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PLANETS Telescope: Building Toward Colossus

Let me call your attention to the PLANETS telescope, now seeking a funding boost through an ongoing Kickstarter campaign. Currently about halfway built, the PLANETS (Polarized Light from Atmospheres of Nearby ExtraTerrestrial Systems) instrument is located on the 10,000 foot Haleakala volcano on the island of Maui. When completed, it will be the world’s largest off-axis telescope (at 1.85 meters) for night-time planetary and exoplanetary science. And it’s part of a much larger, scalable effort to find life around nearby stars in as little as a decade.

An off-axis design removes obstructions to the light path like the secondary mirror supports that can cause diffraction effects and lower image quality in axially symmetric reflective telescopes. Here light from the primary mirror is deflected slightly out of the incoming lightpath, limiting diffraction and scattered light. The PLANETS Foundation, the international collaboration of scientists and engineers behind the new telescope, sees it as a test of “low scattered light off-axis optics” as well as cutting edge “thin mirror technology.” The lightweight PLANETS mirror is 90 percent polished — using a tool called HyDRa (developed at the National Autonomous University of Mexico) that has demonstrated 1/100th of a wavelength polish — and key mechanical components of the off-axis design are waiting to be built.

The PLANETS instrument will be optimized for studying the exo-atmospheres of the rocky planets in our own Solar System, but will also delve into the atmospheres and surfaces of bright nearby exoplanets and examine circumstellar disks in young stellar systems. It also sets the stage for biosignature detection as we begin to upgrade its scalable technologies.

As a pathfinder, the PLANETS instrument is the beginning of a 10-year roadmap that aims to make telescopes that are lighter and less costly than the large instruments we currently use to probe the universe. The goals here are impressive: To create a census for life on several hundred of the nearest habitable zone exoplanets. The next step would be an instrument called ExoLife Finder, a circular array of sixteen 5-meter mirrors, using the ‘printed mirror’ technology and lessons learned from the PLANETS telescope to create a hybrid interferometer. With a total diameter of some 40 meters, ELF would be the first telescope to create surface maps of nearby exoplanets, including the one on our doorstep, Proxima b.

But beyond ELF we have Colossus, consisting of 58 independent off-axis telescopes that combine their data using interferometric methods to produce a 74-meter diameter effective resolution. Colossus and its capabilities will be the subject of tomorrow’s post, but for today I’ll note that the $600 million instrument could itself be built in a scant 96 months, according to the PLANETS Foundation site, once funding has been secured. An array based on scalable Colossus concepts could even become an optical system for beamed sailcraft of the kind envisaged by Breakthrough Starshot. But before we do all this, we have to build PLANETS.

The PLANETS telescope is backed by a number of academic sources including Japan’s Tohoku University, Germany’s Kiepenheuer Institute and the Institute for Astronomy in Hawaii, along with technology organizations like HNu Photonics and Dynamic Structures. Completion is expected in 2019, with a total cost of $4 million and approximately $500,000 left to raise. Thus the Kickstarter campaign is a cog in a larger effort. The initial Kickstarter goal of $20,000 goes toward finishing the polishing of the secondary mirror for the instrument, with a stretch goal of $45,000 that would be applied to building the primary telescope support system.

This instrument will demonstrate the ultra thin mirror concepts and hybrid interferometry needed to create an ELF within five years, and a Colossus within a decade. If you can help, please join this effort, and note the ExoCube, a 3D laser engraved glass map of potentially habitable worlds, that is available to supporters in a variety of styles featuring a range of mineral sphere ‘planetary’ add-ons. The Kickstarter site’s videos give you the overview.


Tomorrow we’ll delve deeper into Colossus and talk about the markers it could identify not only in terms of biosignatures but signs of possible technological civilizations.


Comments on this entry are closed.

  • Marshall Eubanks May 15, 2017, 12:28

    NASA is also working on an large _space_ telescope, to come after WFIRST, the Large UV/Optical/IR Surveyor (LUVOIR). This should be 8 to 16 meters, and is intended (among many other goals) to be used for imaging exoEarths.


    • Jeff Kuhn May 15, 2017, 15:21

      Hi Marshall,
      Great question. LUVOIR or HABEX will be fantastic space telescopes, but our blood sweat and tears are on the first detection of exolife from the ground. For telescopes that have good adaptive optics and wavefront control their sensitivity increases like the diameter of the telescope to the 4th power (D^4). Seeing biosignatures from a 4-12m telescope is more than an order of magnitude weaker than, say, a 25m telescope and almost two orders of magnitude more expensive from space.

      • Ashley Baldwin May 16, 2017, 19:18

        Any ideas on future observatory sites ? To minimise the background sky and image best at the thermal infrared wavelengths proposed for the various Colossus telescope concepts is going to require a dry, high ( >5000m) site surely ? The high Atacama in Chile ( or Argentina ?) in other words as even Mauna Kea doesn’t have the elevation , regardless of law suits.

    • Harry R Ray May 15, 2017, 15:53

      ALSO: Don’t forget the High Definition Telescope(HDT),NASA’s PROPOSED optical successor to Hubble.

      • Ashley Baldwin May 16, 2017, 19:50

        I think it’s always worth remembering that it’s much easier to build and maintain / upgrade a much bigger telescope on the ground than in space. Especially as adaptive optics have improved Strehl ratios and diffraction limits to close the gap on their space rivals . Adittedly at the cost of field of view, but as we have seen that isn’t a problem for exoplanet imaging .

        The JWST is going to come in at $8.5 billion or more allowing for launch . Imagine the ground based scope that could be created for that ? Even the 40m E-ELT doesn’t top $1.5 billion and with ever improving coronagraph technology ( admittedly driven by space planned WFIRST) too , the far greater apertures possible on the ground more than compensate for reduction in angular resolution at longer infrared wavelengths (where Ang Res= 1.22 X wavelength in m / Aperture in m ( D) ) . Perfect for exoplanet science . If say a $5 billion Habex has an aperture of 4m , diffraction limited to say a typical 0.5 microns , that is still only half the angular resolution of an equivalent cost 80m Colossus scope out to a far more informative 5 microns. Habex can image to this extent too with passive cooling but with twenty times less resolution at 5 microns . Add to that equivalent stellar light contrast reduction at this wavelength , near three hundred times greater light gathering capacity and a far larger ( and higher res ) spectrograph for characterisation and high definition spectroscopy in combination with the coronagraph . If the Colossus is high enough up to get above most of the atmosphere ( and its water vapour ) -No contest . Unlike JWST, such a telescope would still be operational ( and significantly improved ) in 50 years time.

      • Jeff Kuhn May 16, 2017, 23:30

        Yes, I agree. With good mirror coatings we can attenuate the thermal signal of the telescope out to 5 microns to perhaps 5% of the bright ambient thermal glow. Our calculations included this background, but you’re right that it may be the sensitivity limiting factor beyond 5 microns. If we’re allowed to dream…let’s build the second of these telescopes at the south pole Dome C…put the first one in the high Atacama. M. Kea is not an option.

  • Joe May 15, 2017, 13:49

    Let’s hope that the PLANETS telescope finds a way to avoid the controversy of the Thirty Meter Telescope, also proposed for Hawaii.


    I find it ironic that a people who used the stars to navigate the vast Pacific are now opposed to telescopes that will advance the science of astronomy. This is an unfortunate example of the “marching morons” I referenced in a previous comment on mankind’s future in space.

    • Adam Crowl May 15, 2017, 17:19

      To be fair to the Hawaiians, many want the telescopes, but there seem to be many mainland ‘activists’ who’ve gotten involved. Some of the more able defenders of the telescope plans are Hawaiians who recognize the kinship between astronomers and Polynesian navigators.

    • J. Jason Wentworth May 21, 2017, 2:17

      I support the Thirty Meter Telescope (TMT) and the PLANETS telescope, but I do understand the Hawaiians’ position (although, having a monoceran outlook, I have little patience with the notion that only *some* places are sacred, while others, “by default,” aren’t). Being partly Caribbean Indian (my paternal grandfather was mostly Carib; I believe they were the tribe about whom Columbus wrote in his logbook: “They will make excellent slaves”), I know that Hawaiians, like the Indian tribes, were treated shabbily–at best–by most Europeans (Captain James Cook, who was also a scientist, was a happy exception) and by the U.S. government. The opponents of the TMT are expressing their justified frustration over past injustices to their people. However:

      I have *NO* desire to return to living as a hunter-gatherer, bereft of the benefits of science and technology, as my Carib ancestors (and my European and black ancestors, further back in history) lived. When I see indigenous peoples being so “one-sidedly strident,” trying to live in the past, as it were–yet availing themselves to “white technology” and the comforts that it makes possible–they strike me as being hypocritical (I fear that the TMT project is just a convenient “target” for them to vent their anger over past injustices on), and:

      Frankly, I’m infuriated by such attitudes, which are no less racist than those of the white people who treated them badly in the past–*these* white people, in the TMT project, have nothing to do with the white people of centuries past who abused the Hawaiian people (and the Indian tribes), nor can they be held responsible for what the people of long ago did. In addition:

      This *effectively* anti-scientific attitude (despite what the TMT opponents say) makes no sense to me spiritually, either, and it ^does^ make their spiritual traditions appear to be ignorant and even foolish to others. I have engaged in shamanic Journeying and have contacted–and been contacted by–spirits, *AND* I am a supporter and student of science (interestingly, some quantum physicists have said that their science is an alternative description of magic–the Hawaiians also practice shamanism, although they have their own terms for it). I don’t see science and shamanism (which, like science, was developed empirically–it’s not a belief system) as being in opposition at all; both are methodologies for gathering information about reality. As well:

      I see no reason why the two groups’ interests must be at irreconcilable odds with each other. As is done here in Alaska regarding Native antiquities, construction on the TMT could be temporarily stopped–but not for very long–if the construction workers come across burial sites or other archaeological sites, so that they can be documented and preserved. Giving the locals “skin in the game” (by hiring Hawaiian contractors, employing them at the observatory, conducting continuing outreach to local schools, etc.) will help make it *their* telescope.

      • ljk November 10, 2017, 10:53

        Definitely one of the more interesting and rich comments I have seen on this blog, and that is saying something. Thank you for sharing, J. Jason, and so eloquently and with passion at that.

  • Jeff Kuhn May 15, 2017, 15:28

    Hi Joe,
    Yes the collision of science culture and religion. Some telescopes are still being built in Hawaii — the Daniel K. Inouye Solar telescope for example (on Haleakala, Maui). It has been a 7 year effort for the community to allow this to go forward, and there are supporters even from the Hawaiian community. Support for the PLANETS project (also on Haleakala) was polled by the Honolulu newspaper and, by an overwhelming majority (something close to 90%), it was seen as a favorable project.

  • DJ Kaplan May 15, 2017, 15:55

    It’s unfortunate for anyone to be called a moron; the PLANETS telescope is slated for a different mountaintop than the Thirty Meter Telescope.

    • Paul Gilster May 15, 2017, 21:21

      Although I think Joe was referring to a famous C. M. Kornbluth story titled “The Marching Morons,” whose themes account for the reference.

      • ljk November 10, 2017, 10:50

        Perhaps so, but it was both careless and insensitive for Joe not to explain that phrase, especially since not everyone may be familiar with a science fiction story written in the 1950s. Especially in these incredibly sensitive times.

  • ljk November 10, 2017, 10:48

    Jason Davis • November 10, 2017

    Reminder: The Giant Magellan Telescope is going to be awesome


    To quote:

    So far, we know of about 30 Earth-size exoplanets in their stars’ habitable zones. Could the GMT, or one of its brethren like the European Extremely Large Telescope or James Webb Space Telescope, make one of the biggest scientific discoveries of all time? The prospect is enticing.

    [The final parts of this paragraph reminded me of this recent blog post on an episode of The Big Bang Theory and why those who are invested in a major science project must never publicly admit that their work may not find or produce anything, truthful or not: http://www.math.columbia.edu/~woit/wordpress/?p=9623 ]

    And if we detect nothing? Perhaps it will inspire us to take better care of our own fragile world, which could actually be a cosmic outlier—the only known oasis in the lifeless void of space.

    [That same explanation has been used for SETI turning up no alien signals for decades, but has it really influenced the masses to take better care of Earth and subsequently be nicer to each other?]