Getting to Alpha Centauri in 16 years via Laser Propulsion

Something i read a lot here from skeptics of interstellar space travel is the enormous trip times to even the nearest star. there are however many options for shortening that trip time drastically. Skeptics blink and fail to credit even likely near term developments like fusion powered ion ships or fusion propelled ships. here is yet another solution that could be done near term with an appropriate attitude and funding:

Apparently research on laser propulsion is picking up pace a bit. this project is ambitious and maybe 90 percent aspirational but they have thoroughly researched many of the particulars. It could send a very small probe to alpha centauri in 16 years. That's travel time and not the commencement date. the commencement date would depend mostly on funding.

nextbigfuture.com...

The impossible task of traveling 25.6 trillion miles to Alpha Centauri, our closest star, is now possible. Using a Directed Energy System for Targeting of Asteroids and exploRation (DE-STAR), a versatile, scalable phased-array laser system, it can be reached in a short 16 years. Our project entails carrying out both computational and experimental studies of specific uses of DE-STAR to investigate photon recycling and spacecraft propulsion. Photon recycling is a unique term used to describe a form of energy conservation relative to this project. This effect will greatly improve the efficiency of spacecraft making interstellar flight more plausible. What lies beyond our solar system is one of the biggest mysteries of mankind and it finally has the potential to be solved.

personally while this will do to send probes i don't find it appealing because i am for manned solutions. probes are worthwhile too but only as a precursor to manned exploration. never the less this demonstrates you do not need some magical technology and improbable physics to get to the nearby stars.

bear in mind that there are many other realistic options too especially for manned missions.

space craft on a chip...

Wafer Scale Spacecraft. Recent work at UCSB on Si photonics now allows us to design and build a "spacecraft on a wafer". The recent (UCSB) work in phased array lasers on a wafer for ground-based optical communications combined with the ability to combine optical arrays (CMOS imagers for example) and MEMS accelerometers and gyros as well as many other sensors and computational abilities allows for extremely complex and novel systems. Traditional spacecraft are still largely built so that the mass is dominated by the packaging and interconnects rather than the fundamental limits on sensors. Our approach is similar to comparing a laptop of today to a super computer with similar power of 20 years ago and even a laptop is dominated by the human interface (screen and keyboard) rather than the processor and memory. Combining nano photonics, MEMS and electronics with recent UCSB work on Si nano wire thermal converters allows us to design a wafer that also has an embedded RTG or beta converter power source (recent LMCO work on thin film beta converters as an example) that can power the system over the many decades required in space. Combined with small photon thrusters (embedded LEDs/lasers for nN thrust steering on the wafer gives a functional spacecraft

so the biggest problem i see is you can get it to alpha centauri in 16 years....ok. How is it going to transmit the about 5 MW signal necessary for delivering data back to earth?

a reply to: stormbringer1701

Dr. E Vyl proposed this earlier
www.youtube.com...

a reply to: M5xaz

curses. prempted again!

I'm already there! Alpha Centauri ROCKS!!!

Great thread!!!!! S+F


I think of the possibilities of something like this with self organizing "smart dust" for remote sensing!

What an amazing era of discovery that would permit!

a reply to: stormbringer1701

In answer to your final question, you could 'drop' a couple of relay transponders along the way.

You'd reduce mass with each drop off and create a semi-permanent comms network all the way to another star.

To my way of thinking, the real issue is how do you decelerate the probe?

Jade's "smart dust"would be great but not if it blows on by too fast.

originally posted by: chr0naut
a reply to: stormbringer1701

In answer to your final question, you could 'drop' a couple of relay transponders along the way.

You'd reduce mass with each drop off and create a semi-permanent comms network all the way to another star.

To my way of thinking, the real issue is how do you decelerate the probe?

Jade's "smart dust"would be great but not if it blows on by too fast.

Full Disclosure: My pet SETI project is one which looks to detect "someone eles's" smart dust in the near Earth and solar system environment. Shhh…. no paper yet

originally posted by: chr0naut
a reply to: stormbringer1701

In answer to your final question, you could 'drop' a couple of relay transponders along the way.

You'd reduce mass with each drop off and create a semi-permanent comms network all the way to another star.

To my way of thinking, the real issue is how do you decelerate the probe?

Jade's "smart dust"would be great but not if it blows on by too fast.

well maybe something like an m2p2 for a star powered parachute? or actually the outward stellar wind even without an m2p2 parachute. but i think they actually have a complicated mirror system that allows then to invert the laser beam direction at the probe end.

my issue is still getting a useful signal all the way home once there.

you could get a radio signal home at 1 MW on a 40 meter high gain antenna with about a 900 baud rate. for broadband you'd need 5 MW.

news.discovery.com...

originally posted by: JadeStar



Full Disclosure: My pet SETI project is one which looks to detect "someone eles's" smart dust in the near Earth and solar system environment. Shhh…. no paper yet

Outstanding! Someone has to do it.

originally posted by: JadeStar

originally posted by: chr0naut
a reply to: stormbringer1701

In answer to your final question, you could 'drop' a couple of relay transponders along the way.

You'd reduce mass with each drop off and create a semi-permanent comms network all the way to another star.

To my way of thinking, the real issue is how do you decelerate the probe?

Jade's "smart dust"would be great but not if it blows on by too fast.

Full Disclosure: My pet SETI project is one which looks to detect "someone eles's" smart dust in the near Earth and solar system environment. Shhh…. no paper yet

Very cool!

I'd think that detecting nanoprobes would be damn near impossible but their comms chatter might be (either between themselves or back to base).

I still think that the establishment of a relay line makes sense across interstellar distances.

The other thing is that the probes would most likely be intelligent, so as to adapt to what ever conditions they find. If we did discover them, we may think that they are the main guys rather than their builders.

at the risk of derailing off the topic of laser powered flight here is another thing that would work but you'd have to do two things: get something to go .3 to .5 c if only temporarily. Fusion can theoretically do this. and secondly you'd have to be crazy enough to fly it at full speed towards a big gravity well on a collision course.

physics.stackexchange.com...

once you do this though (and changed your drawers) you'd get a hyper relativistic speed boost and could get to AC in about 4.5 years not counting deacceleration time.

Edit: Deaccleration time for a manned craft had better be about a year. you'd need far less time for a unmanned probe that won't die under a higher g load.

now back to the OP:

nextbigfuture.com...

it seems this project intends to get the laser/wafer sats to .25 C.

EDIT: and the second articles does awaywith my first objection by proposing 100 ton craft:

Mass and speed wkith 100 GW laser

1 gram 24% of lightspeed
10 grams 14% of lightspeed
100 grams 7.8% of lightspeed
1 kg 4.3% of lightspeed
10kg 2.4% of lightspeed
100kg 1.4% of lightspeed
1000kg 0.77% of lightspeed
10 tons 0.43% of lightspeed
100 tons 0.24% of lightspeed

a reply to: stormbringer1701

At that speed, a 100 ton craft would take over 400 years to travel 1LY, if Im understanding this correctly.

a reply to: stormbringer1701
all these technicalities just to traverse a few light years...

wouldnt it be easier to convert our conciousness into a form that we can manipulate and send ourselves anyhwere we want in the form of light?

Some quick calculations:

Assuming 50% efficiency (very high), to accellerate a 1 kilogram (2.2 pound) object to .25c would require

~8.333x10*14 Joules
which is equivalent to
231,870,000 KiloWatt-hours, or
834,000 GigaWatt-seconds
(Don't ask me what that is in pirate-ninjas)

The total energy-generating capacity of the United States is ~1,100 GigaWatts,
so it would take every single Watt of power produced in the U.S. for ~12 minutes 40 seconds
to accellerate 1Kg to .25c.

Ballpark figures, but it definitely gives you an idea of the magnitude of the task.

originally posted by: Saint Exupery
Some quick calculations:

Assuming 50% efficiency (very high), to accellerate a 1 kilogram (2.2 pound) object to .25c would require

~8.333x10*14 Joules
which is equivalent to
231,870,000 KiloWatt-hours, or
834,000 GigaWatt-seconds
(Don't ask me what that is in pirate-ninjas)

The total energy-generating capacity of the United States is ~1,100 GigaWatts,
so it would take every single Watt of power produced in the U.S. for ~12 minutes 40 seconds
to accellerate 1Kg to .25c.

Ballpark figures, but it definitely gives you an idea of the magnitude of the task.

Thanks for doing the math. In many of these speculative scenarios,it is always a somber wake-up.

... but I'd really like to know the pirate-ninja value!

Also, no one seems to have considered what happens when a slight misalignment spins the probe and exposes its non-mirrored side. With the energy being poured into it, it would (by my estimation) last one only poofteenth* of a second.

originally posted by: 3n19m470
a reply to: stormbringer1701

At that speed, a 100 ton craft would take over 400 years to travel 1LY, if Im understanding this correctly.

That is true...at least for now but (stolen from posterJohnSmith19 at NSF) :

Exhaust velocity for an Ion thruster c 30 000 m/s or 0.01% of lightspeed
Exhaust velocity for a fission fragment rocket 3-5% of lightspeed.

we are at third generation ion drives now. and ion drives went from wimpy to awesomely fast in just three generations of technology evolution. they can go one one hundredth of one percent of the speed of light. but their potential is not limited as laser sails are by making huge improbable laser arrays and PV panels to power them.

currently the biggest spaceborne PV array, the one on the ISS is 200KV. the laser sails guys are talking one a million times bigger than the ISS array.

But it's not really the point. the point is we can get to interstellar speeds. and its not 100s of years off and it stems from well understood physical principles and science.

originally posted by: combatmaster
a reply to: stormbringer1701
all these technicalities just to traverse a few light years...

wouldnt it be easier to convert our conciousness into a form that we can manipulate and send ourselves anyhwere we want in the form of light?

You can get right on that. meanwhile we'll get out the toolboxes and get building real hardware.

originally posted by: Saint Exupery
Some quick calculations:

Assuming 50% efficiency (very high), to accellerate a 1 kilogram (2.2 pound) object to .25c would require

~8.333x10*14 Joules
which is equivalent to
231,870,000 KiloWatt-hours, or
834,000 GigaWatt-seconds
(Don't ask me what that is in pirate-ninjas)

The total energy-generating capacity of the United States is ~1,100 GigaWatts,
so it would take every single Watt of power produced in the U.S. for ~12 minutes 40 seconds
to accellerate 1Kg to .25c.

Ballpark figures, but it definitely gives you an idea of the magnitude of the task.

WRT PV power we might get there though:

nextbigfuture.com...