# How much mass could Earth safely lose and retain its atmosphere? **URL:** \ **Category:** Factual Questions\ **Created:** [July 9, 2010, 7:06am UTC](https://boards.straightdope.com/t/how-much-mass-could-earth-safely-lose-and-retain-its-atmosphere/546074 "2010-07-09T07:06:32Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Quartz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quartz/32/267_2.png) [@Quartz](https://boards.straightdope.com/u/Quartz)\ **Post date:** [July 9, 2010, 7:06am UTC](https://boards.straightdope.com/t/how-much-mass-could-earth-safely-lose-and-retain-its-atmosphere/546074/1 "2010-07-09T07:06:32Z")
Mars lost its atmosphere because it didn’t have the gravity to retain it. Earth retains its atmosphere because it has. But we’re beginning to explore beyond Earth. This involves the Earth losing mass. Right now these are trivial amounts, but soon enough we’ll want large structures in space. So how much can we safely chuck up there without losing the atmosphere? Venus is 80% of the mass of Earth and retains its atmosphere so is the answer, ‘Rather a lot’? ---
**Author:** ![Oakminster](https://avatars.discourse-cdn.com/v4/letter/o/77aa72/32.png) [@Oakminster](https://boards.straightdope.com/u/Oakminster)\ **Post date:** [July 9, 2010, 7:15am UTC](https://boards.straightdope.com/t/how-much-mass-could-earth-safely-lose-and-retain-its-atmosphere/546074/2 "2010-07-09T07:15:35Z")
I’m not a science guy, but don’t we gain some mass from meteorites and such pretty much daily? Could we even manage a net loss of mass from exports? ---
**Author:** ![Simplicio](https://avatars.discourse-cdn.com/v4/letter/s/c37758/32.png) [@Simplicio](https://boards.straightdope.com/u/Simplicio)\ **Post date:** [July 9, 2010, 7:35am UTC](https://boards.straightdope.com/t/how-much-mass-could-earth-safely-lose-and-retain-its-atmosphere/546074/3 "2010-07-09T07:35:56Z")
I get something crazy small, like .0004 the current mass till the average velocity of N2 at 300K is at the escape velocity. Is late though, I’ll try again in the morning when I’m more awake. ---
**Author:** ![Quartz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quartz/32/267_2.png) [@Quartz](https://boards.straightdope.com/u/Quartz)\ **Post date:** [July 9, 2010, 7:40am UTC](https://boards.straightdope.com/t/how-much-mass-could-earth-safely-lose-and-retain-its-atmosphere/546074/4 "2010-07-09T07:40:56Z")
> [@Oakminster](#): > > I’m not a science guy, but don’t we gain some mass from meteorites and such pretty much daily? Could we even manage a net loss of mass from exports? Just wait until we start lofting millions of tonnes via mass drivers or whatever. ---
**Author:** ![user\_hostile](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/user_hostile/32/474_2.png) [@user\_hostile](https://boards.straightdope.com/u/user_hostile)\ **Post date:** [July 9, 2010, 7:43am UTC](https://boards.straightdope.com/t/how-much-mass-could-earth-safely-lose-and-retain-its-atmosphere/546074/5 "2010-07-09T07:43:02Z")
It wasn’t the low gravity on Mars–the lack of a magnetic field is the “why” for Mars atmosphere being so paltry. What little “Tesla” it had at its creation, soon died out eons ago. Take a look at Titan; much smaller than Mars, but still maintains an rather robust atmosphere (about 20 psia). Which is ironic when you realize it doesn’t have a magnetic field. Instead, [Saturn](http://www.newscientist.com/article/dn14717-saturn-magnetises-its-moon-titan.html) serves as a proxy field for part of the time. ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [July 9, 2010, 8:04am UTC](https://boards.straightdope.com/t/how-much-mass-could-earth-safely-lose-and-retain-its-atmosphere/546074/6 "2010-07-09T08:04:47Z")
The mass loss is insignificant compared to the size of the planet. Plus the earth gains mass every year. > [@](#): > > Is Earth gaining weight? At the present rate, Earth gains about 40,000 metric tons each year from space debris that bombard our planet. Yet it loses an amount so small (atmospheric gases, etc.) as to not really warrant any serious consideration. So, will Earth’s weight gain have an impact on its orbit, relative mass (gravitational pull) or any other properties? Although 40,000 metric tons a year sounds like a huge gain, when you compare it to the immense size of Earth, it dwindles to a meager 0.000003 of one percent of the Earth’s mass. The impact is insignificant. > > SOURCE: [http://ecology.com/features/earthataglance/youarehere.html](http://ecology.com/features/earthataglance/youarehere.html) Note the percentage compared to the size of the planet. Works both ways. So while we toss stuff out into space we gain more and even if we didn’t the amount would be insignificant in the scheme of things…even done for thousands of years. ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [July 9, 2010, 8:06am UTC](https://boards.straightdope.com/t/how-much-mass-could-earth-safely-lose-and-retain-its-atmosphere/546074/7 "2010-07-09T08:06:29Z")
> [@user\_hostile](#): > > It wasn’t the low gravity on Mars–the lack of a magnetic field is the “why” for Mars atmosphere being so paltry. This is partly true. Lack of a magnetic field allowed the stellar wind to strip the atmosphere. That said a larger mass (more gravity) would have retained more atmosphere. I do not know where the balance is struck between those two things though. ---
**Author:** ![user\_hostile](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/user_hostile/32/474_2.png) [@user\_hostile](https://boards.straightdope.com/u/user_hostile)\ **Post date:** [July 9, 2010, 8:30am UTC](https://boards.straightdope.com/t/how-much-mass-could-earth-safely-lose-and-retain-its-atmosphere/546074/8 "2010-07-09T08:30:54Z")
> [@](#): > > Originally Posted by **Whack-a-Mole** > Lack of a magnetic field allowed the stellar wind to strip the atmosphere. That said a larger mass (more gravity) would have retained more atmosphere. > > I do not know where the balance is struck between those two things though. Well, come to think of it, Venus is pretty much an identical twin to Mars in the lacking a magnetic field category. And atmospheric density wise, it’s the champ in for inner Solar system. Insolation and the solar wind density would also be important factors in an atmosphere’s lifetime. Per your above comment: I, too, don’t know where the balance is struck. ---
**Author:** ![Quartz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quartz/32/267_2.png) [@Quartz](https://boards.straightdope.com/u/Quartz)\ **Post date:** [July 9, 2010, 9:02am UTC](https://boards.straightdope.com/t/how-much-mass-could-earth-safely-lose-and-retain-its-atmosphere/546074/9 "2010-07-09T09:02:53Z")
Deleted - never mind ---
**Author:** ![Quartz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quartz/32/267_2.png) [@Quartz](https://boards.straightdope.com/u/Quartz)\ **Post date:** [July 9, 2010, 9:05am UTC](https://boards.straightdope.com/t/how-much-mass-could-earth-safely-lose-and-retain-its-atmosphere/546074/10 "2010-07-09T09:05:44Z")
> [@Whack-a-Mole](#): > > The mass loss is insignificant compared to the size of the planet. Currently, yes, but what about the future? And besides, as Global Warming proponents tell us, there are inflection points. ---
**Author:** ![si\_blakely](https://avatars.discourse-cdn.com/v4/letter/s/d9b06d/32.png) [@si\_blakely](https://boards.straightdope.com/u/si_blakely)\ **Post date:** [July 9, 2010, 10:08am UTC](https://boards.straightdope.com/t/how-much-mass-could-earth-safely-lose-and-retain-its-atmosphere/546074/11 "2010-07-09T10:08:57Z")
If we want mass in space, we are not going to waste energy throwing it up from earth, we are going to collect mass that is already up - plenty of asteroids and stuff to use. We might even steal momentum from those objects to move other things around, saving (or generating) additional energy. Si ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [July 9, 2010, 12:23pm UTC](https://boards.straightdope.com/t/how-much-mass-could-earth-safely-lose-and-retain-its-atmosphere/546074/12 "2010-07-09T12:23:41Z")
> [@Simplicio](#): > > I get something crazy small, like .0004 the current mass till the average velocity of N2 at 300K is at the escape velocity. Is late though, I’ll try again in the morning when I’m more awake. Its not the average you have to worry about. Its the FASTEST ones. You loose them, then new ones become the fastest ones. Rinse and repeat. And you need to worry about hydrogen too. Water in the upper atmosphere breaks up due to UV. It normally recombines, but if the hydrogen escapes first it cannot recombine with the oxygen to make water. You don’t want an Earth that ended up virtually water free either. ---
**Author:** ![RickJay](https://avatars.discourse-cdn.com/v4/letter/r/bb73d2/32.png) [@RickJay](https://boards.straightdope.com/u/RickJay)\ **Post date:** [July 9, 2010, 1:50pm UTC](https://boards.straightdope.com/t/how-much-mass-could-earth-safely-lose-and-retain-its-atmosphere/546074/13 "2010-07-09T13:50:16Z")
> [@Quartz](#): > > Just wait until we start lofting millions of tonnes via mass drivers or whatever. You’ll be waiting a long time, I suspect. The Earth gains about 30,000 tons of mass a year from space debris. So just going back a million years - a blink of an eye, geologically speaking - the Earth is about 30,000,000,000 tons heavier than it was in 998,000 BC, when presumably the atmosphere was pretty much just as thick as it is today. One has to assume we could lose that much and it’d make no difference, since our planet did not run out of atmosphere a million years ago. We’d have to work a very long time indeed to fire thirty billion tons of stuff off the planet just to make up for the last million years of space dust. ---
**Author:** ![dracoi](https://avatars.discourse-cdn.com/v4/letter/d/90db22/32.png) [@dracoi](https://boards.straightdope.com/u/dracoi)\ **Post date:** [July 9, 2010, 9:12pm UTC](https://boards.straightdope.com/t/how-much-mass-could-earth-safely-lose-and-retain-its-atmosphere/546074/14 "2010-07-09T21:12:00Z")
> [@Quartz](#): > > Just wait until we start lofting millions of tonnes via mass drivers or whatever. I suspect that we’ll start bringing back a lot of material at that point from activities like asteroid mining. Before long, we’d reach some kind of equilibrium, I think. I also think you’re underestimating the size of the Earth. The Earth weighs 6 x 10^24 kg. A million tons is 1 x 10^9 kg. If we removed 200 million tons every year, the Earth would cease to exist before we could remove 1% of it (that is, it would take 5 billion years to remove just 1% at that rate). For another example: if you removed the oceans entirely, you’d have removed only 0.1% of the Earth’s mass. ---
**Author:** ![Quartz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quartz/32/267_2.png) [@Quartz](https://boards.straightdope.com/u/Quartz)\ **Post date:** [July 9, 2010, 9:40pm UTC](https://boards.straightdope.com/t/how-much-mass-could-earth-safely-lose-and-retain-its-atmosphere/546074/15 "2010-07-09T21:40:50Z")
No, I haven’t underestimated the mass of the Earth. I’m sure you noted the comparison with Venus in my OP. ---
**Author:** ![user\_hostile](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/user_hostile/32/474_2.png) [@user\_hostile](https://boards.straightdope.com/u/user_hostile)\ **Post date:** [July 10, 2010, 1:35am UTC](https://boards.straightdope.com/t/how-much-mass-could-earth-safely-lose-and-retain-its-atmosphere/546074/16 "2010-07-10T01:35:17Z")
> [@billfish678](#): > > Its not the average you have to worry about. Its the FASTEST ones. You loose them, then new ones become the fastest ones. Rinse and repeat. > > And you need to worry about hydrogen too. Water in the upper atmosphere breaks up due to UV. It normally recombines, but if the hydrogen escapes first it cannot recombine with the oxygen to make water. You don’t want an Earth that ended up virtually water free either. Which this little abstract in [SciAm](http://www.scientificamerican.com/article.cfm?id=how-planets-lose-their-atmospheres)explains is likely happens to earth in a few billion years. (Sorry, pay type subscription ) ---
**Author:** ![Quartz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quartz/32/267_2.png) [@Quartz](https://boards.straightdope.com/u/Quartz)\ **Post date:** [July 10, 2010, 5:35am UTC](https://boards.straightdope.com/t/how-much-mass-could-earth-safely-lose-and-retain-its-atmosphere/546074/17 "2010-07-10T05:35:27Z")
According to that article and some quick maths, the Earth is losing 100K tonnes of hydrogen per year. Not a lot, but significant over time. ---
**Author:** ![jackdavinci](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jackdavinci/32/3259_2.png) [@jackdavinci](https://boards.straightdope.com/u/jackdavinci)\ **Post date:** [July 12, 2010, 6:58am UTC](https://boards.straightdope.com/t/how-much-mass-could-earth-safely-lose-and-retain-its-atmosphere/546074/18 "2010-07-12T06:58:04Z")
> [@RickJay](#): > > The Earth gains about 30,000 tons of mass a year from space debris. > [@Quartz](#): > > According to that article and some quick maths, the Earth is losing 100K tonnes of hydrogen per year. Not a lot, but significant over time. Hundreds of thousands of anything sound arbitrarily impressive to be sure. Earth mass is 5.9742 × 10^24 kg so… it gains 27 215 542.2 kilograms and loses 90 718 474 kilograms so theoretically a net loss of 63,502,931.8 kg/year Of course, I have to wonder, what would the situation be like without life? What would our planet look like without the benefit of organic processes? ---
**Author:** ![Quartz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quartz/32/267_2.png) [@Quartz](https://boards.straightdope.com/u/Quartz)\ **Post date:** [July 12, 2010, 7:24am UTC](https://boards.straightdope.com/t/how-much-mass-could-earth-safely-lose-and-retain-its-atmosphere/546074/19 "2010-07-12T07:24:24Z")
> [@jackdavinci](#): > > Of course, I have to wonder, what would the situation be like without life? What would our planet look like without the benefit of organic processes? Organic processes have significantly reduced Earth’s atmosphere, in both senses of the word. There’s a lot of CO2 stored in carbonates, particularly Calcium Carbonate, and a lot of CO2 and H2O stored in fossil fuels. But a lot of oxygen was released by cyanobacteria working on iron oxides, and plants to this day take in CO2 and H2O and emit oxygen. ---
**Author:** ![Rigamarole](https://avatars.discourse-cdn.com/v4/letter/r/77aa72/32.png) [@Rigamarole](https://boards.straightdope.com/u/Rigamarole)\ **Post date:** [July 12, 2010, 7:42am UTC](https://boards.straightdope.com/t/how-much-mass-could-earth-safely-lose-and-retain-its-atmosphere/546074/20 "2010-07-12T07:42:26Z")
Wouldn’t a large loss of mass have a more significant impact on the Earth’s orbit (and by extension - climate) than its atmosphere? [Next page](https://boards.straightdope.com/t/how-much-mass-could-earth-safely-lose-and-retain-its-atmosphere/546074.md?page=2)