Sailing in space!

[mlydon]

Below I’ve posted a link to an article on a new lightsail project being built. Interesting ‘rollable booms’, and a neat animation of how it will sail using photons. While I get how they will generate thrust to speed up and slow down, the film doesn’t address how they will deal with leeway. While the photons bouncing off are angled ‘fore or aft’, a component of the force vectors will drive the craft to solar ‘leeward’.

Perhaps trace atmosphere will act like water on a keel.....tbd

Matt

https://nanoavionics.com/news/nasas-...satellite-bus/

[Zanshin]

Make me think of a great short story by my favorite SciFi author, Jack Vance:

Gateway to Strangeness - Sail 25

[StuM]

The direction of travel (final vector result) will depend on the angle of incidence of the light on the sail at any given point of time. By adjusting the satellite's attitude it can effectively be steered in any direction.

[resistor]

Originally Posted by StuM

The direction of travel (final vector result) will depend on the angle of incidence of the light on the sail at any given point of time. By adjusting the satellite's attitude it can effectively be steered in any direction.

Not exactly. You need a second force working in opposition to the wind in order to be able to sail upwind. On a sailboat, that force comes from the resistance of the water. Without that force, you can't tack a lightsail upwind like you can a sailboat.

What you can do, however, is use the lightsail to change your orbital height if you're orbiting the sun. While orbiting, slowing your orbital movement will decrease your orbital height, while speeding it up will increase it. You're using the sun's gravity as the second force. This gives you something sort of like sailing upwind in that you can move towards the sun by changing your orbital height, but you still can't sail in any arbitrary direction.

[GordMay]

I imagine that solar beating, up-photon (towards the sun) would entail furling the sail, to reduce photon thrust, and allowing the sun’s gravity to draw the craft in (up-photon towards the sun).

Solar Sailing
LightSail is a citizen-funded project from The Planetary Society to send a small spacecraft, propelled solely by sunlight, to Earth orbit.

“... When a solar sail faces the Sun directly, photons push the spacecraft forward, away from the Sun. But a solar sail can move in other directions by tacking like a sailboat, changing the angle of the sail relative the Sun. It’s even possible to shift the spacecraft's orbit around the Sun, by angling the sail so that solar photons push against the direction it is traveling. Solar sails can also control their direction in other ways, such as changing their center of mass or using tip vanes ...”

➥ https://www.planetary.org/explore/pr...r-sailing.html