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Light Sail Propulsion Could Reach Sirius Sooner Than Alpha Centauri (arxiv.org)
RockDoctor writes: A recent proposition to launch probes to other star systems driven by lasers which remain in the Solar system has garnered considerable attention. But recently published work suggests that there are unexpected complexities to the system. One would think that the closest star systems would be the easiest to reach. But unless you are content with a fly-by examination of the star system, with much reduced science returns, you will need to decelerate the probe at the far end, without any infrastructure to assist with the braking. By combining both light-pressure braking and gravitational slingshots, a team of German, French and Chilean astronomers discover that the brightness of the destination star can significantly increase deceleration, and thus travel time (because higher flight velocities can be used). Slingshotting around a companion star to lengthen deceleration times can help shed flight velocity to allow capture into a stable orbit. The 4.37 light year distant binary stars Alpha Centauri A and B could be reached in 75 years from Earth. Covering the 0.24 light year distance to Proxima Centauri depends on arriving at the correct relative orientations of Alpha Centauri A and B in their mutual 80 year orbit for the sling shot to work. Without a companion star, Proxima Centauri can only absorb a final leg velocity of about 1280km/s, so that leg of the trip would take an additional 46 years. Using the same performance characteristics for the light sail, the corresponding duration for an approach to the Sirius system, almost twice as far away (8.58 lightyears), is a mere 68.9 years, making it (and it's white dwarf companion) possibly a more attractive target. Of course, none of this addresses the question of how to get any data from there to here. Or, indeed, how to manage a project that will last longer than a working lifetime. There are also issues of aiming -- the motion of the Alpha Centauri system isn't well-enough known at the moment to achieve the precise maneuvering needed without course corrections (and so, data transmission from there to here) en route.
Thats how it begins. a "Thought Experiment" that is. 70 years is a great amount of knew tech... we will likely have something in 40 years that will sail right past our sail ships.,,, hmmm
[($)]
So you have to replace the apostrophe with a dwarf apostrophe?
Ezekiel 23:20
we aren't going to travel between the stars until we figure out something a whole lot better than chemical rockets
If only somebody would put some serious effort into solar sail trajectories!
and probably FTL drive... Everything else is just fantasy...
Umm.....
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
No, this is a way to significant increase BRAKING power. The speed up is tied to Sol no matter where we point a light sail, by changing the destination we can slow down a LOT faster.
Getting a person there with something better than chemical rockets is just fantasy since if you got the vehicle to move fast enough even the cosmic background radiation will be shifted enough to irradiate people to death.
Of course, a different fantasy of cryosleep plus slow travel or FTL removes that in SF at least, but not so much in reality.
This thing on the other hand looks like a way to get a machine to another star using something that needs nothing more than some years of development (https://en.wikipedia.org/wiki/Solar_sail#Projects_operating_or_completed) instead of wishing so I do not get why you are calling it fantasy.
We've already "worked out" quantum entanglement enough to know that we can't "siwtch" an entangled particle's spin.
It's impossible to transmit information using entanglement.
systemd is Roko's Basilisk.
Given that you have to take all the fuel for deceleration with you
That's not how a solar sail works.
systemd is Roko's Basilisk.
Lolwut?
My first program:
Hell Segmentation fault
https://en.wikipedia.org/wiki/...
Not faster than light, which is what this was about.
With current technology, that's all you'll be doing. Focus on Mars or Moon bases for now.
This is a Thought Experiment, not a real plan to go anywhere... we aren't going to travel between the stars until we figure out something a whole lot better than chemical rockets and probably FTL drive...
Everything else is just fantasy...
The missions being envisioned here are for small robots that can be accelerated and decelerated with reasonably foreseeable technologies, not humans with life support. Being able to decelerate into a target system would not only increase the data return, but would enable a small probe to locate accessible resources (as in not down a gravity well) to construct a transmitter large enough to return the data in the first place.
It's impossible to transmit information using entanglement.
Just to clear this up, parent meant it's not possible to communicate faster-than-light using entanglement.
would enable a small probe to locate accessible resources (as in not down a gravity well) to construct a transmitter large enough to return the data in the first place.
I'm not sure how you think a small robot can find suitable resources, fly over there, and convert those resources into a large working transmitter, provide it with energy, and keep it aimed at the Earth. That's not a small robot, but a very large manufacturing base.
Some people think on longer time frames than you do.
https://en.wikipedia.org/wiki/...
Elon Musk will build a 3D printer that can do it. It'll be powered by blockchains.
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
Thought experiments are how you come up with an idea that nobody has thought of before.
Back in the late 1980sI was on an email discussion group for Traveller (a sci-fi RPG). Someone asked why hydrogen fuel (for fusion) was stored as water aboard ships. Someone answered that water stores hydrogen atoms more densely than hydrogen gas, and the energy needed to chemically break off the hydrogen atoms off of water was trivial compared to the energy you could get from fusing them into helium. That spawned a discussion about whether there were other molecules which stored hydrogen even more compactly. Methane (CH4) was an obvious choice - 4 hydrogen atoms per non-hydrogen base, compared to just 2 for water (H2O). But eventually we settled on ammonia (NH4) because it's liquid at room temperature and wouldn't require pressurization or cryogenic storage in a vehicle sharing space with a life support environment for humans.
It's totally useless info right now (and probably the next few decades). But it's something that will be important in the future.
Coincidentally, I was out walking today through a forest that was originally planted in the 1300s, in order to provide timber for the anticipated navy of the 1600s. Even though the people who planted the trees wouldn't see them grow to a usable size.
Lordy! - they must have been superhumans, those Mediaeval foresters. Able to think centuries ahead, where modern people just cannot do that any more.
Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"
No. The only forces being modelled for deceleration in the target systems are those of light pressure and gravity - which we can calculate from the light flux (observed at Earth), the range (parallax), and orbital mechanics.
Once someone has a design for a probe (mass, sail area, reflectivity) then the analysis can be re-done to calculate the travel times (and important things, like how much ahead of the proper motion of the target object you have to aim. to hit the target) with your actual device. This analysis compared travel times for otherwise identical probes dispatched to different targets, and an optimal course strategy for getting there quickest and slowing down to orbital speeds at the far end. There are a few other constraints (e.g., a maximum probe temperature of 100C / 373K, to allow plausible electronics to survive) which could be revisited with an actual "release to manufacturing" design, but this paper provides a road map for how to optimise the trajectory once you get to that point.
Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"