
Can we build a Starship with our current technology in the next 10 years? - galazzah
https://www.quora.com/Can-we-build-a-Starship-Enterprise-with-our-current-technology-in-the-next-10-years?share=1
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informatimago
YES.

Remember that the only condition for a star ship, is to be able to have thrust
all the time. Even a very small thrust is enough to reach relativistic speeds,
and therefore make the travel-time human-scale. FOR THE TRAVELERS!

Now, the problem is that unless the travelers include the trillionaire that
will finance the projects, nobody will want to finance a travel, where the
travellers reach the destination after their dead, and can give back news only
after the payers' children are dead.

But travelling one year on board to reach Proxima Centauri (4 light years
away) wouldn't even be tiring for the traveller.

(Ok, perhaps we could pay for this destination, after all, we'd get news about
landing ten years later).

~~~
dalke
NO.

There are two limitations you did not take into account. The first is the
rocket equation,
[https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation](https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation)
. You need a thrust with a very high exhaust velocity - much higher than what
an ion drive can produce - to get to relativistic speeds. Otherwise something
like 99.999999999999% of the ship's mass will need to be propellant. I worked
it out a few weeks ago at
[https://news.ycombinator.com/item?id=12281830#12282399](https://news.ycombinator.com/item?id=12281830#12282399)
. The ratio of payload to propellant for ~0.8c using engines 10x better than
an ion engine was 1 to 74 quadrillion.

The second is to have enough thrust to get to relativistic speeds for the
human passengers in their lifetime. A engine with an ISP of 8000 s (about 10x
better than the current best ion engine) would get there eventually, but long
after any crew died of old age.

To get 4.25 lightyears in a year requires a continuous acceleration of a good
sized fraction of a gravity. We simply don't know how to do that, outside of
theoretical proposals like Dyson's "Super" Orion. Quoting
[https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propuls...](https://en.wikipedia.org/wiki/Project_Orion_\(nuclear_propulsion\))
:

> At 0.1c, Orion thermonuclear starships would require a flight time of at
> least 44 years to reach Alpha Centauri, not counting time needed to reach
> that speed (about 36 days at constant acceleration of 1g or 9.8 m/s2). At
> 0.1c, an Orion starship would require 100 years to travel 10 light years.

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shams93
We've already sent 5 unmanned probes meant for interstellar space, one of them
Voyager 1 is in interstellar space. Sending actual people is a tremendously
hard thing to do, sending probes is much easier, we already have they're just
moving so slowly it will probably take 300 years to reach Alpha Centauri.

~~~
dalke
Voyager 1 is going about 17 km/s. It's the probe with the fastest speed away
from the sun.

Alpha Centauri is 4.37 light years away. That trip would take about 77,000
years, were Voyager 1 pointed the right direction.

