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Will we ever live in space long-term?
我们会长期生活在太空吗?
Prominent scientists have argued that the future of our species could lie off-world.
著名科学家认为，人类的未来可能在地球之外。
But there’s one thing we’d need to make that work: babies.
但要实现那一点，我们还需要：孩子。
It’s not just about parenting — surely our intrepid astronauts would be up to that challenge.
这不仅仅是养育孩子的问题——我们勇敢的宇航员肯定能应对那一挑战。
It’s that some of them would eventually have to get pregnant in the first place.
而是得有人先怀孕才行。
As wild as it sounds, researchers are already trying to figure out if people can make space babies — but so far, the results don’t look great.
虽然听起来很疯狂，但研究人员已经在尝试弄清楚人们能否在太空中造人——但到目前为止，结果并不乐观。
One major hurdle is the lack of gravity.
一个主要的障碍是缺乏重力。
That includes near-weightlessness, or microgravity, as well as places with less gravity than our home planet — like Mars, where gravity is less than half of what we’re used to.
这包括近失重状态，或微重力，以及重力比地球还小的地方——比如火星，那里的重力不到我们所习惯的一半。
Most experiments that have tried to shed light on this have been done in real or simulated microgravity, so that’s what we’ll focus on here.
多数试图解释这一点的实验都是在真实或模拟的微重力环境下进行的，所以这就是我们今天所关注的内容。
But so far, scientists think that even Martian gravity would pose problems for conception and gestation.
但到目前为止，科学家们认为，即使是火星的重力也会对怀孕和孕育造成问题。
Overall, the story starts out okay: Menstruation in space seems to work normally, at least for short trips — astronauts often choose to skip their periods for longer missions.
总的来说，一开始还算顺利:在太空中月经依然会正常来临，至少在短途旅行中是这样的——宇航员通常会在经期避免参与长期任务。
So although we don’t know for sure, that suggests that ovulation would also happen normally.
虽然我们不能确定，但这表明排卵也会正常发生。
Meanwhile, sperm seem to fare, well, kind of okay in microgravity.
同时，精子在微重力环境下状态也还行。
Like, in 1979, researchers flew live rats on a research satellite for eighteen days.
比如，在1979年，研究人员让老鼠在研究卫星上飞行了18天。
And when they got home, they successfully mated with ovulating rats.
等它们回到家后，也成功与排卵的老鼠完成了交配。
Except not all of their offspring were totally healthy — the growth and development of babies fertilized by mature sperm that were exposed to zero-g effects lagged behind control litters.
但这种情况下产出的后代有些不太健康——受到零重力影响的成熟精子受精的小鼠的生长发育落后于对照组。
The nice thing is, we might be able to get around this by using space sperm banks instead.
好消息是，我们可以通过使用太空精子库来解决这个问题。
In research presented in 2019, scientists in Barcelona reported some preliminary evidence that frozen human sperm can survive short bursts of microgravity with no ill effects —
在2019年提交的研究报告中，巴塞罗那的科学家报告了一些初步证据，表明冷冻的人类精子可以在短时间的微重力环境下存活，不会产生不良影响——
though their evidence came from specialized aircraft, not from space.
不过他们的证据来自专门的航空器，而不是太空。
Still, it’s a start. Now, having healthy cells is one thing, but to get a fetus, an egg needs to be fertilized.
但这毕竟是个开端。现在，有健康的细胞是一方面，但是要获得胎儿，卵子还得受精。
And there is evidence that sperm can fertilize eggs in microgravity.
有证据表明，在微重力环境下，精子可以使卵子受精。
One 2009 study used a spinning machine to simulate microgravity, and successfully carried out in vitro fertilization using mouse sperm and eggs.
2009年的一项研究使用纺纱机模拟微重力，并成功地利用小鼠精子和卵子进行了体外受精。
But even then, fertilization is still a step or three away from pregnancy.
但即便如此，受精到怀孕还有几步之遥。
Pregnancy isn’t official until an embryo can implant into its host’s uterine wall.
只有胚胎成功植入宿主的子宫壁，才算真正怀孕。
For that, you need the formation of the blastocyst — a hollow, fluid-filled ball of cells that forms within a few days of fertilization.
为此，你需要形成胚泡——一个充满液体的空心细胞球，在受精后几天内形成。
The layer of outer cells is called the trophoblast, which helps the embryo to burrow into the uterine wall and form the placenta.
外层细胞被称为滋养层，它可以帮助胚胎植入子宫壁，然后形成胎盘。
There’s also a clump of inner cells called the embryoblast, which gives rise to the fetus itself.
还有一团叫做胚细胞的内部细胞，它产生了胎儿本身。
And it seems like embryos might be able to do all that in space.
胚胎似乎可以在太空中完成以上所有步骤。
Although it hasn’t been reported in a peer-reviewed journal, an experiment containing mouse embryos that flew on China’s first microgravity satellite saw some of them form blastocysts.
虽然没有在同行评审的期刊上发表过相关报道，但在中国首颗微重力卫星上进行的一项包含小鼠胚胎的实验中，一些小鼠胚胎形成了胚泡。
Which is promising, but we’ll need more studies to confirm.
这给了我们希望，但我们还需要更多研究来证实。
But even if blastocysts can form in space, it’s unclear whether they could implant and keep growing.
但即使胚泡能在太空中形成，它们是否能植入并继续生长仍不清楚。
In that same 1979 mission we mentioned, male and female rats were also sent into orbit and allowed to… mingle.
在上述提到的1979年那次任务中，雄鼠和雌鼠也被送入轨道，并且可以……交配。
Some of them did get pregnant, but none of them gave birth — the researchers believed that the implanted embryos died and were absorbed back into the rats’ bodies.
其中一些雌鼠确实怀孕了，但没有一只老鼠生育——研究人员认为植入的胚胎已经死亡，并被老鼠自身吸收。
Scientists are trying to figure out what exactly it is about microgravity that messes with blastocysts and their ability to implant and grow, but they do have ideas.
科学家们正试图弄清楚到底是微重力的哪一点干扰了胚泡以及它们植入和生长能力，但他们确实有了思路。
Like, embryonic stem cells are part of the equation.
比如，胚胎干细胞就是这个过程中的一部分。
These are the cells in the blastocyst that differentiate, or diversify into all of the different kinds of tissues in the fetus.
胚胎干细胞是胚泡中的细胞，它们会分裂，或分化成胎儿所有的不同组织。
Microgravity appears to make them more resistant to differentiating into those more mature cells.
微重力似乎会让它们更难分化为更成熟的细胞。
It’s possible that microgravity interferes with DNA methylation, a process known to affect cell differentiation.
微重力可能会干扰DNA甲基化，这个过程会影响细胞的分化。
Or there could be other factors — like how microgravity messes with the behavior of fluids, and how cells float in fluids.
也可能还有其他因素——比如微重力对液体行为的影响，对细胞在液体中漂浮状态的影响。
So, at this point, it’s up in the air whether space pregnancy is feasible, outside of inventing prolonged artificial gravity.
所以，在这一点上，太空怀孕是否可行依然无法明确，除非发明长期人工重力。
That said, even if we did figure that part out, there’s evidence that a fetus couldn’t develop in a healthy way in space.
也就是说，即使我们弄清楚了那部分，依然有证据表明胎儿在太空中不能健康发育。
After all, gravity isn’t only important for the earliest stages of pregnancy.
毕竟，重力不仅对怀孕初期很重要。
Scientists are pretty sure that it’s also important in the third trimester, when it helps the fetus develop its muscles, including in the heart.
科学家们非常确定，重力在妊娠晚期也很重要，因为它能帮助胎儿发育肌肉，包括心脏。
Gravity may even play key roles in the development of synapses in the brain and sensory tissue in the inner ear.
重力甚至可能在大脑突触和内耳感觉组织的发育过程中发挥了关键作用。
And based on evidence from pregnant mice, it seems like microgravity during orbital spaceflight affects the development of vestibular functions — basically the sense of balance and motion.
根据怀孕老鼠身上的证据，轨道太空飞行中的微重力似乎影响了前庭功能的发展——前庭功能基本是指平衡感和运动感。
So, not great news.
所以，这不是什么好消息。
And even if we can compensate for microgravity, developing radiation shielding technology strong enough to protect a fetus is a whole other matter.
即使我们能弥补微重力，研发出足够强的辐射屏蔽技术来保护胎儿又是另一回事。
Outside of Earth’s magnetic field, the effects of solar radiation are a lot stronger.
在地球磁场之外，太阳辐射的影响要大得多。
And we’ve learned that the developing brain is extremely sensitive to radiation exposure, which can cause DNA damage, brain defects, and increased incidence of cancer.
我们知道，发育中的大脑对辐射非常敏感，辐射会导致DNA损伤、大脑缺陷和癌症发病率增加。
So, while there’s a lot we still don’t know about how this all works, and while we’ll need many more studies in mammals,
因此，虽然我们还不知道这一切要如何运作，虽然还需要对哺乳动物做更多研究，
one thing’s for sure: We may get there someday, but there are a lot of small steps to come before humanity can make the giant leap to pregnancy in space.
但有一点是肯定的：终有一天我们或许能实现在太空中怀孕的巨大飞跃，但在那之前，人类还需多积跬步。
If you like deep dives into incredibly specific questions like this one, and absurdly competitive trivia, and also science poetry, then boy do we have a podcast for you.
如果你喜欢深入研究像本期内容一样非常具体的问题，以及竞争激烈的荒谬琐事，还有科学诗歌，那么我们有为你量身打造的播客。
It’s SciShow Tangents!
那就是科学秀切线！
Produced by Complexly and WNYC Studios, it’s made by the same people who bring you SciShow!
它由Complexly和WNYC工作室制作，与《科学秀》的制作人相同哦!
Well, some of them.
额，至少有些是相同的。
Lately, they’ve been recording from home in the name of social distancing, which has involved host Ceri building a blanket fort.
最近，因为要保持社交距离，他们都在家里录制节目，主持人赛瑞还搭建了一个毛毯堡垒。
Geez, who doesn’t have a fully equipped podcast studio in their home already?
天啊，谁家里还没有一个设备齐全的播客工作室呢?
Get with the program! Check it out at the link in the description -- and thanks for watching.
请持续关注我们的节目！点击描述中的链接查看——感谢收看。
