Oak Ridge engineer seeks to assist make interstellar journey potential

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Presenting paper at American Nuclear Society assembly in D.C. Nov. 10

• Engineers are growing an idea for interstellar journey utilizing a swarm of 1,000 ultra-light “laser sails.”
• The mission goals to ship these sails to Proxima b, an exoplanet 4.25 light-years away, utilizing a robust laser system on the moon.
• These tiny spacecraft would journey at 20% of the pace of sunshine, reaching their vacation spot inside a human lifetime.
• The mission, which acquired a NASA Phase I research grant, seeks to ship again high-resolution photographs of the exoplanet.

Imagine a big, spherical, flat, skinny disk 4 meters (13 toes) in diameter that weighs simply 4 grams (0.14 ounce, about the identical weight as a small coin) and that’s large enough to nearly cowl the wall of a small bed room.

Imagine that 1,000 of those so-called interstellar laser sails will every be pushed into outer house at completely different instances over a number of months by laser beams from a yet-to-be-built, 100-billion-watt launch laser system situated on the far aspect of Earth’s moon. It would encompass a large number of phased lasers that might mix to be by far probably the most highly effective launch laser on the planet anytime this century

The highly effective laser system would speed up a “swarm” of laser sails – say, 1,000 – to twenty% of the pace of sunshine, enabling them individually to flee from the photo voltaic system at completely different instances and every full a file long-distance flight on the identical time.

Their vacation spot: Proxima b, one of many two identified exoplanets revolving round Proxima Centauri, the closest star to our solar.

Their objective: To arrive on the identical time – inside a human lifetime (perhaps 20 years after launch in 2075) – to allow them to ship again the highest-resolution photographs of the exoplanet to Earth, the place the info can be acquired simply over 4 years later (perhaps by 2099).

The exoplanet Proxima b has roughly Earth’s mass and revolves in Proxima Centauri’s “Goldilocks zone,” stated Robert G. Kennedy III, noting that NASA scientists are keen on realizing if this b planet exhibits indicators of water and even life. Kennedy spoke about this envisioned mission just lately to the League of Women Voters of Oak Ridge.

A contemporary spacecraft, he added, would take nearly 75,000 years to succeed in Proxima Centauri, a pink dwarf star that’s 4.25 light-years away, or over 25 trillion miles, from Earth. (See https://youtu.be/XXW_keR5OIM.)

The swarm of those smallest of spacecrafts ought to be capable to fly towards the star and ship knowledge as mild pulses in synchrony to extraordinarily massive telescopes on Earth.

This info was supplied by Kennedy, a methods engineer in Oak Ridge who spoke on “This Is What It Looks Like: Interstellar Flight This Century” on the “Lunch with the League” in September. He is the co-founder of two community-scale, grassroots, open-source nonprofit organizations for house in Oak Ridge: the Tennessee Valley Stellar Corp. (www.stellarcorp.tv) and the Institute for Interstellar Studies–U.S. (www.i4is.us).

Kennedy is a co-investigator on a workforce led by Thomas Marshall Eubanks at Space Initiatives, Inc. (SII). The workforce’s mission was chosen for a 2024 Phase I research by NASA’s Innovative Advanced Concepts (NIAC) program. It didn’t make the listing for a Phase II research this yr, however Eubanks plans to strive once more in 2026, in line with an article in an IEEE journal.

Kennedy and different engineers with these nonprofit house organizations have been selling the communications idea to NASA. He gave a chat on their work in September 2024 on the NIAC Symposium in Pasadena, California.The almost full-scale mockup of an interstellar laser sail that he constructed with the help of Denise Johnson of Oak Ridge, who makes wedding ceremony clothes, was displayed at this symposium and on the current League assembly.

Kennedy stated the flight model of the laser sail should weigh three grams, leaving only one gram for your entire scientific payload, which is able to consist of a giant array of flat ringlike optical transceivers. He acknowledged that the black aspect of the mockup of the laser sail he confirmed will possible be product of “aerographene,” q foamy layer of carbon atoms just a few hundred nanometers thick, atop a metallic dielectric to maintain the temperature throughout launch beneath 600 kelvins (620 levels Fahrenheit) so no a part of a laser sail will soften.

The reverse aspect of the sail is roofed with gold foil or another reflective floor that might face the launch laser system. Its beams will propel the laser sails, accelerating them one after the other at 10,000 gravities, about the identical as an artillery shell, however for 10 minutes, so it attains 20% of the pace of sunshine.

After the fleet is launched, Kennedy stated, the laser system will keep on at decrease energy so it may talk with the fleet like a metronome in the course of the laser sails’ 20-year flight. The launch system may even illuminate the Proxima system 4 mild years away with a little bit bit of additional mild, like that from a full moon, to assist the probes keep away from darkish obstacles. They name this invention “the interstellar flashlight.”

Kennedy stated he believes it would take not less than 50 years for the launch laser system and laser sails to be constructed. But it needs to be potential, he famous, since humankind “went from Sputnik to Neil Armstrong on the moon in 22 years.”

Each of 1,000 laser sails would start at different times but “at some point, during the journey, all 1,000 of them come together briefly,” Kennedy stated. “The navy calls that ‘time on target.’

“The ones in the tail going faster will pass the ones at the head flying slower. It’s like the cop chasing you on the freeway. He’s not going to zoom past you, because he wants to pull you over and give you a ticket. So, after he catches up to you, he’s got to match velocities with you.”

To enable the laser sails flying behind to catch up with the ones ahead, Kennedy and others invented a way to make each laser sail maintain its velocity by traveling “edge on” to prevent it from presenting its frontal area to hydrogen atoms and interstellar magnetic fields that will slow it down.

But to allow the laser sails behind to catch up with the ones ahead, the tiny spacecraft in front will slow down by turning from “edge on” to flying “face on” as they sail toward Proxima Centauri.

Kennedy said this scheme will ensure that all laser sails arrive at the same time in the vicinity of the exoplanet – what he and his colleagues call “velocity on target” – and send back a single coordinated intelligible signal to Earth. The technologies enabling this achievement will be a tiny atomic clock in each probe and little infrared lasers on the side so fleet members can discover and talk to each other.

“It’s like the synchronous fireflies in the Smokies,” he added.

The original idea of pushing miniature spacecraft to near-relativistic velocities using visible light lasers was proposed in 2014 by Phil Lubin of the University of California at Santa Barbara. His concept was published in his paper that appeared in the spring 2016 issue of the Journal of the British Interplanetary Society.

Yuri Milner, a Russian-born billionaire who has lived in Israel and the United States, approached Lubin and high-profile (but now deceased) scientists like Stephen Hawking and Freeman Dyson about the Lubin concept. Breakthrough Starshot was announced with Milner as the facilitator and sponsor.

“He proposed launching a very lightweight spacecraft to a fraction of the speed of light to the star and getting data back within a human lifetime,” Kennedy said. “But he wanted to put on Earth a launch laser so powerful that the world’s militaries would never tolerate it. It needs to go on the far side of the Moon where it can’t see us from there or hit anything here. It took a long time to convince him that a swarm of tiny spacecrafts – the laser sails – was the way to go, but he came around to it.”

Milner hired Kennedy’s team to take on the systems engineering task of solving the communications problem – that is, to ensure that the launch laser system and the laser sails are all communicating with each other and can send up to 150 kilobits of data from space to Earth about four light-years away. They called this approach “operational coherence.”

It also includes ensuring that each four-gram spacecraft has sufficient onboard electricity to power its scientific payload. Kennedy allotted a third of a gram for a tiny atomic battery that for 30 years will generate 10 milliwatts of electrical power converted to one milliwatt of optical power, meaning that all 1,000 laser sails together would generate one optical watt in synchrony.

One concept for providing very low onboard power over a long lifetime for a four-gram spacecraft was developed by Kennedy and a colleague.

“My co-author and I are presenting a paper on Nov. 10 at the American Nuclear Society meeting in Washington, D.C., on strontium-90 beta voltaic power,” he said.

Strontium-90, a common radioactive isotope produced by nuclear fission that has a half-life of about 29 years, decays by emitting beta particles. They are high-energy electrons that can, by colliding with atoms in semiconductor material, trigger the flow of a direct current.