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  • [ intro ]

  • Venus is sometimes referred to as Earth's sister planet.

  • It's close by, and pretty similar in size.

  • It's thought to have been fairly Earth-like early in its history.

  • Once upon a time,

  • it may even have had lots of nice, shallow seas

  • -- a great place to form life.

  • But it's not so nice to visit any more.

  • A runaway greenhouse effect caused Venus

  • to undergo massive, rapid climate change,

  • boiling off the seas and transforming it from what may have been a pleasant, beachy planet

  • into a desolate nightmare complete with sulfuric acid rain.

  • Earth's got a bit of a greenhouse effect problem too.

  • So it seems like studying Venus could help us understand both our past and our future.

  • Too bad -- because Venus is so awful,

  • sending missions there just isn't worth it.

  • So, we know Venus is hellish, but how bad is it, really?

  • Well, the average surface temperature is 471°C.

  • Mercury is closer to the Sun, but it tops out in the neighborhood of 430°C.

  • Venus is hotter thanks to its atmosphere.

  • That atmosphere is made mostly of carbon dioxide,

  • so it traps tons and tons of heat.

  • And the clouds are made of sulfuric acid.

  • And those clouds do indeed rain!

  • Meanwhile, the atmosphere is so thick

  • that the surface pressure is a whole 90 times greater than Earth's.

  • Which would feel like being almost a kilometer beneath the ocean,

  • if that was something human beings could experience

  • and survive to make the comparison.

  • We could try to engineer something akin to a deep-sea submersible

  • to keep astronauts alive under the pressure of Venus' atmosphere,

  • but that would still fall somewhere between very risky and /certain death/.

  • Astronauts are brave, and they're also very smart.

  • Smart enough that there's not a lot of motivation for a human mission to Venus.

  • But what about robots?

  • They don't need to breathe!

  • The USSR actually sent not one or two,

  • but 16 robots to Venus.

  • This was the Venera project,

  • in which a whole bunch of probes were sent to Venus

  • in the 70s and 80s.

  • They did send some good data back.

  • But the absolute toughest of the landers, Venera 13,

  • lasted a whole 127 minutes.

  • That was longer than its predicted lifespan of half an hour,

  • but still shorter than the shortest Harry Potter film.

  • Which is Deathly Hallows, part 2.

  • We checked.

  • At that time,

  • it was really impressive that humans were able to build something

  • that could survive the conditions on Venus for longer than 30 minutes.

  • It's still impressive today.

  • And that's because machines have their limits too.

  • If we think of a rover or lander as a set of instruments

  • contained in a single package,

  • we don't just need the packaging to survive,

  • but those instruments too.

  • It's kind of like building a spacecraft for humans,

  • actually: the outside needs to be strong enough to withstand the environment,

  • and the inside needs to be hospitable to its inhabitants.

  • Hypothetically, we could build a lander or rover out of something that is primarily carbon,

  • which has a melting point of 3550 °C.

  • But that's just the body, the casing.

  • Inside that casing,

  • we need to create the pressure and temperature conditions necessary

  • for computers and scientific instruments to function.

  • And while we've made lots of advances in high temperature computing,

  • like innovating new heat-resistant materials for circuitry,

  • we're not ready to put a computer on Venus for a long mission just yet.

  • Essentially, we'd have to radically rethink and re-engineer everything we know

  • about space rovers in order to send one to Venus.

  • And the time, money, and energy it would take to do that is just

  • not worth the results,

  • and not really in line with NASA's current goals.

  • Right now, we're big into astrobiology.

  • We really want to unravel the origins of life and probe its limits.

  • If Venus once had life on it,

  • before its seas boiled and its air became poison,

  • evidence of that life would be incredibly difficult to get to,

  • if it exists at all.

  • That evidence would have to have survived billions of years of... Venus,

  • and if we can't get state-of-the-art technology to last longer than two-thirds of Avengers:

  • Endgame,

  • again we checked

  • we don't have much chance of finding it in time.

  • Space exploration is inherently risky,

  • so exploration plans are very much about risk mitigation.

  • And whatever interesting science might theoretically be on Venus,

  • it's not worth investing huge amounts of energy on a mission so risky when there are

  • other,

  • much less risky targets for exploration.

  • Take Mars, for example.

  • Mars is very hard to get to,

  • but it won't immediately break your machines when you get there.

  • And every time we go,

  • we find new and exciting evidence for a once-habitable red planet,

  • like dry lake beds and extinct hot springs.

  • And just past Mars is a field of more great targets: asteroids.

  • There's a lot we want to look into there,

  • from water to chemicals similar to ones used for life on Earth.

  • And asteroids are comparatively easy to explore.

  • You can't have acid rain if you don't have an atmosphere.

  • So, yes, Venus is metal as heck.

  • But that's precisely why it's not a good target.

  • t's too metal for us.

  • Or rather, we are not metal enough for it.

  • Yet.

  • By now, we're extended our search for life far beyond our solar system.

  • And if you enjoy learning about how we look for habitable worlds,

  • you might enjoy Living Universe,

  • a CuriosityStream original.

  • Living Universe explores how we could identify and explore potentially habitable worlds in

  • other star systems.

  • And it's just one of the over

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  • ( outro )

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為什麼金星是最糟糕的 (Why Venus Is THE WORST)

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    林宜悉 發佈於 2021 年 01 月 14 日
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