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.

Happy Birthday to Vera Rubin, Discoverer of Dark Matter

Peering through their powerful telescopes, scientists observe a stunningly diverse array of phenomena, including comets, planets, stars, gaseous nebulae, novae, quasars, galaxies, and numerous other exciting things. But astrophysicists argue that these light-emitting objects only amount to a tiny fraction of the universe. According to the latest measurements from the European Space Agency’s Planck telescope earlier this year, they account for less than 5% of the universe’s matter and energy, while mysterious-sounding “dark matter” accounts for nearly six times as much. Nevertheless, dark matter cannot be seen and does not interact with normal matter, so how did astronomers figure out that so much invisible, intangible stuff exists out there?

Vera Rubin measuring spectra, circa 1970. (Credit: American Institute of Physics)

Vera Rubin measuring spectra, circa 1970. (Credit: American Institute of Physics)

As I recently wrote in a post for the International Year of Light, the story of scientists’ discovery and exploration of dark matter began many decades ago. Physicists had long utilized Newton’s and Einstein’s gravitational laws to estimate our sun’s mass by measuring planets’ distances from it and examining how fast they travel around it. For example, Mercury is very close to the sun and orbits it much faster than Pluto, which takes 248 Earth-years to complete an orbit. (If you’re wondering, the sun has a mass larger than a trillion billion billion kilograms. That’s a lot!) Similarly, it turns out that one can make such calculations for stars within galaxies and infer the enclosed mass, but the results of the analysis are not so simple to understand.

Detailed image of the Andromeda Galaxy, recently surveyed by the Panchromatic Hubble Andromeda Treasury
. (Credit: NASA, ESA, J. Dalcanton et al.)

Detailed image of the Andromeda Galaxy, recently surveyed by the Panchromatic Hubble Andromeda Treasury
. (Credit: NASA, ESA, J. Dalcanton et al.)

In the 1960s and 1970s, American astronomer Vera Rubin measured and analyzed the precise velocities of stars in spiral galaxies and came to a startling conclusion. Most stars at outer radii orbit the center at surprisingly large speeds, much faster than they should be based on the mass of the stars themselves, but the galaxies do not tear themselves apart or fling their stars hurtling away. Studying galaxies, such as Andromeda, as a whole, she found that they rotate too quickly for their stars’ gravity to keep them intact. It was as if the galaxies contain and are surrounded by much more unseen dark matter, which gravitationally binds the galaxies together. Rubin’s crucial discovery has not yet received the recognition it deserves.

This critically important area of research came to be known as galaxy “rotation curves,” in which Rubin became an influential figure. Rotation curve measurements of spiral galaxies from two of her many highly-cited publications appear in the reference, Galactic Astronomy, which every respectable astrophysicist has on their bookshelf. Her measurements from hundreds of galaxies constitute strong evidence for the existence of massive clumps of dark matter extending to many thousands of light-years beyond the edge of the galaxies themselves. Astrophysicists also considered the alternative hypothesis that Newton’s gravitational laws need to be modified for objects separated by large distances, but that approach has been less successful and lacks support among the community.

Rotation curves of three spiral galaxies of varying brightness, adapted from an influential 1985 paper by Rubin. (Credit: Binney & Merrifield, "Galactic Astronomy," Princeton, 1998.)

Rotation curves of three spiral galaxies of varying brightness, adapted from an influential 1985 paper by Rubin. (Credit: Binney & Merrifield, “Galactic Astronomy,” Princeton, 1998.)

Vera Rubin turns 87 years old today. She continues her work at the Department of Terrestrial Magnetism at the Carnegie Institution of Washington, and she still publishes research in galactic astronomy. In addition, she writes popularly such as in Scientific American and Physics Today. Moreover, she inspires, supports, and encourages young people, especially women, in science. This includes her four children, all of whom have earned Ph.D. degrees in the natural sciences or mathematics.

In 1965, Vera Rubin was the first woman permitted to observe at Palomar Observatory. When she applied to graduate schools, she was told that “Princeton does not accept women” in the astronomy program; she went to Cornell instead. As she put it in a recent astronomical memoir, “Women generally required more luck and perseverance than men did.” In her 1996 book, Bright Galaxies, Dark Matters, she wrote

Since the 1950s, opportunities for women in astronomy have increased, but serious problems have not disappeared…The saddest part, of course, is that only about one-fifth of the women who enter college intend to study science. Lack of support and encouragement at an early age has by then taken its toll. A young woman who enters graduate school to study science is a rare creature indeed…but the colleges are often a part of the problem rather than part of the solution.

Now with many years of hard work and persistence, people are making gradual progress. For example, Meg Urry leads the American Astronomical Society, France Córdova is the director of the National Science Foundation, and Marcia McNutt now heads the National Academy of sciences. But much more work needs to be done to reduce gender inequality and underrepresentation throughout science research and education.

Many people argue that Vera Rubin would be a strong contender for a Nobel Prize in Physics, and I join that call. She has already won many other awards, including the National Medal of Science, but the Nobel would officially recognize her enormous contributions to astrophysics and her critical role in illuminating the way to dark matter. Considering that the 2011 Nobel Prize went to Saul Perlmutter, Brian Schmidt, and Adam Riess for discovering dark energy, it’s time for dark matter to have its day.

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).]

How Does Pope Francis’s Encyclical Affect the Climate Change Debate?

In a bold and surprising move, Pope Francis waded into the global climate change debate last month. He did not mince words or make a few minor remarks about these contentious issues; he wrote a lengthy and widely circulated encyclical discussing the “gravity of the ecological crisis.” Even before the official document, Laudato Si, came out, the Italian magazine L’Espresso leaked a draft of it (and it’s been translated into English; Wired wrote a good summary), generating considerable media attention, applause from environmental organizations, and criticism from climate-denying religious conservatives. Throughout the document, the Pope unequivocally calls for major lifestyle, economic and societal changes while condemning the “exploitation of the planet” and “excessive consumption” of energy and water especially by “wealthier sectors of society.”

Pope Francis at the Vatican, 17 June 2015 (Reuters)

Pope Francis at the Vatican, 17 June 2015 (Reuters)

While this did not come completely out of the blue—Francis has spoken about environmental stewardship, sustainability, and solidarity in the past and he describes environmental degradation in theological language—the Pope’s strong words and detailed discussion of wide-ranging issues from agriculture to biodiversity to economic liberalism surprised some. The “gravity of the ecological crisis” has clearly concerned him for some time, and he felt it was important to take a stand as the leader of the world’s Catholics.

What implications can we draw from these developments? Firstly, it increases pressure on political officials preparing for the UN climate talks in Paris in December to develop ambitious binding commitments. China and India have yet to submit their proposed commitments, and the US’s (except for California’s) commitments remain weak. “I applaud the forthright climate statement of Pope Francis, currently our most visible champion for mitigating climate change, and lament the vacuum in political leadership in the United States,” says Marcia McNutt, editor-in-chief of Science journals. According to some climate scientists, current pledges by 36 countries insufficiently cut carbon emissions: they will only delay dangerous global warming (2 degrees C above pre-industrial levels) by two years. In addition, some governments of countries with large Catholic populations, such as Brazil, now have cover to take stronger action.

Secondly, the Pope has weighed in and entered the domain of science. He may not be a scientist but he has clearly done his homework. He recognizes that the problems of climate change involve scientific analysis and assessments, but science plays just one part in a global conversation involving social, economic, and political issues as well. This pressing problem is not only a scientific one, and its solutions will not be either.

US conservatives have adopted the refrain, “I am not a scientist,” as a cop-out to cast doubt on climate change and avoid taking action. But no more. The fact that the Pope—an important figure in an inherently conservative position—has now taken an unambiguous stance on human-caused climate change and the need for a global response, shows that conservative climate deniers are out of touch and should concede that it is time to work together to face this challenge. As much as 25% of US evangelicals approve of the pope but deny the science; I hope that they will listen to him and consider changing their minds.

Fourthly, Pope Francis remains very conservative on population issues such as contraception and birth control. In his encyclical, he avoided these issues as part of the solution, even though overpopulation will continue to strain the planet’s resources and will result in increased energy consumption. However, in my opinion, too many people focus too much on population, perhaps because it’s an explanation that makes sense: since the time of Thomas Malthus, many assumed that if N people consume x, then if the population grows to a larger N, more will be consumed. But the problem is more complex than this. Focusing on places with growing populations puts the burden on the world’s poor, while rich countries are primarily responsible for the bulk of carbon emissions. Moreover, with a fairer distribution of wealth and increased access to education and employment, population growth will likely decrease, but if billions were to consume like Americans, the planet would not have long to survive. A focus on consumption and emissions per capita is warranted and puts the responsibility where it belongs.

Finally, as before, Pope Francis made strong statements about economic inequality, social justice, excessive consumerism among the rich, and solidarity with the poor. After all, he chose his name after Saint Francis of Assisi, “the man of the poor.” According to Bill McKibben, environmentalist and co-founder of 350.org, environmental degradation is leading to climate change that is harming the poor. “The people who have done the least to cause this suffer the most.”

We may not agree with everything the pope says or writes, but he has begun a dialogue between religion and science. “Any technical solution which science claims to offer will be powerless to solve the serious problems of our world if humanity loses its compass, if we lose sight of the great motivations which make it possible for us to live in harmony, to make sacrifices and to treat others well.” As Francis eloquently put it, humanity must maintain its moral compass, and we all—believers and nonbelievers alike—need to find a way to bridge our differences and take action now to protect our planet and its inhabitants.