Getting from here to there, Orion NI interstellar navigation

[vogon13]

{as time permits, thought I would look at guiding an Orion Nuclear Impulse Starship through some practice voyages}

For the first case, let's look at a .1C capable craft, launched towards a hypothetical stellar system located 10 ly away from here. Further, the target has no proper motion, and is moving directly away from us at 100 km/sec (this is a VERY fast speed for a galactic star in our vicinity, BTW)

Our Orion craft will achieve ~30,000 km/sec (300 times the recessional velocity of the target) and the flight time will be around 160 years. (30 year accel, 70 year cruise, 30 year decel) During that period, the target will move away from us an additional .05 lys. I don't think we need to worry about that, during the 70 year cruise period of our flight, our craft can cover that extra distance in 6 months.

Additionally, at arrival, we need not cancel out our entire 30,000 km/sec velocity, just 29,900 km/sec. So we will have propulsion modules leftover, or-

we can travel 100 km/sec faster during cruise (30,100 km/sec), and save the 6 months additional flight time for 'free'.


See how that works?? Regardless of the recessional velocity (as long as we are in the speed regime of our Orion craft) of our target in this example, we do not have to allow extra time (or propulsion modules!) to our flight to cover the additional distance the target moves away during the flight.


So we also can see for a star with an approaching velocity to our solar system of 100 km/sec, that we can cruise there at 29,900 km/sec, save some extra propulsion modules to decel 30,100 km/sec at the target, to again rendezvous with our 10 ly distant star in 130 years.

I realize this is a special case (no proper motion) but I intend to work up to some more challenging trajectories in the next exercise.

 

[Boris_Badenov]

While this is an excellent exercise, I'd like to pick a real star. I recommend Alpha Procyon. It is an F5 Main Sequence star 11.5 ly distance, but I can't find out any other info on it. Are you willing to change your target destination to this star?

 

[vogon13]

While this is an excellent exercise, I'd like to pick a real star. I recommend Alpha Procyon. It is an F5 Main Sequence star 11.5 ly distance, but I can't find out any other info on it. Are you willing to change your target destination to this star?

EEEEK !!

The math is making my brain hurt enough as it is !!

I want to keep the numbers manageable. Eventually, I think I can go over enough combinations of radial velocity and proper motion that it will be easier to see that navigating a flight to an actual star will not be that difficult.

 

[MeteorWayne]

This is one of many threads that don't belong in SS&A. When we figure out where it belongs it will be moved...

 

[vogon13]

Navigation in space, and proper motion and radial velocities of neighboring stars are prominent in this modest discussion. In future postings I hope to be considering various orientations of our stellar neighbors' equivalent of our plane of the ecliptic.

I did put some thought in to this before I stuck it here.

 

[vogon13]

And,

to revise and extend my prior remark:


Probe the vast reaches of space, virtually!

 

[Boris_Badenov]

While this is an excellent exercise, I'd like to pick a real star. I recommend Alpha Procyon. It is an F5 Main Sequence star 11.5 ly distance, but I can't find out any other info on it. Are you willing to change your target destination to this star?

EEEEK !!

Ok, ok. I'll go for your fictional star.

 

[Boris_Badenov]

In the OP you asked if we wanted to make the trip in 6 months shorter time or have the propulsion modules left over. IMO making the trip .003% faster is a poor trade off with having the nukes available for construction purposes on arrival. I'd keep em & take the extra 6 months.

 

[vogon13]

I think any actual Orion craft would have in reserve quite a pile of propulsion modules. Maneuvering requirements in the target system will remain largely unknowable until arrival. Also, considering the length of the voyage, a loss of potency of the nukes must be allowed for.

With a speed capability of 30,000 km/sec, I am not sure what % of safety margin you would want or need, but even 1% would leave you with a capability of 300 km/sec at the target. Note earths' velocity about the sun is <40 km/sec, any planet deemed suitable for a colony would be similar. A major 'burn' might be to align with the stars equatorial plane, as that is where the planets will be, but even in a 'worst' case (like Uranus, plane is perpendicular) the delta vee to align is well less than <300 km/sec, and the requirement decreases the further out you do it.

 

[MeteorWayne]

Actually vog, Uranus orbits in the same plane as the rest of the planets in the solar system. It's rotational axis is tilted ~ 90 degrees, but that is irrelevent to the problem of orbiting the star, or landing on a planet for that matter.
Taking off from a planet, you would want to be as close to the equator to gain the benefit of the rotational speed, but that doesn't apply to landing.

Wayne

 

[vogon13]

Thanx for the clarification.

I was imagining approaching Uranus in lieu of the target star, the appropriate plane in this regard would be the Uranian equatorial plane.

The craft would have the opportunity to thrust somewhat off the approach alignment to induce a sideways velocity component to match that desired once the approach velocity is neutralized.

The gist of all this is, compared to the 30,000 km/sec approach speed, just about any conceivably useful maneuvering in the target system will be tiny, and could be accomplished with the propulsion reserves.

 

[_110501_]

Howdy...hello...for sci-fi..."Getting from here to there" is a sentence of Human histories'. Each step a new adventure, going forth to touch the textured face of Nature, for all things......As long as the public continues forward with its' understandings of Nature and its' desire to know the truths, then successes will be forth-coming. At the present epoch of world domination, exploration with exhaust-thrust rockets is the very best of all worlds. People satisfy their exploration, people design new systems, and great advances occur. The American masses have proven their worth, they plus acorn have given up the greatness of all history, Life, Liberty, and Freedom, for the sake of a socialist-communistic state. Ergo they do not, and am not worthy to, receive non-exhaust thrust, at least as I see it. Others may try, good luck. I'll do mine when Americans show me that they are worthy. They must vote out the despots, they must repair American Capitalism, such that it cannot be abridged. The shame of the Supreme Court in not stopping obummer and his heil gang from changing freedom to governmental slavery must never ever exist again. The people must always be free, independent, and worthy. What happened to checks and balances? Because of the error in not being able to protect American Capitalism, the sweat and effort of the peoples' effort doesn't belong to them, but to the government. Now and well into the future. " From here to there", I have defined. Vote, be sure 100% that is is honest. Then rescind the programs installed......otherwise.....enjoy the suffering, you voted for it........an added note........ There are many styles for non exhaust, some only fit for robots, the types that don't protect life. The best of course is that which naturally protects life. 100%. Velocity at c+1...n. etc. etc.