr. Jill Tarter, SETI (Search for Extraterrestrial Intelligence) Institute co-founder and inspiration for Sagan’s protagonist in Contact (Dr. Arroway), gave a provocative presentation on attempts to detect “technosignatures” from distant planets. (She clarified that possessing technology doesn’t imply an intelligent civilization; however, technologies serve as a proxy for intelligence.) Advanced species on these planets could be giving off radio and optical signals that could reach the Earth, but we’d have to listen really really hard to hear them. But if they had a Dyson sphere or an “alien superstructure,” that would be easier.

Other astronomers and astrobiologists talked about their work on related subjects. Margaret Turnbull, also of the SETI Institute, spoke about the “massive harvest” of planets reaped by NASA’s Kepler probe, which confirmed more than 1,000 planets in our Milky Way neighborhood and which showed that about 1 in 5 stars has a planet in the “habitable zone.” Stephen Kane (San Francisco State University) made a convincing case that we should view the habitable zone boundaries as uncertain, and that many planets in the zone would actually be not very hospitable to life. Natalie Batalha (NASA Ames) argued that we should be open-minded about planets in other systems. In one of a few relationship-like quotes, she said, “In our search for a [Earth-like] soul-mate, we may be a bit myopic.” But she was talking about the fact that we have no planets between Earth and Neptune sizes here, while according to Kepler observations, such planets seem rather common throughout the galaxy. She and others also made the point that we need detailed imaging or spectra of planetary systems to learn more about their habitability.

Niki Parenteau (SETI) talked about her efforts to study exoplanets and spot signs of life, which would likely be microorganisms and would have to cover the world to be detectable. “There’s no one smoking gun for biosignatures,” she said. “We need multiple lines of evidence.” She looks for things like biogenic gases and certain planetary surface features. But for her, water is the #1 requirement…and then Morgan Cable, a nerdy joke-telling astrochemist from Jet Propulsion Laboratory, considered a range of other liquids life might be able to develop in, including ammonia, carbon dioxide, petroleum, and liquid hydrocarbons. She ended with her main argument: “NASA shouldn’t just be looking for places with liquid water.”

Artist's illustration of NASA's NEA Scout CubeSat, which is scheduled to launch aboard the maiden flight of the agency’s Space Launch System rocket in 2018. (Credit: NASA)

Artist’s illustration of NASA’s NEA Scout CubeSat, which is scheduled to launch aboard the maiden flight of the agency’s Space Launch System rocket in 2018. (Credit: NASA)

A bunch of people gave presentations about propulsion systems, trying to push the boundaries of space travel. I thought the most interesting one was by Les Johnson, Deputy Manager for NASA’s Advanced Concepts Office at Marshall Space Flight Center. In back-to-back talks, he described current efforts to design and construct giant solar and electric sails. The sails involve ultra-thin reflective materials that are unfurled in space and use solar energy to propel a spacecraft to the distant reaches of the solar system and beyond. In an important step toward that goal, Johnson and NASA engineers are currently building a solar sail for the Near-Earth Asteroid Scout mission to transport a CubeSat “nanosatellite” to study asteroids past Mars in two years. He and his colleagues are also currently testing electric sails for fast solar wind-powered spacecraft, which—if as powerful as hoped—could even send a probe to another star.

Finally, I saw a few strange talks at the conference, and I wasn’t sure what to make of them. For example, one person spoke about the new field of “astrosociology.” He avoided giving any specifics though, even though he had been discussing “deviant” behavior, and admitted after the talk that he had envisioned studying multi-year trips transporting tens of thousands of colonists beyond the solar system. Maybe for the 200 Year Starship! Unfortunately, the speaker had not considered small missions, such as handfuls of astronauts traveling to Mars or private ventures conducting asteroid mining. I’d imagine that such small groups of people stuck together for long periods could benefit from sociological study.

Book Review: Five Billion Years of Solitude

As long as humans have roamed the Earth, they have looked up to the skies, speculating and pondering about the celestial wonders populating the distant cosmos. From the early astronomers and natural philosophers until today’s (including me), people have observed and studied the billions of twinkling dots, all the while wondering whether there are other worlds out there and whether they might host lifeforms like us.

FiveBillionYearsofSolitude

In his first book, “Five Billion Years of Solitude: The Search for Life Among the Stars,” Lee Billings explores these and related questions. He chronicles the story of space exploration, planet-hunting and the growing field of astrobiology, while meeting fascinating characters and discussing their research, telescopes, discoveries and challenges. He offers clear and compelling explanations, such as of planetary physics and habitability, and he takes important asides into debates on space exploration budgets and the fate of our own planet, including the ongoing climate change crisis.

Billings is a talented science journalist. Like his work for Scientific American and other publications, the book is excellently written and researched. It won the 2014 American Institute of Physics science communication award in the book category, announced at the American Astronomical Society meeting in January.

Over the course of the book, Billings tracks down and speaks with important figures in planetary astronomy. He begins with Frank Drake, who along with nine other scientists in 1961 attempt to quantify the abundance of life-supporting planets in the galaxy in a calculation now known as the Drake Equation. He also meets with other astrophysicists, including University of California, Santa Cruz professor Greg Laughlin, Space Telescope Science Institute director Matt Mountain and MIT professor Sara Seager.

Since the time-scale or life-time of civilizations plays a role in the Drake Equation, his investigations lead to an examination of our own history and the longevity of humanity on Earth. Billings discusses the planet’s changing climate and other looming threats, for which our society appears unprepared. His reporting takes him to southern California too, where he quotes from my former colleague, UC San Diego physicist Tom Murphy, who considered the question of growing global energy consumption.

Other important questions come up as well. How far away are planets beyond our solar system and how long would it take to get there? What kind of atmospheric, geological and climatic conditions must a habitable planet have? How do astronomers detect planets, when they are so small, so faint and so close to their brightly glowing suns? What are our prospects for finding more Earth-like planets?

And what will happen to the Earth and humankind—if we’re still around—over the next few billion years, as our sun brightens, expands and transforms into a red giant star? As Billings starkly puts it in his interview for The Atlantic, “We may have—we may be—the only chance available for life on Earth to somehow escape a final, ultimate planetary and stellar death.”

Artist's conception of NASA's Kepler spacecraft. (Image credit: NASA/Ames/JPL-Caltech)

Artist’s conception of NASA’s Kepler spacecraft. (Image credit: NASA/Ames/JPL-Caltech)

With the Kepler telescope, we have the good fortune to be living at a time when actually Earth-like worlds, not just super-Earths and gas dwarfs, can be identified. Astronomers have already used the telescope to find a few potential Earth cousins, which have the right size and the right “Goldilocks” distance from their stars, and many many more candidates are on the horizon. Under certain conditions, follow-up observations can measure the planets’ atmospheres and climates to further assess their habitability.

It’s an exciting time! With even more advanced planet-finding telescopes coming up, such as the Hubble successors, the James Webb Space Telescope and High-Definition Space Telescope, we can look forward to more detailed images and observations of exoplanets in the near future. Maybe Earth has twins and maybe we are not alone.

I have a few criticisms of Five Billion Years, but they’re very minor ones. I liked the analysis of federal budget debates at multiple points in the book, but Billings could have written a little more about why as a society we should prioritize space exploration and astronomical research. If, say, a member of the House Science Committee (or more likely, their staffer) were to read this, it would be helpful to spell that out. Early in the book, he provides an engaging historical survey of astronomy, but he neglected Eastern contributions, such as from Persians, Arabs and Chinese. A few chapters meandered quite a bit too, but I enjoyed his writing style.

In any case, this is a beautifully written and thoroughly researched book, and I recommend it. Billings puts the search for extraterrestrial life in a broader context and pushes us to think about our place in the vast universe. The story continues.

[P.S. I’m extremely busy these days with the UC Santa Cruz science communication program and writing internships, so I may write posts here less often. But I will link to pieces I’ve written elsewhere, which have the benefit of rigorous editing, so if you like my blog, you’ll like them even more.]

Why do we engage in space exploration?

A review of diverse perspectives on space exploration and extraterrestrial life reveal fundamentally human hopes, fears and flaws

Since the dawn of civilization thousands of years ago, humans have looked to the skies. Archaeologists have found evidence of people from China, India, and Persia to Europe and Mesoamerica observing and contemplating the many stars and planets that fascinated them. We humans have also wondered about—and often hoped for—the existence of other intelligent life out there. Considering the large number of planets in the Milky Way and in billions of other galaxies, perhaps we are not alone, and maybe even while you are reading this, extraterrestrials could be looking in our direction through their telescopes or sending us interstellar telegrams. But if our galaxy teems with aliens, following Italian physicist Enrico Fermi’s persistent question, we must ask, “Where are they?”

Artist's depiction of a travel poster for a "Tatooine-like" planet orbiting two suns, recently discovered by NASA's Kepler spacecraft. (Courtesy: NASA)

Artist’s depiction of a travel poster for a “Tatooine-like” planet orbiting two suns, recently discovered by NASA’s Kepler spacecraft. (Courtesy: NASA)

Two recent pieces in the New Yorker and New York Times, as well as numerous books over the past couple years, motivate me to consider this and related questions too. Astronomers and astrophysicists around the world, including scientists working with NASA, the European Space Agency (ESA), the Japanese Space Agency (JAXA) and many others, have many varieties of telescopes and observatories on Earth and in space, just because we want to investigate and learn about our galactic neighborhood and beyond. We also attempt to communicate, like sending a message in a bottle, with the Golden Records aboard the Voyager spacecrafts, and we listen for alien attempts to contact us. In our lifetime, we have dreams of sending humans to Mars and to more distant planets. Why do we do this? We do it for many reasons, but especially because humans are explorers: we’re driven to see what’s out there and to “boldly go where no one has gone before.” As Carl Sagan put it in Cosmos, “Exploration is in our nature. We began as wanderers, and we are wanderers still.”

Views of human space exploration

Elizabeth Kolbert reviews three recently published and forthcoming books by Chris Impey, an astronomer at the University of Arizona (where I used to work three years ago), Stephen Petranek, a journalist at Discover, and Erik Conway, a historian of science at Jet Propulsion Laboratory. (She did not mention an award-winning book by Lee Billings, Five Billion Years of Solitude, which I will review in a later post.) She fault finds with the overoptimistic and possibly naïve “boosterism” of Impey and Petranek. “The notion that we could…hurl [humans]…into space, and that this would, to use Petranek’s formulation, constitute ‘our best hope,’ is either fantastically far-fetched or deeply depressing.” She asks, “Why is it that the same people who believe we can live off-Earth tend to believe we can’t live on it?”

Kolbert’s assessment has some merit. Astrophiles and space enthusiasts, of which I am one, sometimes seem to neglect Earth (and Earthlings) in all its wonder, marvels, complexity, brutality and messiness. But is the primary reason for exploring the universe that we can’t take care of ourselves on Earth? Mars should not be viewed as a backup plan but rather as one of many important steps toward better understanding our little corner of the galaxy. Furthermore, we should be clear that sending humans to Mars and more distant worlds is an incredibly complicated and dangerous prospect, with no guarantee of success. Even if the long distances could be traversed—at its closest, Mars comes by at least a staggering 50 million miles (80 million km) away, and then the nearest star, Alpha Centauri, is about 25 trillion miles from us—future human outposts would face many obstacles. The popular novel by Andy Weir, The Martian, demonstrates only some of the extraordinary challenges of living beyond our home planet.

Overview of components of NASA's Journey to Mars program, which seeks to send humans to the red planet in the 2030s. (Credit: NASA)

Overview of components of NASA’s Journey to Mars program, which seeks to send humans to the red planet in the 2030s. (Credit: NASA)

Though Kolbert criticizes Conway’s dry writing style, she clearly sympathizes with his views. “If people ever do get to the red planet—an event that Conway…considers ‘unlikely’ in his lifetime—they’ll immediately wreck the place just by showing up…If people start rejiggering the atmosphere and thawing the [planet’s soil], so much the worse.” This line of criticism refers to flaws of geoengineering and of the human species itself. Many times in history, humans ventured out acting like explorers, and then became colonists and then colonialists, exploiting every region’s environment and inhabitants.

Note that Kolbert is a journalist with considerable experience writing about climate, ecology and biology, while astrophysics and space sciences require a stretch of her expertise. In her excellent Pulitzer Prize-winning book, The Sixth Extinction, Kolbert argues provocatively that humans could be viewed as invasive species transforming the planet faster than other species can adapt, thereby constituting a danger to them. “As soon as humans started using [language], they pushed beyond the limits of [the] world.” I agree that humans must radically improve their relationship with nature and Earth itself, but this does not preclude space travel; on the contrary, the goal of exploring other worlds should be one aspect of our longer-term and larger-scale perspective of humanity’s place in the universe.

Views of extraterrestrial intelligence

Dennis Overbye, a science writer specializing in physics and astronomy, covers similar ground, but focuses more on the search for extraterrestrial intelligence (SETI). He mentions the Drake Equation, named after the American astronomer Frank Drake, which quantifies our understanding of the likelihood of intelligent life on other planets with whom we might communicate. Both Drake and Sagan “stressed that a key unknown element in their equations was the average lifetime of technological civilizations.” If advanced species don’t survive very long, then the possibility of contact between overlapping civilizations becomes highly improbable. It would be unfortunate if similarly advanced civilizations, like Earthlings and Klingons, could never meet.

Overbye introduces the controversial University of Oxford philosopher, Nick Bostrom, who is rooting for us to fail in our search for ETs! “It would be good news if we find Mars to be sterile. Dead rocks and lifeless sands would lift my spirit.”

Bostrom bases his argument on a concept he refers to as the Great Filter. Considering the likelihood of advanced civilizations, many conditions and criteria must be satisfied and steps must be taken before a planet in the “habitable zone” has a chance of harboring intelligent life. The planet probably must have the right kind of atmosphere and a significant amount of liquid water and some kind of possibly carbon-based building blocks of life, and after that, the alien species’ evolutionary developments could go in any direction, not necessarily in a direction that facilitates intelligence. In addition, asteroids, pandemics, or volcanic eruptions could wipe out this alien life before it got anywhere. In other words, myriad perils and difficulties filter out the planets, such that only a few might have species that survive and reach a level of social and technological advancement comparable to those of humans.

On the other hand, if we do find life on other planets and if intelligent extraterrestrial life is relatively ubiquitous, our lack of contact with them could mean that advanced civilizations have a short lifetime. Perhaps the Great Filter is ahead of us, “since there is no reason to think that we will be any luckier than other species.” Maybe nuclear war, climate change, or killer robots might wipe us out before we have the chance to explore the galaxy.

I am not convinced by Bostrom’s pessimism. Even if the Great Filter is ahead of us, implying that humans face more existential threats in the future than have been overcome in the past, this doesn’t mean that we are doomed. Humanity does have major problems with acknowledging large-scale impacts and long-term outlooks, but I hope we could learn to change before it is too late.

A more positive outlook

We have learned a lot about planets, stars, galaxies, black holes and the distant universe from our tiny vantage point. But we would be immodest and mistaken to brazenly presume that we’ve already figured out the rest of the universe. We really don’t know how many other “intelligent” species might be out there, and if so, how far they are, what level of evolution they’re at (if evolution is a linear process), or whether or how they might communicate with us. We should continue to discuss and examine these questions though.

While traveling to other planets will take a long time, in the meantime astronomers continue to make exciting discoveries of possibly “Earth-like” planets, such as Kepler-452b, an older bigger cousin to our world. It seems likely that the Earth has a very big family, with many cousins in the Milky Way alone.

So why do we engage in space exploration and why do we seek out extraterrestrial life? This question seems to transform into questions about who we are and how we view our role in the universe. I believe that humans are fundamentally explorers, not only in a scientific sense, and we have boundless curiosity and wonder about our planet and the universe we live in. Humans also explore the depths of the oceans and dense rainforests and they scour remote regions in arid deserts and frigid glaciers (while they still remain), just to see what they’re like and to look for and observe different lifeforms.

More importantly, even after tens of thousands of years of human existence, we are still exploring who we are, not just with scientific work by psychologists and sociologists but also with novelists, poets and philosophers. We still have much to learn. To quote from Q, a capricious yet occasionally wise Star Trek character, “That is the exploration that awaits you: not mapping stars and studying nebulae, but charting the unknown possibilities of existence!”

High-Definition Space Telescope: Our Giant Glimpse of the Future?

Where do you see yourself in a decade? What is your vision for two decades from now? What could you accomplish if you had billions of dollars and infrastructure at your disposal? A consortium of astrophysicists attempt to answer these questions as they put forward their bold proposal for a giant high-resolution telescope for the next generation, which would observe numerous exoplanets, stars, galaxies and the distant universe in stunning detail.

Artist’s conception of proposed proposed High-Definition Space Telescope, which would have a giant segmented mirror and unprecedented resolution at optical and UV wavelengths. (NASA/GSFC)

Artist’s conception of proposed proposed High-Definition Space Telescope, which would have a giant segmented mirror and unprecedented resolution at optical and UV wavelengths. (NASA/GSFC)

The Association of Universities for Research in Astronomy (AURA), an influential organization of astronomers from 39 mostly US-based institutions, which operates telescopes and observatories for NASA and the National Science Foundation, lays out its vision of High-Definition Space Telescope (HDST) in a new report this month. Julianne Dalcanton of the University of Washington and Sara Seager of the Massachusetts Institute of Technology—veteran astronomers with impressive knowledge and experience with galactic and planetary science—led the committee who researched and wrote the 172-page report.

As the HDST’s name suggests, its wide segmented mirror would give it much much higher resolution than any current or upcoming telescopes, allowing astronomers to focus on exoplanets up to 100 light-years away, resolve stars even in the Andromeda Galaxy, and image faraway galaxies dating back 10 billion years of cosmic time into our universe’s past.

A simulated spiral galaxy as viewed by Hubble and the proposed High Definition Space Telescope at a lookback time of approximately 10 billion years. Image credit: D. Ceverino, C. Moody, G. Snyder, and Z. Levay (STScI)

A simulated spiral galaxy as viewed by Hubble and the proposed High Definition Space Telescope at a lookback time of approximately 10 billion years. Image credit: D. Ceverino, C. Moody, G. Snyder, and Z. Levay (STScI)

In the more recent past, the popular and outstandingly successful Hubble Space Telescope celebrated its 25th birthday a few months ago. Astronomers utilized Hubble and its instruments over the years to obtain the now iconic images of the Crab Nebula, the Sombrero Galaxy, the Ultra Deep Field, and many many others that captured the public imagination. Hubble continues to merrily float by in low-earth orbit and enables cutting-edge science. But the telescope required 20 years of planning, technological development, and budget allocations before it was launched in 1990.

For the newly proposed space telescope, some headlines describe it as NASA’s successor to Hubble, but it really constitutes a successor to a successor of Hubble, with other telescopes in between (such as the Wide-Field InfraRed Survey Telescope, WFIRST). If the astronomical community comes on board and if astronomers convince NASA and Congressional committees to fund it—two big “ifs” for big projects like this—it likely would be designed and constructed in the 2020s and then launched in the 2030s.

The James Webb Space Telescope (JWST), proposed two decades ago by AURA and now finally reaching fruition and set for launching in 2018, could be considered the HDST’s predecessor. All of these major projects require many years of planning and research; Rome wasn’t built in a day, as they say. James Webb scientists and engineers hope that, like Hubble, it will produce spectacular images with its infrared cameras, become a household name, and expand our understanding of the universe. Nevertheless, JWST has been plagued by a ballooning budget and numerous delays, and Congress nearly terminated it in 2011. When a few large-scale programs cost so many billions of dollars and years to develop, how do people weigh them against many smaller-scale ones that sometimes get sacrificed?

Approximately every ten years, members of the astronomical community get together and determine their set of priorities for the next decade, balancing large-, medium- and small-scale programs and ground- and space-based telescopes, given the budget realities and outlook. Back in 2001, they prioritized James Webb, and then a decade later they put WFIRST at the top of the list. For the next generation though, in the 2010 Decadal Survey (named “New Worlds, New Horizons”), they highlighted the need for a habitable (exo)planet imaging mission. Everyone loves planets, even dwarf planets, as revealed by the popularity of NASA’s missions exploring Pluto and Ceres this year.

Building on that report, NASA’s 2014 Astrophysics Roadmap (named “Enduring Quests, Daring Visons”) argued that much could be gained from a UV/optical/infrared surveyor with improved resolution, which could probe stars and galaxies with more precision than ever before. According to the AURA committee, the High-Definition Space Telescope would achieve both of these goals, taking planetary, stellar and galactic astronomy to the next level. Importantly, they also argued that astronomers should prioritize the telescope in the 2020 Decadal Survey, for which planning has already commenced.

How do scientists balance the need for different kinds and sizes of projects and missions, knowing that every good idea can’t be funded? Astronomers frequently disagree about how to best allocate funding—hence the need for periodic surveys of the community. They hope that what is best for science and the public will emerge, even if some scientists’ favorite projects ultimately aren’t successful. James Webb Space Telescope’s budget has been set to $8 billion, while the High-Definition Space Telescope would cost $10 billion or more, according to Alan Dressler of the Carnegie Observatories. This is big money, but it’s small compared to the cost of bank bailouts and military expenditures, for example. While the scientific community assesses which programs to focus on, we as a society need to determine our own priorities and how space exploration, astrophysics research as well as education and outreach are important to us. In the meantime, HDST scientists will continue to make their case, including in an upcoming event at the SPIE Optics & Photonics conference in San Diego, which I will try to attend.

Scientists and journalists alike frequently talk about Big Science these days. The recently published and much reviewed book by Michael Hiltzik about the physicist Ernest Lawrence describes its history since the Manhattan Project and the advent of ever-bigger particle accelerators. Big Science is here to stay and we clearly have much to gain from it. Only some Big Science ideas can be prioritized and successfully make the most of the effort and investment people put in them. Hubble exceeded all expectations; the High-Definition Space Telescope has astronomical shoes to fill.

New Discoveries as New Horizons Flies by Pluto!

You may be wondering, what’s the deal with Pluto? First, astronomers demote Pluto’s planetary status in a controversial move, to say the least, and then NASA sends a spacecraft on a mission to observe it in detail? Why is this important, and what could we learn about Pluto that we didn’t know already?

Image from the Long Range Reconnaissance Imager (LORRI) aboard NASA's New Horizons spacecraft, taken on 13 July 2015. Pluto is dominated by the feature informally named the "Heart." (Image Credit: NASA/APL/SwRI)

Image from the Long Range Reconnaissance Imager (LORRI) aboard NASA’s New Horizons spacecraft, taken on 13 July 2015. Pluto is dominated by the feature informally named the “Heart.” (Image Credit: NASA/APL/SwRI)

Of course, we have quite a bit to learn. Moreover, as one of the least studied objects in the outer regions of our solar system, Pluto is ripe for exploration and investigation. Within a few days, NASA’s New Horizons probe already produced detailed and exquisite photos of Pluto, much better than has been done with Hubble or any other telescope. Its mission is far from over, but it’s already an amazing success and has inspired public interest in space exploration once again.

Back in 1930, 85 years ago, a young astronomer by the name of Clyde Tombaugh at Lowell Observatory in Flagstaff, Arizona noticed a distant possibly planet-like object moving across photographic plates. When other astronomers confirmed the discovery, thousands of people suggested names for the planet. In the end, the name that caught on in the community came from an 11-year-old girl in Oxford, Venetia Burney, and the Lowell astronomers approved “Pluto” unanimously. (Contrary to some rumors, she did not name it after the cartoon dog.) Burney (later Phair) lived to witness the launching of New Horizons, but she passed away in 2009. Some of Tombaugh’s ashes are aboard the spacecraft, and his children and grandchildren were present for the events of New Horizons.

NASA's New Horizons spacecraft.  (Artist's impression.)

NASA’s New Horizons spacecraft.
(Artist’s impression.)

NASA’s New Horizons spacecraft launched from Cape Canaveral in January 2006. Its journey took it 3 billion miles (about 5 billion km) from Earth, including a slingshot around Jupiter—covering nearly 1 million miles per day!—to reach Pluto. To paraphrase Douglas Adams, you may think it’s a long way to the chemist’s, but that’s just peanuts compared to the distance New Horizons traveled. Principal investigator Alan Stern of the Southwest Research Institute in Boulder, Colorado leads the mission, which also includes a relatively large fraction of women on the team. In another important point, the mission had a relatively small cost ($700M) considering its huge impact on planetary physics, space exploration, and science outreach.

Once Pluto was demoted (or even dissed) by the astronomical community back in 2006, it’s never been more popular! New Horizons’ flyby only rekindled interest in Pluto in popular culture. I’ve seen many comics, memes and jokes about it, including XKCD, a cartoon showing Neil deGrasse Tyson and Pluto giving each other the finger, a cartoon with a sad Pluto as New Horizons flies by while saying “HEYWHATSUPGOTTAGOBYE!,” and another cartoon with Pluto saying, “So you dumped me years ago, but now you’re driving by my house real slow?”

As I wrote in a previous post, Pluto has many characteristics, including its small size and mass, that give it a questionable planetary status. It is one of many objects hurtling about the edge of our solar system called the Kuiper Belt, named after Dutch-American astronomer Gerard Kuiper. According to the International Astronomical Union (IAU), these are some of the solar system’s non-planets, ranked by size: Ganymede (Jupiter moon), Titan (Saturn moon), Callisto (Jupiter moon), Io (Jupiter moon), Earth’s moon, Europa (Jupiter moon), Triton (Neptune moon), Pluto, and Eris. Much further down the list comes Ceres (in the asteroid belt between Mars and Jupiter), which is actually smaller than Charon, one of Pluto’s moons. Eris, which was previously known as 2003 UB313 (and also as Planet X, and then Xena, as in the Warrior Princess) is slightly more massive than Pluto. In addition to Pluto, Eris, and Ceres, Haumea (a trans-Neptunian object) and Makemake (another Kuiper Belt object) are the other two dwarf planets the IAU recognizes. In any case, Pluto may be small and may be less unique than we thought and may have an abnormally elliptical orbit, but we all love it anyway.

New Horizons made its closest approach on 14 July, Tuesday morning, about 50 years after the first spacecraft landed on Mars, Mariner 4. It will take many months for New Horizons to transmit all of the Pluto flyby data back to Earth, but what has the probe discovered so far? First, New Horizons already obtained the most detailed images of Pluto ever. Second, based on the imagery, astronomers calculated that Pluto is slightly larger than previously thought: it turns out to have a radius 1.9% larger than Eris’s, making it the largest dwarf planet.

New Horizons scientists also found that Pluto is icier than previously thought, with its polar ice cap and with icy mountains nearly as high as the Rockies. The ice consists of a frozen mixture of methane, ethane, carbon monoxide and nitrogen—not the sort of thing you’d want to put in a drink. Pluto’s mountains likely formed less than 100 million years ago, which is a relatively short time in the history of a (dwarf) planet. At least some of Pluto’s surface might still be geologically active today—some scientists think they have spotted potential geysers as well—but planetary physicists are not sure about what could have caused this activity. Furthermore, Pluto exhibits very few impact craters from Kuiper belt objects (KBOs), which would also be consistent with recent geological activity.

Charon also lacks such craters—a surprising observation considering that it appears to have no atmosphere. Charon’s diameter is over half of Pluto’s, which makes it big enough to cause Pluto to wobble as it orbits. Scientists believe that Charon likely formed from a huge collision with a young Pluto, and debris also settled into Pluto’s four other moons: Nix, Hydra, Kerberos, and Styx. Alternatively, Pluto could have gravitationally captured Charon a few hundred million years ago, which could explain the “tidal interactions” between them.

Finally, New Horizons astronomers discovered vast frozen craterless plains in the center of Pluto’s “heart,” which they have informally named the “Tombaugh Regio.” The plains region has a broken surface of irregularly-shaped segments that either may be due to the contraction of surface materials, like when mud dries, or may be the result of convection. The New Horizons team released the following zoom-in images at a press conference today, and we expect more to come.

What’s next for New Horizons? The probe continues to send more valuable data from its seven instruments in our general direction. Project scientists will sift through these data to try to learn more about Pluto and Charon’s surface, geology, and atmosphere, and therefore to infer how these interesting objects formed and evolved. In the meantime, New Horizons continues on its merry way throughout the Kuiper Belt. Assuming NASA approves funding for its extended mission, in a couple years it will use its limited fuel to investigate much smaller and newly discovered KBOs, such as 2014 MT69. In any case, we shall keep in touch with New Horizons as it follows the Voyager spacecrafts into the outskirts of our solar system and boldly ventures beyond.

[For further reading, you can find great coverage about these exciting discoveries in many places. For example, take a look at Nature (Alexandra Witze), Science, Scientific American, National Geographic (Nadia Drake), Wired, NBC (Alan Boyle), as well as New York Times, Los Angeles Times, Guardian, BBC, etc… For the most up-to-date information, I suggest taking a look at NASA’s website and the Planetary Society (Emily Lakdawalla).]

Challenges of the James Webb Space Telescope, NASA’s Successor to Hubble

Everyone grows up eventually. It’s hard to believe, but the Hubble Space Telescope (HST), which many astronomers and astronomy fans consider to be one of the most important telescopes of our generation, turns 25 this month. Hubble, built and funded by NASA and the European Space Agency, was launched on 24th April 1990, only a half year after the fall of the Berlin Wall. Its instruments produced numerous iconic images, including the spectacular ones below.

Everyone is celebrating this anniversary! Check out hubble25th.org for more images, news, and information. The 2010 documentary, “Saving Hubble,” is now viewable for free. Plus, in a public lecture on 1st April as part of National Academies’ Space Science Week, Jason Kalirai (Space Telescope Science Institute) highlighted Hubble’s many scientific contributions.

Crab Nebula (Credit: Hubble Space Telescope)

Crab Nebula (Credit: Hubble Space Telescope)

Galaxy M83 (HST)

Galaxy M83 (HST)

Ultra Deep Field (HST)

Ultra Deep Field (HST)

Now astronomers and the astronomy-loving public are anticipating and preparing for Hubble’s successor, the James Webb Space Telescope (JWST, named after a former NASA administrator). Over its ambitious 5 to 10-year mission (a Star Trek-style time-scale!), its powerful cameras and spectrometers will focus on near- to mid-infrared wavelengths and will examine planetary systems in our galaxy as well as distant galaxies forming in the early universe, only a few hundred million years after the Big Bang. As you can see, it’s built with a folding segmented mirror and a deployable sunshield. It’s not servicable like Hubble was, as JWST will orbit one million miles from Earth.

Artist's impression of NASA's James Webb Space Telescope.

Artist’s impression of NASA’s James Webb Space Telescope.

As I’ve written in previous posts, JWST’s gigantic budget has been contentious in the astronomical community. While astronomers believe that JWST will likely have a big scientific impact, especially on the fields of planetary physics and galaxy formation, others are unhappy that its cost inevitably results in smaller programs being cut. NASA officials prioritize the missions and programs the agency invests in, and it is simply not feasible to fund every exciting project astronomers propose. (JWST’s budget constituted nearly half of NASA’s astrophysics budget for FY 2015.) Based on my conversations with astronomers, the community remains divided about JWST, though many astronomers are excited about the telescope and note its importance for public outreach.

Credit: NASA Astrophysics Division Director Paul Hertz

Credit: NASA Astrophysics Division Director Paul Hertz

Large projects rarely stay on schedule and on budget in astrophysics, but JWST was perhaps an extreme case. A decade ago, JWST faced considerable criticism, such as in this Nature article by Lee Billings, because of its many delays and cost overruns. But after much pressure and threats from Congress to cancel the program, NASA officials rebaselined JWST’s budget and conducted a management overhaul in 2011. Since then, scientists have kept JWST within its new $8.8-billion budget and the telescope is on schedule for launch in 2018.

Last Tuesday, the House Science Committee held a hearing reviewing JWST’s progress, called “Searching for the Origins of the Universe: An Update on the Progress of the James Webb Space Telescope (JWST).” According to the American Institute of Physics, the committee’s Chair and Ranking Member, Rep. Steven Palazzo (R-MS) and Rep. Donna Edwards (D-MD), “expressed, as did other subcommittee members, great interest in and support for the telescope.” According to Cristina Chaplain of the Government Accountability Office, JWST has ten months of unused budget reserves, which will be more than enough as it moves into the integration and testing phase.

A few challenges remain. For example, technicians have had difficulty with a “cryocooler” component, which needs to operate at much colder temperatures than other such units in order to keep the Mid-Infrared Instrument sufficiently cool, but it is still scheduled to be delivered this summer. In any case, both John Grunsfeld, associate administrator of NASA’s Science Mission Directorate, and John Mather, JWST’s Senior Project Scientist, expressed confidence to the Committee that this observatory will launch in 2018. “Expect amazing discoveries,” Mather said.

For more coverage, take a look at these articles in Scientific American, Space News, and Space.com. [Full disclosure: I am a member of the American Institute of Physics, and former colleagues at the University of Arizona helped design JWST’s NIRCam instrument.]

NASA Missions Exploring Dwarf Planets Ceres and Pluto

Now I’m not a planetary astronomer, but like you, I’m excited by any kind of space exploration, and this year the NASA missions, Dawn and New Horizons, will give us the closest and most detailed views of dwarf planets yet.

What is a “dwarf planet,” you ask? Excellent question. Until about ten years ago, astronomers usually referred to small planet-like objects that were not satellites (moons) as “planetoids.” In some ways, they resembled the eight more massive planets in our solar system as well as Pluto, which had a borderline status. Astronomers discovered Charon, Eris (previously called 2003 UB313), and Ceres, and they expected to discover many more, likely rapidly expanding the ranks of our esteemed class of planets. Either they all had to be included, or a clear classification system would have to be determined and Pluto would be reclassified.

Courtesy: IAU

Courtesy: IAU

At the International Astronomical Union (IAU) meeting in Prague in 2006, astronomers opted for the latter in Resolution 5. They demoted poor Pluto, but I think they did the right thing. (I was working in Heidelberg, Germany at the time, and if I’d known how historic this IAU meeting would be, maybe I would’ve tried to attend!) The IAU’s defines a dwarf planet as “a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.” The criterion (c) is the important one here, because it means that the object has not become gravitationally dominant in its orbital zone, which is the case for Pluto and the other planetoids beyond Neptune and for Ceres, the only dwarf planet in the asteroid belt between Mars and Jupiter. These are contentious issues, and the debate even made it into the New Yorker. But let’s be clear: these things are small, and they’re all less massive than Earth’s moon.

We don’t know as much about dwarf planets as we do about the planets in our system, so let’s go exploring! What do these new space missions have in store for us?

Ceres

In 2007, NASA launched the Dawn spacecraft to study Ceres up close. A couple days ago, two centuries after Sicilian astronomer Father Giuseppe Piazzi discovered Ceres, Dawn became the first spacecraft to orbit a dwarf planet. As the deputy Principal Investigator Carol Raymond put it on Friday, this is an “historic day for planetary exploration.” Jim Green, NASA’s Planetary Science Division Director, says that with Dawn, we are “learning about building blocks of terrestrial planets in our solar system.”

Dawn has obtained excellent detailed images already, as you can see in the (sped up) animation below.

Credit:  NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Credit:
NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

The pair of bright spots in a crater stand out, and astronomers are trying to figure out what they are. They might be an indication of geological activity on it’s changing surface. Ceres has a rocky core and an ice layer, and it’s also possible that these are reflective patches of ice that have been exposed by space rocks falling in and striking the surface. For more information, check out this blog post by Emily Lakdawalla and these articles in the LA Times and Wired.

As Dawn uses its propulsion systems to reshape its orbit and get closer views, astronomers expect to learn more about those spots, look for plumes, and examine the surface for strange craters or other distinguishing features. The spacecraft will later turn on its spectrometers and determine which minerals are present and how abundant they are.

Pluto

NASA launched New Horizons in 2006, and it had much farther to travel to reach Pluto. In January, NASA announced that New Horizons is making its approach to the erstwhile planet, though it’s still about 200 million kilometers away. Mark your calendars: it will fly by Pluto (as it will be traveling too fast to orbit) on 14th July, and at a distance of only 13,000 km, New Horizons’ instruments will obtain the best images yet of it. For more information, check out this article by Jason Major in Universe Today and Phil Plait in Slate.

Distant image of Pluto by New Horizons. Credit: NASA/Johns Hopkins APL/Southwest Research Institute.

Distant image of Pluto by New Horizons. Credit: NASA/Johns Hopkins APL/Southwest Research Institute.

A couple ago, leaders in planetary astronomy highlighted the importance of Dawn and New Horizons in their Decadal Survey. I think both space missions will turn out to be worthwhile, and let’s stay tuned to see what they discover over the next few months.

New Science at the American Astronomical Society Meeting

I’d just like to summarize some of the exciting new scientific results presented at the American Astronomical Society meeting in Seattle last month. I think it will be interesting to those of you science lovers who’re wondering what all the hubbub was about and for you astronomers who weren’t able to make it.

This is my third and final post in a series about the AAS meeting. The first two dealt with science policy, and diversity and sustainability. As I mentioned in a previous post, I enjoyed attending as both a scientist and science writer, and I was happy to personally meet the journalists writing excellent stories about the meeting (some of which I’ve linked to below).

I’ll start with some special sessions and other sessions focused on interesting science that included results I hadn’t seen before, and then I’ll end with some interesting plenary talks given by great speakers. It was a busy meeting and many of the sessions ran in parallel, so it’s inevitable that I missed some things and that this summary is incomplete. (Plus, I’m usually drawn to the sessions about galaxies, dark matter, and cosmology, and I often miss the other ones.) If you know of interesting announcements or talks that I missed here, you’re welcome to comment on them below.

Sloan Digital Sky Survey (SDSS)

After 15 years of great science, it was exciting to see the SDSS have its final public data release—until SDSS-IV data eventually come out, that is. At the press conference, Michael Wood-Vasey gave an overview, Constance Rockosi spoke about the data release, Daniel Eisenstein spoke about the Baryon Oscillation Spectroscopic Survey (BOSS), Jian Ge spoke about the Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS), and Steven Majewski spoke about the APO Galactic Evolution Experiment (APOGEE). According to Rockosi, more than 6,000 papers have been published using publicly released SDSS data. The SDSS has observed tens of thousands of stars, hundreds of thousands of quasars, and millions of galaxies.

In addition, members of the BOSS collaboration presented (nearly) final results at a session dedicated to the survey. If you’re interested, check out this article I wrote about it for Universe Today. (Thanks to Nancy Atkinson for editing assistance.)

Distribution of galaxies in a slice of the BOSS survey. (Courtesy: SDSS-III)

Distribution of galaxies in a slice of the BOSS survey. (Courtesy: SDSS-III)

3D-HST

Researchers presented newly published results and interesting work-in-progress about the evolution of distant galaxies using spectroscopic data from the 3D-HST survey, which is led by Pieter van Dokkum (Yale Univ.) and Ivelina Momcheva (Carnegie Observatories), combined with imaging data from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS), taking advantage of instruments aboard the Hubble Space Telescope. The figure below shows the spectral features of tens of thousands of galaxies, which indicate star formation activity, active galactic nuclei activity, and stellar age. If you’re interested, I wrote an article about some of these results for Sky & Telescope. (Thanks to Monica Young for editing assistance.)

Spectral features of high-redshift galaxies. (Courtesy: Gabriel Brammer, 3D-HST)

Spectral features of high-redshift galaxies. (Courtesy: Gabriel Brammer, 3D-HST)

Andromeda Galaxy

In a session dedicated to Andromeda—known as M31 by astronomers—as well as in other related sessions, research scientists and Ph.D. students presented studies about the stars, globular clusters, molecular clouds, dust, structure, dynamics, surface brightness profile, and stellar halo of the galaxy. The continued interest in our fascinating neighbor is understandable; Andromeda’s only 2.5 million light-years away from our galaxy! Like our Milky Way, Andromeda is a spiral galaxy, and it’s the most massive galaxy in the Local Group.

Many of these AAS results came from the Panchromatic Hubble Andromeda Treasury (PHAT) Survey, which is led by Julianne Dalcanton (Univ. of Washington), who presented highlights in a press conference as well. Dalcanton and her colleagues released this PHAT panoramic image of the galaxy below, and it received well-deserved press attention, including in NBC and Sky & Telescope.

Map of Andromeda galaxy. (Courtesy: HST, PHAT)

Map of Andromeda galaxy. (Courtesy: HST, PHAT)

Exoplanets

Many people were understandably excited about extra-solar planets, or exoplanets, detected by scientists with NASA’s Kepler space telescope. Every day of the meeting included talks and posters about the masses, abundances, dynamics, compositions and other properties of exoplanets as well as those of stars and supernova remnants examined with Kepler. In addition, astronomers’ announcement that they now have more than 1,000 confirmed exoplanets with Kepler and follow-up observations garnered considerable media attention (including these articles in Nature, BBC, and New York Times). They have at least 3,000 more planet candidates, and they will surely identify many more as Kepler continues its mission through 2016.

Of course, astronomers seek to find as many as possible Earth-like planets in or near the habitable regions orbiting Sun-like stars (often referred to as the “Goldilocks” zone). When these are successfully identified, the next step is to characterize their properties and try to assess the likelihood of life forming on them. Astronomers have found at least eight Earth-size planets in the habitable zone, including two of the newly announced ones, Kepler-438b and Kepler-442b. They also released these cool old-school travel posters. If you have a space ship that can travel 500 light-years a reasonable time, you should check out 186f on your next vacation!

Kepler's alien planet travel posters. (Courtesy: NASA)

Kepler’s alien planet travel posters. (Courtesy: NASA)

“Pillars of Creation”

On the 25th anniversary of the launch of the Hubble Space Telescope, astronomers released new images of the iconic star-forming region in the Eagle Nebula in the Serpens Cauda constellation, known as the “pillars of creation.” Journalists at Slate, CBS, and elsewhere shared these amazing images. At first I thought not much science was done with them, but by combining observations at visible and infrared wavelengths, astronomers can investigate what’s happening with the cold gas clouds and dust grains and assess how rapidly new stars are forming and where. For more, you can also see Hubble’s press release, which coincided with the press conference on the first day of the meeting.

Image of "pillars of creation." (Courtesy: NASA and ESA)

Image of “pillars of creation.” (Courtesy: NASA and ESA)

Other Results

I saw many other interesting talks and posters at the meeting, but I don’t have the time/space to get into them here. On galaxies and the large-scale structure of the universe (which I’m interested in), I saw talks involving modeling and measurements with the Galaxy And Mass Assembly (GAMA) survey, the Six-degree Field Galaxy Survey (6dF), and I presented research using the PRIsm MUlti-object Survey (PRIMUS). But the SDSS dominated the field.

In addition, Joss Bland-Hawthorn, Sarah Martell, and Dan Zucker presented some impressive early science results from the GALactic Archaeology with HERMES (GALAH) survey of the Milky Way, which uses an instrument with the Anglo-Australian Telescope. (GALAH is named after an Australian bird.) Astronomers combine GALAH observations with astrometry from Gaia and over the survey’s duration will produce detailed data for 1 million stars in our galaxy! In particular, they utilize a technique called “chemical tagging” to study the abundances of at least 15 chemical elements for each star, allowing for studies of stellar dynamics and merger events from infalling “satellite” galaxies. I look forward to seeing more results as they continue to take data and analyze them; their first public data release is planned for 2016.

PLENARY SESSIONS

I’ll briefly describe a couple of the plenary talks below, but I missed a few others that sounded like they could be interesting, including “The Discovery of High Energy Astrophysical Neutrinos” (Kara Hoffman); “Gaia – ESA’s Galactic Census Mission” (Gerry Gilmore); and “The Interactions of Exoplanets with their Parent Stars” (Katja Poppenhaeger).

Also, Paul Weissman (JPL/Caltech) gave an overview of the Rosetta mission and the comet C-G/67P, and Al Wootten (NRAO) gave an overview of many recent science papers using the Atacama Large Millimeter Array (ALMA). Rosetta and its lander Philae has run a few experiments already, and scientists with the mission have found that the bulk density of the nucleus is less than half the density of water ice and that its D/H ratio is different than the abundance ratio of the Earth’s oceans. More recently, Rosetta detected a crack in the “neck” of the comet, and they’ve abandoned an idea for a close flyby search for the lost lander, which might wake up in a few months when it receives more solar power. And if you’re interested in ALMA science, such as involving the gas kinematics of protostars and protoplanetary disks and the gas and dust clouds of distant galaxies, watch for proceedings from their recent Tokyo meeting, which are due to be published next month.

Cosmology Results from Planck

Martin White (UC Berkeley) gave an excellent talk about cosmological results from the Planck telescope, which he described as having the “weight of a heavy hippo and the height of a small giraffe.” Based on analyses of the power spectrum of the cosmic microwave background (CMB) radiation, so far it seems that the standard model of cold dark matter plus a cosmological constant (ΛCDM) is still a very good fit. Scientists in the collaboration are obtaining tighter constraints than before, and the universe still appears very flat (no curvature). They are planning a second data release this year, including more simulations to assess systematic uncertainties and more precise gravitational lensing measurements. White ended by saying, “I can explain to you what really well, but I can’t tell you why at all.”

White also hinted at, but didn’t reveal anything about, the joint analysis by Planck and BICEP2 astrophysicists. That analysis was completed recently, and now it seems that the detected polarization signal might be at best a mixture of primordial gravitational waves produced by inflation and of Milky Way dust, and they’ve obtained only an upper limit on the tensor-to-scalar ratio. Check out my recent article in Universe Today about this controversy.

Courtesy: ESA

Courtesy: ESA

Inflation and Parallel Universes

Max Tegmark (MIT) has talked and written about both inflation and the multiverse for many years, such as in a 2003 cover article and a recent blog post for Scientific American and in his book, “Our Mathematical Universe.” From the way he presented the talk, it was clear that he has discussed and debated these issues many times before.

Tegmark began by explaining models of inflation. According to inflation, the universe expanded for a brief period at an exponential rate 10-36 seconds after the Big Bang, and the theory could explain why the universe appears to have no overall curvature, why it approximately appears the same in all directions, and why it has structures of galaxies in it. In one entertaining slide, he even compared the expansion rate of a universe to that of a fetus and baby, but then he said, “if the baby kept expanding at that rate, you’d have a very unhappy mommy.”

Expansion rates of a baby (human) and a baby universe

Expansion rates of a baby (human) and a baby universe

He subtitled his talk, “Science or Science Fiction?”, and that question certainly came up. Tegmark argued that inflation seems to imply at least some levels of a multiverse (see his slide below), which makes many astrophysicists (including me) nervous and skeptical, partly because parallel universes aren’t exactly testable predictions. But he made the point that some general relativity predictions, such as about what happens in the center of a black hole, aren’t testable yet we accept that theory today. He discussed “modus ponens” arguments: once we accept “if p then q,” then if p is asserted, we must accept q, whether we like it or not. In other words, if inflation generally predicts parallel universes and if we accept inflationary theory, then we must accept its implications about parallel universes. This is an important issue, and it’s another reason why BICEP2 and Planck scientists are trying to resolve the controversy about polarization in the CMB.

Predictions of different levels of the multiverse.

Predictions of different levels of the multiverse.

The Dark and Light Side of Galaxy Formation

Finally, in another interesting talk, Piero Madau (UC Santa Cruz), who was recently awarded the Heineman Prize for Astrophysics, spoke about galaxy formation and dark matter. In particular, he spoke about difficulties and problems astrophysicists have encountered while attempting to model and simulate galaxies forming while assuming a cold dark matter (CDM) universe. For example, he described: the cusp-core controversy about the inner profiles of dark matter clumps and galaxy groups; the problem of angular momentum, which is conserved by dark matter but not gas and stars; the missing satellites problem, in which more simulated dark matter subclumps (“subhaloes”) than observed satellite galaxies are found; and the “too-big-to-fail” problem, such that simulated subhaloes are much more dense than the galaxies we see around the Milky Way. These problems motivated astrophysicists to rethink assumptions about how galaxies form and to consider warm or self-interacting dark matter.

Madau ended by saying that evidence that the universe conforms to expectations of the CDM model is “compelling but not definitive,” and warm dark matter remains a possibility. Considering all of the exciting work being done in this field, this could be “the DM decade”…but then he said people have been talking of a DM decade for the past thirty years.

Comet Update! Rosetta’s Philae landed, but not as planned

Now here’s what you’ve been waiting for! You really need more comet, like Christopher Walken/Bruce Dickinson needs more cowbell, so here you go…

In a blog post few months ago, I told you about the European Space Agency’s (ESA’s) Rosetta mission. Nine years after its launch and after four gravity assists, Rosetta reached the comet 67P/Churyumov-Gerasimenko and began to orbit it. On 11th November, Rosetta maneuvered its position and trajectory to eject its washing machine-sized lander, Philae, which sallied forth and landed on the comet the next day, and MADE HISTORY! (Wired‘s apt headline, “Holy Shit We Landed a Spacecraft on a Comet,” beat The Onion, which is known for that sort of thing.) Its landing was confirmed at ESA’s Space Operations Centre in Darmstadt, Germany at 17:03 CET that day.

Lander_departure

Above you can see Philae on its fateful journey, and below you can see its first image of the comet, both courtesy of ESA. The landing happened to take place while friends of mine were at a Division of Planetary Sciences meeting in Tucson, Arizona, and we and others discussed the Philae landing at Friday’s Weekly Space Hangout with Universe Today. And if you’re interested in more information than what I’ve written here, then check out the ESA Rosetta blog and posts by Emily Lakdawalla, Matthew Francis, and Phil Plait.

First_comet_panoramic_node_full_image_2

From what we can tell, Philae did initially touch down in its predicted landing ellipse (its planned landing zone) but its harpoons—which were supposed to latch onto the surface—failed to fire, and it bounced! Considering how small the comet is and how weak its gravitational force (about 100,000 weaker than on the Earth), this could have been the end as the lander could then have floated away, never to be seen again. However, after nearly two hours, it landed again…and bounced again, and a few minutes later finally settled on the surface and dug in its ice screws, about 1 km from its intended landing spot on a comet 4 km in diameter. (This would be like trying to land a plane in Honolulu and ending up on another island—it’s unfortunate but at least you didn’t drown.)

ESA_Rosetta_OSIRIS_FirstTouchdown-1024x702

At first, it wasn’t clear exactly where Philae actually was; it could have dropped into a crater where it would be nearly impossible to find. But then based on images from the OSIRIS camera and NavCam (navigational camera) on Rosetta, ESA scientists were finally able to locate it a couple days ago. The mosaicked images above came from the OSIRIS Team, and the NavCam image below as annotated by Emily Lakdawalla, to give the larger-scale context. After its last bounce, Philae rotated and headed “east”, finally becoming settled among dust-covered ice at the bottom of a shadowed cliff. It’s not an ideal position but at least it’s not totally precarious. (They considered securing the position with the harpoons, but the momentum from firing them could push the lander back up into space, which would be “highly embarrassing” according to Stephan Ulamec, head of the lander team.)

20141117_Comet_on_14_September_2014_-_NavCam_annotated_postlanding_f840

But the cliff situation is a problem. Philae’s battery had a little more than two days of juice in it, and once that ran out, it would be dependent on its solar panels. However, Philae’s current position only receives about 1.5 hours of light per 12-hour rotation of the comet, much less than hoped. Philae did attempt to run some of its experiments and activities during the time allotted, the battery ran late on Friday. This was @Philae2014’s last tweet: “My #lifeonacomet has just begun @ESA_Rosetta. I’ll tell you more about my new home, comet #67P soon… zzzzz #CometLanding”

Before Philae dreamt of electric sheep, it managed to collect some data using instruments on board. (See this Nature news article.) For example, Philae deployed its drilling system (SD2) as planned, in order to deliver samples to the COSAC and Ptolemy instruments, which probe organic molecules and water (and which I described in my previous Rosetta post). But ESA scientists don’t know how much material SD2 actually delivered to the lander; if the ground is very dense, it’s possible that since Philae isn’t totally anchored, it could have moved the lander rather than drilling into the surface. We do know for sure that some instruments operated successfully, such as the downward-looking ROLIS camera and ROMAP, the magnetic field mapping system.

In any case, scientists have obtained some data already while other data stuck on the snoozing lander will be retrieved later. In the meantime, Rosetta is keeping busy and continues to take observations. Philae has already been a success, and who knowsmaybe it will “wake up” when its solar panels absorb enough sunlight to recharge the batteries.

[Note that the NavCam images we’ve seen so far are pretty good, but I have heard that Rosetta scientists have much better resolution color images that are embargoed and won’t be released for six months. I haven’t confirmed this fact yet, so if you have more up-to-date info, please let me know.]

Finally, I’ll end with some comments about what some people are referring to as #shirtstorm or #shirtgate. (For more info, see this Guardian article and this blog post and this one.) On the day of the worldwide live-stream broadcast last week, Matt Taylor, the Rosetta Project Scientist, wore a shirt covered with scantily clad women. I get the impression that Taylor is a cool guy and wants to get away from the scientist stereotypes people have, but this is completely inappropriate. (And he’s worn this shirt to work before. Apparently none of his colleagues told him to leave it at home.) But it’s not just the shirt; during the middle of his broadcast, Taylor referred to Rosetta as the “sexiest” mission. “She’s sexy, but I never said she was easy.”

b288d9a2-6fc6-4f6c-b143-09bc706bfaa0-620x372

We debated many aspects of this on astronomers’ official and unofficial social media, and for the most part, our community is very unhappy about this. You may say that we should focus on the science, and who cares about what this scientist wears or says when he’s excited about his mission’s success. But we have been working really hard to increase diversity in STEM fields and to achieve gender equality in science. Many aspects to working in the current scientific establishment are not particularly welcoming to women, and Matt Taylor’s shirt and poor choice of words are part of the problem. A few days later, Taylor made a heartfelt apology. As far as I know, ESA itself has not issued an official apology yet. The American Astronomical Society made a statement today (Wednesday) that “We wish to express our support for members of the community who rightly brought this issue to the fore, and we condemn the unreasonable attacks they experienced as a result, which caused deep distress in our community. We do appreciate the scientist’s sincere and unqualified apology.”

In any case, our focus is on the science and on this amazing scientific achievement. But Science is for everyone.

A Bad Week for Commercial Spaceflight

The US commercial space industry did not fare well last week. Two accidents on 28th and 31st October highlight the risks, costs, and difficulties of spaceflight—as well as pointing to potential setbacks for commercial spaceflight. (If you’re interested, other news outlets have commented on these issues as well, such as here and here and here.) Pardon the self-promotion, but you can check out our discussion with Ken Kremer on a Weekly Space Hangout with Universe Today on the 31st for more information.

Orbital Sciences’ Antares rocket

First, on Tuesday (the 28th), an unmanned 13-story rocket designed by Orbital Sciences Corp. exploded a few seconds after liftoff off the coast of Virginia at NASA’s Wallops Flight Facility. It carried a Cygnus capsule with more than 5,000 pounds (2,300 kg) of hundreds of millions of dollars of supplies and equipment, as well as school students’ science experiments. It was bound for the International Space Station (ISS) and was the first time a resupply mission contracted by NASA to a private company failed. Fortunately, no one was hurt. Though the flight facility is designed to handle explosion and fire, there was significant damage to the launch infrastructure.

Journalists were pretty close to the launch zone, and this video (tweeted by Pamela Gay) shows the launch, explosion, and fleeing from the potentially dangerous area (see also videos at LA Times):

It will take time to recover from this. And we will have to see how much this damages Orbital Science Corp.’s reputation and NASA’s efforts to outsource orbital flights. Four previous Antares flights, including three to the station, had launched successfully, and five resupply flights remain in the company’s multi-billion dollar contract, the next one being scheduled for April. This likely will be delayed though, and according to Orbital’s press release, they will implement a propulsion system upgrade previously planned for 2016. The loss of this supply vessel doesn’t pose an immediate problem for the ISS’s crew, which includes two from NASA, one from the European Space Agency (ESA), and three Russians. The second US supply line to the ISS is with Space Exploration Technologies (SpaceX), which has its next launch planned for 9th December. Although the ISS crew and their missions are not in any danger, this loss significantly affects Orbital Sciences, and more work and investment will be needed to proceed.

NASA held a press conference the same day as the accident, and their investigation into the cause(s) of the explosion and failed launch continues. These space-bound rockets have many components—many things that could go wrong—and there is considerable debris to examine, so it could take awhile. It’s not clear whether extra weight and length were factors in the accident, for example. A turbopump-related failure in one of the two Aerojet Rocketdyne AJ26 stage-one engines might have been the culprit. These liquid oxygen and kerosene fueled engines, produced during the Soviet era in Russia (with modifications), likely will be discontinued in future Antares rockets.

Virgin Galactic’s SpaceShipTwo

And now for Act Two. Virgin Galactic’s SpaceShipTwo, part of a commercial space program founded by Richard Branson, suffered an “in-flight anomaly” on Halloween. It crashed midflight during testing and broke into several pieces over the Mojave Desert (north of Los Angeles, for you non-Californians). One pilot (Michael Alsbury) was killed and was unfortunately still strapped to his seat in the wreckage. The other pilot (Peter Siebold) successfully ejected at an altitude of around 50,000 feet and deployed his parachute. He was airlifted to a hospital and treated for injuries.

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After successful programs like Mercury, Gemini, and Apollo, NASA has been attempting to privatize spaceflight and redefine its missions partly because of tighter budgets over the past couple decades. According to the NY Times and Lori Garver (former deputy administrator at NASA), public funds should be focused on activities that advance technology and provide public benefits to all, like planetary science. At the same time, Garver said, the government should encourage private companies to move ahead and find innovative ways of reducing costs.

The National Transportation Safety Board (NTSB) held a press conference last Sunday with more details. A new fuel was being tested on this flight, which may or may not have been an issue, and a “feathering mechanism” might have been deployed prematurely on the spacecraft, when it was traveling beyond the speed of sound. But the investigation is still in progress, and I’ll give you more details in the near future. In any case, our thoughts are with the pilots and their families.

So what does the future hold? I’m not sure, but it looks like Orbital Sciences (and SpaceX) and Virgin Galactic will continue their spaceflight programs, as they should. Both of these accidents are unfortunate and costly—to say the least—but they should not deter us from space exploration. We have much to gain from continuing these programs. At the same time, I think we should be careful about outsourcing too much; I believe that our best prospects lie with continuing to invest funding, resources, and personnel in NASA, ESA, and other space agencies, where our scientific expertise and oversight are the greatest, and where short-term setbacks are less likely to affect our long-term objectives or derail whole exploration programs.