Author Topic: Photonic Propulsion to Mars in 3 Days  (Read 5798 times)

Offline cjackson

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« Last Edit: 02/23/2016 05:35 AM by cjackson »

Offline Prober

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Online TrevorMonty

Re: Photonic Propulsion to Mars in 3 Days
« Reply #2 on: 02/23/2016 06:32 PM »
Could be used to propel spacecraft involved space debris cleanup.
A cubesat with solar sail powered by remote laser maybe able deorbit
( or move to graveyard orbit) large satellites even old upper stages.

Offline qraal

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Re: Photonic Propulsion to Mars in 3 Days
« Reply #3 on: 02/23/2016 07:22 PM »
So long as you have enough laser power. Lasers aren't quite efficient enough for the top speed quoted in the article, but they'd be quite effective for near-Earth applications.

For interplanetary speeds, multiple reflection beam propulsion reduces the total laser power significantly. The maximum efficiency is about ~50%. The laser light loses a bit of energy with each bounce, due to the red-shift from reflecting off a moving reflector.

http://www.sciencealert.com/nasa-scientists-are-investigating-a-propulsion-system-that-could-reach-mars-in-3-days

http://livestream.com/viewnow/niac2015seattle/videos/105034354

Could Philip Lubin's idea actually work?

Offline Admiral_Ritt

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Re: Photonic Propulsion to Mars in 3 Days
« Reply #4 on: 02/24/2016 03:19 PM »
   Since this "Giant Laser" based on the Earth, is capable of knocking rival nations satellites out of position
and may even have a "fry that satellite" setting,  I can see a treaty being floated to prevent such devices
from being developed.   
       To send a substantial amount to mass to Mars this thing will need a dedicated power plant.
I don't recommend accelerating any payload to .3C  within the solar system.    at that speed a 1 gram
meteorite impacting at .3C will release result in the equivalent of 2.2 pounds of TNT.   It might be ok
in interstellar space where only dust is likely to be an obstacle.

  This seems like  distraction to Mars missions.  I am no fan colonizing the red planet, but
it is possible set up an outpost there w/0 too much trouble.  But if were going to wait lets wait until
a better space drive engine is available rather (some of which are close to being demonstrated)
 build some white elephant.

Online Stormbringer

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Re: Photonic Propulsion to Mars in 3 Days
« Reply #5 on: 02/24/2016 03:38 PM »
treaties seem to be worth less than the TP they are written on though. they are violated regularly at will by everybody.
When antigravity is outlawed only outlaws will have antigravity.

Offline aceshigh

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Re: Photonic Propulsion to Mars in 3 Days
« Reply #6 on: 02/24/2016 05:22 PM »
Reaching Mars in 3 days using a giant laser 100 times the mass of the ISS, on LEO, sounds super swell!!

only problem is STOPPING on Mars. Better start positioning 1 of these HUGE lasers on Mars orbit, so we can decelerate payloads or spaceships. That is, IF they use nuclear fusion power.

If they are solar powered, we better position 2-3 of those huge lasers on Mars orbit, since they will get much less power from the Sun at that distance.

Online Robotbeat

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Re: Photonic Propulsion to Mars in 3 Days
« Reply #7 on: 02/25/2016 01:29 AM »
Reaching Mars in 3 days using a giant laser 100 times the mass of the ISS, on LEO, sounds super swell!!

only problem is STOPPING on Mars. Better start positioning 1 of these HUGE lasers on Mars orbit, so we can decelerate payloads or spaceships. That is, IF they use nuclear fusion power.

If they are solar powered, we better position 2-3 of those huge lasers on Mars orbit, since they will get much less power from the Sun at that distance.
Or use a bigger solar array.

Solar power is beamed fusion.
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Offline sanman

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Re: Photonic Propulsion to Mars in 3 Days
« Reply #8 on: 02/26/2016 03:59 AM »
What about if you had a giant blimp floating at the top of the atmosphere, with a cable running back to a nuclear reactor on the ground? This would then power your laser beam to propel the sail quickly to Mars.

When he says "3 days to Mars" - is he talking about during that once-in-3-years window when Mars is closest to Earth?

Or can it get you to Mars in 3 days, no matter when you launch?

Is this something Musk would ever be interested in?
« Last Edit: 02/26/2016 03:59 AM by sanman »

Offline Asteroza

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Re: Photonic Propulsion to Mars in 3 Days
« Reply #9 on: 02/26/2016 06:36 AM »
If Musk was interested in laser launch/laser interplanetary propulsion, he would have invested in Lasermotive...

Online Robotbeat

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Re: Photonic Propulsion to Mars in 3 Days
« Reply #10 on: 02/26/2016 12:13 PM »
The reason this is hard is because you need tens of Gigawatts for your laser. This would cost a trillion dollars just for the laser. MCT sounds super cheap in comparison.

Musk's strategy is to develop a self-sustaining-capable megacity on Mars, which will provide the incentive to develop better and better transport systems. This feedback loop would eventually produce something capable enough for interstellar travel, perhaps beamed propulsion or maybe super-efficient fusion ("regular" fusion wouldn't be better than a really good solar array, at least not in the inner solar system).
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

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Offline Vultur

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Re: Photonic Propulsion to Mars in 3 Days
« Reply #11 on: 02/26/2016 10:38 PM »
("regular" fusion wouldn't be better than a really good solar array, at least not in the inner solar system).

fusion-powered NEP, maybe not, but couldn't you do other forms of fusion propulsion that would have really high exhaust velocity and very high thrust? Something like a fusion only (no fissionables) "Orion" / nuclear pulse drive? I believe something like that was proposed for 'Project Daedalus' which was something like a 50 year Alpha Centauri flyby?

Offline cjackson

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Offline qraal

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Re: Photonic Propulsion to Mars in 3 Days
« Reply #13 on: 03/04/2016 09:46 AM »
"Daedalus" was meant to go to Barnard's Star, which was thought to have at least two planets in the 1970s. It doesn't, but the "discoverer" didn't want to admit he'd been fooled by his telescope's wobbles.

Interstellar "Orion" uses pure deuterium "bombs" - something we can't presently make.

"Daedalus" used electron-beam compression to ignite fusion between deuterium and helium-3. Unfortunately the e-beams aren't stable enough for the job, but in the 1970s no one knew that.

("regular" fusion wouldn't be better than a really good solar array, at least not in the inner solar system).

fusion-powered NEP, maybe not, but couldn't you do other forms of fusion propulsion that would have really high exhaust velocity and very high thrust? Something like a fusion only (no fissionables) "Orion" / nuclear pulse drive? I believe something like that was proposed for 'Project Daedalus' which was something like a 50 year Alpha Centauri flyby?

Offline KelvinZero

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Re: Photonic Propulsion to Mars in 3 Days
« Reply #14 on: 07/19/2016 08:00 AM »
Does this version exploit multiple bounces of the laser light?

That version of the light propulsion idea has always interested me. Billions of reflections would be almost as effective as a billion times as much power. You just need some sort of super retroreflector. Quantum mechanics always seems to be throwing out weird things like that: superconductors, superfluids..

Offline john smith 19

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Re: Photonic Propulsion to Mars in 3 Days
« Reply #15 on: 07/19/2016 10:54 AM »
http://www.sciencealert.com/nasa-scientists-are-investigating-a-propulsion-system-that-could-reach-mars-in-3-days

Listen to the audio.

8GW for 10 mins.  That's 4.8 Tj. Typical large commercial power plants are in the 0.5-1.0 Gw range.

Which you then have to punch through the Earths atmosphere (compensating for heat distortion using some kind of active optics system).

The alternative would be to put an 8 GW battle  launch station in orbit with a pulse power system of some kind. BTW the entire ISS PV array generates 200Kw, taking about 278 days to generate the power needed for such a launch, assuming you can store it of course.

This is very much the SDI system re-born.

Didn't some Russian Oligarch propose something similar quite recently?
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Online TrevorMonty

Re: Photonic Propulsion to Mars in 3 Days
« Reply #16 on: 07/19/2016 04:05 PM »
With multiple stations in GEO it should be possible to deliver significant payloads (100s kg) to GEO and beyond in reason able time frame. To get from LEO to GEO the vehicle spirals out with each GEO station giving it boost on each orbit of earth.

When not boosting space craft the stations would be beaming power to earth via microwave. You can also use same technique in reverse for GEO to LEO trips.


Offline Dr_Zinj

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Re: Photonic Propulsion to Mars in 3 Days
« Reply #17 on: 08/05/2016 01:31 PM »
Reaching Mars in 3 days using a giant laser 100 times the mass of the ISS, on LEO, sounds super swell!!

only problem is STOPPING on Mars. Better start positioning 1 of these HUGE lasers on Mars orbit, so we can decelerate payloads or spaceships. That is, IF they use nuclear fusion power.

If they are solar powered, we better position 2-3 of those huge lasers on Mars orbit, since they will get much less power from the Sun at that distance.
Or use a bigger solar array.

Solar power is beamed fusion.

Mars is twice the distance from the Sun as Earth.  You'd need a solar array 4 times the size to gather the same amount of solar energy.

Online Robotbeat

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Re: Photonic Propulsion to Mars in 3 Days
« Reply #18 on: 08/07/2016 08:44 PM »
Reaching Mars in 3 days using a giant laser 100 times the mass of the ISS, on LEO, sounds super swell!!

only problem is STOPPING on Mars. Better start positioning 1 of these HUGE lasers on Mars orbit, so we can decelerate payloads or spaceships. That is, IF they use nuclear fusion power.

If they are solar powered, we better position 2-3 of those huge lasers on Mars orbit, since they will get much less power from the Sun at that distance.
Or use a bigger solar array.

Solar power is beamed fusion.

Mars is twice the distance from the Sun as Earth.  You'd need a solar array 4 times the size to gather the same amount of solar energy.
False. Mars is ~1.5x as far away, requires ~2-2.5x. And still solar electric beats nuclear electric. Solar is that good.

In principle, you can make a solar array almost as thin as a solar sail and use the same kind of structure as a solar sail uses to support it. This can allow kilowatts or even tens of kilowatts per kilogram of specific power, even at Mars' distance.
« Last Edit: 08/07/2016 08:44 PM by Robotbeat »
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Offline jstrout

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Re: Photonic Propulsion to Mars in 3 Days
« Reply #19 on: 03/01/2017 03:38 AM »
Sorry to chime in late, but I've just stumbled across this, and I'm really having trouble with my incredulity.

He claims he can accelerate a 100 kg probe to 0.3 c in 10 minutes.  By my rough calculation, that's an acceleration of over 15,000 G's.

No matter how shiny your reflector is... are we really accelerating a macroscopic object at 15,000 G's with photon pressure alone?  Without vaporizing it?

I find it hard to believe, but no, I haven't done the math.  So I fully recognize it may be simply a failure of imagination on my part.  But since this particular figure hasn't been brought up in this thread, I throw it out there for reaction from people smarter than me.

Offline Proponent

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Re: Photonic Propulsion to Mars in 3 Days
« Reply #20 on: 03/01/2017 08:56 AM »
He claims he can accelerate a 100 kg probe to 0.3 c in 10 minutes.  By my rough calculation, that's an acceleration of over 15,000 G's.

It's 100 kg to Mars in three days; that corresponds to a speed of much less than 0.3c.  No mass is quoted for the probe to be accelerated to 0.3c.

Offline rdheld

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Re: Photonic Propulsion to Mars in 3 Days
« Reply #21 on: 03/01/2017 11:28 AM »
What spacecraft can stay intact and fucntional after a 15K g acceleration period?

Offline IRobot

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Re: Photonic Propulsion to Mars in 3 Days
« Reply #22 on: 03/01/2017 12:50 PM »
All of these mega projects (mega-laser, space elevator, etc) are doomed to fail because of initial investment cost and the huge risk of being technologically surpassed before they have return of investment.

The path forward is to use existing technology and cut down costs by organizational measures. Basically what SpaceX is doing and what others are starting to do (ULA, Arianespace, etc).

Of course, keeping an eye for technologies reaching a useful readiness level and that can be employed on small scale.

Offline jstrout

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Re: Photonic Propulsion to Mars in 3 Days
« Reply #23 on: 03/01/2017 01:40 PM »
It's 100 kg to Mars in three days; that corresponds to a speed of much less than 0.3c.  No mass is quoted for the probe to be accelerated to 0.3c.

In the , he says: "It takes us about 10 minutes to get to 30% of the speed of light.  ...We could propel a 100 kg craft to Mars in a few days."

It's this "10 minutes to get to 30% the speed of light" figure that I was reacting to.  Now it's possible the "3 days to Mars" is referring to a completely different flight profile (it's not even mentioned in the paper I could find), but from the juxtaposition in the video, it sure sounds to me like he's talking about the same thing.

Offline KelvinZero

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Re: Photonic Propulsion to Mars in 3 Days
« Reply #24 on: 03/02/2017 03:56 AM »
https://www.extremetech.com/computing/162322-mit-creates-the-first-perfect-mirror

Im not sure if that is actually perfect, but that is what would make the idea interesting to me. Light is about the most inefficient way of pushing something. If you had perfect mirrors it would be the perfect way of pushing something. You just have one mirror on a heavy object like the moon, the other on your vehicle, trap some photon energy between the mirrors and after billions of reflections it would pretty much all end up as kinetic energy on your vehicle.

If there is such a thing as a truely perfect mirror, you could also understand it not heating up.

Offline john smith 19

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Re: Photonic Propulsion to Mars in 3 Days
« Reply #25 on: 03/22/2017 11:11 PM »
What spacecraft can stay intact and fucntional after a 15K g acceleration period?
Pretty much the same kind of tech that's used to developed GPS guided naval artillery shells at something like 15 000g's.

It's not impossible but it's not easy.
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Online MATTBLAK

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Re: Photonic Propulsion to Mars in 3 Days
« Reply #26 on: 03/22/2017 11:50 PM »
What spacecraft can stay intact and fucntional after a 15K g acceleration period?
Let alone the crew! Even accelerating at a constant 1/10th of a G or similar after achieving Earth escape would give outstanding performance to anywhere in the Solar System.
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Offline Proponent

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Re: Photonic Propulsion to Mars in 3 Days
« Reply #27 on: 03/23/2017 09:12 AM »
In the , he says: "It takes us about 10 minutes to get to 30% of the speed of light.  ...We could propel a 100 kg craft to Mars in a few days."

It's this "10 minutes to get to 30% the speed of light" figure that I was reacting to.  Now it's possible the "3 days to Mars" is referring to a completely different flight profile (it's not even mentioned in the paper I could find), but from the juxtaposition in the video, it sure sounds to me like he's talking about the same thing.

That is very confusing, but "30% of the speed of light"  and "3 days to Mars" have nothing to do with each other.  It takes light 8 minutes to cover 1 AU, so at 30% of the speed of light it would take about half an hour to cover 1 AU.  Even when Mars, about 1.5 AU from the sun, is on the opposite side of the sun, the travel time would be less than an hour and a half.
« Last Edit: 03/23/2017 09:15 AM by Proponent »

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