Today at 2:55 EST Philip Lubin, who is involved with the Starshot project, will present some work on the study he is doing for NASA investigating the feasibility of this.
The craziest thing to me is that if we sent a generational spaceship there that was expected to take 1,000 years, it seems likely that better technology would allow the next generation of spaceships to get there much faster. So by the time the 1,000 year spaceship arrived, there would already be people there!
This is a known paradox, I forget what it's called though. The concept is that it's arguable that any long-term space travel is pointless because there will always be a faster ship surpassing it as the originating civilization improves its technology, and so on for that faster ship. So, it's irrational to ever launch anything...
Improving the speed of a 1000-year ship may only require improvements in propulsion or structure (lighter ships). There are nearby incentives to create better propulsion and structure. We do not necessarily have to launch a 1000-year ship to create a 500-year ship.
Seems like you'd reach a point where it becomes worth it even with continuous improvement. If the speed of light really is a speed limit, then you'll get to a point where the maximum theoretical improvement is still some small amount. If there's a way to go faster than light, then you'll get to a point where it only takes two seconds to get to your destination.
Even without the speed limit, you can expect to reach this point. Let's say your technology gets 10% faster every 25-year generation, you should launch a 200-year trip but not a 250-year one. We'll probably keep improving at that pace or better for a few iterations at least, but eventually space travel will be a stable technology, speed improvements will be rare and incremental, and 1000-year journeys will be justified.
Right, barring time travel, once you can make the voyage at all, you'll always reach a point where it makes sense to depart on it. If you invent technology that takes a million years to arrive, then you have a maximum deadline of a million years. Past that point, even instantaneous travel won't be worth waiting for, if your goal is simply to get there as early as possible.
I just finished reading the entire novel series that Turtledove spun out of that short story concept. It's really good, well-researched and imaginative.
But technology that would be able to send spaceships significantly faster would probably cost significantly more, so it might not be worth pursuing given the cost.
no problem, we train them with a convolutional neural net w/ examples from earth to provide for them. should suffice until about an age of 7 after which they'll just continue to use the nanobots to provide raw materials.
If you're limiting it to generational ships then there isn't much improvement to be made, we can still only accelerate at ~1G. The only variable is how long that acceleration can be maintained.
Maybe there could be a kind of factory-ship that was built to be self-improving, so during those 1000 years it would improve itself and increase it's speed.
After we build the laser it might not cost that much more just to keep a constant stream of these guys going to the planet relaying their information back along the stream. Effectively giving us a streaming feed of what's happening on the planet.
A single probe in orbit could obviously do this but with this idea there's no way to slow down.
>The lightsail is built in two sections, an outer doughtnut-
shaped ring, and an inner circular section 30 km in diameter.
This 30 km payload section of the sail has a mass of 71 metric
tons, including a science payload of 26 metric tons. The
remaining, ring-shaped "decel" stage has the mass of 714
metric tons, or ten times the smaller payload "stage".
The central payload section of the sail is detached from the
larger stage and turned around so that its reflecting surface
faces the reflecting surface of the ring-shaped portion (see Fig.
4). At a time 4.3 years earlier, the laser power from the solar
system was upgraded to 26 TW (there are 37 years to get ready
for this increase in power). The stronger laser beam travels
across the space to the larger ring sail. The increased power
raises the acceleration of the ring sail to 0.2 m/s2
, and it
continues to gain speed. The light reflected from the ring sail
is focused onto the smaller sail, now some distance behind.
The light rebounds from the 30-km sail, giving it a momentum
push opposite to its velocity, and slowing it down. Since the
smaller sail is 1/10 the mass of the larger one, its deceleration
rate is 2.0 m/s2
, or 0.2 g. The light flux on the smaller sail has
increased considerably, but it is only two-thirds of the
maximum light flux that the sail can handle.
This is from the same people who announced the "Breakthrough Message", an open competiton with a $1 million dollar prize pool, whose details were "to be announced soon". [1]
The press release was made in July 2015, and there has been no communication about it since then. I'm not sure how seriously to take this group.
You can slow down - just that the probe won't remain intact. But perhaps that isn't necessary for the probe to be useful. We can also use these space probes to do geological and atmospheric surveys of the planet when they arrive.
Simply: we slam the probe into the planet, a few milliseconds after it transmits the final images. One gram going at 20% of the speed of light has kinetic energy that bears comparison to the Hiroshima bomb.
At a steep angle of entry, the huge entry glow will give a reading of the atmospheric molecular makeup. And if we can ionize some of the crust, massive space telescopes can get a spectroscopic measurement of the composition, four light years away.
now that's a way to say Hi to a foreign species! there isn't high chance this wouldn't be considered as an act of hostility, and if they would check our history of our current world, they would probably just decide to erase this dangerous species from the face of the universe for greater common good.
Could they carry mini solar sails to slow down? Solar parachutes if you will.
Or if we sent them in single file several seconds apart they could each relay what they see to the ones behind them and then back to us. Effective oh giving us a long exposure.
if even a tiny fraction of those 1000 tiny probes hit that planet at 20% of speed of light, could that pose a problem? it sounds like a shotgun approach, not so figuratively, using pellets loaded with plutonium.
The probes would each be only a few grams, so they'd have about 10^13 J of relativistic kinetic energy, or a half kilotons of TNT equivalent. This can be compared with the 15 kilotons for the (small, by modern standard) Little Boy atomic bomb. So it's probably noticeable for any inhabitants in the area, depending on how the energy is dissipated in the atmosphere, but still quite small on the scale of a planet.
It should be noted that meteors explode with Hiroshima-like force fairly regularly within Earth's atmosphere, on the order of once a decade or so. It happens high up enough that nobody notices beyond an occasional light show. The meteor explosion which hurt a bunch of people in Chelyabinsk a few years back was about 500 kilotons.
Indeed, that's pretty much what "duck and cover" was all about. There was even a school teacher in Chelyabinsk who apparently remembered her Cold War drills and had her students take cover, saving them from injury.
cool, good to know that raining down a bunch of probes in this manner would most likely be a pretty light show. still i wonder about the plutonium aspect of this?
it might be prudent to first consult with the legal experts and diplomats of the Galactic Council, to clear this type of activity with them first, minimize interpretation of this probing as a hostile interstellar act.
I don't think the plutonium would be enough to have any real effect, although it might irritate the inhabitants if there are any. Certainly, we've put far more plutonium into Earth's atmosphere by blowing up thousands of nuclear bombs in it, and we survived.
Clearing it with the Galactic Council definitely sounds like a good idea. Do you have their phone number handy? I seem to have deleted their contact info by accident.
>>So it's probably noticeable for any inhabitants in the area
An intelligent civilization with a 1000 year head start whose presence was just proven by device that arrived at 10% the speed of light would pretty much scare any government on earth.
I would assume it would scare the aliens there too.
