NASA goes to Jupiter, but humans surely cannot
Today’s post will mostly be a repost because 1) I want you clowns to enjoy some of my reddit shenanigans for the day and this is some of the most beautiful work i’ve ever read about space; 2) oddly, this post answers the very question that I initially wanted to answer. As some of you might know, the two gas giants in our solar system are Jupiter and Saturn. No human has ever witnessed the surface of Jupiter from up close, but man made satellites have. On September 21, 2003, the Galileo spacecraft plunged into Jupiter’s atmosphere at 30 miles/sec.
We are currently in the process of collecting more data on Jupiter with NASA’s JUNO spacecraft (if you’re interested, the Wikipedia, Official Website, and Subreddit are all great resources to find everything from amazing images to a detailed history of the craft itself) which will ultimately dispose of itself in a burnup in Jupiter’s atmosphere over the course of 5 days in a semi-controlled descent. Ultimately, no one knows what happens to the leftover scraps of metal and plastic. Curiosity piqued, I decided to look into what would happen if we could somehow explore the “depths” of Jupiter (whatever tf that means, as you will soon understand). A fellow redditor has already asked this question and u/wazhoheat gave a mesmerizing answer. So, boyos, join me on this journey to the center of Jupiter:
Well, if you weren’t wearing a space suit, no matter where you started you would die almost instantly because there is essentially no oxygen at any level of Jupiter’s atmosphere.
But let’s say you do have a space suit. What do you mean by “step foot on it”? Jupiter is, as you noted in your question, a gas giant, meaning it’s made of gas. There is no solid surface. And just like Earth’s atmosphere, the gas doesn’t really have a “top”, it just gets thinner and thinner as you get further and further from the planet, until at some point it is indistinguishable from interplanetary space (which, you may be interested to know, is not a true vacuum.
But let’s say you just get dropped from some height way outside of Jupiter’s visible atmosphere. Once you got within about 200,000 miles (about 300,000 km) of the planet’s surface, you’d die fairly quickly from radiation poisoning.
But let’s say your space suit has radiation-resisting superpowers. Well due to Jupiter’s extreme mass, you’d quickly accelerate through the tenuous upper atmosphere at about 2.6 g, and burn up just like a meteor flying through Earth’s upper atmosphere.
But let’s say we dropped you in the middle of Jupiter’s upper atmosphere, where the pressure were just about the same as Earth’s surface pressure (1 bar). Now we’re getting somewhere. You’d be falling, but since you’re already in the thicker part of the atmosphere, your terminal velocity will be fairly low (taking Jupiter’s higher gravity and the atmosphere’s lower density into account (it is mostly hydrogen, so its density is about 10 times less than Earth’s even though the pressure is similar), your terminal velocity would be about 3200 km/h (2000 mph)). This is probably slow enough that frictional heating and heating from supersonic compression would not burn you up.
But hell, for shits and giggles, and in the name of keeping you alive as long as possible, let’s give you a parachute, a little smaller than the one given to the Galileo probe, so that you fall at about the same velocity initially (~100 m/s, or about 360 km/h, 220 mph). Now we’re cooking. Not literally though, because the temperature at this level is fairly comfortable: The temperature is just about 0 C (32 F), so you’d actually be pretty comfy.
So okay, now you’re in your radiation-proof spacesuit, with your handy parachute, falling through the atmosphere just at the top of the clouds. These clouds are made of ammonia, but let’s just assume your spacesuit and parachute are okay with that. You’d actually be okay for quite a while; maybe a little bored, but hey, you’re on motherfucking Jupiter.
After about 5 minutes, you’ve fallen to the 2-bar level (about twice the average surface pressure on Earth). You are now falling through different clouds, made of ammonium hydrosulfide and ammonium sulfide. They don’t look much different than regular clouds, but they do have a brownish tint that gets browner the deeper you go. Some people may find this surprising, but you won’t feel many ill effects, even as the pressure increases rapidly. The bends are only seen with rapid decompression; the only ill effects from rapid compression are if the compression is too rapid to allow your body cavities (such as inner ear, sinuses, etc) to equalize. So as long as your ears are clear of wax, you should be fine.
About 10 minutes later, you have reached the 4 bar pressure level, which is about 4 times the average atmospheric pressure at sea level, or about the pressure you’d experience under 30 meters (100 feet) of water. The temperature has actually gotten quite cold, and is now around -40 C (-40 F). But assuming all the capabilities your spacesuit already had, I’m sure it wouldn’t be too much to ask for a small heater. You are now passing through clouds of water ice, just like you might see at high altitudes on Earth, but it is getting very dark. You are also being whisked along horizontally by winds reaching 200 m/s (450 mph, 720 km/h), but you barely notice as they are not very turbulent.
15 more minutes go by, and you are now at a pressure of 10 bar, or 10 times normal sea-level atmospheric pressure. At bit before this level you should have changed the mixture of air you are breathing; if you breathed normal air at a pressure of 10 bar or more, you would suffer from acute oxygen toxicity, which can be quickly fatal (oxygen is actually toxic at much lower pressures, but it would take much longer than our quick decent through jupiter). At the same time, you can suffer from nitrogen narcosis, which has similar symptoms to inhaling nitrous oxide initially, but can quickly progress to severe symptoms like coma or death. So as you dive deeper your magic space suit also changes the mixture of air you are breathing, so that the partial pressures of oxygen and nitrogen remain the same as you are used to breathing, with the rest filled with helium or neon, which are the only known gasses which don’t exhibit a toxic effect at high pressures. But provided this is all taken care of, you are actually quite comfortable, as the temperature has risen back up to about 23 C (73 F).
Another 25 minutes pass, and you are starting to realize you’re in trouble. You are in complete darkness now, and the temperature has been steadily increasing as you go further down: now over 100 C (212 F) and still rising fast. Your spacesuit’s systems are starting to fail. Within a few minutes, the temperature is over 200 C (392 F), and you don’t have much longer to survive. Not wanting to endure a miserable, burning death, you take your conveniently placed cyanide capsule and end your interplanetary adventure.
But your body keeps falling.
Down into interior regions where we have little ideas of the exact composition. Pressure and density are increasing drastically, slowing your descent to a crawl. The atmosphere of mostly hydrogen is actually a liquid now, and is now several thousand degrees, but with essentially no oxygen around your body turns into a charcoal-like substance. Your parachute cuts away, but your spacesuit remains intact because it is convenient to the story, and your compressed, dead chunk of bodily substance slowly sinks, beyond 1,000 bar, beyond 10,000 bar…
Until finally, at an insanely crushing pressure of 2,000,000 bar (and a temperature of 5,000 K, about the temperature of the surface of the sun!), you stop sinking. Because your super-spacesuit is conveniently still intact, your body is still mostly water, which is essentially incompressible, even at these incredible pressures. As such, at this level, where the density is about 1 g/cm3 or about 1000 kg/m3 (this is approximately the density of water) you and the surrounding atmosphere are the same density, so you will no longer sink! So there your carbonated corpse floats, for all eternity, until the heat death of the universe.
Sources (among some others linked above in-line):