It looks like you're using an Ad Blocker.
Please white-list or disable AboveTopSecret.com in your ad-blocking tool.
Some features of ATS will be disabled while you continue to use an ad-blocker.
originally posted by: Tripnman
a reply to: muSSang
I'm just riffing here, but couldn't we use some sort of gravitational breaking at the destination end of the trip, slowing down faster than just reversing thrust vectors at the half-way point?
originally posted by: eriktheawful
a reply to: Tripnman
On the other hand, I'd shrudder to think what would happen to an object traveling that fast to get to the nearest star if it tried aerobraking.
originally posted by: Iamnotadoctor
originally posted by: Teikiatsu
I imagine a combination of gravity slingshot and solar sail could allow reverse thrusting to be held off until the 2/3 or 3/4 point of the journey.
You have quite an imagination then.
Really interesting thread, just wish I had the math, a constant acceleration of 1 G must build into a huge speed,
Excel works fine.
Anyone got a CRAY computer?
strictly speaking this is true but it assumes no other technology is involved in deacceleration. The EM drive is compact and light weight even if it must be scaled up to be a practical primary propulsion drive. this means there is fudge room for the mass of the rest of the package mass of the craft. So there is nothing to preclude you from adding a M2P2 generator the size of a coffee can to the craft. and that means you can use a tens to 100s of kilometer diameter magneto-plasma sail parachute on the deacceleration phase. This works best inside the "helio"sphere of the target star but can significantly boost deacceleration and shorten deacceleration time. And of course you can use it to accelerate at the beginning of the trip too.
originally posted by: muSSang
Don't forget you need the same amount of power/thrust to slow it down, so multiply the time of arrival by 2.
you have time dilation wrong you know. from the rest frame (proximal start point of trip) there is no difference in the passage of time generated by the act of sending a relativistic ship. on the ship (depending on how close to c it travels) the crew experiences something weird. the trip appears to only take (for example) a few weeks despite the ships clocks appearing to run normally. but when they get back they will find that ten years has passed at home. they will have about ten years of food water and other consumables left on thier ship that they did not use.
originally posted by: Flyingclaydisk
Whenever one of these motive design theories comes forward people always start speculating about deep space travel, but they always conveniently leave out one critical (albeit depressing) reality about the whole concept. Deep space travel, no matter how you slice it, will always be a one-way affair.
First, deep space travel at orbital speeds is not really practical for humans because it would take thousands of generations to complete. These speeds are relatively low when compared to the vast distances involved in such a journey. The known hazards of long term space travel would render the travelers to globs of traveling "goo" after such an endeavor reducing the value of such an effort to zero.
Second, and most importantly, inter-stellar space travel really only becomes a reality when / if mankind develops the ability to travel at high percentages of the speed of Light...but there's a catch, a BIG catch. When / if such velocities are achieved, good ol' Relativity kicks in making the 'trip' a value only to the traveler, not to those left behind.
Without getting into too much complex mathematics, high speed travel affects the traveler differently than those left behind. Specifically, the traveler ages at a much different, much slower, rate relative to the non-traveler. And, there's no way to "un-do" this phenomenon when the trip is complete.
The analogy I use to explain this concept to people is as follows:
Let's say mankind miraculously devises a spaceship capable of traveling at 99% the speed of light (we'll forget the mass and energy requirements implications for a moment just for the sake of discussion). So, Buzz Lightyear hops in his new space Ferrari and heads off to Proxima Centauri with hopes to save the human race on Earth. His journey takes him roughly 5 years to get there. Once there, Buzz finds a planet just like Earth, but far more advanced (let's call it Earth Redux). Earth Redux has infinite energy reserves, all diseases have been cured, there is no war, no starvation...and the streets are paved with pure gold. In short, Buzz has found Utopia. The people of Earth Redux give Buzz the comprehensive instruction manual on how to fix Earth. The mission has been a smashing success...so far.
Buzz hops back in his space Ferarri and heads back to Earth with the instruction manual to save mankind. With no time to waste, Buzz accelerates to maximum velocity and races back to Earth. Five years later, when he arrives back on Earth he excitedly jumps out of his spaceship, instruction manual in hand, and exclaims "I MADE IT...I'M BACK!" as he holds the manual to save mankind above his head. Puzzled, Buzz looks around and wonders why no one is there to greet him after his long journey. Stranger still, the birds look different and, and...and, everything looks different. Very different.
You see, the 'Earth' Buzz returned back to is not the same Earth Buzz left 10 years ago. Buzz was only gone 10 years, but in that 10 years (for Buzz) the Earth aged hundreds of years. The Earth Buzz returned to had long since forgotten about Buzz and his journey, Buzz was, at best, some distant memory written down in a history book somewhere. Buzz's great grandchildren had grown old and died while he was gone. The Earth that Buzz returned to had either already unlocked the secrets Buzz brought back with him or had evolved in such a way that those secrets were no longer relevant.
...and Proxima Centauri is a really "close" star (relatively speaking). At further distances this effect is even more pronounced.
originally posted by: Xeven
I am sure they would calculate at what point to stop accelerating and coast or even reverse thrust the rest of the way, in order to be able to slow down on the other end. Not sure if they calculated that in the 100 year trip hypothesis however.
Just being able to quickly survey all the asteroids in the asteroid belt for resources would surely create a robotic mining industry if not human mining.
Tech like this seems like it could allow us to at least start gathering solar system resources and human outposts could be readily resupplied in timely fashion.
For Probes I would think it would sling shot around while surveying each star system and possibly move on to the next or return to earth all the while broadcasting what it finds. If it detects Earth like planets on the way in to a system it could swing past and return images and sensor data. Of course it would be future generations that would receive the signals but at least humanity would be moving forward.
"Over periods of months, this small force can accelerate the spacecraft to enormous speeds — on the order of 100-150 km/s (~ 20 to 30 AU/year)."
originally posted by: pikestaff
Really interesting thread, just wish I had the math, a constant acceleration of 1 G must build into a huge speed, and then at the half way point a flip over to use the 1 G to slow down, all the while still coasting towards the 'target' , Anyone got a CRAY computer?
Considering that is has unknown effect exhaust velocity, it would likely be possible to accelerate to high%s of c.