It has been well known for quite some time now that single-sex crews are a very bad idea for long voyages.

Like 98% of military crews throughout modern human history?

Believe it or not, humans can and do live in isolation in single family units all over the world. It's not exactly a good environment to grow up in, but it doesn't turn someone into a murderous beast or whatnot. Do also realize the alternative. Every person you add - and their corresponding mass overhead - dramatically slows down your spacecraft or dramatically scales up the size of its launch stack. There are huge costs; launching only the absolute bare minimum is critical. The slower you go, the more consumables you need, which increases its mass on its own (see the aforementioned problem), and the greater the likelihood of catastropic collapse).

No, a semi-working society ready to hit the ground is most definitely not a requirement, you don't want a "society" until you have a base set up that can sustain them, and automatic robotic labor, not human power, is far more efficient (both in mass and energy terms). But even if such a ready society was a requirement, that'd only be a task for the last generation or two, not every generation in transit. Again, minimizing mass (and thus in-transit consumables) is critical.

The biggest challenge of the whole thing is the massive difficulty of setting up a truly independent colony with as little hardware as possible. Modern technology is based on ridiculously long resource and production chains, with each part produced requiring consumables from numerous other different production chains; a single random piece of modern technology may ultimately have required some tiny degree of the usage of tens to hundreds of thousands or more chemicals or parts that will eventually wear out, in thousands of systems scattered all across the world. Every bolt on every mining truck, every hydraulic fluid in every piston, every seal, every fluxing agent, every tire tread, every hammer-mill hammer, they all need to able to be produced at a faster rate than they are consumed. One obviously gravitates toward "generalized"production processes like 3d printing for part manufacture and plasma centrifuging for refining; however, low volume / high consumable production techs such as these may be fine for low volume consumables but become a consumes-more-than-it-yields dead-end when it comes to making high volume consumables. And you can't just send an emergency resupply boat to a different starsystem. It's fundamentally critical that technology chains be condensed to their absolute simplest cores. Nor are all of your raw mineral inputs going to be found in the same location, which means a cross-planetary shipping system is needed. All of this sort of stuff is the real challenge.

Mass.

Space doesn't think much of the mass of your puny space ship. Minimizing mass is absolutely critical ONLY during launch, and only if thrust during launch must be provided by a combustion engine that burns tons of fuel per second.

Mass is always relevant in accordance with the rocket equation. It's not merely "relevant", it's fundamentally critical to transit time, at a not-even-close-to-linear scaling ratio.

Furthermore, if you have some ready-to-go technology that combines high thrust and high ISP, to the degree required for fast interstellar travel with heavy spacecraft, please inform NASA immediately. And no, Orion is not even close to a ready-to-go technology, and it's not even that great ISP; with practical-sized pusher plates, it only gets a couple thousand. Medusa does better, but not "write off mass concerning an interstellar mission" better. And they plus all of the other proposed high ISP/high thrust techs are all very, very far from ready-to-go.

The 6 I mentioned (starting at 18a) were manned missions. As in, people riding in the vehicle.

Dear Drew,

HELP I'M STUCK IN SOMETHING CALLED HUNCH HOUSE AND I CAN'T FIND MY WAY OUT i killed the hunch but theres no exits and i need to be in class in 15 minutes and im out of sp from all of this shouting will somebody pleeeeease help me?

Sincerely,
Confused in Chaos

And where would one investigate spinning a spacecraft up for artificial gravity? Exactly, in space. Not on the moon.

Lunar surface science could address some issues not addressable in space but they're really not the interesting ones. Things like manufacture with or refining of regolith can be done here in Earth (or in space if you want reduced or zero gravity) using simulants for far, far cheaper. And working on the moon increases your costs and risks by an order of magnitude. It's just not the answer. Even if you want to work on "space mining" experiments it'd be far cheaper to do so on an asteroid rather than to drop down into the lunar gravity well. And asteroids are a much more interesting mining target anyway.

You're kidding, right? Soyuz has had dozens of major failures. Even killed a guy in 2002 when the rocket failed seconds into launch and fell back on the pad. Also, the manned Dragon costs per seat are $25M. For Soyuz it's $75M. Hardly cheaper. Same for cargo comparisons, Soyuz is said to be as little as $6000-7000/kg++, Falcon 9 is $4500/kg, and Falcon Heavy is supposed to come in around $1700/kg.

++ - Doubtful in general; looking up actual delivered contracts makes one question whether that's actually that cheap. For example, Soyuz STB launches for the Galileo satellites were contracted at $114m per launch. That rocket has a max capacity of 7800kg to LEO. That comes out as a whopping $14,600/kg.

Maybe there were too many women involved in building the craft compared to the number of men; they should ban that too. Or to "prevent sexual tension", perhaps they should just get it over with and ban women from approaching within several kilometers of all facilities at all related to rocketry. Then they'll finally fix Soyuz's reliability problems!

Collision with the 3rd stage sounds eminently believable. This would be, what, the 4th major 3rd stage separation failure they've had in the past 15 years? Pathetic that they can't get that fixed. It's not like the Soyuz family has been Russia's workhorse for the past half century or anything.

If you look at the ratio of serious accidents on the Soyuz compared to the shuttle, it's actually higher. Soyuz has gotten very lucky several times in nearly killing its occupants, and had several complete would-have-been-deadly failures in modern times on unmanned launches.

Just looking at crewed vehicles, here's some of the more significant Soyuz accidents since 1971:

18a (1975): second stage separation failed, the craft accelerated toward earth, the crew hit over 21g on abort, rolled down a hill, and stopped just short of a cliff. Serious injuries.

23 (1976): Landed off target, broke through a frozen lake, and sank to the bottom; with great difficulty, the crew was ultimately rescued in time.

33 (1979): Engine failure in orbit; the mission had to be aborted but the craft was thankfully low enough to achieve reentry in a reasonable length of time.

T-10-1 (1983): Rocket engulfed in flames on the launch pad. The emergency escape system was activated just two seconds before the craft exploded.

Expedition 6 (2003): Malfunction during reentry, causing the craft to reenter too hard and way off target. Landed on its side and left one of the crew with a broken shoulder.

(2008): Separation failure on reentry, causing incorrect reentry orientation for part of aerobraking and a rough landing; another crew member injured. Russia responded by blaming the problem on a superstition that having more women than men in a spaceship at any given time is unlucky and banning the practice for all future missions, and no, I'm not kidding though I wish I was.

It's not even accurate to say that the last fatality from a Soyuz was in 1971, in that a Soyuz-U launch in 2002 failed 29 seconds after launch, fell back on its pad and exploded, killing a man on the ground.

Soyuz's "spotless safety record for decades" is anything but. They've gotten really lucky, many times. And now Russia has made bug cutbacks in their space program due to the current economic climate, yet still wants to pursue grandiose programs like their own space station and even moon base. What do you think the result will be?

Crimea river.

For anyone who wants the latest news, Russia has given up on trying to recover it, saying recovery is impossible and it will be left to break up in the atmosphere.

Embryos seem just ripe for moral debates. Here's another one I've been thinking about recently.

The current most realistic way for humans to get to another star system is via a generation ship; it's the only way out there that doesn't require some sort of revolution in other technologies, such as long-term cryogenic hibernation or relativistic travel. Minimizing mass is of course absolutely critical. The most practical implementation would be to have a crew of three young, short-statured women with a family history of good fertility, a large embryo bank onboard, and appropriate facilities for implantation, with the embryos chosen for implantation in-transit also being female and from family histories of short stature and good fertility. One would try to maintain it so that there's always at least (but ideally not much more than) three people at or younger than a reasonably fertile age, so that there's a few chances to compensate should one woman prove infertile, die, or not wish to take part in furthering the population of the generation ship. Upbringing would be handled by the older generation, with the main focus of education being on medicine and repair skills. If a successful colony could be established on the other end then could a broader range of embryos be used to increase the genetic diversity, including males and people of larger stature and higher caloric consumption.

Now, best would be to start out with a staggered age for the initial crew of the generation ship and keep a staggered age throughout the transit. But here we start to get a problem. No ethics review board is going to approve the decision to, say, lock a six year old girl on a tiny, highly risky spacecraft for the rest of her life and give her a future responsibility to bear other peoples' children and then die in space. She's too young to give informed consent to such a monumental decision. Even if she were to travel with her mother, most ethics review panels would find that morally equivalent to a mother locking her child in a bunker for the rest of her life and refuse it. An infant is even worse - she couldn't even give uninformed consent, let alone informed. But the solution of only starting out the crew with informed consenting adults only postpones the issue. For each child they carry en-route is born without a choice in the matter, into a small, highly dangerous, probably uncomfortable craft with few to no peers, limited opportunities for enrichment, and no ability to leave the situation except death. Is that morally any better than sending young, non-consenting children to begin with?