Solar sails

[skylifeplays]

When i hear about realistic interstellar travel, I think about solar sails. This addition could also utilize lasers as propulsion away from sunlight, and use sunlight to move it when in range of a star. And of course a near infinite energy source comes at the expense of a very large craft, and a slow retraction speed when you want to slow down or stop. The thrust would be controlled by how far the sails are extended, the smaller the area, the less thrust.

[Klapaucius]

6 hours ago, skylifeplays said:

When i hear about realistic interstellar travel, I think about solar sails. This addition could also utilize lasers as propulsion away from sunlight, and use sunlight to move it when in range of a star. And of course a near infinite energy source comes at the expense of a very large craft, and a slow retraction speed when you want to slow down or stop. The thrust would be controlled by how far the sails are extended, the smaller the area, the less thrust.

You won't slow down by retracting them--that will only slow your acceleration, not your velocity. The way you slow down a solar sail is, as you approach another star, the pressure pushing against you overrides the pressure exerted by the star you departed from.

But I agree, they would be great to have in the game.

Edited April 5, 2023 by Klapaucius

[DerkyJerkyWreaksHavoc]

Yeah and direction control can be dependent on the angle of the solar sail against the photons, managed by RCS thrusters or the now less powerful reaction wheels. after all, a solar sail pointed 45 degrees from the direction of travel of photons shouldn't have the same effect as 0 degrees

6 hours ago, skylifeplays said:

When i hear about realistic interstellar travel, I think about solar sails. This addition could also utilize lasers as propulsion away from sunlight, and use sunlight to move it when in range of a star. And of course a near infinite energy source comes at the expense of a very large craft, and a slow retraction speed when you want to slow down or stop. The thrust would be controlled by how far the sails are extended, the smaller the area, the less thrust.

it would also come at the cost of not being able to control efficiently and no gimballing. 

Spoiler

boy i can't wait to "gimbal" light 

 

[Lyneira]

Can you give an example of real-life interstellar travel concepts that use solar sails? I've been looking and while I found examples of lightsails powered by giant laser batteries from the home star system, I found nothing suggesting an interstellar trip is possible on the Sun's radiation alone.

[skylifeplays]

On 4/6/2023 at 3:09 AM, Lyneira said:

Can you give an example of real-life interstellar travel concepts that use solar sails? I've been looking and while I found examples of lightsails powered by giant laser batteries from the home star system, I found nothing suggesting an interstellar trip is possible on the Sun's radiation alone.

I mentioned that you would have to use lasers to accelerate whenever you get too far away from the star. you could also use the lasers for regular propulsion, but it would waste energy. NASA has been working on a solar sail demonstration craft since 2011 here: https://www.nasa.gov/mission_pages/tdm/solarsail/index.html

Edited April 8, 2023 by skylifeplays

[Lyneira]

When I read the original post, I interpreted it as a suggestion for just solar sails (without lasers) as a method of interstellar travel, but it's now clear that you meant sails in conjunction with lasers for interstellar travel. It'd be interesting to see!

[Strawberry]

On 4/6/2023 at 3:09 AM, Lyneira said:

Can you give an example of real-life interstellar travel concepts that use solar sails? I've been looking and while I found examples of lightsails powered by giant laser batteries from the home star system, I found nothing suggesting an interstellar trip is possible on the Sun's radiation alone.

Apparently if you start accelerating inside mercury's orbit speeds of 10% the speed of light are possible https://www.wired.com/story/travelers-guide-to-the-stars-interstellar-travel/

[JoeSchmuckatelli]

The way Warp works... Couldn't I just put something with the TWR and ISP of a birthday cake candle on my colony craft and then warp till I get there? 

Whee! 

[Lyneira]

13 hours ago, Strawberry said:

Apparently if you start accelerating inside mercury's orbit speeds of 10% the speed of light are possible https://www.wired.com/story/travelers-guide-to-the-stars-interstellar-travel/

Reading the article closely, it does appear there is the catch of "adding lasers" again:

Quote

If you have a light enough sail, you can get a really big acceleration. If you get well inside the orbit of Mercury and you have a sail that only weighs 1 or 2 grams per square meter—which is about 20 times better than we can do today—and you have a sail that’s like a square kilometer, if you add a laser to boost it, you can get enough thrust to go out of the solar system at a significant fraction of the speed of light, like 10 percent.

...

And if you augment that with a high-power laser, like the folks at the Breakthrough Starshot want to do, it’s like a lot more suns falling on it, which means you can accelerate it to much higher speeds, potentially up to 5, 10, 20 percent the speed of light.

And the margin of uncertainty here seems to be rather large, "potentially up to 5, 10, 20 percent." with a "high-power laser" included, and if the sail can be built as light as 1 or 2 grams per square meter. Some numbers I found on project rho for a first interstellar probe that could be sent: http://www.projectrho.com/public_html/rocket/slowerlight2.php#lassail1

Laser:

• Requires a fresnel lens of 1000 kilometers in diameter (as big as Texas) consisting of wide rings of one-micrometer-thick plastic film.
• Mass: about 560 000 tons
• Focal length: 40 Ly
• Solar-pumped lasers with power capacity of 65 000 MW (65 GW)

Probe:

• Probe mass: 1 ton (about 1/3rd each of payload, support structure, and sails)
• Sail diameter: 4 km
• Acceleration: 0.03 g
• Speed after 3 years: 0.11c, after traveling 1/6th of a Ly.
• Takes 40 years to fly through Alpha Centauri without stopping.

If we want to push a colony ship to alpha centauri that also needs to slow down, I think we're talking a sail of hundreds if not thousands of kilometers in diameter, and far more laser power.

Edited April 9, 2023 by Lyneira

[stephensmat]

I'd like to see it too, but I feel like it'd be shown in a trailer by now if it was going to be there...

[skylifeplays]

On 4/9/2023 at 4:30 AM, stephensmat said:

I'd like to see it too, but I feel like it'd be shown in a trailer by now if it was going to be there...

Remember these are suggestions, not ingame features. They might add it in the future.

[GaussFlux]

On 4/9/2023 at 1:11 AM, Lyneira said:

If we want to push a colony ship to alpha centauri that also needs to slow down

There are designs out there that account for deceleration, such as this one by Robert L. Forward:

deceleration could also be achieved via mag sail which would only need an internal power source like a nuclear reactor.

[Lyneira]

5 minutes ago, GaussFlux said:

There are designs out there that account for deceleration, such as this one by Robert L. Forward:

deceleration could also be achieved via mag sail which would only need an internal power source like a nuclear reactor.

I saw it while browsing that website, whether the colony ship is more massive and slows down on engines (like Avatar's ISV Venture Star) or less massive and has a decelerator lightsail stage, we are still talking parts that are comparable in scale to (or larger than) the planets themselves in KSP2! As epic as that would be, I doubt whether this is even viable within the game engine.

[Lowi_Sace]

On 4/5/2023 at 4:23 PM, skylifeplays said:

When i hear about realistic interstellar travel, I think about solar sails. This addition could also utilize lasers as propulsion away from sunlight, and use sunlight to move it when in range of a star. And of course a near infinite energy source comes at the expense of a very large craft, and a slow retraction speed when you want to slow down or stop. The thrust would be controlled by how far the sails are extended, the smaller the area, the less thrust.

Would indeed be very cool. Like having to set up the laser infratructure with recource gathering. But I think this would be something for a far later stage of the game or maybe even an DLC