Quickest way to get to The Super Earth, will this work?

[JoeRoccoCassara]

As you know, with our current technology and resources, it would take many thousands of years to get to Gliese.

 

Unless you pick up speed perpetually.

 

Stage One, The Space Craft is propelled from earth by a series of small atomic explosions, preferably anti-matter for the invornment.

 

 

Stage 2, once out of Earth Orbit, the nuclear pulse engine saparates from the upper Craft, and the upper craft switches to Ion propulsion.

 

 

Stage 3, The craft uses the sun's rotation to steer it in the right direction for it's destination.

 

 

Stage four, the ion thrusters saparate from the top of the Craft, which will be traveling for the longest duration of time on the trip there.

 

 

Stage 5, The top of the Craft opens into two Micro Wave Transmitters, and inbetween them ejects a light reflecting sail, the microwave emitters blast the Sail, and the weak Ion Thrusters on the bottom of the craft push the craft slightly, canceling out the recoil of the Micro Wave Emitters.

 

 

Top Text: Light Reflecting Sail

 

Middle Text: microwave Transmitters

 

Bottom Text: 150 year home for Hyper Sleep crew and cargo.

 

My Questions:

 

How much would this craft have to weigh.

 

How many Joults do the atomic explosions need to propel all of the Craft out of Earth Orbit, and what percentage of the Hafnium on Earth is needed to create all of these atomic explosions?

 

How many Joults do the Ion Thrusters have to produce to propel the Craft to the sun?

 

What percentage of Helium 3 on the Moon would be needed to fuel the Sail Blasting Micro Waves, and the Micro Wave recoil canceling Ion Thrusters in Stage 5 to produce the right number of Joults to get there?

[Moontanman]

How large a percentage of C do you see this space craft achieving?

[JoeRoccoCassara]

How large a percentage of C do you see this space craft achieving?

 

The space craft doesn't achieve near light speeds, what makes it get there so fast is the amalgam of ion propulsion's steady non-stop travel, solar masses sling shotting it, and Gliese 581 moving toward it at great speeds.

 

I haven't calabrated it yet, but it might get there faster than light would, even though the actual ion propulsion isn't making it move very fast.

[Janus]

Using other stars as gravity slingshot is pretty fruitless. Only a small number would have the proper motion to be of any use, and the zig-zag course you would have to take in order to use them would add more time to your trip than you could possibly gain in the slingshots.

 

You are really over-estimating the efficiency of Ion propulision. Assume that you want to get to Gliese in 1000 years, this means you would have to average 6,000,000 m/s for your velocity. Your top velocity would have to be greater, but let's be conservative and use this as our top velocity. The best ion propulsion system on the drawing boards have a top ISP of 10,000 sec, which works out to an exhaust velocity of 98,000 m/s . Using the rocket equation, we can determine what our mass ratio (ship+fuel)/ship must be to reach the needed velocity. For the given values, this works out to 3.89e26. or IOW, for every kilogram of empty ship mass you would need 65 times the mass of the Earth's worth of fuel.

[JoeRoccoCassara]

Using other stars as gravity slingshot is pretty fruitless. Only a small number would have the proper motion to be of any use, and the zig-zag course you would have to take in order to use them would add more time to your trip than you could possibly gain in the slingshots.

 

Then I would propuse a new Stage 3, amalgamated with a Stage 4, that together would make it much faster.

 

Stage 3: The Craft uses the earth's gravity as a sling shot to get to the sun, and then orbits around the sun several times, each time orbiting to a further distance to immitate a super sling shot

 

 

Stage 4: The top of the craft ejects a solar sail, and then saperates from the lower end, and the lower end of the craft ejects two super battery canons that can rotate closer to each other in order to avoid the solar sail getting so far away from the battery canons that the light particles don't propel it as fast.

 

 

 

Since the solar battey canons are moving at great speeds from the sun's super sling shot, the light particles have less distance to travel to get to the solar sail, thus, the top of the craft moves even faster. This combined with Gliese orbiting against the craft's flight path, will make the craft get their in under 40 years, seeing as how conventional solar sails move at half the speed of light.

[freeztar]

This combined with Gliese orbiting against the craft's flight path, will make the craft get their many times faster than light.

 

Nope. Light will always beat you. :)

[JoeRoccoCassara]

Nope. Light will always beat you. :)

 

The solar sail would be moving at over half the speed of light, now this trip might not be fast, over 20 years, maybe over 40, but it's still under 100, which is why this is our best alternative, and the quickest way to get there.

[Janus]

Then I would propuse a new Stage 3, amalgamated with a Stage 4, that together would make it much faster.

 

Stage 3: The Craft uses the earth's gravity as a sling shot to get to the sun, and then orbits around the sun several times, each time orbiting to a further distance to immitate a super sling shot

 

 

 

That's not how gravity slinghots work.

 

Stage 4: The top of the craft ejects a solar sail, and then saperates from the lower end, and the lower end of the craft ejects two super battery canons that can rotate closer to each other in order to avoid the solar sail getting so far away from the battery canons that the light particles don't propel it as fast.

 

 

 

Since the solar battey canons are moving at great speeds from the sun's super sling shot, the light particles have less distance to travel to get to the solar sail, thus, the top of the craft moves even faster. This combined with Gliese orbiting against the craft's flight path, will make the craft get their in under 40 years, seeing as how conventional solar sails move at half the speed of light.

 

Where in the world did you ever hear this?

[JoeRoccoCassara]

That's not how gravity slinghots work.

 

Where in the world did you ever here this?

 

Correction, in several years it can reach that speed,

 

How fast does a solar sail go?

The speed of an interplanetary solar sail spacecraft will depend on how long it has been propelled by the pressure of sunlight. The acceleration from sunlight is very small -- approximately five ten-thousandths of a meter per second per second, depending on the size and weight of the sail and the spacecraft. Over one day, that is a velocity increase of 45 meters per second or about 100 miles per hour.

[C1ay]

I haven't calabrated it yet, but it might get there faster than light would...

 

I think you might find this enlightening....

[Janus]

Correction, in several years it can reach that speed,

 

After 9,513 years at the acceleration given in the quote.

 

Besides that, in order to get your ship up to 0.5c, still requires the equivalent of the the entire energy comsumption of the US for a year per metric ton of ship. And that is at 100% efficiency (which is not acheivable).

 

Your plan is just not feasable in many respects.

 

For one, Gleise's radial velocity towards the solar system is only 9 km/sec, which is not going to shave any real time of the trip. (For instance, at 0.5c for the ship speed, it would only shave about 40 seconds off of the trip time.)

[JoeRoccoCassara]

After 9,513 years at the acceleration given in the quote.

 

Besides that, in order to get your ship up to 0.5c, still requires the equivalent of the the entire energy comsumption of the US for a year per metric ton of ship. And that is at 100% efficiency (which is not acheivable).

 

Your plan is just not feasable in many respects.

 

For one, Gleise's radial velocity towards the solar system is only 9 km/sec, which is not going to shave any real time of the trip. (For instance, at 0.5c for the ship speed, it would only shave about 40 seconds off of the trip time.)

 

My solar sail will be moving and accelerating many times faster than the solar sail designed in the quote, because the battery canons are following it at GREAT speeds, I'm not propusing using any more fuel than needed, if it doesn't reach half light speed it doesn't reach half light speed.

 

If your saying that any other propulsion would be faster or cheaper you are greatly mistaken, take Nuclear Pulse for example, quick jolts of speed doesn't equal a shorter flight there, the explosions that propel a craft aren't constant, therefore a craft that uses weaker yet constant propulsion will be moving in between each explosion of a nuclear pulse rocket, saving time.

 

Janus, it's the quickest/cheapest/best way to get there face it, there is no better way.

[C1ay]

Janus, it's the quickest/cheapest/best way to get there face it, there is no better way.

 

And you can prove this how?

[Moontanman]

My solar sail will be moving and accelerating many times faster than the solar sail designed in the quote, because the battery canons are following it at GREAT speeds, I'm not propusing using any more fuel than needed, if it doesn't reach half light speed it doesn't reach half light speed.

 

If your saying that any other propulsion would be faster or cheaper you are greatly mistaken, take Nuclear Pulse for example, quick jolts of speed doesn't equal a shorter flight there, the explosions that propel a craft aren't constant, therefore a craft that uses weaker yet constant propulsion will be moving in between each explosion of a nuclear pulse rocket, saving time.

 

Janus, it's the quickest/cheapest/best way to get there face it, there is no better way.

 

How do you get the laser cannons to follow your ship? Also what is the specific impulse of your set up? Manned or unmanned?

 

I postulate that a magnetic sail would be more efficient and able to accelerate even a huge mass to about .01 C given a large (nuclear) power source. The best thing about magnetic sails is they get bigger with no more power input as they get further from the sun, allowing the acceleration to be constant even though the power per square meter is always getting smaller as you get further from the sun.

[Janus]

My solar sail will be moving and accelerating many times faster than the solar sail designed in the quote, because the battery canons are following it at GREAT speeds, I'm not propusing using any more fuel than needed, if it doesn't reach half light speed it doesn't reach half light speed.

 

What GREAT speed is this? The speed you expect to get from the gravity slingshot just isn't there.

1. You can't continually gain speed by the way you show.

2. While you can pick up some speed by close flyby of planets, at best, you will gain a couple of km/sec above escape velocity from the Solar system. Meaning by the time you leave the Solar system you will only be moving at a couple of km/sec towards your target star. Meaning the rest of the speed of the craft will being from an increasing velocity difference between the cannons and the craft.

3. The cannons themselves won't even maintain the few km/sec they have. They will experience recoil from their own laser output, constantly slowing them down.

 

Your laser cannons would have to be huge. So huge, that the fuel needed to even get them into Solar orbit would be put to much better use just applied to the space craft proper and leaving the cannons on Earth. You don't gain anything by having the cannon "chasing" after the craft. You are actually robbing yourself of the best advantage of the light sail/laser cannon system; leaving the engine at home, where it has the resources of the planet to draw from to power it and keep it maintained.

 

You still haven't addressed the fact of the immense amounts of energy needed to get the craft up to any significant fraction of the speed of light.

 

To be quite frank, you simply have not displayed enough understanding of the basic orbital mechanics. engineering or physics involved.

[JoeRoccoCassara]

What GREAT speed is this? The speed you expect to get from the gravity slingshot just isn't there.

1. You can't continually gain speed by the way you show.

2. While you can pick up some speed by close flyby of planets, at best, you will gain a couple of km/sec above escape velocity from the Solar system. Meaning by the time you leave the Solar system you will only be moving at a couple of km/sec towards your target star. Meaning the rest of the speed of the craft will being from an increasing velocity difference between the cannons and the craft.

3. The cannons themselves won't even maintain the few km/sec they have. They will experience recoil from their own laser output, constantly slowing them down.

 

Your laser cannons would have to be huge. So huge, that the fuel needed to even get them into Solar orbit would be put to much better use just applied to the space craft proper and leaving the cannons on Earth. You don't gain anything by having the cannon "chasing" after the craft. You are actually robbing yourself of the best advantage of the light sail/laser cannon system; leaving the engine at home, where it has the resources of the planet to draw from to power it and keep it maintained.

 

You still haven't addressed the fact of the immense amounts of energy needed to get the craft up to any significant fraction of the speed of light.

 

To be quite frank, you simply have not displayed enough understanding of the basic orbital mechanics. engineering or physics involved.

 

 

Let me make sure you understand,

Stage 3: The Craft uses the earth's gravity as a sling shot to get to the sun, and then orbits around the sun several times, each time orbiting to a further distance to immitate a super sling shot

 

Just putting that out there.

 

Your laser cannons would have to be huge. So huge, that the fuel needed to even get them into Solar orbit would be put to much better use just applied to the space craft proper and leaving the cannons on Earth.

 

Leaving the canons on Earth is so stupid, the Solar Sail would stop moving after a certain range, if the Baterry Canons were following the sail then it would stay in range to push it, and the Baterry Canons might slow the Craft down, but the Ion Boosters still provide greater thrust than the recoil of Battery Canons.

 

You still haven't addressed the fact of the immense amounts of energy needed to get the craft up to any significant fraction of the speed of light.

 

Yeah I did, the fact that the battery canons stay in range long enough for the sail to accelerate to a fraction.

 

Even if the two canons went closer to each other, on Earth, they would still lose range after a long period of time.

[CraigD]

Unfortunately, Gardamorg, the criticism made by Janus and others in this thread are, I think, right on: you must, at least approximately, work out the numbers for your design, not just sketch it (including the word “super” as many labels as you can :D) and imagine it will perform as you hope. When you do, you’ll no doubt discover not only some fundamental problems involving mass and power, but upon attempting to adjust the design to overcome them, why “rocket science” is a common synonym for “a difficult task”, and why “the cold equations” are a famous literary metaphor for the unforgiving nature of spaceflight mechanics.

 

On the positive side, the idea of artificially powered light sails is widely considered one of the most promising approaches for spacecraft capable of reaching an extrasolar star withing a human lifetime. The main main advantages of this approach include (most of which Janus mentioned)

• that the propulsion power system (a gigantic, precisely focused laser, typically closely orbiting the sun) can be made as massive as needed, without affecting the acceleration of the low-mass lightsail spacecraft if propels
• and kept near our best (and, for all intents, only really big) available power source (the sun)
• and near all the maintenance and support people and materials it will need.

The main disadvantages include

• that even the most well-collimated lasers beams dissipate (become less powerful) with increased range, so the gigantic laser must be really gigantic,
• Light sails are very energy inefficient compared to mechanical motors and reaction-mass rockets, so the gigantic laser must be really, really gigantic,
  
• that, because the laser beam must be as narrow as possible to minimize power dissipation, keeping it on the distant spacecraft requires that it be really precise, many times more than the most precise existing aiming systems, such as those on space telescopes.

There are many variations on the “big propulsion system stays at home, little propelled craft goes on the trip” design theme, some of the most promising ones addressing the “light sails are very inefficient” issue by replacing the laser beam with a stream of bullet-like projectiles - which, if each is given a guidance and small course-correction propulsion system, can address the “must be really precisely aimed” issue.

 

Some of the best serious speculation on powered lightsail spacecraft were published by the late Robert Forward, who holds several patents on their technology. His 1985 hard science fiction novel “Rocheworld” has an excellent description of such a manned spacecraft the Prometheus, including illustrations and specifications in the book’s appendixes. The fictional Prometheus accelerated to .2 c in 20 years, coasted about 20 years, then used it’s separable multi-part sail to decelerate in about 2 years to rendezvous with planets in the Barnard's Star system, about 6 light-years from earth.

 

We’ve discussed powered lightsails several times in these forums, such as in this 5/1/2007 post, which has a few numbers on the aiming problem.