Rectangular space telescopes could reveal dozens of Earth-like planets nearby

One of the boldest dreams in modern astronomy is the search for Earth-like worlds beyond our solar system. These exoplanets may hold oceans, rocky ground, and even atmospheres rich in oxygen or ozone—conditions that hint at life. If such planets orbit stars close to the Sun, future probes or even people might one day reach them. But finding these faint companions around bright stars has proven far harder than early scientists imagined.

Most of today’s exoplanet discoveries rely on indirect techniques. One common approach is the transit method, which looks for the slight dimming of a star when a planet crosses in front of it. This works only if the orbit happens to line up perfectly with our view.

Another is radial velocity, where the tug of a planet makes its star wobble. That too misses many targets, especially those in orbits viewed straight on. To uncover every Earth-like planet in the neighborhood, astronomers need to see the planets directly. And that is no simple task.

Spotting an Earth-sized planet near a star is like trying to pick out a firefly next to a searchlight. Even the closest stars are millions of times brighter than their planets. Earth itself glows most strongly in infrared light around 10 micrometers in wavelength. At that wavelength, resolving Earth from the Sun at a distance of 30 light-years would require a telescope with a mirror at least 20 meters wide.

That is far larger than the James Webb Space Telescope, which already pushed the limits of what can be launched. At 6.5 meters across, JWST required complex folding and unfolding in space. Building a cold, 20-meter-class infrared telescope feels nearly impossible with today’s technology.

Some scientists have proposed fleets of smaller telescopes flying in formation, but keeping them aligned within molecular-scale distances is out of reach for now. Other ideas involve flying a giant starshade thousands of miles ahead of a telescope to block out starlight, but moving the starshade for each new target would demand huge amounts of fuel.

A new proposal offered by scientists at Rensselaer Polytechnic Institute, NIST and NASA, offers a surprisingly simple alternative. Instead of designing a massive circular mirror, researchers suggest using a long, narrow rectangle—20 meters in length and only one meter wide. This slim mirror would deliver the sharp resolution needed along its long axis. By slowly rotating the telescope to different angles, astronomers could build up a full view of the region around each star.

The design takes advantage of technology already developed for JWST, including segmented beryllium mirrors and folding structures. The rectangular mirror would launch folded up, then unfold once in space. A lightweight sunshield, also similar to JWST’s, would keep it cool enough for infrared work.

The real trick lies in pairing the mirror with a coronagraph called the Achromatic Interfero Coronagraph, or AIC. This clever device splits incoming light, introduces a phase shift, and recombines it so the starlight cancels out. That leaves behind the much dimmer glow of the planet, appearing as two distinct spots of light.

The proposed telescope would use 20 square mirror segments arranged into a one-by-20-meter strip. A smaller secondary mirror, about 2.3 by 1 meters, would sit to the side to avoid blocking the main mirror’s view. When folded, the spacecraft would measure about 11 meters long and 2.5 meters wide—compact enough to fit within the payload fairing of rockets like the Falcon Heavy.

Once launched to the stable L2 point, a million miles from Earth, the mirror would unfold and align itself. After cooling to its working temperature, it would begin scanning nearby stars. Rotating the long mirror axis over time would allow the system to tease out planets in every direction. The process might take longer than with a huge circular telescope, but the payoff would be immense.

The authors of the study ran calculations to see how many habitable-zone planets this design could reveal. A one-year mission, they argue, could spot around 11 potentially life-supporting worlds orbiting 15 nearby sun-like stars. Extending the mission to three and a half years could increase that to 27 planets around 46 stars. That would mean finding nearly half of all possible Earth-like planets within 30 light-years—an extraordinary yield from a relatively small and affordable spacecraft.

Better yet, the telescope would not just see the planets. It could also detect ozone in their atmospheres, a gas often linked to oxygen and potentially to life. Identifying even a handful of such planets would transform the search for life in the universe.

Of course, no idea comes without hurdles. A long, narrow mirror could flex or vibrate during launch or as it cools. Infrared observations also demand strict temperature control, which adds complexity. But engineers point out that the mirrors of JWST were built to survive similar stresses. Adapting those lessons to a rectangular design may be challenging but not impossible.

The authors stress that their work is a proof of concept. Many details—such as the exact mirror width, the observing wavelength, the list of target stars, and exposure times—would need to be refined. Still, unlike other ambitious proposals, this design does not require breakthroughs in physics or massive leaps in technology. It builds on proven methods in a new configuration.

A rectangular space telescope would not be limited to exoplanet hunting. The design could also sharpen views of many other astronomical objects that demand high resolution. With the ability to adapt across different wavelengths and science goals, the instrument could support multiple missions over its lifetime. Its simplicity and relatively modest cost make it especially appealing compared to more complicated setups involving starshades or multiple spacecraft.

Why does all this matter? Because life, as far as we know, exists only on Earth. For billions of years, microbes thrived before multicellular organisms evolved. Humans themselves represent just a fleeting moment in Earth’s 4.5-billion-year history.

The conditions that make complex life possible may be rare. Stars similar to the Sun, stable over billions of years, are the best places to look for planets with oceans and atmospheres. Roughly 60 such stars lie within 30 light-years of us. Among them, Earth-like planets may number in the dozens. Finding them is like searching for needles in the cosmic haystack.

By offering a realistic way to separate a planet’s faint glow from the glare of its star, the rectangular telescope could take us much closer to spotting these hidden worlds. Once identified, the most promising candidates could be studied further, perhaps even visited by robotic probes in the distant future.

If this telescope design works, it could give you a front-row seat to discovering planets much like our own. It would help scientists not only detect them but also read their atmospheres for signs of oxygen and ozone. This could shift the hunt for life from speculation to direct observation.

For humanity, such discoveries might inspire new missions, international cooperation, and deeper investment in space exploration. In the long run, finding another Earth could even guide the path of future generations beyond our solar system.

Research findings are available online in the journal Frontiers in Astronomy and Space Sciences.

Note: The article above provided above by The Brighter Side of News.

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