Guest Blog: The ExoLife Finder: A next-generation telescope for imaging exoplanets

Posted by Alison Klesman
on Friday, September 15, 2017

By Jake Parks

With a proposed location in the Atacama Desert in Chile, The ExoLife Finder (ELF) will be the world’s first and only telescope capable of mapping the surface of exoplanets by imaging oceans, continents, and even life. // All photos: The PLANETS Foundation

A few years back, a group of astronomers put forth a proposal for a beast of a telescope—The Colossus.

At 77 meters in diameter, the Colossus telescope would have been nearly eight times the diameter of Hawaii’s Keck Observatory, currently one of the largest ground-based observatories in the world. And since a telescope’s light-gathering power increases by the square of its diameter, the Colossus telescope would have also had a whopping 60 times the resolution of Keck Observatory.

With this level of resolution, astronomers were planning to capture the first ever surface images of a planet outside of our own solar system, ideally spotting continents, oceans, and even alien cities at a distance of up to 70 light-years.

However, partly due to its price tag of about $750 million, Colossus was never built.

This is where ELF comes in. The ExoLife Finder (ELF) telescope is most accurately described as Colossus-lite. Using a similar design as Colossus, ELF will be composed of sixteen 5-meter mirrors. These mirrors will be made using a thin “printed-mirror” technology that will help reduce weight, and perhaps more importantly, reduce cost.

Made of smooth, inexpensive, fire-polished window glass, the mirrors will be embedded with thousands of tiny, 3-D printed actuators, which will provide incredibly small and precise adjustments to the mirrors to ensure they maintain proper alignment.

By using lightweight mirrors, astronomers will be able to mount all 16 of them into a single circular array, bringing the overall diameter of ELF to about 25 meters. That is plenty big enough to image the surfaces of exoplanets up to 24 light-years (or 120 trillion miles) away. 

Above: Formed from a circular array of off-axis parabolic segments, ELF will create a single diffraction-limited image. By using thin, electronically embedded mirrors, ELF will be able to minimize both weight and cost, thereby maximizing resolving power.

But, as so often is the case, there is a catch—money.

ELF is expected to cost anywhere from $10-50 million, with the range in price due to the fact that ELF’s individual mirrors can be scaled down (or up) depending on available funding. For example, while a 15-meter design could cost less than $20 million, a 25-meter design may cost upwards of $50 million.

Although $50 million is drastically cheaper than Colossus’ $750 million price tag, it’s still a lot of money to shell out for an unproven design.

So, at this point, you’re probably asking yourself, “Why does this guy keep bringing up telescopes that don’t exist yet?” Well, as it turns out, there is something you can do to help make ELF a reality.

ELF is the brainchild of The PLANETS Foundation—a consortium of astronomers and institutions from around the world that have dedicated themselves to understanding the techniques and equipment necessary to search for life in the universe.

And if their mission is something you feel passionately about, I strongly encourage you to check out their KickStarter page. With just 23 days left to reach their goal of $35,000, The PLANETS Foundation is also offering a wide range of pledge gifts to reward donors. One of my favorites is the Tardigrade Cosmic Light. 

Tardigrades, also known as water bears or space bears, are ubiquitous microscopic animals with the ability to survive even the most extreme conditions. In 2007, scientists discovered these resilient critters could survive at least 10 days in the cold, irradiated vacuum of space.

As of today, 151 people from all over the world have come together through the crowd-funding website to support the ELF telescope. In all, people just like you have already donated over $15,000 to help fund the construction of the mirror actuator system prototype.

Although a mirror actuator system may not seem like the most interesting piece of a telescope, manufacturing the prototype is a crucial step to help The PLANETS Foundation build and test the thin, electronically embedded mirrors, which will then be scaled up for ELF.

If all goes according to plan, The PLANETS Foundation aims to complete and test the necessary prototypes for ELF within the next year. Once that is done, they will move on to the main funding stage—which, unless you have a few million dollars lying around, you probably won’t be able to help with. After ELF is fully funded, the telescope should then only take about five years to build, at which point the real fun can begin.

What is ELF’s first planned target, you ask? Well, that would be Proxima b. This exoplanet, which is slightly more massive than Earth, was discovered last August orbiting the star Proxima Centauri, the closest star to our Sun. At just 4.2 light-years away, Proxima b offers one of the best opportunities for ELF and The PLANETS Foundation to test the emerging field of Rotational Exoplanet Imaging.

So far, astronomers have only been able to discern the atmospheric composition for a handful of exoplanets. But with ELF and similar projects, we will finally have the tools we need to physically view worlds outside our solar system. Furthermore, imaging exoplanets allows us to search them for molecular biosignatures, study their atmospheres, oceans, and continents, and monitor any surface variations caused by changing seasons—or possibly life.

And just think, if you donate now, you’ll be able to say you personally helped spawn a whole new branch of astronomy. 

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