Solar Sails in the Electric Universe

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Solar Sails in the Electric Universe

Unread postby allynh » Tue Feb 27, 2018 12:44 am

I was talking about solar sails and the problems that full size sails would have with the electricity in space, and someone mentioned IKAROS. So I looked it up. Yikes!

Wiki - IKAROS
IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun) is a Japan Aerospace Exploration Agency (JAXA) experimental spacecraft. The spacecraft was launched on 21 May 2010, aboard an H-IIA rocket, together with the Akatsuki (Venus Climate Orbiter) probe and four other small spacecraft. IKAROS is the first spacecraft to successfully demonstrate solar sail technology in interplanetary space.[3][6]

On 8 December 2010, IKAROS passed by Venus at about 80,800 km (50,200 mi) distance, completing the planned mission successfully, and entered its extended operation phase.

IKAROS
https://www.youtube.com/watch?v=wUSjggdG9KU

IKAROS II
https://www.youtube.com/watch?v=UZwnMjmJdPk

Then they mentioned a future system called HELIOS that is deeply disturbing. Watching the video and reading the pdf I can see a ton of failure modes, but I want to see it spin. I want to see how it fails. HA!

NASA / JPL HELIOS* solar sail (animated/CGI video)
https://www.youtube.com/watch?v=HTyHejIpNGg

Heliogyro Solar Sail Research at NASA - 20130014933
https://ntrs.nasa.gov/archive/nasa/casi ... 014933.pdf

I did a google search on the Forum and did not find a solar sail thread. I think that it's time to start one, and keep track of future flights.

The TEAM might start looking at what may happen to solar sails that are scaled up to carry a payload like the Galileo probe, at two tons. I suspect that it will end in tears.

But, I want to see it spin. I want to see how it will fail. HA!
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Re: Solar Sails in the Electric Universe

Unread postby allynh » Fri Jun 21, 2019 9:32 pm

One legacy of Carl Sagan may take flight next week—a working solar sail
https://arstechnica.com/science/2019/06 ... olar-sail/
"We are carrying on a legacy that has been with us since the founders."

Eric Berger - 6/20/2019, 7:40 AM
Artist's concept of LightSail 2 above Earth.
Enlarge / Artist's concept of LightSail 2 above Earth.
Josh Spradling / The Planetary Society

As early as next Monday night, a SpaceX Falcon Heavy rocket will launch a cluster of 24 satellites for the US Air Force. Known as the Space Test Program-2 mission, the rocket will deposit its payloads into three different orbits. Perhaps the most intriguing satellite will be dropped off at the second stop—a circular orbit 720km above the Earth's surface. This is the Planetary Society's LightSail 2 spacecraft.

After a week in space, allowing the satellites deposited in this orbit to drift apart, LightSail 2 will eject from its carrying case into open space. About the size of a loaf of bread, the 5kg satellite will eventually unfurl into a solar sail 4 meters long by 5.6 meters tall. The Mylar material composing the sail is just 4.5 microns thick, or about one-tenth as thick as a human hair.

This experiment, which will attempt to harness the momentum of photons and "sail" through space, is the culmination of decades of work by The Planetary Society. "This goes back to the very beginning, to Carl Sagan, Bruce Murray, and Lou Friedman," the organization's chief executive, Bill Nye, told Ars in an interview. "We are carrying on a legacy that has been with us since the founders. It’s just an intriguing technology because it lowers the cost of going all over the place in the Solar System."

Starts with Sagan

As he popularized space and science in the 1970s on television talk shows and in books, Sagan sometimes espoused the virtues of solar sailing. Theoretically, the continual acceleration of photons, although much more gradual than chemical propulsion, could push spacecraft to other stars because this acceleration is continual. Originally, he'd hoped to launch a solar sail to catch up to Halley's Comet in 1986, but that never happened.

After Sagan co-founded The Planetary Society in 1980 to advocate for government support for space exploration, he and others continued to push the technology. But because the US government was focused on more traditional modes of exploration—the space shuttle program and chemical-powered probes to the outer Solar System—the Planetary Society eventually took up the cause on its own.

LightSail 2 undergoing health checks following vibration testing at the Air Force Research Laboratory.
Enlarge / LightSail 2 undergoing health checks following vibration testing at the Air Force Research Laboratory.
AFRL

In the late 1990s, the society began work on the Cosmos 1 project to demonstrate a solar sail. This was an ambitious project that involved eight "blades" of a solar sail that covered 600 square meters, and, from an initial altitude of 800km, was intended to raise its orbit by 50km or 100km over a month in space.

Unfortunately, Cosmos 1 never reached space. It lifted off in 2005 aboard a Volna rocket, which was launched from a Russian submarine in the Barents Sea. The rocket's first stage failed, and the payload was lost. Undeterred, the Planetary Society built a demonstrator named LightSail 1 that launched in 2015 aboard an Atlas V rocket. This version experienced several technical problems, however, which led to improvements for Light Sail 2. This latest project has cost about $7 million, paid for by the society's members.

LightSail 2

This version of a solar sail will have a total area of 32 square meters, and mission planners will deploy the sail about two weeks after launch if all goes well. (More details about what will happen can be found here). Using a momentum wheel to adjust the orientation of its sail, the spacecraft will essentially attempt to demonstrate that it can "tack" into the stream of photons emanating from the Sun. Success will come as the spacecraft manages to raise its orbit over the course of a month.

And then what? Japan's space agency, JAXA, flew a solar sail demonstration mission in 2010 named IKAROS, and NASA flew a very tiny demonstrator named NanoSail-D in 2010 as well. But since then governments have largely ignored the sci-fi-like technology that could provide a much cheaper means of propulsion around the Solar System and beyond. Too much fiction, apparently, and too little science.

Nye hopes the Planetary Society's solar sail mission will put a little more science behind the technology, leading to additional technical developments by NASA or other international space agency because of its potential to democratize space travel. "It's the most romantic of space technologies," he said. "Really, we're sailing among the stars. It's fantastic."
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Re: Solar Sails in the Electric Universe

Unread postby Roshi » Sat Jun 22, 2019 12:11 am

So - even "photon pressure" can defeat gravity, but it's gravity that holds galaxies together.
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Re: Solar Sails in the Electric Universe

Unread postby allynh » Wed Jul 24, 2019 4:30 pm

Spacecraft designed to ride on sunlight deploys its reflective solar sail
https://www.theverge.com/2019/7/23/2070 ... solar-sail
Loren GrushJul 23, 2019, 3:00pm EDT

An artistic rendering of Planetary Society’s LightSail 2 with its sail deployed
Image: Planetary Society

On July 23rd, a tiny spacecraft in orbit around Earth unfurled a thin sheet of mylar that’s the area of a boxing ring. The result is a reflective sail that rides not on wind, but on light from the Sun to propel the vehicle through space.

The spacecraft that’s now sporting a shiny new accessory is called LightSail 2, which is operated by The Planetary Society, a nonprofit organization that advocates for space exploration. Its goal is to demonstrate a way to move a vehicle through space without relying on chemical propellants, which can be heavy, toxic, and expensive to use. This solar technology could provide a cost-effective alternative to propelling vehicles around Earth and through the Solar System. “You never run out of fuel,” Bill Nye, the CEO of The Planetary Society, told The Verge prior to LightSail 2’s launch. “That’s ideal for certain missions.”

“You never run out of fuel.”

Instead of relying on traditional fuels, LightSail 2 will rely on particles of light, known as photons, to maneuver through space. Photons may not have any mass, but they have momentum. Whenever photons collide with a reflective surface, they bounce off, imparting a tiny push on whatever they hit.

Over the course of the next month, LightSail 2 will perform something of a dance in orbit, twisting its sail back and forth to ride on sunlight. As it approaches the Sun, the spacecraft will keep its sail edge on toward the light. Then, once it’s directly in front of the Sun, it will twist and face the sail toward the Sun. “It’ll work very much like a sailboat, where you push, twist, and pack into the ‘wind,’” Nye said. “And then you twist and take advantage of sailing ‘downwind.’” If all goes well, the sunlight will push on LightSail 2, and the spacecraft’s orbit will rise slightly as it whips around the Earth.

This concept of sailing on sunbeams was a dream of famous astrophysicist Carl Sagan, who co-founded The Planetary Society. Sagan even presented a model of a solar sail on the Tonight Show Starring Johnny Carson in 1976. “It can go out from the Sun. It can tack inwards to the Sun,” Sagan told Carson at the time. “And because it has a constant acceleration, it can get you around the inner part of the Solar System a lot faster and a lot more conveniently than the usual sorts of rocket propulsion.”

For the last 10 years, The Planetary Society has worked hard to turn the dream of its former boss into a reality. It developed a CubeSat — a type of standardized small satellite about the size of a shoebox — that can deploy its own sail in space. Their design extends four cobalt-alloy beams from the spacecraft, pulling a mylar sail into its square configuration. It’s a delicate process; the mylar is thinner than the width of a human hair.

the mylar is thinner than the width of a human hair

In 2015, The Planetary Society launched its first solar sail spacecraft, called LightSail 1, aboard the United Launch Alliance’s Atlas V rocket. After a few snafus, the sail deployed successfully, proving the technique could work. However, LightSail 1 was in too low of an orbit to sail properly. The atmosphere was just thick enough to overcome any pushing from the Sun’s light.

With lessons learned from that mission, The Planetary Society created LightSail 2 and launched it into space on June 25th aboard SpaceX’s Falcon Heavy rocket. Soon after the launch, it was deployed into an orbit just over 720 kilometers above Earth. At this altitude, there is less resistance from Earth’s atmosphere, which means, this time, LightSail 2 should be able to harness the momentum from the Sun to raise its orbit by about 15 kilometers.

The LightSail 2 spacecraft with its solar panels and solar sail deployed.
Image: The Planetary Society

Eventually, this orbit raising will lead to the spacecraft’s demise. LightSail 2 will only be able to raise its orbit on one side of the Earth, and each time the orbit gets higher on that side, the orbit gets lower on the other. In about a year, LightSail 2 will pass close enough to Earth that it will be dragged into the planet’s atmosphere, burning up during its descent.

it’s possible that you could catch a glimpse of LightSail 2

However, its fiery demise won’t be a tragedy since LightSail 2 is only intended to prove that this type of in-space propulsion can work. If it manages to do that, The Planetary Society plans to share its solar sail technique with other spacecraft developers that are looking for innovative ways to maneuver vehicles through space. A solar sail could be used for something as simple as maintaining a spacecraft’s position in orbit, or it could be amplified for something as complex as sending cargo to Mars.

It all depends on how this mission goes. In the meantime, it’s possible that you could catch a glimpse of LightSail 2 as it steadily climbs to its higher orbit. Its large sail is so reflective that it may be visible to the naked eye if you happen to be looking up at just the right time. The Planetary Society will provide information about where LightSail 2 is in the sky so that stargazers can potentially spot the satellite as it rides on sunbeams.

This is the video they have for the flight.

LightSail 2 mission highlights
https://www.youtube.com/watch?v=gUEuMQivNOo

This animation is deeply scary.

LightSail 2 Animation
https://www.youtube.com/watch?v=-OmGvycgNCg

This is Carl Sagan's first mention on TV.

LightSail Then and Now
https://www.youtube.com/watch?v=-cEXKu_Onlk

This is the Kickstarter, equally scary. HA!

Kickstart LightSail
https://www.youtube.com/watch?v=kDBzRa9RzfM
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Re: Solar Sails in the Electric Universe

Unread postby crawler » Wed Jul 24, 2019 5:33 pm

Roshi wrote:So - even "photon pressure" can defeat gravity, but it's gravity that holds galaxies together.
Methinx that all orbiting bodies have fought gravity & the result is a tie.
Then a little push gives victory.
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Re: Solar Sails in the Electric Universe

Unread postby Sci-Phy » Thu Jul 25, 2019 6:16 am

It was a project Echo. Echo-1 in 1960 and Echo-2 in 1964.
Nothing to do with sail itself, but one of the objectives of the project was the study of solar pressure.
Unfortunately could not find any data related to the pressure, probably that part of the mission fail.
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Re: Solar Sails in the Electric Universe

Unread postby Sci-Phy » Thu Jul 25, 2019 6:53 am

Solar sail could work using Solar wind, but it will never work using light.
Light exert no pressure. there is no way to transfer momentum with zero mass particle.
Moreover, in the experiments on photo effect, the electrons emitted in the direction opposite to incoming photons:

https://upload.wikimedia.org/wikipedia/ ... effekt.png
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