Planet Found in Habitable Zone Around Nearest Star

[BrianSoddingBoru4]

(our first truly interstellar vehicle is likely going to be a hybrid craft with high dv low impulse "x" to bridge the distance between stars, high impulse low dv chemical for manouvering in the well and when it matters, and clever use of the wells of all involved bodies in addition to onboard ai/computing for the course corrections... no one system or strategy without the others is going to be capable of solving the different navigational problems presented by long distance space travel.)

Not to mention what a colossal downer it's going to be when that mile-wide comet that's been out there lurking in the Oort Cloud for aeons - just WAITING for a chance like this (naturally, I assume sentient, malevolent comets) - bangs into your trillion dollar space vehicle and turns it into something resembling what Gotham would look like if the Joker won.

Boru

[Anomalocaris]

Laser propulsion is also subject to the rocket equations diminishing returns in the case of local power generation, and external source devices are limited by their proximity to source which..in case of solar devices, decreases as their velocity and therefore distance form the source increases regardless of their potential dv and in the context of their dismally low impulse values...just another way that precisely the same sort of diminishing relationship presents itself.  

Forget all that, though, how do we effect an accurate mid course correction in a timely manner over such vast distances - remotely?  That has to be step one, because it doesn't matter whether or not we can build the engine or the payload if we can't hit the target.  If we could solve that, though...we wouldn't wonder how to build the engine.

Godammit..I'm never going to get to see any fucking aliens!

(our first truly interstellar vehicle is likely going to be a hybrid craft with high dv low impulse "x" to bridge the distance between stars, high impulse low dv chemical for manouvering in the well and when it matters, and clever use of the wells of all involved bodies in addition to onboard ai/computing for the course corrections... no one system or strategy without the others is going to be capable of solving the different navigational problems presented by long distance space travel.)

It seems improbable that any spaceship driven by an external laser to a fraction of speed of light could carry enough chemical fuel to slow down to make orbit at its destination.    Most likely it would be designed to zip by the destination star without slowing down or having its trajectory appreciably altered by the tiny (compare to the space craft's velocity) gravity pull of the destination star.   It can maybe sending out a blizzard of smaller probes to get closer up looks, but all will just blast by the destination at cruising speed and then sail on into oblivion.

To get there fast and then slow down almost to zero in order to ba captured by gravity squares the technical difficulty.

I wonder if it is possible to first send  ahead A a massive Mirror, and then bounce a laser off the mirror to stop or slow the spacecraft  on approach to the destination.

I don't I think accurate auto mated navigation would be difficult. Auto mated star tracking navigation system had been perfected in the late 1950s for missile guidance

[Anomalocaris]

One concern, any laser focused and powerful enough to propel a spacecraft over interstellar distances would be blazingly conspicuous along its line of sight for many times further then the destination star of the spacecraft. Is it wise to so advertise ourselves

[vorlon13]

The military utility of such a laser on earth is awesome to contemplate . . .

[Anomalocaris]

The military utility of such a laser on earth is awesome to contemplate . . .

A laser suitable for interstellar propulsion would be characterized more by very high sustained power output rather than truly enormous instantaneous power output. Sustained power output implies enormous power sources, such as many nuclear power plants or a truly huge photovoltaic farm. So I am not sure a laser tethered to such power sources would be militarily useful, since the power source itself is easily neutralized.

Lasers with truly enormous instantaneous power outputs by capable of extremely short burst durations we already have.

[The Grand Nudger]

It seems improbable that any spaceship driven by an external laser to a fraction of speed of light could carry enough chemical fuel to slow down to make orbit at its destination.    Most likely it would be designed to zip by the destination star without slowing down or having its trajectory appreciably altered by the tiny (compare to the space craft's velocity) gravity pull of the destination star.   It can maybe sending out a blizzard of smaller probes to get closer up looks, but all will just blast by the destination at cruising speed and then sail on into oblivion.

Theoretically...it can be done, accelerate for half the trip, decelerate for half the trip.  That solves the low impulse problem inherent to any (current) engine with enough delta to get there.  It would require constant operation of the engines for so long...though......that shits bound to just break.

To get there fast and then slow down almost to zero in order to ba captured by gravity squares the technical difficulty.

I wonder if it is possible to first send  ahead A a massive Mirror, and then bounce a laser off the mirror to stop or slow the spacecraft  on approach to the destination.

I don't  I think accurate auto mated navigation would be difficult. Auto mated star tracking navigation system had been perfected in the late 1950s for missile guidance

That's a bit like saying that biplanes perfected global circumnavigation..in context, and even that's an massive understatement.  Burn even the tiniest fraction of a degree off grade halfway to the nearest star and by the time you get there, "there" won't be anywhere near where you were aiming.  That's assuming you don't get navigational wobbles or pulls from any number of things between here and there.  The things that can get a missile from one continent to the next (or even the moon) aren't suitable for interstellar distances. OFC...since we're talking about interstellar distances, your star map would neccessarily change as you crossed them. It all gets a little more difficult to resolve than anything we currently have. We could get reasonably close, but reasonably close in context might still be one hell of a miss.

As to the mirror...you'd have the same problem getting the mirror there, then stopping it, so that it could stop the craft. I suppose you could just let it pass by straightline while it attempted to slow down the chase craft.......but that would present it;s own problems, as the slower the chase craft was moving relative to the mirror the greater the distance between the two and the lesser the effect of the mirror. Essentially, the harder you brake, the more difficult it becomes to brake. I'd just go with the lofting method above, as well as picking a good capture window that has a periapsis which could provide a hefty amount of oomph itself. Even with a really eccentric orbit even a small amount of chemical fuel ought to be able to burn at apo and drop the periapsis to surface. Might take a few* passes, is all.

(I've met a fellow super nerd...haven't I, lol?)

[Anomalocaris]

Don't need to stop the mirror.  The mirror just need to be ahead of the space craft.   A laser can keep accelerating the mirror, so long as the reflected light slows the space craft.

As to stellar navigation, the basic technology is there.  You need optical sensors to locate and position three stars, presumably the sun, the destination star, and a near by star around 90 degrees off from intended trajectory.   If you are going to just the near by stars, say within 10 LYs, most of the star field won't change too much from any vantage point with the 10 LY sphere centered around the earth.

The basic navigation technology that use star position to located in 3D space for interstellar travel is the same stellar navigation technology from the 1950s times three.   The only difference is you need to be able locate the stars much more precisely.  This is very easy to do.  In the 1950s location of the star is resolved with a photocell shaded by a spinning slotted disk.  When the starlight is intermittently shaded, the star is off center.  The timing of the star light shows in which direction the star is off center.  When the star is shinning continuously the sensor is aligned with the star.   Now we have very high pixel count CMOS sensors with long focal length optics.  We have portable technology to pin point star location to within a fraction of arc second.

[The Grand Nudger]

It all sounds nice here on the ground, but does it work before or -after- it's burnt it's way to the nearest star? Still stuck with the problem that a fraction of an arc second could be a miss by a distance greater than the size of our entire solar system, in context, unless it's always working, always correcting (and has sufficient impulse behind it to pull off any correction)...and never fails.

There won't be an army of techs with scheduled maintenance runs for anything headed out of our solar system.

[Anomalocaris]

It all sounds nice here on the ground, but does it work before or -after- it's burnt it's way to the nearest star?  Still stuck with the problem that a fraction of an arc second could be a miss by a distance greater than the size of our entire solar system, in context, unless it's always working, always correcting (and has sufficient impulse behind it to pull off any correction)...and never fails.

Actually, the radius of earth's orbit would span 1 arc second at exactly one parsec (unit of distance, not a unit of time to measure Millenium falcon's kessel run).  One parsec is about 3.25 light years.   So if a spacecraft is able to resolve to within an arc second the location of Proxima Centauri, 4.2 light years from earth, while half way there, and make just one course correction, it should be able to get well within 1 AU of Proxima Centauri.

[The Grand Nudger]

Even 1 au isn't a workable margin or error for a low impulse engine which would be traveling at or near it's max speed when it arrived. We'd be stuck with the drone rain you described (and they'd have all the same problems getting closer as the main craft). A total downer (for me, ofc, for me, lol).