/sci/ - Science & Math

Imaginary, but something like it might work if the world put sufficient resources into the project.
Robot interstellar probe,

>>9545343
>>9545050
>>9545119
Some of the people on this board are totally clueless about the scale of the universe.
The planets are a MILLION times further away than the Moon is.
The stars are a MILLION times further away than the planets are.

By the time we're prepared to build starships, students will be asking "back at the dawn of space travel, what the heck was so hard about going into orbit?" or "Why was 'reaching for the Moon' used as an allusion for 'an impossible goal'?"

Look up Project Daedalus! It was a British Interplanetary Society study for an unmanned probe to a nearby star. The goal was to have the trip made within a human lifetime.
That span didn't include the decades of building a massive industrial complex near Jupiter and mining the planet to obtain He3 for the Orion drive ("pulsed" fusion micro-explosions.). That didn't count because the technology and the fuel could then be used to make travel WITHIN the Solar System comparable to taking a mid 20th century ocean liner.

>>9505341
Helium 3 fusion is an atomic reaction whose products are mostly charged particles. Little or no neutrons. So He3 rockets wouldn't need much shielding and the particles could be focused by magnets into an exhaust jet.
The exhaust velocity would be 9 or 10 percent of lightspeed. That would give an Isp around 3,000,000. That means 1 lb of fuel would produce 1 lb of thrust for 3 million seconds (or about a month.) Chemical rockets top out at around Isp 450 and fission-thermal rockets at 1000 or so.

So, yeah, you could have very fast interplanetary ships, MAYBE even ones which could maintain 1 gee the whole trip. Still not enough for continuous-boost starships where the engines would run for years. And I wouldn't try hovering in an atmosphere; even a little bit of the energy reflected back would likely vaporize your ship.

It's certainly more realistic than the Alcubierre drive.
But we can't produce sustained fusion reactions yet, not even easier-to-ignite ones like deuterium-tritium. And He3 is rare. There are schemes to mine it on the Moon. The British Interplanetary Society once had a vision of an interstellar robot probe. It would consume so much He3 that they suggested a massive effort to extract it from the atmosphere of Jupiter. Picture shows Project Daedalus.

To learn more about not-yet-possible spacecraft, go to http://www.projectrho.com/public_html/rocket/

>>9493908
Expanse?
I started reading the books and a ship receives a distress call. They are the closest ship and, by law, they have to go to the rescue. Which is a stupid law. They might be nearby but doing 800 KPS relative in the wrong direction. A ship further away, but which was already on more favorable vector could get there first.
I concluded the authors either didn't understand ballistics or didn't give a s*** so I stopped reading.
"More realistic than most sci-fi shows" is damning with faint praise.

Now, THIS is more like what a fusion-engine spacecraft should look like!

>>9416637
Technical flaws were found in Daedalus.
Even if the engine worked as designed, acceleration would be much lower and the boost period longer than the allocated 50 years. Much longer.
30 years on we STILL don't have fusion.
Nor do we have an infrastructure in place to mine Helium 3.
The current iteration is https://en.wikipedia.org/wiki/Project_Icarus_(interstellar)
Wikipedia supplied a link to http://icarusinterstellar.org/
God forbid! They used a design from Star Trek for their header-image. That doesn't mean that their engineers and designers are brainlets -- only that their web-guru is.

The new scheme is much less audacious, the craft quite a bit smaller, other fusion reactions are considered, and the flight duration longer.
The hope is to LAUNCH in 50 years and then maybe 60-100 years in flight.
Nothing prevents interstellar travel (at least not for unmanned probes which don't decelerate) but the world doesn't seem all that interested in funding such projects.

>>7055542
it is, just not for you, human.