Gravitational lens it happens when things with mass create ripples and dents in the fabric of space-time, and light must follow along these lines, which sometimes create a magnifying glass effect. That's what it sounds like it looks like something wild out of science fiction, but it's actually a very important tool in astronomy. The James Webb Space Telescope has been in the news a lot recently for just that: watching how light bends around massive galaxy clusters in space, revealing fainter, more distant old galaxies behind them.
Now, Slava Turyshev, a scientist at NASA's Jet Propulsion Lab, is trying to harness one of those gravitational lenses closer to home, using our sun. In a new paper published on the arXiv preprint serverTuryshev calculates all the detailed mathematics and physics needed to show this is it is actually possible to harness our sun's gravity in this way, with some very neat uses. A so-called 'solar gravitational lens' (SGL) could help us beam bright messages to stars for interstellar Communicate or explore the surfaces of distant exoplanets.
"By exploiting the gravitational lensing effect of our star, astronomy would experience a revolutionary leap in observational power," he says Nick Tusay, a Penn State astronomer not involved in the new work. "Light works both ways, so it could also enhance our ability to transmit if we had someone out there to communicate with."
When it comes to telescopes here on Earth, bigger is definitely better. To collect enough light to spot really faint objects far away, you need a huge mirror or lens to focus the light — but in reality we can only make them so big. This is where the SGL comes in, as an alternative to building larger telescopes, rather than relying on spacetime being bent by the sun's gravity to do the focusing for us.
"Using the SGL eliminates the need to build larger telescopes and instead raises the problem of how to get a telescope to the focal length of the Sun (and how to keep it there),” he explains. Macy Houston, a Berkeley astronomer not involved in the new research. "And there's a lot of work to do development to try to solve this," they add.
Turishev is is actively working on a mission plan to send a one-meter telescope (less than half the size of the famous Hubble) at the center of the sun's gravitational well. It's a long journey—this focal point is about 650 AU from our star, nearly five times as far as humanity's current distance record holder, Voyager 1. To reach such a huge distance in less than a lifetime, the team relies on cutting-edge solar sail technology to move faster than ever before.
The James Webb Space Telescope is currently investigating the atmospheres of planets around other stars and the future Inhabitant Worlds Observatory in the 2040s we hope to be able to see enough detail in exoplanet atmospheres to find evidence of life. Turyshev's mission would be the next big step toward confirming life on other worlds, hopefully launching around 2035. Once JWST and HWO spot potentially interesting worlds, the SGL telescope will then map the surface of an exoplanet in detail . Turyshev claims he could see a planet blown up to 700 by 700 pixels – a huge improvement over the current 2 or 3 pixels of direct imaging. "If there's a swamp on that exoplanet, emitting methane, we'll know that's what's on that continent on that island, for example," he explains.
Looking further into the future of science fiction, this same SGL technology could be used not only "as a telescope that we could use from within the solar system to see other planetary systems in great detail" but also as "an interstellar communication network (for intentional communications ),” Houston says. A laser placed at the gravitational focus of the sun could send messages to other stars without losing as much signal as the current beacon technology we connect to Earth.
"If we ever become an interstellar civilization, this [SGL] could potentially be the most effective means of communication between star systems," says Tusay. Us broadcasting, which have been leaking out of Earth's atmosphere since the early 1900s, quickly become fainter the farther they are from our planet. Turyshev's mathematical calculations show that the signals sent by the SGL could easily be observed at the distances of nearby stars, even when accounting for the noisy background of the real world. Transmission through the SGL "is not prohibited, it is actually encouraged by physics," says Turyshev.
However, this technology would not solve all of our interstellar obstacles. We may be able to send messages, but we don't have a way to send them yet we ourselves out among the stars to travel. There would also be a huge delay in our galactic calls—more like sending a letter across the country on horseback than FaceTiming your friends. “The light has one more maximum speed", Tusay recalls. As a result, sending a message to a star four light years away would take four years to get there and another four for the reply to reach us. However, solar gravitational lensing is a big step in making our science fiction future a reality.