# Besides Moon & Mars, what other "heavenly bodies" could astronauts explore? **URL:** \ **Category:** Factual Questions\ **Created:** [February 17, 2004, 4:17am UTC](https://boards.straightdope.com/t/besides-moon-mars-what-other-heavenly-bodies-could-astronauts-explore/229607 "2004-02-17T04:17:23Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Grey](https://avatars.discourse-cdn.com/v4/letter/g/b782af/32.png) [@Grey](https://boards.straightdope.com/u/Grey)\ **Post date:** [February 17, 2004, 9:38pm UTC](https://boards.straightdope.com/t/besides-moon-mars-what-other-heavenly-bodies-could-astronauts-explore/229607/21 "2004-02-17T21:38:12Z")
> [@Carnac the Magnificent!](#): > > 1. Dopers have talked about the intense gravitational field on Mercury, given the planet’s closeness to the Sun. About how strong would this gravity be experienced by a 200-lb astronaut? The issue isn’t so much how much you would weigh on Mercury, but rather how much energy would be expended to move into and out of the deep gravity well the planet exists in. > [@Carnac the Magnificent!](#): > > 1. Wouldn’t the Sun’s radiation make visiting Mercury very risky—even if approaching from the “dark side”? The while planet would be between you and the sun, therefore not much radiation would get in to kill you. Cosmic ray yeah but you’d be safe from solar flares. > [@Carnac the Magnificent!](#): > > 1. I thought Venus’ atmospheric pressure is so dense that it would crush astronauts, but maybe I’m confusing atmospheric pressure with gravity. Can someone explain what an astronaut would likely experience on Venus? The pressure is roughly 90 atmospheres or what you would experience about 900 m under water. Some one check my math please. > [@Carnac the Magnificent!](#): > > 1. Roughly how intense is the radiation emitted by Jupiter, as experienced by an astronaut on one of its moons? For the inner moons (Io, Europa et. al) the dosage is 10s to hundreds of time the lethal dose for humans. ---
**Author:** ![Bricker](https://avatars.discourse-cdn.com/v4/letter/b/977dab/32.png) [@Bricker](https://boards.straightdope.com/u/Bricker)\ **Post date:** [February 17, 2004, 10:18pm UTC](https://boards.straightdope.com/t/besides-moon-mars-what-other-heavenly-bodies-could-astronauts-explore/229607/22 "2004-02-17T22:18:23Z")
Stupid question: why is Venus, a planet with lighter gravity, possessed of an atmosphere so higher pressured than Earth’s? I always pictured that the heavier the gravity, the higher the atmospheric pressure. No? ---
**Author:** ![Loopydude](https://avatars.discourse-cdn.com/v4/letter/l/e56c9b/32.png) [@Loopydude](https://boards.straightdope.com/u/Loopydude)\ **Post date:** [February 17, 2004, 10:46pm UTC](https://boards.straightdope.com/t/besides-moon-mars-what-other-heavenly-bodies-could-astronauts-explore/229607/23 "2004-02-17T22:46:11Z")
> [@robo99](#): > > Genetically engineered bacteria might. Aren’t there Earth bacteria that live at the Mid Atlantic Ridge that can survive extreme termperatures of 300[sup]o[/sup]F and pressures. Such modified life forms could be used to begin the terraforming process. > > I wonder if it’s easier to terraform Titan with its intense cold or Venus with its intense heat. > > Some things going for Titan. There are Earth bacteria that can live on Methane and it’s conjectured that Titan has an ocean of Methane. While it might be cold on the surface, if Titan has tectonic activity there might be hot spots deep below. They’d have to be some pretty heavily engineered bacteria. There are acidophilic bacteria that can survive a pH near zero, which is thought to exist in the Venusian atomosphere. The pressure isn’t so much of a problem, as there are loads of bugs that live in the deepest depths of the ocean…even coliform bacteria can survive significant squeezing and come out OK. But the temperature on the surface is high enough to melt lead, and there’s little variation in global temparature because the atomosphere conducts heat so well. If you could stand on Venus at night (which you can’t, but just for shits and giggles), the ground would literally glow beneath your feet. Even proteins from thermophilic bacteria denature at temperatures well below that. At typical Venusian temperatures, organic molecules are broken down at the level of molecular bonds. In that kind of heat, with that low pH, there isn’t a biogenic macromolecule that I can think of that wouldn’t be destructively altered at the chemical level in less than a few seconds or maybe a minute. Venus is a super-turbocharged-hyperbaric-acid-bath-autoclave of a nightmare, and its surface is likely completely and unchangeably sterile without global climactic adjustments. ---
**Author:** ![robo99](https://avatars.discourse-cdn.com/v4/letter/r/a8b319/32.png) [@robo99](https://boards.straightdope.com/u/robo99)\ **Post date:** [February 17, 2004, 10:47pm UTC](https://boards.straightdope.com/t/besides-moon-mars-what-other-heavenly-bodies-could-astronauts-explore/229607/24 "2004-02-17T22:47:59Z")
> [@Bricker](#): > > Stupid question: why is Venus, a planet with lighter gravity, possessed of an atmosphere so higher pressured than Earth’s? I always pictured that the heavier the gravity, the higher the atmospheric pressure. No? I believe it’s because the planet is so hot that carbon which normally exists only in solid form on Earth exists as a gas on Venus (in the form of CO2). ---
**Author:** ![Loopus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/loopus/32/15343_2.png) [@Loopus](https://boards.straightdope.com/u/Loopus)\ **Post date:** [February 17, 2004, 10:50pm UTC](https://boards.straightdope.com/t/besides-moon-mars-what-other-heavenly-bodies-could-astronauts-explore/229607/25 "2004-02-17T22:50:19Z")
> [@robo99](#): > > Genetically engineered bacteria might. Aren’t there Earth bacteria that live at the Mid Atlantic Ridge that can survive extreme termperatures of 300[sup]o[/sup]F and pressures. Such modified life forms could be used to begin the terraforming process. I don’t know. Three-hundred degrees F is one thing, but surviving at 800[sup]o[/sup]F, about 200 degrees higher than the melting point of lead, is another matter entirely. Would it really be possible to genitically engineer something that could survive those temperatures? Wouldn’t they just melt, unless they were made of gold or something? ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [February 17, 2004, 11:20pm UTC](https://boards.straightdope.com/t/besides-moon-mars-what-other-heavenly-bodies-could-astronauts-explore/229607/26 "2004-02-17T23:20:49Z")
> [@Bricker](#): > > Stupid question: why is Venus, a planet with lighter gravity, possessed of an atmosphere so higher pressured than Earth’s? I always pictured that the heavier the gravity, the higher the atmospheric pressure. No? It’s actually not a stupid question at all. But it’d be better if reversed: given that Venus has such a dense atmosphere, why is Earth’s so thin? This is actually a fairly complex topic and more than I wanted to type in here about. This page here: [Goldilocks and the Three Planets](http://www.phys.lsu.edu/faculty/cjohnson/climate.html) covers it fairly well. Basically, though, the answer is that the vast bulk of carbon dioxide on Earth is tied up in carbonate rocks, while on Venus it’s in the atmosphere doing the Greenhouse Effect thing. BTW, Mars could easily hold a much denser atmosphere than it currently has and that page also covers why its atmosphere is so thin. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [February 17, 2004, 11:25pm UTC](https://boards.straightdope.com/t/besides-moon-mars-what-other-heavenly-bodies-could-astronauts-explore/229607/27 "2004-02-17T23:25:53Z")
> [@Carnac the Magnificent!](#): > > 1. Wouldn’t the Sun’s radiation make visiting Mercury very risky—even if approaching from the “dark side”? We could just go there at night. In all seriousness, I think the most potential for manned exploration is going to be those places where liquid water exists or once existed - to search for traces of life. ---
**Author:** ![Grey](https://avatars.discourse-cdn.com/v4/letter/g/b782af/32.png) [@Grey](https://boards.straightdope.com/u/Grey)\ **Post date:** [February 17, 2004, 11:45pm UTC](https://boards.straightdope.com/t/besides-moon-mars-what-other-heavenly-bodies-could-astronauts-explore/229607/28 "2004-02-17T23:45:32Z")
> [@Loopydude](#): > > They’d have to be some pretty heavily engineered bacteria. There are acidophilic bacteria that can survive a pH near zero, which is thought to exist in the Venusian atomosphere. The pressure isn’t so much of a problem, as there are loads of bugs that live in the deepest depths of the ocean…even coliform bacteria can survive significant squeezing and come out OK. But the temperature on the surface is high enough to melt lead, and there’s little variation in global temparature because the atomosphere conducts heat so well. If you could stand on Venus at night (which you can’t, but just for shits and giggles), the ground would literally glow beneath your feet. Even proteins from thermophilic bacteria denature at temperatures well below that. At typical Venusian temperatures, organic molecules are broken down at the level of molecular bonds. In that kind of heat, with that low pH, there isn’t a biogenic macromolecule that I can think of that wouldn’t be destructively altered at the chemical level in less than a few seconds or maybe a minute. Venus is a super-turbocharged-hyperbaric-acid-bath-autoclave of a nightmare, and its surface is likely completely and unchangeably sterile without global climactic adjustments. There’s also the fact that the total amount of water in the atmosphere would cover Venus to a depth of 2 inches. Photosynthesis requires water to “crack” the carbon dioxide, so the over all impact would be negligible. ---
**Author:** ![The\_Broken\_Column](https://avatars.discourse-cdn.com/v4/letter/t/b9bd4f/32.png) [@The\_Broken\_Column](https://boards.straightdope.com/u/The_Broken_Column)\ **Post date:** [February 18, 2004, 12:17am UTC](https://boards.straightdope.com/t/besides-moon-mars-what-other-heavenly-bodies-could-astronauts-explore/229607/29 "2004-02-18T00:17:50Z")
> [@Loopus](#): > > Yes, it would be nice if we could terraform Venus, considering its mass (only slightly less than the Earth’s) and distance from the sun. However, Venus’s atmosphere pretty much rules that out. It’s very thick, and made up almost entirely of CO[sub]2[/sub]. At the surface the atmospheric pressure is about 90 atmospheres, and temperatures can reach 800[sup]o[/sup]F. There are also clouds and rain of H[sub]2[/sub]SO[sub]4[/sub] (sulfuric acid). The Soviets landed a few probes on Venus back in 70s, and none of them remained functional for more than an hour. No one’s ever bothered sending any more probes to the surface because it just isn’t worth it. > > If machines can’t function down there, plants and animals certainly can’t live. Short of sucking off the whole atmosphere and starting over, I can’t really think of a way to terraform (or even visit) Venus. No it doesn’t. Venus’s atmosphere is the easiest hurdle to over come. Far easier than CREATING AN ATMOSPHERE FROM NOTHING such as with Mars. It’s 92 atms actually, not 90. And it is 900+ degrees. And I know what the clouds are formed of…it is that very formation that gives us a chance. Bacteria on earth thrive on H2SO4 and therefore can not only eat the acid in the sky, but most of the atmosphere is sulfurous and therefore can be condensed into organisms relieving the pressure problem. This process occurs on earth around thermal vents, stalagmites of bacterial deposits forming around sulfur vents at the bottom of the ocean. Introducing such bacteria into the atmosphere of Venus would more or less theoretically result in the same product. Rain of bacterial product as “stone” to the surface that would lock Venus’s atmosphere into deposits. To finish your quote, I just answered your “I can’t think of any way…” The way has already been thought up, all we need to do is attempt it. Loopydude answered another person asking if there were a possibility of genetically engineered bacteria to do the job. You don’t even have to have genetically engineered bacteria, as there are bacteria today that can survive not only extreme pressures but heat as well. Besides the Bacteria can work from the “top down”…that is floating in the atmosphere’s surface and as they eat up the atmosphere, float down towards the surface. Removing the atmosphere from the top down so that all that remains are Nitrogen and Hydrogen and Oxygen. With that gone we shouldn’t have much problem introducing carbon such that we can create enough limestone to remove excess amounts of Oxygen. With that the atmosphere would be far less than what it is today. How long that will take who knows…and it’s an oversimplified explaination of a complex issue, but still, it is the most probable. dtilque…I’m going to just go beyond your article from a physics department, and interject a more important issue that the article seems to not recognize…hold on let me scan it better…phew good that I scanned it, nope it explains the process…it’s trying to tie it into a “Green House” effect was at first a confusing bit of propoganda but then it got into tectonics which is the heart of the matter. Like I said before, Venus has vulcanism, therefore is the ONLY planet that can be terraformed. Mars’s atmosphere is locked in Limestone deposits in a 15+ mile thick crust. There is no way in hell short of a meteorite impact (I was thinking Eros or Ceres), that Mars will ever reignite into the vulcanism needed to produce an atmosphere. ---
**Author:** ![Bosda\_Di\_Chi\_of\_Tricor](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bosda_di_chi_of_tricor/32/16845_2.png) [@Bosda\_Di\_Chi\_of\_Tricor](https://boards.straightdope.com/u/Bosda_Di_Chi_of_Tricor)\ **Post date:** [February 18, 2004, 12:24am UTC](https://boards.straightdope.com/t/besides-moon-mars-what-other-heavenly-bodies-could-astronauts-explore/229607/30 "2004-02-18T00:24:21Z")
[Hallee Barry](http://www.wutzplanet.de/Wallpapers/Halle%20Barry/pages/003_jpg.htm) [Bai Ling](http://www.exleyphoto.com/images/gallery-actors/7-00/bai%20ling.JPG) Ah! Astronomy! 😃 ---
**Author:** ![Ale](https://avatars.discourse-cdn.com/v4/letter/a/f19dbf/32.png) [@Ale](https://boards.straightdope.com/u/Ale)\ **Post date:** [February 18, 2004, 5:27am UTC](https://boards.straightdope.com/t/besides-moon-mars-what-other-heavenly-bodies-could-astronauts-explore/229607/31 "2004-02-18T05:27:51Z")
> [@Bosda Di'Chi of Tricor](#): > > [Hallee Barry](http://www.wutzplanet.de/Wallpapers/Halle%20Barry/pages/003_jpg.htm) > > [Bai Ling](http://www.exleyphoto.com/images/gallery-actors/7-00/bai%20ling.JPG) > > Ah! Astronomy! 😃 My… Astronomy indeed, I´m seeing stars. 😃 ---
**Author:** ![Carnac\_the\_Magnificent](https://avatars.discourse-cdn.com/v4/letter/c/ccd318/32.png) [@Carnac\_the\_Magnificent](https://boards.straightdope.com/u/Carnac_the_Magnificent)\ **Post date:** [February 18, 2004, 5:42am UTC](https://boards.straightdope.com/t/besides-moon-mars-what-other-heavenly-bodies-could-astronauts-explore/229607/32 "2004-02-18T05:42:53Z")
> [@The\_Broken\_Column](#): > > No it doesn’t. > > Venus’s atmosphere is the easiest hurdle to over come. Far easier than CREATING AN ATMOSPHERE FROM NOTHING such as with Mars… Interesting idea, but let’s return to my question about visiting astronauts. Wouldn’t 90+ atmospheres instantly CRUSH an astronaut? How would NASA (or its successor 200 years from now) get beyond that? ---
**Author:** ![Ale](https://avatars.discourse-cdn.com/v4/letter/a/f19dbf/32.png) [@Ale](https://boards.straightdope.com/u/Ale)\ **Post date:** [February 18, 2004, 5:50am UTC](https://boards.straightdope.com/t/besides-moon-mars-what-other-heavenly-bodies-could-astronauts-explore/229607/33 "2004-02-18T05:50:23Z")
> [@Carnac the Magnificent!](#): > > Interesting idea, but let’s return to my question about visiting astronauts. > > Wouldn’t 90+ atmospheres instantly CRUSH an astronaut? > > How would NASA (or its successor 200 years from now) get beyond that? Well, they could try something like [this](http://www.divingheritage.com/jimkern.htm) although some sort of power assisted legs would be needed. ---
**Author:** ![Ranchoth](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ranchoth/32/1066_2.png) [@Ranchoth](https://boards.straightdope.com/u/Ranchoth)\ **Post date:** [February 18, 2004, 6:09am UTC](https://boards.straightdope.com/t/besides-moon-mars-what-other-heavenly-bodies-could-astronauts-explore/229607/34 "2004-02-18T06:09:50Z")
> [@The\_Broken\_Column](#): > > Venus’s atmosphere is the easiest hurdle to over come. Far easier than CREATING AN ATMOSPHERE FROM NOTHING such as with Mars. > > […] > > Mars’s atmosphere is locked in Limestone deposits in a 15+ mile thick crust. There is no way in hell short of a meteorite impact (I was thinking Eros or Ceres), that Mars will ever reignite into the vulcanism needed to produce an atmosphere. That’s not entirely true…there’s a lot of CO2 and even water ice frozen up in Mars’ [polar caps and permafrost.](http://www.mira.org/fts0/planets/097/text/txt003x.htm) It’d be a tad easier to thaw out _that,_ before you have to start melting Limestone. ---
**Author:** ![Arturius](https://avatars.discourse-cdn.com/v4/letter/a/ecc23a/32.png) [@Arturius](https://boards.straightdope.com/u/Arturius)\ **Post date:** [February 18, 2004, 6:28am UTC](https://boards.straightdope.com/t/besides-moon-mars-what-other-heavenly-bodies-could-astronauts-explore/229607/35 "2004-02-18T06:28:54Z")
Everyones talking about fixing up Venus so we can live on it, but it sounds a hell of a lot easier just to fix up earth to me 😃 ---
**Author:** ![The\_Flying\_Dutchman](https://avatars.discourse-cdn.com/v4/letter/t/9fc348/32.png) [@The\_Flying\_Dutchman](https://boards.straightdope.com/u/The_Flying_Dutchman)\ **Post date:** [February 18, 2004, 6:40am UTC](https://boards.straightdope.com/t/besides-moon-mars-what-other-heavenly-bodies-could-astronauts-explore/229607/36 "2004-02-18T06:40:17Z")
> [@Malacandra](#): > > Provided that you have taken your own oxygen with you… Sure, and then you’ll have water to drink. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [February 18, 2004, 7:30am UTC](https://boards.straightdope.com/t/besides-moon-mars-what-other-heavenly-bodies-could-astronauts-explore/229607/37 "2004-02-18T07:30:52Z")
> [@The\_Broken\_Column](#): > > No it doesn’t. > And I know what the clouds are formed of…it is that very formation that gives us a chance. > > Bacteria on earth thrive on H2SO4 and therefore can not only eat the acid in the sky, but most of the atmosphere is sulfurous and therefore can be condensed into organisms relieving the pressure problem. The real problem with terraforming Venus was pointed out by **Grey** in the post just before yours. It’s the lack of water. Adding bacteria to Venus’ atmosphere won’t do much good until you add a few hundred teratons of water. Enough to give it some decent seas once it cools down. Where that much water can be found is a good question. Lots and lots of comets, I guess. ---
**Author:** ![Sam\_Stone](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Sam\_Stone](https://boards.straightdope.com/u/Sam_Stone)\ **Post date:** [February 18, 2004, 8:38am UTC](https://boards.straightdope.com/t/besides-moon-mars-what-other-heavenly-bodies-could-astronauts-explore/229607/38 "2004-02-18T08:38:52Z")
Plus, what’s the thermal mass of Venus? That whole planet is ungodly hot. Even if you could wave a magic wand and put a perfect Earth-type atmosphere on Venus, it’ll still be a long, long time before it’s cool enough to hang out. Thousands of years, I’d guess. Maybe much longer. ---
**Author:** ![Ranchoth](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ranchoth/32/1066_2.png) [@Ranchoth](https://boards.straightdope.com/u/Ranchoth)\ **Post date:** [February 18, 2004, 8:44am UTC](https://boards.straightdope.com/t/besides-moon-mars-what-other-heavenly-bodies-could-astronauts-explore/229607/39 "2004-02-18T08:44:28Z")
Besides that…isn’t Venus’ day longer than it’s year? Even with an Earth-type atmosphere, that might get a little uncomfortable. ---
**Author:** ![Loopus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/loopus/32/15343_2.png) [@Loopus](https://boards.straightdope.com/u/Loopus)\ **Post date:** [February 19, 2004, 12:32am UTC](https://boards.straightdope.com/t/besides-moon-mars-what-other-heavenly-bodies-could-astronauts-explore/229607/40 "2004-02-19T00:32:37Z")
> [@The\_Broken\_Column](#): > > It’s 92 atms actually, not 90. I said it was **about** 90 atms. Which is correct. > [@](#): > > And it is 900+ degrees. I stand corrected. > [@](#): > > You don’t even have to have genetically engineered bacteria, as there are bacteria today that can survive not only extreme pressures but heat as well. Surely you aren’t saying that there are bacteria on Earth today which can survive 900+ degree temperatures? As I said previously, that’s well past hot enough to **melt lead** , along with, I would assume, bacteria. I’m prepared to accept a reputable cite proving me wrong. > [@](#): > > Besides the Bacteria can work from the “top down”…that is floating in the atmosphere’s surface and as they eat up the atmosphere, float down towards the surface. > > Removing the atmosphere from the top down so that all that remains are Nitrogen and Hydrogen and Oxygen. I can **maybe** buy this, but would the bacteria be able to survive the variation in temperature from day to night, which would be much greater in the upper atmosphere than on the surface? Also, ditto to **Grey** and **dtilque** about the lack of water. And even if it worked, how long would it take? Thousands of years? Longer? Would it be worth the expense of time and resources? > [@Ranchoth](#): > > Besides that…isn’t Venus’ day longer than it’s year? > > Even with an Earth-type atmosphere, that might get a little uncomfortable. Yes, Venus’s day is equal to 243 Earth days; its year is about 226 Earth days. This is another serious concern in terraforming Venus. Even if we could overcome the problems with the atmosphere as **The\_Broken\_Column** suggests, how would we overcome the huge temperature variation that the extra-long days would cause? [Previous page](https://boards.straightdope.com/t/besides-moon-mars-what-other-heavenly-bodies-could-astronauts-explore/229607.md?page=1) [Next page](https://boards.straightdope.com/t/besides-moon-mars-what-other-heavenly-bodies-could-astronauts-explore/229607.md?page=3)