SETI’s Colossus

For the most part, the focus of SETI since Project Ozma has been directed at intercepting signals deliberately sent our way. It doesn’t have to be so, of course, because extraneous signals from a civilization going about its business would also be profoundly interesting, and even a civilization not much more advanced than ours might be throwing off powerful evidence of its existence through the planetary radars it uses to detect potential impactors in its own system.

Whether or not the Ohio State WOW! signal was a SETI detection remains unresolved, but I always think back to the original Cocconi and Morrison paper “Searching for Interstellar Communications,” published in Nature in 1959. Neither man could know in that year whether exoplanets even existed, but it was a reasonable supposition, and technology had advanced to the point where detecting SETI signals was consistent with all we knew. And as the duo wrote: “The probability of success is difficult to estimate, but if we never search, the chance of success is zero.”

Again I’m reminded of Freeman Dyson’s dictum ‘look for what’s detectable, not for what’s probable,’ which reminds us not to bring too many assumptions into the mix. Thus today we’re seeing the growth of interest in interstellar artifacts, perhaps in the form of gigantic engineering projects that would be observable across light years. And now we have a new proposal, one that would use a gigantic telescope housed here on Earth to look for infrared signatures around other stars. These would not be beacons but the infrared excess inevitably generated by a civilization going about its business. We needn’t, in other words, wait for them to send to us.

The Largest of All Telescopes

Four researchers have outlined the prospect in How to Find ET with Infrared Light, an article appearing in the June, 2013 issue of Astronomy. Jeff Kuhn (University of Hawaii), Svetlana V. Berdyugina (University of Freiburg), David Halliday (Dynamic Structures, Ltd., in British Columbia), and Caisey Harlingten (Searchlight Observatory Network, Norwich, England) believe that a survey out to 60 light years using their methods could make a definitive call on the existence of any civilizations there. The attempt revolves around the use of power.

Consider that Earth’s current terrestrial power production is 15 terawatts, which turns out to be 0.04 percent of the total solar power received on Earth from the Sun. The authors designate the ratio of a civilization’s power production to the amount of solar power it receives as ?. The article points out that the total power used by photosynthesis on Earth is 0.2 percent of the total light falling on the planet from the Sun — it’s interesting to see that our civilization consumes only 20 percent as much power as the biology that supports us. But let’s carry this forward:

As Earth-like civilizations evolve, they use more power. For example, in Roman times, we estimate ? was about 1/1000 what it is today. Humans’ global power consumption is growing by about 2.5 percent per year, even though the world’s population is growing at less than half this rate. In contrast, our knowledge base (the combined total of all recorded information) doubles in just two years. As cultures advance, their information content also must grow, and the power required to manipulate this knowledge eventually dominates a civilization’s total power use.

Finding a civilization through its waste heat radiation thus appears possible, given the right equipment, and what equipment it is. Right now the three largest infrared telescopes being planned are the Giant Magellan Telescope, the Thirty Meter Telescope and the European Extremely Large Telescope. But Kuhn and his colleagues need to go bigger. They’re talking about an instrument with a primary mirror of 77 meters, fittingly called Colossus.

colossus pic - small

Image: The Colossus Telescope, a high-resolution, multiple-mirror giant instrument, will have the ability to directly image the heat generated by other civilizations on planets orbiting stars near us in the Milky Way. Credit: Innovative Optics/Colossus Corporation.

A huge collecting area and an adaptive optics system to correct for the effects of Earth’s atmosphere are essential, as are techniques of ‘thin-mirror slumping’ and polishing technologies being developed by the team through their company Innovative Optics, which operates its research and development out of the University of Hawaii’s Institute for Astronomy in Maui as well as at the National University of Mexico in Ensenada. I pulled this from the Innovative Optics website in a section describing the team’s methodology:

Our proprietary processes drastically reduce the time and cost of production of precision optics. Our optics are produced by fire polishing flat glass (which avoids time-consuming abrasion techniques and leaves a smoother, optically-superior mirror surface), then “slumping” the hot glass under controlled conditions to the desired final shape; no grinding or rough polishing step is required.

The site goes on to describe what it calls ‘Live Mirror’ technologies that provide the adaptive optics needed to eliminate atmospheric distortion. Innovative Optics claims its mirrors can be very thin (2.5 cm thick for an 8-meter diameter Live Mirror) and therefore lightweight, at roughly 70 kg per square meter of surface area, a significant reduction over conventional mirrors. Colossus is envisioned as comprising approximately sixty of these 8-meter mirror segments, with a field of view that would take in only a few arcseconds of the sky at any time, allowing the designers to optimize for star-like sources even as the design holds down costs.

Using a sensitive coronagraph to remove scattered light that would obscure an exoplanet, Colossus would be able to find hundreds of Earth-sized or larger planets in the habitable zone including any civilizations on their surfaces. Innovative Optics is working with Dynamic Structures (Vancouver, BC) on design and construction issues, although issues of funding and location remain to be resolved. Backed by ‘a group of physicists, engineers, telescope builders, philanthropists, and businessmen,’ the team believes the technology exists to make Colossus a reality. “The Colossus would give us insight into whether civilization is a fragile development or if it is common,” the article concludes. “And we’d learn this without announcing ourselves.”


Oceans Under the Ice Worlds?

One of the things we’re going to be looking for at Pluto is evidence of a sub-surface ocean. About eighteen months ago I wrote about the work of Guillaume Robuchon and Francis Nimmo (University of California at Santa Cruz). With Pluto’s outer surface thought to be a thin shell of nitrogen ice covering a shell of water ice, these researchers have been asking what surface features might flag an ocean deep inside. An equatorial bulge left over from the days when Pluto was spinning more rapidly – or the lack of one – could be the evidence they’re looking for.

The thinking is this: Such a bulge could be as much as 10 kilometers high and New Horizons should be able to spot it. The presence of the bulge would indicate no ocean beneath, for the movement of liquid water would over time have reduced or eliminated the protrusion. But if New Horizons finds instead evidence of tensional stresses, indicating the outer shell was stretched because of temperature changes over time, then the possibility of an ocean is enhanced. If it’s there, Pluto’s ocean would most likely be maintained by isotopes undergoing radioactive decay. Robuchon and Nimmo think a planet-wide ocean would be about 165 kilometers deep under a crust of the same thickness. For more on their work, see The Case for Pluto’s Ocean.

Meanwhile, we’re also getting interesting news about Saturn’s moon Dione. Here we’re working with data from the Cassini orbiter, whose magnetometer has found hints of a faint particle stream coming from the moon, with evidence in other imagery of features not unlike those associated with the geyser activity on Enceladus. The findings are examined in a paper published in March in the journal Icarus that focuses on Janiculum Dorsa, an 800 kilometer long, 1-2 kilometer tall mountain under which the crust of Dione seems to be flexing.


Image: The Cassini spacecraft looks down, almost directly at the north pole of Dione. The feature just left of the terminator at bottom is Janiculum Dorsa, a long, roughly north-south trending ridge. Lit terrain seen here is on the anti-Saturn and trailing sides of Dione (1,126 kilometers, or 700 miles across).The image was taken with the Cassini spacecraft narrow-angle camera on March 22, 2008 using a spectral filter sensitive to wavelengths of ultraviolet light centered at 338 nanometers. The view was acquired at a distance of approximately 650,000 kilometers (404,000 miles) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 99 degrees. Image scale is 4 kilometers (2 miles) per pixel. Credit: NASA/JPL/Space Science Institute.

Here again we’re looking for evidence of activity that may have ended long ago, just as we keep our eyes open for that bulge on Pluto. But Noah Hammond (Brown University), lead author of the paper on this work, notes that what we see on Dione is intriguing: “The bending of the crust under Janiculum Dorsa suggests the icy crust was warm, and the best way to get that heat is if Dione had a subsurface ocean when the ridge formed.”

This JPL news release goes into the possibilities in a bit more detail, noting that tidal effects from Dione’s orbit and an icy crust that can move independent from the moon’s core could create the heat we’re witnessing here. But were the tidal forces on Enceladus so much stronger that they produced the geysers still active there? Or are the Enceladus geysers actually the result of more radioactive heating from heavy elements? Whatever the case, a possible ocean under Dione reminds us that other worlds of high interest — Ceres as well as Pluto and Charon — may show evidence for liquid water, which may in fact exist inside objects deep into the Kuiper Belt.

The paper is Hammond et al., “Flexure on Dione: Investigating subsurface structure and thermal history,” Icarus Volume 223, Issue 1, (March 2013), pp. 418–422 (abstract).


The Angle on Pluto

The progress of New Horizons through the outer Solar System has me thinking back to Voyager’s great encounters. In 1986, when Voyager 2 whisked past Uranus, I was about to head off for a weekend of intensive work as a flight instructor — a client we had contracted with had a large number of pilots in need of recurrent training, and I knew I would be in the cockpit well into each night, as indeed I was.


Those long days and the memory of Voyager at Uranus are, of course, tinged with the explosion of Challenger, which took place a scant four days after Voyager’s closest approach to the planet. We were all riveted by the coverage of the event but could only catch it in between training flights, but I remember trying to keep my mind off the fallen Shuttle as we dealt with constantly challenging weather over Maryland and West Virginia. And it was only later that I was able to really sit down and go over the images from Uranus, whose system of moons had always intrigued me — it has continued to do so, especially after my first glimpse of Miranda.

Image: Launch of New Horizons atop an Atlas V rocket. Credit: NASA/KSC.

Triton had much the same effect on me later. Neptune was in the summer of 1989, twelve years after launch, and I remember taping the encounter on a couple of VCR tapes that I still have around here someplace. New Horizons, we can hope, will offer up equal wonders, for it seemed that everything that Voyager — and for that matter, Cassini — saw has re-written our knowledge and assumptions about outer system objects. We’re assuming, of course, that New Horizons can stay healthy through the encounter, which is the subject of principal investigator Alan Stern’s most recent update from the Applied Physics Laboratory at Johns Hopkins University.

Parameters of the Encounter

There are ways of maximizing science, something we definitely want to do, and ways of minimizing danger, and the New Horizons team has to balance between the two. After all, with the discovery of a fifth moon in the system in 2012, rising concern that passage through Pluto/Charon space might be hazardous was inevitable. Stern says a NASA-appointed technical review team and a separate group of senior executives at NASA headquarters has signed off on the findings of the New Horizon team. He adds:

The Pluto system appears to be far safer than early fears and initial calculations indicated when the new moons began popping up. In fact, the best current models predict a 0.3% (1-in-300) chance of a mission-ending impact near closest approach on the nominal trajectory. Much of the reason for this lowered risk assessment is that more sophisticated dust-impact models revealed a decrease (by about a factor of 100) in lethal impact probability for trajectories that fly into the region where New Horizons is aimed now – a region where the gravitational effects of Pluto’s largest moon Charon clear debris. Another important factor is that when we tested spacecraft components against high-velocity impacts using gun ranges in New Mexico and Ohio, we found the spacecraft shielding is considerably “harder”– that is, more resistant to impacts – than preflight estimates indicated.

How will New Horizons maximize its chances? For one thing, the spacecraft’s approach trajectory is steeply inclined to the plane of Pluto’s satellites and any debris that may accompany them. The highest risk would be during closest approach. And that closest approach is in the region where Charon effectively cleanses the area of debris. The encounter plan, then, seems sound despite the recent satellite discoveries. Add to that the fact that New Horizons will itself search for hazards during the final weeks of its approach in the summer of 2015.


Image: The New Horizons trajectory (red line) is steeply inclined to Pluto’s satellite plane, thereby restricting satellite debris hazards – which lie near the satellite plane – to the short time near closest approach. Credit: JHU/APL/Alan Stern.

Stern adds:

…we’ve also added “fail safe” data downlinks just two days and one day before the encounter to send home the best images and spectra stored on the spacecraft’s recorders, just in case our current estimates are wrong and we do lose New Horizons at closest approach.

Moreover, New Horizons has two alternate encounter sequences that can be uploaded to the spacecraft in the final weeks if needed. Stern’s post gives an explanation of these SHBOT’s (Safe Haven by Other Trajectory), in which the spacecraft can be repointed to protect its dish antenna, or the spacecraft itself directed toward a closer encounter with Pluto just inside 3000 kilometers from the surface (the planned encounter is at 12,500 kilometers). Going closer in allows more ‘drag clearing’ of debris particles, caused by Pluto’s tenuous upper atmosphere.

Let’s assume that prudent planning like this will give us a survivable encounter in 2015. New Horizons’ first image of Pluto/Charon is scheduled to be made this July, which happens to be the 35th anniversary of the discovery of Charon. The craft recently emerged from hibernation for summer encounter rehearsals and systems checks, and green onboard beacons continue to tell us that all is well. Ahead of us we have not just Pluto but Charon, a moon the size of Texas (Nix and Hydra are about the size of Rhode Island, according to the New Horizons team, while P4 and P5 are just the size of counties). Interestingly enough, Nix and Hydra are also about the size of the Kuiper Belt objects the team is hoping to flyby years after the Pluto/Charon encounter.


Supporting Starship Congress

Following last week’s highly successful Starship Century conference, I’m looking forward to the Starship Congress coming up in August under the auspices of Icarus Interstellar. Be aware that there is a Kickstarter campaign now in place to support the event and the organization. From the description:

Icarus Interstellar, a non-profit organization dedicated to achieving interstellar spaceflight by the end of the century, will facilitate such a forum as a means for allowing individuals to present and share knowledge and ideas among colleagues within the space exploration community. As an organization run by volunteers, Icarus Interstellar is reaching out to space enthusiasts and supporters to assist in funding this important event, which will incur significant expenses pertaining to venue rental, A/V technical requirements, live streaming of the conference, featured guest speaker travel procurement, and marketing.

I’ve just made my own contribution and hope you’ll consider doing the same. Good luck to our friends at Icarus Interstellar as they move forward with the event. I’m looking forward to seeing many Centauri Dreams readers in Dallas.


An Open Question on Priorities for Interstellar Efforts

At the 2012 100YSS Symposium, Heath Rezabek presented what he calls the ‘Vessel Archives’ proposal, a strategy for sustaining and conveying Earth’s cultural and biological heritage that was directly inspired by Gregory Benford’s Library of Life proposal (preprint available here). Heath tells me his major concern is in “improving the prospects for Earth-originating life through the longevity of our interstellar aspirations and through the application of advanced discoveries to enhance life’s prospects on Earth.” Independent of his role as Outreach and Collaborations Coordinator for Icarus Interstellar’s Starship Congress 2013, he is also an accepted presenter for that conference. Recently Heath contacted me about a research project he is conducting with implications for the interstellar community, as explained below.

In his non-interstellar work, Heath Rezabek (MLIS) is a futurist librarian, technology grants coordinator, writer, and systems designer. He lives in Austin, TX, where he serves as the Teen Services Coordinator within Youth Services at the Austin Public Library, focusing on digital literacy initiatives for at-risk youth.

by Heath Rezabek


If you’re interested in space and space exploration, or if you’re interested not only in space but in long-term efforts to achieve interstellar travel in the fullness of time, I would like to survey your thoughts and feedback for a research project. The survey data collected will be presented in an accepted session at the 2013 Starship Congress (August 15-18, Dallas TX). Results will be fully documented online and reported for the benefit of all stakeholders in the future.

Through the use of the open source surveying platform at, I am asking long-term space exploration advocates the following question:

What do you see as a priority for interstellar efforts over the next 10-20 years?

The survey is stocked with priorities submitted thus far, running the gamut from the very specific to the broad and general. Skeptical or constructively critical submissions are also welcomed! I am gathering as many new or additional ideas as you are willing to submit.

Because of the way a wikisurvey works, the system can handle a very large number of ideas, and individuals can vote as many times as they like. This inclusive approach yields nonchaotic results because of the way a wikisurvey strictly limits poll matchups to two randomly drawn ideas per round.

The resulting data and polling set will be designated CC0 (public domain), so that the ideas this open question yields can be of open benefit to others who may explore this same question in the future. This project is an experiment in a new series of such surveys on a wide range of challenges, called Open Questions: Questions of priority whose answers may be developed and used by all.

If you want to know more, feel free to email me at — and if you are interested in Starship Congress, join us at —

And register at —

Thanks for participating and passing this on.