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Deeper Into the Golden Age

The golden age of exoplanets? I’ve often described our time as such, referring to the fact that we’re finding planets at such a fast clip and learning so quickly about the wide range of planetary systems out there, including those with ‘hot Jupiters’ and ‘super-Earths.’ But the next step in the discovery process is a bit murkier. If we’re learning how exoplanets are distributed — and even with a hobbled Kepler, we still have a great deal of data still to be analyzed — we’re not yet ready to take the spectra of exoplanet atmospheres on conceivably habitable worlds.

This is important, because light scattering off an atmosphere bears the signature of things like water vapor, oxygen, methane and carbon dioxide, the right combination of which could signal life. And just as Kepler is useful at developing a statistical read on the distribution of smaller planets, so we’ll want to have a way to measure the frequency of worlds that actually do bear life. It’s a problem Lee Billings notes in How We Could Find Alien Life Soon — and Why We Probably Won’t, an essay in Nautilus. After touching on the technologies of spectrum gathering, Lee says this:

The bigger, more fundamental problem is that obtaining the spectrum from just one potentially habitable exoplanet is unlikely to be enough; satisfying our search for life, gaining some inkling of our cosmic context, will probably require surveying hundreds or thousands of worlds in the relatively short timespan of one space-telescope mission. To quickly, efficiently perform such a search requires one or more very large, very sophisticated starlight-suppressing space telescopes—telescopes that currently have no funding and very little public awareness.

Billings’ take is that a fully developed space telescope capable of taking atmospheric spectra of Earth-like worlds would cost in the range of $5 billion, a step up from the $600 million Kepler and higher than the $3.6 billion Cassini. He’s quick to point out that the cost is substantially lower than Americans pay per year for chocolate candy — Neil deGrasse Tyson makes this same point using lip balm as a cost per year comparison to the Cassini orbiter. And even though I think Lee’s $5 billion figure is optimistically low, it’s hard to deny his point: Finding life signatures on habitable zone planets is within our grasp if we have the will to make it happen.

Kopie von 1594_Orbis_Plancius2

Image: Orbis Terrarum, a world map published by the Dutch astronomer, cartographer and clergyman Petrus Plancius in 1594, charting a century of European exploration. Filling in the gaps in maps like this took centuries. How long will it be before we begin building a cartography of terrestrial worlds around other stars?

For his part, Seth Shostak calls this enterprise, and Kepler in particular, “the most exciting research experiment going.” In How Ordinary Are We?, Shostak runs through the current woes, centering on the failure of a reaction wheel used to point the telescope. A command sequence to torque the wheels may eventually clear the material causing the friction, or perhaps not. But with two years of Kepler data still in the pipeline, we’re going to get an important read on the fraction of Sun-like stars that have Earth-sized planets in the habitable zone no matter what.

Fix the reaction wheel and another year of data gathering could occur. But without it, we still get an answer, although one, as the SETI Institute’s Jon Jenkins tells Shostak, with slightly larger error bars. Both results may well act as a spur to public interest in the question of what we do next, relating the statistical Kepler findings to the stars closer to our own Sun. Missions like TESS (Transiting Exoplanet Survey Satellite) will help us find some of these potentially habitable worlds, but until we have spectral information about their atmospheres, we’ll be left to wonder the age-old question of Earth’s place in the cosmos and the frequency of life elsewhere.

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  • Alex Tolley June 5, 2013, 13:11

    $5bn seems very little. Yet it will have to compete with other, possibly much more important projects, like $2tn in US infrastructure repairs. That $5bn is more than half of the NSF budget or less than a quarter of Nasa’s. Imagine the howls of scientists if that $5n was expropriated from one of those two budgets, even at $0.5bn pa over 10 years.

    But the sad fact is, we spend a pitifully small amount of the federal budget on science. Yet we seem quite happy to maintain a vast military capability and fight unnecessary and costly wars.

    A quick BOE calculation suggestion that the $0.5bn in annual program costs could be met with well under $10 extra taxes from the median US family. The knowledge and worldview changes that could elicit, night well be worth that cost.

  • Ariff June 5, 2013, 13:33

    Would it be possible to use a fleet of smaller space telescopes, such as the Arkyd or something derived or similar, to replace a single larger telescope? I would think that in this case the big issue would be the starlight suppression system. Do you kniw what the other benefits or drawbacks of this would be? It seems like it would allow much more flexibility and the ability to replace individual parts of the fleet as they fail rather than potentially losing an entire larger telescope. Since the Arkyd 200 will have an engine, I believe, there’s also the potential to put them around the sun which would give a very large effective diameter. It would certainly collect less light though. Is it something that would be effective then? It seems like an especially relevant question, since it’s entirely possilbe that there could be an array of telescopes out there soon. If they have downtime, maybe someone could rent the fleet to use for observations while it’s not busy doing other things.

  • Paul W June 5, 2013, 15:13

    I have frequently read that the only reason we know much anything about astronomy in general is the result of spectroscopy. So it’s hardly surprising that that will continue into the era of exo-planets.
    BTW, how much is the James Webb costing? Last I heard that one is still being funded, though it’s not an exo-planet finder.
    The problems with Kepler highlight the danger of putting a very expensive and high science value scope out “there” where we can’t work on it. One only has to reflect that, without servicing, the Hubble would have been DOA in orbit. Kepler is still good, except it can’t be pointed. Just imagine what could have eventually come from Kepler if the robot arm could snag it and place it in the shuttle cargo bay while the dudes with wrenches replaced those wheels, and other worn parts. Webb makes me shiver to think what might happen if/when something on it breaks.
    Without a space ship, even low earth orbit can’t be a safe place. Without a space ship, we might as well keep putting telescopes on the high mesas and hope for advances in adaptive optics.
    I suggest, build a moon capable vehicle and put the scopes there. Now the scope is anchored! That crater at the lunar south pole provides cryogenic conditions for the gathering of the faintest light. No starships required, no longtime missions. The moon has the smallest gravity well. Some private entrepreneurs will probably have to do it, the government is hopeless and everybody has their hand out.

  • William Patrick Haines June 5, 2013, 18:22

    There were some uncertainties about some stellar mass observed by Kepler thus brining into question the ratio to stellar mass versus planet size . However it should not by no means eliminate all Earth size planets in the habitable zone !
    http://news.discovery.com/space/alien-life-exoplanets/kepler-stars-and-planets-bigger-than-thought-130605.htm

  • Joy June 5, 2013, 19:03

    Big flagship space telescopes cost on the order of their contemporary aircraft carriers. From Wikipedia regarding the next big boat:

    “Construction began on components of CVN-78 in the spring of 2007,[32] and is planned to finish in 2015. It is under construction at Newport News Shipbuilding, a division of Huntington Ingalls Industries (formerly Northrop Grumman Shipbuilding) in Newport News, Virginia, the only shipyard in the United States capable of building nuclear-powered aircraft carriers. In 2005, it was estimated to cost at least $8 billion excluding the $5 billion spent on research and development (though that was not expected to be representative of the cost of future members of the class).[12] A 2009 report said that the Ford would cost $14 billion including research and development, and the actual cost of the carrier itself would be $9 billion.[33] The daily operating cost is estimated at $7 million.”

    From this perspective $5 billion in current federal reserve units is rather optimistic. Triple that cost is more likely. However, the US finds a way to keep 10 aircraft carriers in service plus 2 in reserve and 2 under construction, so the telescope is possible if the rulers wanted one. Of note the first tranche of the TARP bank bailout in 2008 was for a blank check for $700 billion, no questions asked.

  • Joy June 5, 2013, 19:45

    As for the history of Hubble, in 1968, NASA developed firm plans for a space-based reflecting telescope with a mirror 3 m in diameter, with a launch slated for 1979 (an optimistic 11 year development time). As we know, Hubble shrunk to 2.4 meter and didn’t launch until 1990 – a 22 year wait made worse by a flawed mirror.

    More background. The JWST program started in 1996 with a target of a 2007 launch (that hopeful 11 year development time again). Now we are looking at a 2018 launch and costs have been capped (for now) at $ 8 billion. If it does launch in 2018 that would be a 22 year development program (22 yrs again – NASA is nothing if not consistent) and aircraft carrier cost.

    Suppose a miracle happens and astronomers and NASA can agree on a plan and design for a space telescope to take spectra of exo Earths by 2015. Such a beast might then launch in 2037. I hope this does happen, but I am not confident of living to see it.

  • David Cummings June 5, 2013, 19:58

    Paul W, I like your idea of a telescope on the moon. What a perfect way to make our presence on the moon permanent and practical. Even if our presence consists entirely of our robots doing the construction and repairs. It will still be us up there. Right now we have nothing on the moon… and that’s a shame.

  • Sedjak June 5, 2013, 21:20

    China has just built the worlds fastest supercomputer at 55 Petaflops, leapfrogging the Oak Ridge Titan at 17.6 Petaflops.
    http://nextbigfuture.com/2013/06/china-tianhe-2-supercomputer-based-on.html
    So, on many fronts we have sort of a horse race with the Chinese like defense and space. Perhaps characterizing the first nearby habitable world (or perhaps inhabited world) will capture the public’s attention and be like the new moon race.

  • Alex Tolley June 6, 2013, 9:43

    Given Joy is correct about the time and cost overruns, and assuming the US will continue with existing policies, is there a better way to achieve the goals of the mission?

  • ljk June 6, 2013, 10:32

    David Cummings said on June 5, 2013 at 19:58:

    “Paul W, I like your idea of a telescope on the moon. What a perfect way to make our presence on the moon permanent and practical. Even if our presence consists entirely of our robots doing the construction and repairs. It will still be us up there. Right now we have nothing on the moon… and that’s a shame.”

    There is a serious issue with dust on the Moon, which the Apollo astronauts can tell you gets into everything and its gritty, basaltic-based nature could cause lots of damage, especially to sensitive astronomical instruments. No Apollo mission stayed on the lunar surface longer than three Earth days, so what might happen to machinery and people exposed to this dust for long periods of time is a currently unknown factor. Think coal miners and the effects of breathing in coal dust on their lungs.

    There were also reports from the Lunakhod rovers that a nighttime glow from elevated dust prevails on the Moon after dark, making the lunar night skies potentially less dark than presumed. Will this affect optical observations?

    Who or what is going to keep the dust out and away from these telescopes? Who or what will maintain them on a regular basis? Will spending fourteen Earth days in daytime temperatures above the boiling point of water and then fourteen more consecutive Earth days of nighttime temperatures below minus 200 degrees F. prematurely end the telescopes’ lifetimes? Or at the least warp the optics and damage the electronics?

    NASA’s administrator recently announced that the agency has no plans to go back to the Moon any time soon. Other spacefaring nations or corporations may therefore attempt to place telescopes on our celestial neighbor.

    However, again, the issues I raise above will still apply. If we cannot get a mission robotic or human to fix a satellite in high Earth orbit like Kepler at the moment (and the JWST?), how will reaching the Moon be any less difficult?

  • James D. Stilwell June 7, 2013, 9:03

    Joys comments yesterday have been saved should anyone need a refresher course in R&D: the first duty of the research scientist is to become indispensible to a politician with clout. That way the long distance runners among you can survive the 22 year program run….

  • Eniac June 7, 2013, 19:56

    Good comments by LJK on problems with telescopes on the moon. Add to that: gravity. A real nuisance when operating large mirrors.

    Deep space is the optimal location for telescopes, by almost all measures.

  • coolstar June 8, 2013, 20:24

    Yes, the problem with telescopes on the moon is that you have to get there SLOWLY! If you are going back anyway, then you should certainly bring even a small telescope along, since your landing is for free. I’ve long thought of proposing to the Lunar X prize folks that they should think of taking a MOST sized instrument with them, or making one of their required cameras dual purpose. If designed in from the start, it needn’t add much complexity or cost to such a lander. The moon’s slow rotation means a lot of good science on “bright” targets could be done without tracking or guiding even.

  • ljk June 12, 2013, 15:31

    12 June 2013

    ** Contacts are listed below. **

    Text & Images:

    http://www.nao.ac.jp/en/news/science/2013/20130612-oao-gj3470b.html

    SUNNY SUPER-EARTH?

    A research team led by Akihiko Fukui (NAOJ), Norio Narita (NAOJ), and Kenji Kuroda (University of Tokyo) observed the atmosphere of super-Earth “GJ 3470b” in Cancer for the first time in the world using two telescopes at OAO (Okayama Astrophysical Observatory, NAOJ). This super-Earth is an exoplanet, having only about 14 times the mass of our home planet, and it is the second lightest one among already-surveyed exoplanets. The observational data revealed that this planet is highly likely to NOT be covered by thick clouds.

    The researchers expect that future detection of the specific composition of the planet’s atmosphere based on highly accurate observations with larger aperture telescopes, such as the Subaru Telescope. This planet orbits around its primary star very closely at a rapid rate. We don’t yet understand the formation process of such planets.

    If future detailed observations of the atmosphere detect any substance that becomes ice at low temperatures, it probably means that this planet was originally formed at a distance (a few astronomical units) from the primary star, where ice could exist, and moved toward the primary star thereafter.

    In contrast, if such a substance cannot be found in the atmosphere, this planet was quite likely formed at its present location (near the primary star) from its early stage. Thus, it is expected that the detailed observations of the atmosphere of GJ 3470b can begin to reveal the mysteries behind the formation of super-Earths.

    It is very difficult to measure the radii of exoplanets, so in many cases we have information only about masses. However, if an exoplanet has a particular orbit of “planetary transit (primary transit)” where it passes in front of the primary star (parent star), we can estimate the radius of the planet. During the transit, the observed brightness of the star slightly drops depending on the size of the planet. So, we can estimate the radius of the planet by measuring the fading rate of light very precisely.

    The research team performed highly accurate observations on the transit of exoplanet GJ 3470b using the Near-Infrared Imager/Spectrograph (ISLE) camera mounted on the 188-cm reflecting telescope and three visible light cameras on Multicolor Imaging Telescopes for Survey and Monstrous Explosions (MITSuME) telescope, all belonging to OAO, simultaneously. They measured the brightness dropping rates of the stars in 4 colors (from visible to near infrared). The observations enabled to estimate each radius by color for the planet (Figure 1).

    As a result, the radius derived from near infrared radiation (1.3 micrometer wavelength) is about 6% shorter than that from visible light. The difference of radii between colors probably is the reflection of the atmospheric characteristics of the planet. When the light from the primary star is transmitted through the thick atmosphere of the planet, certain wavelengths of light are absorbed or scattered by atmospheric molecules, which could cause the difference of apparent radii for each observation wavelength.

    So far, the atmosphere of only two super-Earths including GJ 3470b has been studied in detail. Estimation of the radius of an exoplanet is a very difficult task. Generally, the fading rate of the light from the star caused by the super-Earth’s transit is extremely low. In the case of GJ 3470b, however, the size of the primary star is small, so the planet-to-primary star size ratio is relatively large. Therefore, the fading rate of light from the primary star due to the transit becomes larger so it is measurably observable using ground-based telescopes with a medium size diameter.

    The estimated radius of the planet by the near infrared radiation observations this time turns out to be about 4.3 times larger than that of the Earth. Moreover, theoretical calculations based on the mass and radius of the planet expected that the planet should have huge amount of atmosphere.

    Fukui commented, “Suppose the atmosphere consists of hydrogen and helium, the mass of the atmosphere would be 5 to 20% of the total mass of the planet. Comparing that to the fact that the mass of Earth’s atmosphere is about one ten-thousandth of a percent (0.0001%) of the total mass of the Earth, this planet has a considerably thick atmosphere.”

    Because differences in radii by colors were found in this observation, it is safe to say that thick clouds do not cover GJ 3470b. If thick clouds covered the planet, no differences in radii by color should exist.

    The research team plans to conduct observations of even higher accuracy using the Subaru Telescope or other large telescopes. “GJ 3470b’s orbit of its primary star is very close, at just 0.036 AU (astronomical unit), which is about 28 times less than the distance between the Sun and the Earth, and revolves in a short cycle of only 3.3 days.

    Scientists still don’t understand well how such a planet was formed. GJ 3470b is really possibly not covered by thick clouds, so we believe the composition of the planet’s atmosphere could be detected without being blocked by its clouds. If we find any substance, such as water or methane, which becomes ice at low temperatures, it probably means that this planet was originally formed at a distance (a few astronomical units) from the primary star, where ice could exist, and moved toward the primary star thereafter.

    In contrast, if such substance cannot be found in the atmosphere, it can be thought to be quite likely that this planet was formed near the primary star. We expect to obtain important clues for figuring out how super-Earths were formed through observations of the atmospheric component of GJ 3470b,” said Fukui.

    The frequently sunny weather in Okayama Prefecture was in our favor in obtaining the observation results. A continuously clear sky over several hours through an expected transit time is crucial to precisely measure the radius of an exoplanet. So it can be said that the “Sunny District” Okayama brought on this finding of the “sunny super-Earth.” The researchers will continue observations with the telescopes at OAO, hoping to lead to further progress.

    PIO Contact:

    Hiroyuki Toda
    +81 865-44-2155
    toda@oao.nao.ac.jp

    Science Contacts:

    Akihiko Fukui
    National Astronomical Observatory of Japan
    +81 90-2065-3919
    afukui@oao.nao.ac.jp

    Norio Narita
    National Astronomical Observatory of Japan
    +81 90-8510-6044
    norio.narita@nao.ac.jp

    Research Paper:

    http://iopscience.iop.org/0004-637X/770/2/95