luisair Posted March 2, 2014 Share Posted March 2, 2014 Good morning everyone, as mentioned in the title, i'd like to know how interstellar flight between Stars in galaxys work.Are they the same, just on a way bigger scale?And how would someome get to Alpha Centauri for example? Via Hohmann-transfer?Thanks for Helpful anwers Link to comment Share on other sites More sharing options...
Awaras Posted March 2, 2014 Share Posted March 2, 2014 (edited) Since our Sun and Alpha Centauri orbit around the center of our galaxy, theoretically, you could perform a Hohmann transfer there, but you would probably need to wait a few million years for the right alignment. Besides, even if you did, the speed would probably be so low it would take several thousand years for your craft to get there.And if you are able to reach speeds that would allow you to get there in a single human lifetime, the transfer would involve more or less burning in a straight line towards Alpha Centauri (with a bit of leading to account for the relative velocities of our two star systems). Edited March 2, 2014 by Awaras Link to comment Share on other sites More sharing options...
Ralathon Posted March 2, 2014 Share Posted March 2, 2014 It works exactly the same as normal orbital mechanics, but the timescales and distances are unimaginably longer.For example, if you'd use a hohmann transfer from here to alpha centauri it'd take you around 125 million years to actually get there. So if the dinosaurs of the early cretacious launched a probe it would be arriving now. Therefore people suggest that we go for a so called Brachistochrone transfer. Basically it means: Point at the object and burn for half your dV, when you get there burn the remaining dV. So if you pack enough dV you can make the trip arbitrarily short. And this is the main problem for interstellar flight: How can you build something that has immense amounts of dV, high acceleration and can survive interstellar space for centuries.It's a problem that won't be solved for quite some time... Link to comment Share on other sites More sharing options...
Brotoro Posted March 2, 2014 Share Posted March 2, 2014 You don't need to use a Hohmann transfer to get from the Sun to Alpha Centauri. Both stars are at almost the same location in their very large, very similar orbits... so just aim straight at the point where Alpha Centauri will be, accounting for the stars' relative motions during the time it takes your ship to travel there (the relative motion is small compared to their orbital speeds around the Galaxy). Preferably use a ship that goes as fast as possible. Link to comment Share on other sites More sharing options...
FanaticalFighter Posted March 2, 2014 Share Posted March 2, 2014 Going to Alpha centauri via a Hohmann transfer would be like going rendezvous with a ship 100 m away from you via a Hohmann transfer. What you do is point yourself at the star, burn your rockets until you reach a certain max velocity, then turn around, and burn the other way, and do this such that by the time you finally stop, you are in orbit around Alpha Centauri. Link to comment Share on other sites More sharing options...
DonLorenzo Posted March 2, 2014 Share Posted March 2, 2014 Compare an interplanetary transfer with the final approach on a rendez-vous mission. Yeah, you could use a hohmann transfer to bridge those last 25 kilometers, but mostly you wouldn't. It's quite the same with interstellar travel.Supposing you've got anything close to a good sci-fi propulsion system it's going to be much much closer to 'point and shoot' than a hohmann rendez-vous. I'm not sure if the scales in my example compare to the right ballpark, but the principle is sound.edit: ninja'ed by an hour >< Oh well, it's what you get for opening many tabs at once Link to comment Share on other sites More sharing options...
luisair Posted March 2, 2014 Author Share Posted March 2, 2014 Thank you Question answered, thread can be closed Link to comment Share on other sites More sharing options...
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