I designed a crewed interstellar spacecraft

[alfa0152]

Hi everybody,

I would like to share with you a crewed interstellar spacecraft which I have designed and called Solar One.

It employs a combination of 3 propulsion methods: nuclear fusion, beam-powered propulsion , and photon propulsion.

Basically, several compact fusion reactors power a laser system that propels a huge light sail.

Physicist Robert Forward already proposed in 1983 to use a 26-TW laser system to propel a 100-km light sail, a fresnel lens to focus the beam of the laser, and decelerate the spacecraft with a secondary light sail.

I propose something a bit different, which is to use to use for example a 60 TW-laser to propel a 5-km light sail that would deploy from the spacecraft after the acceleration stage, use parabolic mirrors that gradually change their orientation in order to focus the laser beam, and finally use a photon rocket to decelerate the spacecraft.

In theory, it could be possible to achieve 25% the speed of light, reaching the closest potentially habitable exoplanet in less than 20 years.

There are of course many challenges, like building high-energy continuous-wave lasers, reducing the weight of the nuclear fusion reactors (and of course achieving effective nuclear fusion first), and minimizing the effects of zero gravity during such a long trip.

What do you guys suggest to overcome these challenges?

This is my paper and a short video that summarizes all.

[James Kerman]

Welcome to the forum @alfa0152, actual spaceflight and science was detected so your post has been moved to science and spaceflight.

[Spacescifi]

2 hours ago, alfa0152 said:

Hi everybody,

I would like to share with you a crewed interstellar spacecraft which I have designed and called Solar One.

It employs a combination of 3 propulsion methods: nuclear fusion, beam-powered propulsion , and photon propulsion.

Basically, several compact fusion reactors power a laser system that propels a huge light sail.

Physicist Robert Forward already proposed in 1983 to use a 26-TW laser system to propel a 100-km light sail, a fresnel lens to focus the beam of the laser, and decelerate the spacecraft with a secondary light sail.

I propose something a bit different, which is to use to use for example a 60 TW-laser to propel a 5-km light sail that would deploy from the spacecraft after the acceleration stage, use parabolic mirrors that gradually change their orientation in order to focus the laser beam, and finally use a photon rocket to decelerate the spacecraft.

In theory, it could be possible to achieve 25% the speed of light, reaching the closest potentially habitable exoplanet in less than 20 years.

There are of course many challenges, like building high-energy continuous-wave lasers, reducing the weight of the nuclear fusion reactors (and of course achieving effective nuclear fusion first), and minimizing the effects of zero gravity during such a long trip.

What do you guys suggest to overcome these challenges?

This is my paper and a short video that summarizes all.

 

The challenges are these with regard to fusion:

We do not have fusion reactors. We don't even know how to make them. Fusion propulsion without a sustained fusion reaction is something we know how to do (cause a small nuclear exploson) and manifests. Itself as project Orion, Z pinch fusion (does it with pellers instead of bombs) and more.

Fusion happens in stars via the pressure of worlds worth of mass.

We don't and won't have that, so we resort to high temperatures (higher than core of sun) to cause fusion reactions.

 

With high tempertures stuff melts, and although magnetuc fields do not, plasma which asofar is needed in fusion reactions,  tends to escape the magnetic field and hit the container, lowering the temepature and ending the reaction.

We do not have fusion reactors because we do not have what it takes, or have not found or designef what it takes yet

 So far.

 

Edited July 4, 2020 by Spacescifi

[Nightside]

@alfa0152, why do you need 1600x1600m sail if you are pointing a laser at it? Couldn’t it be much smaller?

Or Is it also working as a solar sail?

Why does it need a second sail for braking? Why not just use the main sail?

Edited July 4, 2020 by Nightside

[wumpus]

Drop the idea of using crewed interstellar spacecraft, unless you are serious about life imprisonment for the crew.  No existing tech will work.  Sorry, haven't had time to go over the full paper.  Maybe in a day or so.

Solar sails:

By definition you can't significantly exceed Solar escape velocity with a solar sail.  Assuming you had to spiral out with a solar sail, you won't get significant braking with a solar sail.  And of course, all available sail should be used for both leaving and braking (in reality this means you ditch the solar sail when leaving the solar system, and don't have any available sail for braking).  Having a 6TW laser in space largely depends on what you would do with the even more powerful power supply once the starship leaves.

Photon rocket: Infinite Isp, but nearly the worst possible energy efficiency known to man.  Expect to carefully design your radiators to assist in selectively radiating black body radiation in the correct way.  Also expect to use them to start braking *immediately* on exiting the solar system if you want to brake in time...  On the other hand, this might be useful in an uncrewed system that would continue to accelerate until the Americanium RTG expired (a century or two), but otherwise shouldn't be taken seriously.

Fusion rocket: pretty much necessary and doesn't require "solved fusion power generation".  Still a lot of work needs to be done to make it happen.

 

[mikegarrison]

16 hours ago, wumpus said:

By definition you can't significantly exceed Solar escape velocity with a solar sail.  Assuming you had to spiral out with a solar sail, you won't get significant braking with a solar sail.  And of course, all available sail should be used for both leaving and braking (in reality this means you ditch the solar sail when leaving the solar system, and don't have any available sail for braking).  Having a 6TW laser in space largely depends on what you would do with the even more powerful power supply once the starship leaves.

With beamed power you can (in theory).

Consider the design in Robert Forward's Rocheworld aka The Flight Of The Dragonfly. The ship is propelled by a fixed laser beam aimed at a reflective sail. When it is time to decelerate, the sail splits in two. A large outer ring catches the beamed light and reflects it back to a smaller inner ring, thus providing the beamed power in the opposite direction. (Of course, this will accelerate the large outer ring, and the ever-increasing distance between it and the ship would be a potential problem.)

It should be obvious that this is a one-way design.

The inverse square law does apply to lasers, so at large distances you need quite a big sail in order to get a decent fraction of the beamed power.

Edited July 5, 2020 by mikegarrison

[wumpus]

True, and after reading it I have to assume that it is entirely based on beamed power, although it looks like you are supposed to decelerate via a solar sail receiving Earth-based power.  My guess is that you are supposed to somehow drag an even larger mirror (presumably mylar or similar) and kick it slightly ahead of you before stopping.  Hopefully the laser will stop the spacecraft before the mirror goes too far past the Alpha Centauri system as it will be traveling significantly higher than .4c (how do you protect mylar from spacedust traveling at >>.2c?).  Perhaps a series of mirrors?

There is a throwaway line suggesting that the lasers might be powered by anti-matter.  Should you have such magic available, there are far, far easier means than using Terawatt lasers.

It also isn't clear where the lasers are stationed.  My guess is some sort of body of ice or rock would make sense (for a heatsink), but without any atmosphere (to block the laser).  I'm guessing a large asteroid, possibly with rotation manually stopped and under human control.  Again, the real question is if you have other uses for the >>26TW power supply (and presumably the laser).

[Spacescifi]

On 7/4/2020 at 5:18 AM, alfa0152 said:

.

What do you guys suggest to overcome these challenges?

 

 

If we knew that we would be cashing in on it, not chatting here on KSP forums.

Simply put, it is far more within modern capability to send a probe.

But even if we did, it would take decades upon decades to give us any useful data back.

So unless we live far longer than we presently do, it's like sending a postcard with RSVP dated for perhaps a century if not a little sooner.

And to do even this the probe would need engines that frankly.... beyond on paper we don't have.

What may be overlooked is the inevitable wear and tear of thrusting an engine for months on end at greater thrust than an ion engine 

It's never been done.

So we won't know what is most likely to break until a test flight.

But stuff breaking is a big deal when we have an operational life of about a century with no ressuply.

Secondly, why sebd ANYONE to proxima centauri?

Current data does not appear to show any inviting place like Earth for the humans to settle down... after being cooped up almost a lifetime in their ships getting there.

Basically there are planets like mars over there, not Earth.

And even Mars is a really questionable choice to settle with humabs even though it us far closer.

So to send humans on a hunch that Earth 2 *might* be in the next star system?

Not gonna happen. Since no one will want to sign up for death if the hunch is wrong.

As it is, I have not seen any confirmation of any life extraterrestrial life beyond Earth.

Until we actually get it, it would be foolhardy to send humans to go colonize worlds that are JUST like the same lifeless ones in our own solar system.

Edited July 5, 2020 by Spacescifi

[Nightside]

2 hours ago, Spacescifi said:

Not gonna happen. Since no one will want to sign up for death if the hunch is wrong.

Check out Frank Herbert’s Destination: Void, the colonists may not have a choice.

Spoiler

They may be cloned specially for this objective.

 

[alfa0152]

On 7/4/2020 at 5:07 PM, Nightside said:

@alfa0152, why do you need 1600x1600m sail if you are pointing a laser at it? Couldn’t it be much smaller?

Or Is it also working as a solar sail?

Why does it need a second sail for braking? Why not just use the main sail?

It could be smaller, but the smaller it is, the more power would be needed to send people.

Also, the material of the light sail has a maximum capacity to receive light.

No second light sail would be used for braking, instead a laser and bussard scoop would be used.

Forward proposed a second light sail to decelerate. 

[alfa0152]

On 7/5/2020 at 3:31 PM, wumpus said:

True, and after reading it I have to assume that it is entirely based on beamed power, although it looks like you are supposed to decelerate via a solar sail receiving Earth-based power.  My guess is that you are supposed to somehow drag an even larger mirror (presumably mylar or similar) and kick it slightly ahead of you before stopping.  Hopefully the laser will stop the spacecraft before the mirror goes too far past the Alpha Centauri system as it will be traveling significantly higher than .4c (how do you protect mylar from spacedust traveling at >>.2c?).  Perhaps a series of mirrors?

There is a throwaway line suggesting that the lasers might be powered by anti-matter.  Should you have such magic available, there are far, far easier means than using Terawatt lasers.

It also isn't clear where the lasers are stationed.  My guess is some sort of body of ice or rock would make sense (for a heatsink), but without any atmosphere (to block the laser).  I'm guessing a large asteroid, possibly with rotation manually stopped and under human control.  Again, the real question is if you have other uses for the >>26TW power supply (and presumably the laser).

how do you protect mylar from spacedust traveling at >>.2c?

A thick protective coating.

[alfa0152]

On 7/5/2020 at 10:47 PM, Spacescifi said:

 

If we knew that we would be cashing in on it, not chatting here on KSP forums.

Simply put, it is far more within modern capability to send a probe.

But even if we did, it would take decades upon decades to give us any useful data back.

So unless we live far longer than we presently do, it's like sending a postcard with RSVP dated for perhaps a century if not a little sooner.

And to do even this the probe would need engines that frankly.... beyond on paper we don't have.

What may be overlooked is the inevitable wear and tear of thrusting an engine for months on end at greater thrust than an ion engine 

It's never been done.

So we won't know what is most likely to break until a test flight.

But stuff breaking is a big deal when we have an operational life of about a century with no ressuply.

Secondly, why sebd ANYONE to proxima centauri?

Current data does not appear to show any inviting place like Earth for the humans to settle down... after being cooped up almost a lifetime in their ships getting there.

Basically there are planets like mars over there, not Earth.

And even Mars is a really questionable choice to settle with humabs even though it us far closer.

So to send humans on a hunch that Earth 2 *might* be in the next star system?

Not gonna happen. Since no one will want to sign up for death if the hunch is wrong.

As it is, I have not seen any confirmation of any life extraterrestrial life beyond Earth.

Until we actually get it, it would be foolhardy to send humans to go colonize worlds that are JUST like the same lifeless ones in our own solar system.

Alpha Cen A would be a better destination yes.

 

[wumpus]

1 hour ago, alfa0152 said:

how do you protect mylar from spacedust traveling at >>.2c?

A thick protective coating.

Or an even thinner protective coating further away.  This is the preferred means of protecting against tiny, high energy collisions and simply lets the "protective" coating get a tiny hole punched through it while the tiny object hit is spread out over a large area.

Unfortunately for those traveling at >>.2c, your "tiny" object is often individual hydrogen atoms (or possibly molecules, not sure).  Don't expect it to work well here.  And your "thick protective coating" will have the same issues, but might possibly work ok as multiple thin layers presumably in hopes of deflecting the impact away from the ship.