NASA, international partners consider solar sail for Deep Space Gateway

[Elderberry]

Planetary Society by Anatoly Zak • September 25, 2017

It sounds like it comes straight from an Arthur C. Clarke story, but an international team of engineers is considering equipping a future human outpost orbiting the Moon with a solar sail. Harnessing the slight pressure of solar radiation, a super-thin reflective film might help steer the Deep Space Gateway, or DSG, which is being designed by five space agencies to succeed the International Space Station.

The solar sail concept was presented last month by the Canadian Space Agency, or CSA, at the latest meeting of ISS partners. The event, specifically dedicated to DSG planning, was held at the European space center, ESTEC, in Noordwijk, Netherlands.

At this point, ISS partners are still debating whether to use the sail for practical purposes on the near-lunar station, or only as an add-on experiment to demonstrate its future potential, including possible use on a Mars-bound spacecraft. One of the declared goals of the DSG is to test technologies which could pave the way to the first human journey to the Red Planet.

It is likely the first time solar sailing technology has been considered for a spacecraft carrying humans. Only Japan's IKAROS, launched with aboard the Venus-bound Akatsuki spacecraft in 2010, has demonstrated controlled flight by light. The Planetary Society's LightSail 2 spacecraft, scheduled to launch next year, would be the second.

According to an internal document presented to the ISS Exploration Capabilities Study Team, Canadian specialists believe a solar sail could play a secondary role in orienting the DSG, saving fuel for traditional rocket thrusters designed to maintain the outpost's position. Under this proposal, the main thrust for the station's maneuvers still comes from electric propulsion and traditional liquid propellant engines.

The baseline concept used for initial calculations calls for a rectangular sail spanning an area of about 50 square meters, deployed on the exterior of the station by a robotic arm. This could reportedly save at least 9 kilograms of hydrazine per year needed to keep the outpost correctly oriented in space. Although a relatively small number, 9 kilograms per year adds up over the station's projected 15-year mission, especially when considering the tremendous cost of delivering cargo to lunar orbit. The station's current design allocates 135 kilograms of hydrazine fuel for counteracting gravitational disturbances, as well as solar radiation pressure exerted on the station's exterior in lunar orbit. At least part of this attitude-control job could be shifted to a solar sail.

More: http://www.planetary.org/blogs/guest-blogs/2017/20170925-solar-sail-dsg.html

[Suppressed]

I like it!

[LateForLunch]

The ghost wind that blows through the solar system travels at or near the speed of light. So catching that wispy momentum could readily accelerate a craft with enough sails to near (faster than?) "C".

[Elderberry]

The ghost wind that blows through the solar system travels at or near the speed of light. So catching that wispy momentum could readily accelerate a craft with enough sails to near (faster than?) "C".

They won't be able to tack into the solar wind and sail faster than the solar wind like a sailboat does.

[LateForLunch]

They won't be able to tack into the solar wind and sail faster than the solar wind like a sailboat does.

Not with current technology, no. But who knows what may be possible in the future. There are interesting experiments which indicate that gravity may be a form of energy which may have it's wave form cancelled out . The Casimir Effect is one such aspect of physics. There have also been other developments with odd physics observed. A Russian suspended a superconducting disk in a magnetic field then got it to spin. He irradiated it with radio waves to measure its mass and measured a 2% drop in mass while it was spinning in the field.

Since gravity is confirmed to travel as a wave, the possibility arises that as all other forms of energy, it may be possible to deflect gravity waves by some controlled means.  The problem with relativity is that the closer one get to "C" the more energy converts to mass, so that ultimately no solid object could ever achieve "C".

However, if one eliminates gravity from the equation, theoretically infinite velocity is possible.

Of course the danger in such things is that gravity is the glue of solar systems, most specifically the thing which prevents stars from exploding. Lessen the force of gravity holding the surface of the sun together by even a fraction of a percent and it would explode.