Author Topic: Photonic Propulsion to Mars in 3 Days  (Read 6284 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.

Offline 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.
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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.

Offline 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 »

Online 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...

Offline 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?
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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.

Offline 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.

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