Later this evening, SpaceX is expected to launch its massive Falcon Heavy rocket on its third and most complicated mission from the Kennedy Space Center in Florida. Previous Falcon Heavy launches each carried a single large payload – a Tesla roadster and an Arabic telecommunications satellite – but this launch will carry two dozen satellites in the Earth's orbit. The whole mission lasts more than six hours because the rocket's upper stage must deliver its payload to three different tracks. Four-hour launch window opens at. 11.30 ET and you can see start approx. 20 minutes before lifting at the live stream below.
The satellites aboard the Falcon Heavy will be used to demonstrate new technology and gather a wealth of scientific data. This includes testing an atomic clock for deep space navigation and a new ultra-safe green satellite fuel that studies radiation and space and demonstrates WiFi communication between cubesats and GPS signals for weather forecasts. But undoubtedly, the star's exhibition is the LightSail 2 of the planetary society, which will navigate its orbit by pressure from light particles that hit the sail.
LightSail 2 consists of a small cubesat about the size of a bread that will catch a ride within the PROX-1
For at least one month, LightSail 2 will use light particle or photon pressure to lift itself in a higher path. Although photons do not have mass, they have speed. When they hit the solar collector, this momentum is transferred to the spacecraft. As the spacecraft orbits the ground, a small flywheel inside the spacecraft will rotate the sail to capture these photons, just as a sailboat adjusts its jib to travel in a desired direction.
Simulations show that LightSail 2 should be able to raise its orbit by half a kilometer a day, but its designers say they will consider any measurable elevation gain a success. The amount of force the photon will apply to the solar collector is equal to approx. 9 microns Newton's Square meters. To put this into perspective, it is about equal to the weight of a house flight on your hand on Earth.
If satellites can utilize photon prints for propulsion, it will make navigation of the solar system with cube rate much cheaper and simpler by eliminating the need for satellite fuel. In the future, solar energy also looks for the possibility of interstellar travel. As a spacecraft moves farther from the sun, the solar flux or the density of photons falls rapidly, so a spacecraft equipped with a solar collector would not reach high enough speeds to allow interstellar travel on human schedules. But if the sun canopy is propelled by a powerful selection of lasers on the ground or moon, a small spacecraft could actually make an interstellar journey. This is actually the goal of Breakthrough Starshot, a plan the bankroll of a Russian billionaire who aims to send the first interstellar probe to Alpha Centauri, our closest star's neighbor. LightSail 2 is a small step towards developing the technology that would make this mission possible.
The LightSail project of the planet society has been almost ten years ago, but the idea goes on in the organization. In 1976, four years before he created planetary societies, Carl Sagan appeared on The Tonight Show and showed a "raw model" of a NASA solar collector for Johnny Carson. The story depicted the sail, which was used to rendezvous with Halley's comet, and Carson imagined it was stamped with a giant McDonald's logo. For better or worse, none of their visions became materialized, but solar shipping remained an integral part of planetary society's identity thereafter.
"This thing grabbed my heart in the 1970s and it is still with me," said Bill Nye, science guy and chief executive of planetary societies.
After failing to secure funding from NASA to start a solar capture, the Planetary Society decided to tackle the project itself. At the end of the 90's it began to work on its first version of a sun seal, Cosmos 1, which looked like a huge fan. In 2005, a Russian submarine launched Cosmos 1 in space, but the rocket's first phase failed and destroyed the sun seal. The Planetary Society pressed on and a decade later, LightSail 1 launched in low ground. The first LightSail was more a technology demonstration mission — it wasn't going high enough to surf the sun. In retrospect, it was probably the best. The LightSail 1 mission was plagued by technical problems from the start, including a faulty battery and problems with radio communication.
The LightSail 2 mission is only the second time the technology has been tested and the first time it has been used in Earth's orbit. In 2010, the Japanese space agency IKAROS, which used sailing as its only form of propulsion on a mission to Venus, demonstrated that technology was actually working for the first time. Although Nye and his partners praised IKAROS, they said the technology would not work if the IKAROS spacecraft had been in low ground. To climb to higher altitudes, LightSail 2 had to have a much higher area-to-mass ratio as well as the ability to quickly reorient to the sun as it encircled the earth.
Assuming it works as planned, LightSail 2 will in many ways be the highest performance sun that ever was launched, but it's not likely to hold that title for too long. By 2020, NASA plans to launch NEA Scout, a cubesat sun seal that will characterize an asteroid of the type that may one day be a target for future human missions. NEA Scout Cubesat is slated to be a secondary payload at the first launch of NASA's Space Launch System – if ever it makes it to the pillow. SLS has been plagued by delays and massive cost overruns that have put its future in the question. So meanwhile, enjoy the launch of LightSail 2 on a rocket that actually exists.
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