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takyon writes:

The Sun could be used as a gravitational lens to magnify normally hard-to-image targets such as exoplanets. The catch? The equipment needs to be 550 AU away from the Sun:

Now Leon Alkalai from the Jet Propulsion Lab and his co-authors have picked up an earlier suggestion from Italian physicist Claudio Maccone to use our Sun, rather than a distant star, to create what might be the ultimate telescope based on the microlensing principle. Alkalai's team has investigated the viability of the method in detail as a breakthrough mission concept. They also presented their findings at NASA's recent Planetary Science Vision 2050 workshop in Washington, D.C.

To build such a "telescope," detecting instruments would be placed at a point in space where the Sun's gravity focuses lensed light from distant stars. Not only is the idea viable, according to the Alkalai team, it would produce images that separate the distant star from its exoplanet, a critical observation that is the goal of future space telescopes equipped with Starshades. And using the Sun as a lens would result in much greater magnification. Instead of a single pixel or two, astronomers would get images of 1,000 x 1,000 pixels from exoplanets 30 parsecs, or about 100 light years, away. That translates to a resolution of about 10 kilometers on the planet's surface, better than what the Hubble Space Telescope can see on Mars, which would allow us to make out continents and other surface features.

[...] There is a downside, however. The telescope's focal plane instruments would have to be at least 550 AU from the Sun (1 AU, or astronomical unit, is the distance from the Sun to Earth), which is well into interstellar space. The only spacecraft that has reached interstellar space so far is Voyager 1, which covered approximately 137 AUs in 39 years. So we would need a spacecraft that is at least 10 times faster, but Alkalai and his colleagues say this is within the reach of current technology.

Also at Engadget, MIT, and The New Yorker.

Mission to the Gravitational Focus of the Sun: A Critical Analysis

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An Anonymous Coward writes:

https://m.phys.org/news/2019-03-black-holes-conquer-space-halo.html

A lot of hopes currently hinge on the use of directed energy and lightsails to push tiny spacecraft to relativistic speeds. But what if there was a way to make larger spacecraft fast enough to conduct interstellar voyages? According to Prof. David Kipping, the leader of Columbia University's Cool Worlds lab, future spacecraft could rely on a halo drive, which uses the gravitational force of a black hole to reach incredible speeds.

Prof. Kipping described this concept in a recent study that appeared online (the preprint is also available on the Cool Worlds website). In it, Kipping addressed one of the greatest challenges posed by space exploration, which is the sheer amount of time and energy it would take to send a spacecraft on a mission to explore beyond our solar system.

[...] "So the binary black hole is really a couple of giant mirrors circling around one another at potentially high velocity. The halo drive exploits this by bouncing photons off the "mirror" as the mirror approaches you, the photons bounce back, pushing you along, but also steal some of the energy from the black hole binary itself (think about how a ping pong ball thrown against a moving wall would come back faster). Using this setup, one can harvest the binary black hole energy for propulsion."

How to travel to, create, capture, and/or contain orbiting black hole binaries is left as an exercise for the reader.

Original Submission

RandomFactor writes:

Phys.org reports on the bold plan to take pictures of an exoplanet so sharp that oceans, continents and even clouds would be discernible.

Right now, it's impossible. From our vantage point, exoplanets—planets orbiting other stars—look like fireflies next to spotlights. In the few images we've managed to take of them, the exoplanets are mere dots. Even as the next generation of space telescopes comes online, this won't change—you'd need a 90-kilometer-wide telescope to see surface features on a planet 100 light years away.

A group of researchers has an audacious plan to overcome these difficulties. It involves using solar sail spacecraft—possibly an entire fleet of them—to fly faster and farther away from Earth than any previous space probe, turn around, and use our distant Sun's gravity as a giant magnifying glass. If it works, we'll capture an image of an exoplanet so sharp that we can see features just 10 kilometers across.

Recently awarded a $2 million grant by NASA's Innovative Advanced Concepts (NIAC) program, and spearheaded by JPL physicist Slava Turyshev, the project,

called the Solar Gravity Lens, or SGL, sounds like something straight out of science fiction. NASA and a collection of universities, aerospace companies and other organizations are involved, as well as Planetary Society co-founder Lou Friedman, the original solar sailing guru.

According to Turyshev

The needed technologies do already exist, but the challenge is how to make use of that technology, how to accelerate their development, and then how to best put them to use. 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."

I wonder if it will come with an EF mount.

Previous Coverage
25 NASA Innovative Advanced Concepts Selected for 2018
Sun Could be Used as a Gravitational Lens by a Spacecraft 550 AU Away

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"Terrascope": Earth's Atmosphere Could be Used as a Refraction Lens for a Space Telescope

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