Solar Sail Success! LightSail 2 Is Officially Soaring on Sunlight - solar sail.png

https://www.space.com/lightsail-2-so...n-success.html

Today (July 31), The Planetary Society announced mission success as LightSail 2
— the bread-loaf-sized, crowdfunded, solar-powered spacecraft orbiting Earth —
officially raised its orbit with the power of sunlight alone.

"Today, we declare mission success — we're going to a higher orbital altitude
without rocket fuel, just with the push of sunlight," Planetary Society CEO Bill
Nye said in a press conference.

"This is a very exciting day for us and for me personally," Nye said in the
conference. "This idea that you could fly a spacecraft and could get propulsion
in space form nothing but photons, it's surprising, and for me, it's very
romantic that you'd be sailing on sunbeams."

After LightSail 2 successfully deployed its solar sail last week, mission
managers remotely optimized the craft's orientation. With these small changes,
the craft began raising its orbit above our planet, raising its apogee, or
orbital high point. Within the past four days, the craft has raised its apogee
about 1.2 miles (2 kilometers). The mission team behind the craft confirmed that
this orbital raising could be due to nothing other than successful solar
sailing, or propulsion from photons, particles that transmit light, from the
sun.

With this accomplishment, LightSail 2 becomes the first spacecraft to be
propelled by solar sailing in Earth orbit; the first small spacecraft to be
propelled by solar sailing; and the second-ever spacecraft, after Japan's IKAROS
mission, to successfully use solar sailing, The Planetary Society said.

On June 25, LightSail 2 launched from NASA's Kennedy Space Center aboard a
SpaceX Falcon Heavy rocket. On July 2, the 11-lb. (5 kilograms) cubesat signaled
to Earth, marking the spacecraft's successful arrival in low Earth orbit. On
July 23, the craft successfully deployed its solar sail and early data showed
that its small motor was rotating and it had begun to turn the sail to the sun.
That maneuver facilitates an extra "push" from the sun once per orbit. So far,
the craft has captured and sent home images of its stellar view and solar sail
deployment.

LightSail 2 aims to prove the effectiveness of solar sails, which propel
spacecraft using photons. While photons have no mass, they can still transfer a
tiny bit of momentum. So, when photons hit a spacecraft, for example, the craft
is pushed very slightly away from the sun. Photons hit us here on Earth as well,
but we aren't affected by their force.

Solar sails, like the one deployed by LightSail 2, are flat, ultrathin,
mirror-like sheets that push a spacecraft forward when hit with photons. The
main benefit of using this technology is that a craft with a solar sail wouldn't
need to carry fuel and so could theoretically travel for longer periods of time,
as it wouldn't need to refuel.

With the success of this mission, The Planetary Society has demonstrated the
capabilities of solar sailing with the LightSail 2 craft. The organization hopes
that this success will support future solar sailing efforts. Because spacecraft
using solar sails don't require fuel, these missions could theoretically help
scientists to reach farther out into the cosmos.

With solar sailing technology, "we'd ferry cargo to Mars, look for signs of life
and change the course of human history!" Nye said to Space.com in the
conference. "This technology enables us to take things to extraordinary
destinations in the solar system and maybe even beyond in a way that's never
been possible before, because you don't need fuel and you don't need all the
systems to control fuel and manage fuel and handle fuel and buy fuel," he said.

Those curious about the spacecraft's continued journey around Earth should check
in at LightSail 2 Mission Control, a dashboard displaying up-to-date information
about the craft. The site is updated every time LightSail 2 beams down to Earth,
and those visiting the site can check out the craft's location, mission time,
battery charge and the status of any new developments like solar sail
deployment.




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