Maximum Velocity Currently Attainable? The Future?

[Nuke]

well we dont know what kind of advances we will see in ai programming, and algorithmic psychological analysis. might be possible to come up with an android that is up to the task of raising children without turning them into a bunch of neurotic psychopaths.

[rkman]

we could probibly get pretty fast with a nuclear-electric ship. we have flown nuclear reactors in space and we have flown ion engines, we just have never flown both in the same spacecraft

The most powerful space going RTG's produce at most a few 100 Watts, not nearly enough to power ion engines (typical power requirements in the order of kiloWatts), and have a mass of about 1000kg. For reference: that is significantly more than the total mass of the ion thruster powered SMART-1, including solar panels for ~1kW electricity supply. So in terms of Watts/kilogram solar panels are actually more efficient than nuclear power.

Even though nuclear power would out-perform solar panels when at a great distance from the sun, it would severely reduce the already very low acceleration of the craft. It might be able to break the speed record - in a couple of thousand years. The question is if it is worth committing to a mission that would take that long to complete.

[NGTOne]

I am a huge fan of Blade Runner and similar type films.

Only two major problems with such Sci Fi. The human female reproductive tract where we all grow from zygote into fetus is by far more sophisticated and complex than any machine ever conceived. Replicating DNA is one thing; replicating a womb and mammary glands, not to mention mothering are something else entirely.

Second, assuming these physiological and behavioral systems could somehow be replicated by cyborg mothers, I'm quite confident of what you would rear from it: insecure, neurotic, short-lived, dysfunctional wrecks. If that is the only choice we got I say lets go extinct.

Ah yes, the famous monkey experiment. Basically, the way it worked was:

There is a set of baby monkeys, and two (creepy as hell) mother monkey dolls. One is covered in a warm, fuzzy material and has a warm interior (like a real mother monkey). The other is made of wire mesh and has a nipple that provides milk. The goal of the experiment was to figure out which mother (and, thus, which need) the baby monkeys would gravitate to most. It turned out that they gravitated to the fuzzy doll, because it (based on the theories as to this behaviour) provided warmth and comfort like a real mother would.

The implications of this on a robotic nursemaid are... profound, to say the least - apparently, in a baby's psychological makeup, emotional needs are far more important than physical ones to overall psychological growth and normal development (whereas, in adults, the paradigm is muted, if not somewhat reversed - depends on the individual).

The most powerful space going RTG's produce at most a few 100 Watts, not nearly enough to power ion engines (typical power requirements in the order of kiloWatts), and have a mass of about 1000kg. For reference: that is significantly more than the total mass of the ion thruster powered SMART-1, including solar panels for ~1kW electricity supply. So in terms of Watts/kilogram solar panels are actually more efficient than nuclear power.

Even though nuclear power would out-perform solar panels when at a great distance from the sun, it would severely reduce the already very low acceleration of the craft. It might be able to break the speed record - in a couple of thousand years. The question is if it is worth committing to a mission that would take that long to complete.

Not necessarily - ion engines and other electric propulsive technologies are subject to significant economies of scale. Problem is, REACHING those economies requires an engine big enough to need a nuclear reactor in the first place. However, once you cross that point, you can get more thrust per unit of electricity as you scale up.

That doesn't change the fact that electric propulsive technologies don't have a high enough Isp to reach another solar system at even 0.005c. You would still need more fuel than spaceship at that point. Fission fragment rockets, though even slower, represent a far more realistic option (Isp of some proposed designs is on the order of 1 million).

Edited August 17, 2013 by NGTOne

[Nuke]

The most powerful space going RTG's produce at most a few 100 Watts, not nearly enough to power ion engines (typical power requirements in the order of kiloWatts), and have a mass of about 1000kg. For reference: that is significantly more than the total mass of the ion thruster powered SMART-1, including solar panels for ~1kW electricity supply. So in terms of Watts/kilogram solar panels are actually more efficient than nuclear power.

Even though nuclear power would out-perform solar panels when at a great distance from the sun, it would severely reduce the already very low acceleration of the craft. It might be able to break the speed record - in a couple of thousand years. The question is if it is worth committing to a mission that would take that long to complete.

i was not thinking about rtgs, i was thinking more like this:

http://en.wikipedia.org/wiki/SNAP-10A

or this:

http://en.wikipedia.org/wiki/TOPAZ_nuclear_reactor

these reactors had power on the order of kilowatts, topaz was a 5kw reactor, i think snap was a 30kw reactor (e: turns out that was thermal, not electrical, the reactor only got up to 590 watts before an unrelated part of the spacecraft failed, causing the reactor to shut down). now this is peanuts to modern solar cells, but they can run with the absence of sunlight at power levels far beyond what long range probes usually have available. for the goal of attaining the highest speed possible (beating voyagerer 1's speed record), such a reactor compound with an ion engine and a large propellant tank would be ideal. this is not practical for interplanetary travel anywhere with the possible exception of the outer solar system, where you absolutely need a non-solar power source to accomplish anything useful. so its pretty much just a drag racer in space.

Edited August 17, 2013 by Nuke

[Diche Bach]

Ah yes, the famous monkey experiment. Basically, the way it worked was:

There is a set of baby monkeys, and two (creepy as hell) mother monkey dolls. One is covered in a warm, fuzzy material and has a warm interior (like a real mother monkey). The other is made of wire mesh and has a nipple that provides milk. The goal of the experiment was to figure out which mother (and, thus, which need) the baby monkeys would gravitate to most. It turned out that they gravitated to the fuzzy doll, because it (based on the theories as to this behaviour) provided warmth and comfort like a real mother would.

The implications of this on a robotic nursemaid are... profound, to say the least - apparently, in a baby's psychological makeup, emotional needs are far more important than physical ones to overall psychological growth and normal development (whereas, in adults, the paradigm is muted, if not somewhat reversed - depends on the individual).

Yes, that is exactly the point of Harlow's famous experiments. You have to keep in mind that, while they are famous, and serve as easy examples of how dependent intelligent primates (including humans) are on parental bonding, they are but one rather 'primitive' example of a vast body of research on what is broadly termed "attachment theory."

I can tell you as a social scientist that the implications of this area of theory are immense, both for addressing the problems of human life as they exist right now, and for projecting hypothetical futures for human space expansion.

If we ever achieve something like what they portray in Blade Runner, i.e., the capacity to create artificially grown people who nonetheless appear superficially 'normal' within the frame of the given culture in which they are 'programmed' I will be amazed.