Interplanetary Sailing Using Laser Beams Luna Phobos

tahanson43206 · 2021-03-14 07:30:12

This topic is a direct spinoff from the work of Quaoar on: Can we build an interstellar starship with current technology? by Quaoar

It appears that the calculations of Quaoar show that it is feasible to accelerate a large spacecraft to a significant fraction of the speed of light.

It would seem reasonable (to me at least) to expect the same technology could be adapted for movement of vessels within the Solar system.

This topic is offered for (what I hope will be) vigorous development of this idea.

Quaoar may become a major contributor to assist with launch of this new topic, if his time permits, and if the topic is of interest.

However, any current registered member of the forum is welcome to contribute to development of realistic proposals worthy of serious consideration.

In addition, any reader of the forum is welcome to assist by contacting NewMarsMember * gmail.com, to apply for membership.

On Earth, sailing vessels have given way to powered ocean transport, but at present, human capability in space is limited to short bursts of chemical propulsion and long periods of coasting between ports. The day will surely come when continuous propulsion in significant amounts will become feasible. However, in between now and then, there exists a window of opportunity for an "Age of Sail" Solar System transportation.

(th)

Terraformer · 2021-03-14 08:17:11

Neptune is, on average, 4.5e12 metres away. Accelerating at 1g for half that distance means hitting a top speed of sqrt(2.25e13) =~ 4.5e6 m/s = 4500 km/s, right in the middle of your flight.

But to push a 100 tonne spacecraft at that acceleration, you need to use, at 300 MW/N, 300 terawatts of power. Whereas, if that energy was used to throw a small amount of mass out the back of the spacecraft, you could get away with far less (or a far higher payload).

That's for Neptune - closer distances mean lower top speeds and are even more favourable to the use of propellent. Mars is 7.5e10m from us, so 1g acceleration gives us a top speed of sqrt(3.25e11) =~ 570 km/s. But we'd still need 300 terawatts to get up to that speed for a 100 tonne spacecraft, whereas if we could use a drive with an exhaust velocity of 1000 km/s, we'd need 1/2(1e6 m/s*1e6 N) = 5e11 W = 500 GW, a far lower energy rate (but still really high compared to where we are now). Well, somewhat higher than that, because we'd need 200 tonnes of propellent as well, but still far lower than a pure laser sail would take.

tahanson43206 · 2021-03-14 10:15:23

For Terraformer re #2

Thank you (a lot!) for giving this new topic a really nice boost.

Thank you for figures that others can now use to compare to their calculations and (hopefully) support yours, or perhaps find alternative results worth study..

The idea of throwing mass out the back of a ship is ** so ** 1950's!

Terraformer ... I like the idea of making a run to Neptune at 1 G!

This topic was started with the Mars/Earth circuit in mind.

The energy needed is coming from the Sun, and the Sun wastes most of it's output trying to illuminate the cosmos.

Why are you trying to save some of what it wastes? There may be logic there, but I need help understanding what it might be.

Edit#1:

https://en.wikipedia.org/wiki/Italian_Space_Agency
This page was last edited on 31 December 2020, at 02:36 (UTC).

Impressive! Promising! Full of potential for future achievement!

(th)

Terraformer · 2021-03-14 14:16:45

Because the energy isn't free. We need vast solar farms and laser batteries to use to to accelerate that fast, all to save a very small amount of mass (which isn't in short supply).

tahanson43206 · 2021-03-15 11:19:59

In Quaoar's original Interstellar topic, Calliban recently posted a suggestion to consume mass at the starship to reduce the amount of laser power needed. His argument would hold for the Interplanetary business case as well.

Here is my reply:

For Calliban re #76

Thank you for the reminder of an alternative way to use the Sun's energy to help to accelerate vessels in the Earth/Mars trade.

While the method requires use of precious mass to accelerate the vessel, there might well be a business case that justifies it. After all, the ** existing ** business case is ** entirely ** dependent upon expenditure of mass from the vessel to achieve the paltry velocity needed for a Hohmann transfer orbit.

You've pointed out that great laser power is needed for the proposed task, but a corollary is the proposition that a LOT of lasers can achieve the collective power output of one large one.

I note that this conversation is taking place in Quaoar's Intersteller topic.

I'll copy my reply into the new Interplanetary topic, which I think has a much greater near-term chance of implementation.

(th)

tahanson43206 · 2021-03-15 11:21:17

For Terraformer re #4

Thank you for your contribution to the development of this new topic.

(th)

tahanson43206 · 2021-03-15 11:59:42

For anyone .... The ideas of Terraformer given in Post #4 are interesting and thought provoking ...

I do not feel qualified to evaluate them properly ... is there someone in the group who would be willing to have a go?

Issues that I am thinking might come up include:

1) The proposal of Quaoar is to accelerate a sailing vessel at the rate of 1 G

Can traditional chemical propulsion accomplish that? I have no idea?

2) Chemical propellants must be hauled up from Earth in order to accelerate a vessel toward Mars

A) What is the cost of propellants needed to propel a Starship from LEO for arrival at Mars using a Hohmann orbit trajectory?

B) Given the stated goal of 1 G acceleration, what would be the cost of propellant needed?

3) The cost of sunlight is given as NOT zero. There may be something about sunlight I'm overlooking, so hope others can help with that.

A) The cost of the first laser boosted flight will be enormous

B) The second boost would (presumably) be less ... not zero, because of salaries and interest payments, but less

I would assume a business entity would expect to recover investments by charging a pro-rated amount for each flight.

Is that what Terraformer might have meant?

(th)

tahanson43206 · 2021-03-16 09:59:46

For all currently registered...

This topic has significant potential for development within this forum.

The advantages identified by Quaoar, in his Interstellar topic, translate into very attractive business opportunities for organizations on Earth who want to achieve a competitive advantage over there horse-and-buggy-chemical-propulsion brethren.

The technologies of solar cells and lasers are well known, and likely to be adaptable to the Lunar environment.

Calliban has proposed, and Quaoar has supported, a proposal to create a hybrid propulsion system in which energy delivered to a vessel is converted to propulsion of matter with very high ISP and therefore with significant efficiency.

A pure laser beam propulsion system would permit a vessel to operate without expending any mass at all under ordinary flight conditions.

On the other hand, a hybrid design would permit use of power hungry technology such as the Very Fast Ion drives discussed in this forum and elsewhere.

Work should (and hopefully will) proceed on both of these alternative paths.

The chemical propulsion methods we (humans) are using today (2021) will (surely) seem outdated in a few years.

The work to make them obsolete needs to start vigorously now!

(th)

tahanson43206 · 2021-03-16 10:03:50

Because of the potential of this topic to bring about significant business development, I would like to remind readers of this forum who are not presently registered members that you may write to NewMarsMember * gmail.com to inquire about applying for membership.

I am looking for members who are part of the generation who will be travelling to Mars, or who will be supporting those who will.

If you are interested in working specifically on ** this ** topic, please let me know when you write.

The essay questions you need to answer are stated in Post #2 of the Recruiting topic.

Answers provided by Captain Torriani and by Noah were published in the Recruiting topic.

I'll be looking for a bit of creativity as time passes.

(th)

Quaoar · 2021-03-31 03:30:31

Another interesting possibility is to use laser arrays to reach the low orbit from the surface: there are two possibilities

1) air-breathing laser pulse detonation engine, like the lightcraft of Leik Myrabo (https://en.wikipedia.org/wiki/Lightcraft)

2) laser ablative propulsion, where the laser comes from an external array while the propellant is stored on the spaceship

I don't know if it is possible to reach orbital velocity on high Earth atmosphere only with the first, but a combination of both might work. Airbreathing up to 3500 m/s then laser ablative propulsion outside the atmosphere

Last edited by Quaoar (2021-03-31 03:34:11)

tahanson43206 · 2021-03-31 06:59:06

For Quaoar re #10

Thank you for this interesting addition to the topic!

While your post seemed to be Earth-centric, I immediately connected with the problem of launch from the Moon. A while ago, Calliban led a discussion of the benefits of various kinds of launch from the Moon. One of those sprang from a post of Void, who was thinking about steam as a propellant.

The issue not solved at that time was how to deliver power to a vehicle so that onboard water could be converted to steam for propulsion.

Your post might be a springboard for renewed contemplation of this topic.

At the time of the original series, I was imagining power might be supplied to the vehicle by trackside sources.

Your post (for some reason) suggested a solution that may well be less expensive and more practical ...

A laser AFT of the vehicle could direct energy toward the vehicle, where mirrors (of suitable capability) would direct the energy to a boiler (of suitable design) able to deliver high energy steam to propel the vehicle along a track to Lunar escape velocity.

Working from memory (the original posts are safely stored in the archive) my recollection is that an acceleration of 2 ( or 3 ? ) along a track of 70 ? miles would deliver a vehicle to escape velocity.

I hope that someone (perhaps not yet a member of the forum) will read this sequence, starting with your post, and decide to explore the practicality of this idea.

Such a launch method would have many advantages over all (ALL) the alternatives.

(th)

Quaoar · 2021-03-31 12:44:13

tahanson43206 wrote:

For Quaoar re #10
Thank you for this interesting addition to the topic!
While your post seemed to be Earth-centric, I immediately connected with the problem of launch from the Moon. A while ago, Calliban led a discussion of the benefits of various kinds of launch from the Moon. One of those sprang from a post of Void, who was thinking about steam as a propellant.
The issue not solved at that time was how to deliver power to a vehicle so that onboard water could be converted to steam for propulsion.
Your post might be a springboard for renewed contemplation of this topic.
At the time of the original series, I was imagining power might be supplied to the vehicle by trackside sources.
Your post (for some reason) suggested a solution that may well be less expensive and more practical ...
A laser AFT of the vehicle could direct energy toward the vehicle, where mirrors (of suitable capability) would direct the energy to a boiler (of suitable design) able to deliver high energy steam to propel the vehicle along a track to Lunar escape velocity.
Working from memory (the original posts are safely stored in the archive) my recollection is that an acceleration of 2 ( or 3 ? ) along a track of 70 ? miles would deliver a vehicle to escape velocity.
I hope that someone (perhaps not yet a member of the forum) will read this sequence, starting with your post, and decide to explore the practicality of this idea.
Such a launch method would have many advantages over all (ALL) the alternatives.
(th)

I'm not Earth-centric but superearth-centric , because in my next novel I need to find a way that an alien civilization would reach the orbit of their planet, which has a mass of 5.1 earth masses, a radius of 1.6 earth radii, a surface gravity of 2 g and an orbital velocity of 14.14 km/s. With a rocket it seems prohibitive, so I shifted to laser propulsion which seems feasible.
An other interesting fact of this planet is that the atmosphere is very dense, almost 6.5 kg/m3, so flying is very easy despite the gravity and even very heavy creature can do it.

For the Moon I suggest a laser ablative propulsion with a parabolic metallic reflective nozzle surrounded by superconductive coils and an ammonia gas drive machine (similar to that of Orion Drive) which expels pellets made of pressed regolith. When the pellets reach the focus of the mirror, they are vaporized and ionized by two laser pulses. Then the plasma is reflected by the magnetic field of the coils generating thrust.

This system uses solar energy from panels to power the laser arrays and regolith as propellant which is very abundant on the moon soil.

Last edited by Quaoar (2021-03-31 13:13:34)

tahanson43206 · 2021-03-31 13:24:25

For Quaoar re #12

Your suggestion for the Moon is interesting and it seems to me worthy of further development. By any chance, could you make even a crude, hand drawn sketch of your idea. If you can create an image of the sketch, you can upload it to imgur.com, and Right click on the image to secure a link for BBCODE, which you can paste in the forum. To see examples of such images, you can find them in the writings of RobertDyck and Void. Void in particular has demonstrated mastery of computer drawing tools, but a hand drawn sketch would be fine!

(th)

Quaoar · 2021-03-31 14:15:58

tahanson43206 wrote:

For Quaoar re #12
Your suggestion for the Moon is interesting and it seems to me worthy of further development. By any chance, could you make even a crude, hand drawn sketch of your idea. If you can create an image of the sketch, you can upload it to imgur.com, and Right click on the image to secure a link for BBCODE, which you can paste in the forum. To see examples of such images, you can find them in the writings of RobertDyck and Void. Void in particular has demonstrated mastery of computer drawing tools, but a hand drawn sketch would be fine!
(th)

The ship in this image is the mini-mag orion a miniaturized version of Orion drive, which uses small fission pellets that reach critical mass after being imploded with a Z-pinch.
My ship is quite similar to her, but she has three differences:

1) there is not the heavy Marx generators for the Z-pinch, so she's lighter.
2) the pellets are not made of uranium (or other fissile material) but inert pressed regolith, because energy comes from an external source.
3) the magnetic nozzle coils are not an empty cage like in the posted design, but surround an hemispherical tungsten or molybdenum mirror, which focus the laser beam on the pellets.

Last edited by Quaoar (2021-04-01 10:33:27)

Quaoar · 2021-04-01 10:31:58

New model:

I have read many articles about laser ablative propulsion: they said that when a laser pulse strikes a plate the ejection plasma jet is almost perpendicular to the plate, even without a nozzle.

https://www.researchgate.net/publicatio … s_in_Space

So I've eliminated the magnetic coils and I have imagined some kind of Orion-like spaceship, with a pusher plate made of multiple ablative layers which are ablated by high frequency laser pulses, generating thrust (probably even the ablative plate needs some kind of shock adsorbers to attenuate vibrations).

What we have is a clean Orion-drive, powered by an external laser array instead of the pulse units, that can reach the low orbit without radioactive fallout.

The multi-layer pusher plate may be very interesting, because we can use high molecular weight materials for the layers ablated in the first phase of the orbital flight, to maximize thrust, and low molecular weight materials for the second phase layers to maximize specific impulse.

Last edited by Quaoar (2021-04-01 16:05:02)

tahanson43206 · 2021-04-01 11:17:27

For Quaoar re #15

Thank you for reporting your research on laser ablative propulsion.

I am most interested in practical applications of advanced ideas, while at the same time appreciating and applauding theoretical contemplations.

In the present instance, with a constant focus on the title of this topic, I am inspired by your post to imagine a configuration of ice in a cylindrical housing, mounted in a rail on the Moon. In this forum, Calliban in particular has written about magnetic rail launch from the Moon. I like this idea, and hope that it comes to pass some day. However, on Earth, no one (in any Nation to the best of my knowledge) has successfully accelerated ** anything ** using magnetic acceleration over a distance greater than the length of an aircraft carrier.

That 70 mile magnetic acceleration track will surely happen some day.

In the mean time, your thinking about laser propulsion in the context of interstellar travel has inspired creation of ** this ** topic, which is about laser propulsion of vessels of various sizes in the Solar System.

Launch from the Moon is a particularly interesting application of the idea.

Water has many advantages as a propellant, so I am focused upon that material for this application.

I hope you will continue developing your ideas for using regolith as a propellant from the surface of the Moon.

The impact of particles of regolith upon the terrain should be fascinating to observe from a safe distance.

The impact of water particles (molecules seem the most likely size) will also be significant, so it would seem best to make sure the output of the propulsion exercise is directed away from the ground.

And ** that ** thought leads to (for me at least) awareness of a fundamental issue with aft laser propulsion ....

The output of the energizing activity will inevitably flow back to the laser at considerable velocity.

For that reason, I find development of this idea somewhat impeded, and hope that other forum members may be able to think of a work-around.

(th)

Quaoar · 2021-04-01 16:19:05

tahanson43206 wrote:

For Quaoar re #15
Thank you for reporting your research on laser ablative propulsion.
I am most interested in practical applications of advanced ideas, while at the same time appreciating and applauding theoretical contemplations.
In the present instance, with a constant focus on the title of this topic, I am inspired by your post to imagine a configuration of ice in a cylindrical housing, mounted in a rail on the Moon. In this forum, Calliban in particular has written about magnetic rail launch from the Moon. I like this idea, and hope that it comes to pass some day. However, on Earth, no one (in any Nation to the best of my knowledge) has successfully accelerated ** anything ** using magnetic acceleration over a distance greater than the length of an aircraft carrier.
That 70 mile magnetic acceleration track will surely happen some day.
In the mean time, your thinking about laser propulsion in the context of interstellar travel has inspired creation of ** this ** topic, which is about laser propulsion of vessels of various sizes in the Solar System.
Launch from the Moon is a particularly interesting application of the idea.
Water has many advantages as a propellant, so I am focused upon that material for this application.
I hope you will continue developing your ideas for using regolith as a propellant from the surface of the Moon.
The impact of particles of regolith upon the terrain should be fascinating to observe from a safe distance.
The impact of water particles (molecules seem the most likely size) will also be significant, so it would seem best to make sure the output of the propulsion exercise is directed away from the ground.
And ** that ** thought leads to (for me at least) awareness of a fundamental issue with aft laser propulsion ....
The output of the energizing activity will inevitably flow back to the laser at considerable velocity.
For that reason, I find development of this idea somewhat impeded, and hope that other forum members may be able to think of a work-around.
(th)

For launching from the moon we can imagine an ablative pusher plate made with very cheap materials taken from the moon surface, like basaltic fibers and pressed regolith as adsorption layers, alternate with transparent silica layers. Moon surface-to-LLO deltaV is only 1.87 km/s, so exhaust velocity doesn't need to be as high as from earth surface to LEO

tahanson43206 · 2023-12-06 12:22:17

This post in inspired by Void, who wrote about the idea of using the solar sail form as a way of sending valuable material from one place in the Solar System to another.

https://newmars.com/forums/viewtopic.ph … 05#p216905

This topic is available if anyone would like to like to develop the idea.

The essence of Void's idea (as I understand it) is to treat the payload as a solar sail.

It seems to me there might need to be some sort of intelligence on the freight sail, so it is properly oriented when photons arrive.

This topic was created with Earth/Mars trade as a theme, but the principles of solar sailing certainly apply to travel between other points.

(th)

GW Johnson · 2023-12-07 10:55:14

Three points:

1. Lasers of the necessary intensity have been built, as beam weapons, but not in the size (total power) necessary for laser-illuminated "sails". You're talking about KW or MW of power in nanosecond pulses, in a beam measuring only about a cm across. Not steady state!

2. Even the coherent beam from lasers is subject to beam spreading, just at a far lower rate than ordinary light. I saw this decades ago with a helium-neon lab demo laser at TSTC airport in Waco. What was a 1 mm dia beam at the "muzzle" at one end of the runway was a fuzzy-edged spot about 100-125 mm in diameter at the other end of the runway, not quite 2 km distant.

3. Beam spreading causes intensity reduction, proportional to diameter squared.

Outcome: Across, say, 100 million km, the beam spread of a 1 mm beam would be to about 50 km diameter. Even if your aim is perfect (and it cannot be), your sail would have to be 50 km dia to capture all the light energy. Smaller, and much of the beam energy misses your sail, even if your aim is perfect.

Another outcome: the intensity reduction by beam spread is by a factor of about 2.5 x 10 ^ 15, applied to your KW or MW on a 1 cm diameter, and ignoring the pulse time effect. There rapidly comes a point where you are better off just capturing the light from the sun for your solar sail propulsion, and that's likely a lot less range than 100 million km! Even that will be too dim to be useful in the outer solar system.

Just food for thought. Sometimes physics and technology really suck, don't they?

GW

Last edited by GW Johnson (2023-12-07 11:01:19)

tahanson43206 · 2023-12-07 12:13:11

For GW Johnson re #19

Thanks for observations and mathematics for laser beam spreading!

SearchTerm:laser beam spreading
SearchTerm:beam spreading of laser beam
SearchTerm:Spread of laser beam - observation and mathematics

(th)

Void · 2023-12-07 14:21:11

Without disrespect: https://spectrum.ieee.org/power-beaming-2665745442
Quote:

NEWS
DARPA Hopes to Beam Power Across 200 Kilometers Lasers could one day relay power to remote areas, or even from orbital arraysCHARLES Q. CHOI02 OCT 20234 MIN READ

But indeed, that is a long way away from interplanetary scale.

Perhaps in a few hundred years the skill might develop for longer sends.

But for now, I would think that using lasers to power a propulsion which vaporizes a substance for propulsion.

In the case where I mentioned Saturn, elsewhere, the substance could be water, or Hydrogen.

If you shoved a solar sail towards the sun using that method, then the solar sail might be pushed to a level of sunlight where it could move it's mass in a reasonable time.

However, reasonable time could be decades, if it were only sending plastic film to a inner world.

As for actually beaming power to Saturn from around Mercury, I think that the receiver might need to be the size of a moon.

You could overlap many, many laser beams and expect a large expansion of the beams. But maybe never. I am just projecting a possible case. Possible maybe but probable? Very questionable.

As for sending a solar sail from Mercury, then CO2 could be the fluid to give the initial boost, and then by the time it got to Saturn, all the light could do for the most part would be to steer it into orbit.

A Ballistic Capture to Saturn should be possible, so no Hohmann Transfer or aeroburn needed. These would likely be of metals, I expect.

But we will have to really get technologically better to make this work.

Not in my lifetime, I am quite sure.

Done

Last edited by Void (2023-12-07 14:31:18)

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Interplanetary Sailing Using Laser Beams Luna Phobos

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