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’?
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?
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.
Just wait until we start lofting millions of tonnes via mass drivers or whatever.
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 serves as a proxy field for part of the time.
The mass loss is insignificant compared to the size of the planet. Plus the earth gains mass every year.
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.
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.
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.
Deleted - never mind
Currently, yes, but what about the future? And besides, as Global Warming proponents tell us, there are inflection points.
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
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.
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.
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.
No, I haven’t underestimated the mass of the Earth. I’m sure you noted the comparison with Venus in my OP.
Which this little abstract in SciAmexplains is likely happens to earth in a few billion years. (Sorry, pay type subscription )
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?
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.
Wouldn’t a large loss of mass have a more significant impact on the Earth’s orbit (and by extension - climate) than its atmosphere?