What if we could take a picture of an earth-like planet around another star sharp enough to see continents, oceans and clouds?
Right now, it̵
A group of researchers have a bold plan to overcome these difficulties. It involves using sunspace spacecraft – possibly a whole fleet of them – to fly faster and farther away from Earth than any previous spacecraft, turn around and use our distant solar gravity as a giant magnifying glass. If it works, we capture a picture of an exoplanet so sharp that we can see features just 10 kilometers across.
The project, called Solar Gravity Lens, or SGL, sounds like something straight out of science fiction. NASA and a collection of universities, carriers and other organizations are involved, as well as co-founder of the planetary community Lou Friedman, the original guru of the sun.
“I’m always thrilled to try to make something happen that can’t happen in any other way,” said Friedman, a consultant for the SGL project who led a 1970s NASA effort to send a sunroof spacecraft for Halley’s Comet. “The whole reason we started sunbathing at The Planetarium Society was because it allowed us to take the first steps toward interstellar exploration. Our LightSail worked really well, and its success lends credence and credibility to the idea that sail through the solar system. “
The plan has many obstacles, but the payoff would be incredible, said Slava Turyshev, a physicist at NASA’s Jet Propulsion Laboratory, who heads the Solar Gravity Lens project.
“In our solar neighborhood, which we classify as within 100 light years, we have identified several exoplanets that may be in their habitable zone for their star,” Turyshev said, referring to the not-too-warm, not-too-cold region around a star where liquid water could exist. “And then we now have the question, what would we do if we found something that indicates the presence of life on an exoplanet? Could we travel there, or at least see it?”
How it works
Over a century ago, Albert Einstein predicted the idea that gravity can bend and magnify light, a concept known as gravitational lensing. From an observer’s point of view, light from a distant object passing close to a massive foreground object becomes distorted and magnified, provided the observer is in the right place, known as the focal point. It is similar to the way you can focus a camera by finding the right distance from your target, rather than adjusting the focus of the camera.
The Hubble Space Telescope and other observatories have seen this phenomenon: whipped arcs and rings of distant galaxies, distorted and magnified by gravity in denser galaxies.
The scientists behind the SGL project say we can do the same for exoplanets – we just have to travel to the focal point. In an exoplanet 100 years away, the focal point is 97 billion kilometers away – 60 times further away from the Sun than Pluto. Voyager 1, which has ventured further into space than any other man-made object, has only traveled about 20 billion kilometers (13 billion miles), and it took the spacecraft 40 years to get there.
The solution to getting there faster? Solsejlads.
Sunsets capture the speed of light from the sun and use that momentum as momentum. Using this technology, an SGL spacecraft would fly close to the sun, pick up speed and plunge into the outer reaches of our solar system and make the journey in just 25 years.
Instead of the large, heavy spacecraft previously used, scientists imagine small, elastic probes that could capture rocket craft into space with other missions to reduce replacement costs. One option is to use swarms of bread-shaped CubeSats, similar to LightSail 2, which could be assembled even to create a larger, single optical system. If the spacecraft is cheap enough, missions can be sent to the contact points of several exoplanets.
At the focal area, the light from the exoplanet would be smeared in a circle called an Einstein ring. The ring will contain 2 parts. One part comes from a single 10-by-10-kilometer section of the exoplanet and provides only a single pixel in the final image. The part will contain light from the rest of the exoplanet. As the spacecraft speeds through the focal area, it would be necessary to move around using mini-ion thrusters – sunlight would be too weak for sunbathing at this distance – to change the focus of the exoplanet.
With the right optics, taking 1 million pictures of rings from different places could provide a picture similar to that taken from the Moon by the Apollo 8 astronauts in 1968, capturing surface features as small as 10 kilometers across.
Is it possible?
The technological challenges for SGL are, to say the least, daunting. First, there is the issue of precise navigation, long distance communication and the need for a parasol to prevent our own sunlight from entering the telescope. A section is also required to block the light from the exoplanet parent star.
NASA believes in the concept enough to have recently awarded it a $ 2 million grant from its NASA Innovative Advanced Concepts (NIAC) program. NIAC, which has been around since 1998, provides seed money to help innovative ideas come off the drawing board. SGL is only the third study in the history of the program to reach the third phase of the project.
The project’s success can be in its diverse team, a unique approach to NIAC projects. The collaborative efforts include several researchers from JPL and several universities, including UCLA, the University of Arizona and Wesleyan University. Aerospace Corporation and NXTRAC Inc. are involved, both of whom specialize in mission design and technical analysis. This multi-organizational effort brings together the latest technology innovations, such as breakthrough technologies in sun canopy, artificial intelligence, nanosatellites and formation flying.
“A mission like SGL can lead to a transformation in how we explore space,” said Thomas Heinsheimer, the technical co-lead of the SGLF mission of the cooperative Aerospace Corporation, “going from the large expensive spacecraft that has served us well in passing to swarms of small crafts working together to make new discoveries far from Earth. SGL creates an investigative architecture for many space-based organizations working together to answer an inspirational question: “Are we alone in the universe?”
Turyshev believes that the current generation may be able to answer this question, with SGL serving as a ‘focal point’ to help transform the aerospace industry into a more collaborative enterprise.
“SGL may be able to provide this point for more technological efforts to really pull us forward to make the first move outside the solar system,” he said. “The necessary technologies already exist, but the challenge is how to use that technology, how to accelerate their development and then how to best use them. I think we are at the beginning of an exciting period in the space industry where getting to SGL would be practical and scientifically exciting. ”
NASA selects technology concepts early on for new, ongoing research
The bold plan to see continents and oceans on another earth (2020, May 22)
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