Author Topic: NASA’s Retiring Top Scientist Says We Can Terraform Mars and Maybe Venus, Too  (Read 33547 times)

Offline su27k

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https://www.nytimes.com/2022/01/02/science/jim-green-nasa-mars.html

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Since joining NASA in 1980, Jim Green has seen it all. He has helped the space agency understand Earth’s magnetic field, explore the outer solar system and search for life on Mars. As the new year arrived on Saturday, he bade farewell to the agency.

Over the past four decades, which includes 12 years as the director of NASA’s planetary science division and the last three years as its chief scientist, he has shaped much of NASA’s scientific inquiry, overseeing missions across the solar system and contributing to more than 100 scientific papers across a range of topics. While specializing in Earth’s magnetic field and plasma waves early in his career, he went on to diversify his research portfolio.

One of Dr. Green’s most recent significant proposals has been a scale for verifying the detection of alien life, called the “confidence of life detection,” or CoLD, scale. He has published work suggesting we could terraform Mars, or making it habitable for humans, using a giant magnetic shield to stop the sun from stripping the red planet’s atmosphere, raising the temperature on the surface. He has also long been a proponent of the exploration of other worlds, including a mission to Europa, the icy moon of Jupiter, that is scheduled to launch in 2024.

Offline Twark_Main

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He has published work suggesting we could terraform Mars, or making it habitable for humans, using a giant magnetic shield to stop the sun from stripping the red planet’s atmosphere, raising the temperature on the surface.

There's one data point which blows away this idea in anything except the extremely long-term (think "geologic time").

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MAVEN has observed the Martian upper atmosphere for a full Martian year, and has determined the rate of loss of gas to space and the driving processes; 1–2 kg/s of gas are being lost.

So the maximum possible gain is 1-2 kg/s of atmosphere.

At this rate, 1% of the atmosphere would be conserved (not added, mind you) every 4-8 million years.

https://www.sciencedirect.com/science/article/abs/pii/S0019103517306917
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Offline Robotbeat

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Yeah, I pointed that out to him. His defense is that he posits a super strong feedback mechanism so once you start reversing the process, the atmosphere will start to warm up and the surface will outgas quickly.

I don’t really buy it, though. I don’t buy the idea that there’s THAT strong of a feedback loop that you’ll get results in decades or centuries what ought to take tens of millions of years.

So you’ll need to provide the atmosphere and/or heat in some other way than indirectly through a magnetosphere. Giant mirrors should do the trick at least to the Armstrong Limit at low altitude and with enough mirrors (that you get off gassing even from tightly bound CO2 in rock and soil, not just CO2 ices, etc) something more comfortable than that. Also, delivery of gases from comets or icy bodies.

The upshot is you don’t even need a magnetosphere except in the extreme long term (millions to tens of millions of years), although annoyingly almost every single person on the Internet who knows anything about Mars at all is convinced you do since that is what every NOVA special or YouTube video about Mars says.
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Offline spacenut

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Mars needs a magnetic field to keep from losing atmosphere, like our Van Allen belt.  This might be done with satellites, before they start terraforming.  Dirty industries on Mars could help heat up the atmosphere producing more CO2, heat and such. 

It seems like it would take a long time.  Much longer on Venus.

Offline Twark_Main

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If he thinks the Martian climate is that sensitive, yeeting 30 payloads of 100 tonnes of SF6 each at Mars would achieve the same warming potential as 100 years of H2 at 2 kg/s.

You wouldn't even need to send the Starship, just a disposable tank. Strap a Starlink to the tank for mid-course burns, keeping the Starship in Earth's SOI for immediate reuse. One Starship could launch many such payloads to Mars in one synodic period.


Of course I don't think the Martian climate is that sensitive to small warming "nudges," so IMHO this would be pointless. But if he believes it's true, why would he support an expensive mission (big magnet thing) over a cheap mission?
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Offline Vultur

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Re sensitivity or not of the Martian climate system: I read years and years ago that Mars' axis tilt is thought to vary way more than Earth's (0 to 60 degrees or something) over hundreds of thousands of years, and at high tilt values, the CO2 ice at the poles probably sublimates.

Is that still thought to be true?

If so, doesn't that set a limit of how sensitive it can be if vaporizing all that CO2 doesn't turn it Earthlike?

Offline Slarty1080

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If he thinks the Martian climate is that sensitive, yeeting 30 payloads of 100 tonnes of SF6 each at Mars would achieve the same warming potential as 100 years of H2 at 2 kg/s.

You wouldn't even need to send the Starship, just a disposable tank. Strap a Starlink to the tank for mid-course burns, keeping the Starship in Earth's SOI for immediate reuse. One Starship could launch many such payloads to Mars in one synodic period.


Of course I don't think the Martian climate is that sensitive to small warming "nudges," so IMHO this would be pointless. But if he believes it's true, why would he support an expensive mission (big magnet thing) over a cheap mission?
Yes I take your point, although in practice can you imagine the reaction to any suggestion that 100 tonne payloads of SF6 (23,000x more potent greenhouse gas than CO2) being launched from Earth? If anything went wrong it would not be good on multiple levels.
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Offline Twark_Main

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If he thinks the Martian climate is that sensitive, yeeting 30 payloads of 100 tonnes of SF6 each at Mars would achieve the same warming potential as 100 years of H2 at 2 kg/s.

You wouldn't even need to send the Starship, just a disposable tank. Strap a Starlink to the tank for mid-course burns, keeping the Starship in Earth's SOI for immediate reuse. One Starship could launch many such payloads to Mars in one synodic period.


Of course I don't think the Martian climate is that sensitive to small warming "nudges," so IMHO this would be pointless. But if he believes it's true, why would he support an expensive mission (big magnet thing) over a cheap mission?
Yes I take your point, although in practice can you imagine the reaction to any suggestion that 100 tonne payloads of SF6 (23,000x more potent greenhouse gas than CO2) being launched from Earth? If anything went wrong it would not be good on multiple levels.

People react in lots of silly ways, but the truth is that it would be a drop in the bucket compared to other SF6 emission sources.

Nike filled all their "Air" shoes from 1992 to 2006 with SF6, all of which eventually leaks out into the atmosphere. In the year 1997 alone they released 277 tons of the stuff.
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Offline Roy_H

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I'm not going to argue that this proposal is practical from a cost/capability viewpoint, but more theoretical.

What if hundreds of large space craft were built designed to orbit between Saturn and Venus. On the low Saturn pass could they drop a long tube into the upper atmosphere and suck up thousands (millions?) of tons of Hydrogen (actually suck is the wrong term, pump at bottom of tube would be required) Then when low over Venus discharge this into the upper atmosphere, but igniting it so it will burn with oxygen and produce water for Venus. If these ships were totally automated maybe in a thousand years lakes and oceans would appear on Venus. Of course there are other major issues such as spinning up Venus and creating a protective magnetic shield like Earth. Venus does have the major advantage of being similar size to Earth. A method of cooling Venus could be huge Mylar reflective shield in orbit around Venus that would partially shade Venus.

Not much pure oxygen in Venus atmosphere, so the hydrogen would burn with Carbon Dioxide producing water and methane gas. Is there a method to get rid of the methane gas?

To answer my own question, plants convert CO2 into carbon and oxygen, so maybe this could be done first?
« Last Edit: 06/03/2022 07:28 pm by Roy_H »
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Offline deadman1204

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Just because someone publishes something doesn't mean its true.

Offline Slarty1080

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I'm not going to argue that this proposal is practical from a cost/capability viewpoint, but more theoretical.

What if hundreds of large space craft were built designed to orbit between Saturn and Venus. On the low Saturn pass could they drop a long tube into the upper atmosphere and suck up thousands (millions?) of tons of Hydrogen (actually suck is the wrong term, pump at bottom of tube would be required) Then when low over Venus discharge this into the upper atmosphere, but igniting it so it will burn with oxygen and produce water for Venus. If these ships were totally automated maybe in a thousand years lakes and oceans would appear on Venus. Of course there are other major issues such as spinning up Venus and creating a protective magnetic shield like Earth. Venus does have the major advantage of being similar size to Earth. A method of cooling Venus could be huge Mylar reflective shield in orbit around Venus that would partially shade Venus.

Not much pure oxygen in Venus atmosphere, so the hydrogen would burn with Carbon Dioxide producing water and methane gas. Is there a method to get rid of the methane gas?

To answer my own question, plants convert CO2 into carbon and oxygen, so maybe this could be done first?
I don't think this is even theoretically possible. Any ship passing by Saturn would have to be traveling in excess of Saturn's escape velocity (35km/s) else it would go into orbit. With a rotation of once every ten hours Saturn's cloud tops won't be moving at more than 10km/s so each tonne of gas extracted from Saturn would need to be supplied with an additional 25km/s of deltaV to leave Saturn. Its a total no starter even theoretically.
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Offline Lampyridae

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I'm not going to argue that this proposal is practical from a cost/capability viewpoint, but more theoretical.

What if hundreds of large space craft were built designed to orbit between Saturn and Venus. On the low Saturn pass could they drop a long tube into the upper atmosphere and suck up thousands (millions?) of tons of Hydrogen (actually suck is the wrong term, pump at bottom of tube would be required) Then when low over Venus discharge this into the upper atmosphere, but igniting it so it will burn with oxygen and produce water for Venus. If these ships were totally automated maybe in a thousand years lakes and oceans would appear on Venus. Of course there are other major issues such as spinning up Venus and creating a protective magnetic shield like Earth. Venus does have the major advantage of being similar size to Earth. A method of cooling Venus could be huge Mylar reflective shield in orbit around Venus that would partially shade Venus.

Not much pure oxygen in Venus atmosphere, so the hydrogen would burn with Carbon Dioxide producing water and methane gas. Is there a method to get rid of the methane gas?

To answer my own question, plants convert CO2 into carbon and oxygen, so maybe this could be done first?
I don't think this is even theoretically possible. Any ship passing by Saturn would have to be traveling in excess of Saturn's escape velocity (35km/s) else it would go into orbit. With a rotation of once every ten hours Saturn's cloud tops won't be moving at more than 10km/s so each tonne of gas extracted from Saturn would need to be supplied with an additional 25km/s of deltaV to leave Saturn. Its a total no starter even theoretically.

Chucking out the ship and its high approach velocity, it would be more feasible with Neptune or Uranus, especially since they have smaller gravity wells. Mine mass from the outer moons, and use that in a biiiig skyhook/tether to exchange momentum for the hydrogen. Obviously this is mega scale engineering with carbon nanotube strengths, cheap and easy fusion etc.

If you're really going to all that effort, rather give Callisto a magnetosphere and an atmosphere.
« Last Edit: 06/15/2022 09:20 am by Lampyridae »

Offline JohnFornaro

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...plants convert CO2 into carbon and oxygen, so maybe this could be done first?

We're certainly not going to try that approach here on Earth, but it might be appropriate for Venus.
Sometimes I just flat out don't get it.

Offline Vahe231991

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I'm not going to argue that this proposal is practical from a cost/capability viewpoint, but more theoretical.

What if hundreds of large space craft were built designed to orbit between Saturn and Venus. On the low Saturn pass could they drop a long tube into the upper atmosphere and suck up thousands (millions?) of tons of Hydrogen (actually suck is the wrong term, pump at bottom of tube would be required) Then when low over Venus discharge this into the upper atmosphere, but igniting it so it will burn with oxygen and produce water for Venus. If these ships were totally automated maybe in a thousand years lakes and oceans would appear on Venus. Of course there are other major issues such as spinning up Venus and creating a protective magnetic shield like Earth. Venus does have the major advantage of being similar size to Earth. A method of cooling Venus could be huge Mylar reflective shield in orbit around Venus that would partially shade Venus.

Not much pure oxygen in Venus atmosphere, so the hydrogen would burn with Carbon Dioxide producing water and methane gas. Is there a method to get rid of the methane gas?

To answer my own question, plants convert CO2 into carbon and oxygen, so maybe this could be done first?
I don't think this is even theoretically possible. Any ship passing by Saturn would have to be traveling in excess of Saturn's escape velocity (35km/s) else it would go into orbit. With a rotation of once every ten hours Saturn's cloud tops won't be moving at more than 10km/s so each tonne of gas extracted from Saturn would need to be supplied with an additional 25km/s of deltaV to leave Saturn. Its a total no starter even theoretically.

Chucking out the ship and its high approach velocity, it would be more feasible with Neptune or Uranus, especially since they have smaller gravity wells. Mine mass from the outer moons, and use that in a biiiig skyhook/tether to exchange momentum for the hydrogen. Obviously this is mega scale engineering with carbon nanotube strengths, cheap and easy fusion etc.

If you're really going to all that effort, rather give Callisto a magnetosphere and an atmosphere.
There was a study published in 2003 by Pat Troutman and Kristen Bethke suggesting that Callisto might be a suitable place for a human base for future exploration of the Jovian system due to its low radiation levels. However, terraforming Callisto would be an astronomically costly task.

Link:
https://web.archive.org/web/20120119170143/http://www.nasa-academy.org/soffen/travelgrant/bethke.pdf

Offline JulesVerneATV

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Venus, not so sure.

Offline AU1.52

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...plants convert CO2 into carbon and oxygen, so maybe this could be done first?

We're certainly not going to try that approach here on Earth, but it might be appropriate for Venus.


How would the plants with stand the surface pressure?

Offline VSECOTSPE

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How would the plants with stand the surface pressure?

Atmospheric algae, which is a thing here on Earth, high enough in the Venusian stratosphere to live in a 1 bar atmosphere.  Presumably genetically engineered to stay/reproduce quickly at that altitude and maximize CO2 extraction.  But algae require hydrogen to process CO2, which the Venusian atmosphere has largely lost to the solar wind due to its lack of magnetosphere.  So even with algae, you’re back to scooping and shipping ridiculous amounts of hydrogen from a gas giant in the outer solar system.

The (likely) more straightforward way to remove CO2 from the Venusian atmosphere is probably some form of solar shading combined with turning over its lithosphere (its surface rock) to expose its calcium and magnesium oxides.  The equilibrium at Venus between the surface oxides and the atmospheric CO2 is really unstable, and once exposed, the oxides will sequester a lot of CO2 in carbonates over a period of hundreds or thousands of years.  There are also catalysts that can to accelerate this process to under a century.  Turning over the lithosphere would probably involve some form of bombardment, and bombardment by meteoroids also rich in calcium and magnesium oxides would also accelerate the process.

That said, the stratosphere of Venus is the one natural location in the solar system that approximates Earth’s gravity and some measure of protection from cosmic radiation, i.e. aerostats in the Venusian atmosphere may be the one safe place besides Earth to live out a natural lifespan and have children.  (And you get a 1-bar atmosphere to boot.)  So we might not want to mess with it.
« Last Edit: 07/13/2022 03:37 pm by VSECOTSPE »

Offline Joffan

How would the plants with stand the surface pressure?

Atmospheric algae, which is a thing here on Earth, high enough in the Venusian stratosphere to live in a 1 bar atmosphere.  Presumably genetically engineered to stay/reproduce quickly at that altitude and maximize CO2 extraction.  But algae require hydrogen to process CO2, which the Venusian atmosphere has largely lost to the solar wind due to its lack of magnetosphere.  So even with algae, you’re back to scooping and shipping ridiculous amounts of hydrogen from a gas giant in the outer solar system.

The (likely) more straightforward way to remove CO2 from the Venusian atmosphere is probably some form of solar shading combined with turning over its lithosphere (its surface rock) to expose its calcium and magnesium oxides.  The equilibrium at Venus between the surface oxides and the atmospheric CO2 is really unstable, and once exposed, the oxides will sequester a lot of CO2 in carbonates over a period of hundreds or thousands of years.  There are also catalysts that can to accelerate this process to under a century.  Turning over the lithosphere would probably involve some form of bombardment, and bombardment by meteoroids also rich in calcium and magnesium oxides would also accelerate the process.

That said, the stratosphere of Venus is the one natural location in the solar system that approximates Earth’s gravity and some measure of protection from cosmic radiation, i.e. aerostats in the Venusian atmosphere may be the one safe place besides Earth to live out a natural lifespan and have children.  (And you get a 1-bar atmosphere to boot.)  So we might not want to mess with it.

I'm a fan of setting up Venus bases in the clouds at the 50-ish km altitude sweet spot, and I don't think there is a serious risk of losing that desirable zone even if we start "improving" Venus. Reducing temperatures through locking up CO2 somehow could only result in the 1-atm zone changing altitude gradually, which a buoyant base would naturally follow without significant difficulty - maybe a little adjustment to buoyancy if the atmospheric composition moved a log way from the current mix..
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Offline deadman1204

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How would the plants with stand the surface pressure?


The (likely) more straightforward way to remove CO2 from the Venusian atmosphere is probably some form of solar shading combined with turning over its lithosphere (its surface rock) to expose its calcium and magnesium oxides.  The equilibrium at Venus between the surface oxides and the atmospheric CO2 is really unstable, and once exposed, the oxides will sequester a lot of CO2 in carbonates over a period of hundreds or thousands of years.  There are also catalysts that can to accelerate this process to under a century.  Turning over the lithosphere would probably involve some form of bombardment, and bombardment by meteoroids also rich in calcium and magnesium oxides would also accelerate the process.

That said, the stratosphere of Venus is the one natural location in the solar system that approximates Earth’s gravity and some measure of protection from cosmic radiation, i.e. aerostats in the Venusian atmosphere may be the one safe place besides Earth to live out a natural lifespan and have children.  (And you get a 1-bar atmosphere to boot.)  So we might not want to mess with it.
Errrr, you really underestimate the size of a PLANET. Also time scales. It took hundreds of millions of years for all the oxygen sinks on earth to be exhausted (and oxygen is WAY more reactive than co2). "Turning over" the entire surface of a planet and letting it absorb all the co2 in a few hundred years? Thats beyond ludicrous.

Add a "catalyst"? So grind up the entire surface of a planet (I don't even have words for this...), and then mix it with another substance - JUST a few hundred trillion tons will do I'm sure...

To try and put terra forming into perspective, imagine moving the entire rocky mountain chain - from Canada to Mexico  to the moon. (Have you ever looked at how big a single mountain actually is?) Making our new lunar mountains would be incredibly easy compared to actually terraforming a planet, as it would involve moving a tiny amount of matter compared to the things you've suggested doing on Venus.
« Last Edit: 07/27/2022 08:49 pm by deadman1204 »

Offline VSECOTSPE

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It took hundreds of millions of years for all the oxygen sinks on earth to be exhausted (and oxygen is WAY more reactive than co2). "Turning over" the entire surface of a planet and letting it absorb all the co2 in a few hundred years? Thats beyond ludicrous.

Comes from research into carbon sequestration efforts on Earth, like this one:

Quote
Scientists have found a rapid way of producing magnesite, a mineral which stores carbon dioxide... A tonne of naturally-occurring magnesite can remove around half a tonne of CO2 from the atmosphere, but the rate of formation is very slow.

Project leader, Professor Ian Power (Trent University, Ontario, Canada) said:

"Our work shows two things. Firstly, we have explained how and how fast magnesite forms naturally. This is a process which takes hundreds to thousands of years in nature at Earth's surface. The second thing we have done is to demonstrate a pathway which speeds this process up dramatically"

The researchers were able to show that by using polystyrene microspheres as a catalyst, magnesite would form within 72 days. The microspheres themselves are unchanged by the production process, so they can ideally be reused.

"Using microspheres means that we were able to speed up magnesite formation by orders of magnitude. This process takes place at room temperature, meaning that magnesite production is extremely energy efficient"...

Commenting, Professor Peter Kelemen at Columbia University's Lamont Doherty Earth Observatory (New York) said "It is really exciting that this group has worked out the mechanism of natural magnesite crystallization at low temperatures, as has been previously observed—but not explained—in weathering of ultramafic rocks. The potential for accelerating the process is also important, potentially offering a benign and relatively inexpensive route to carbon storage, and perhaps even direct CO2 removal from air."

https://phys.org/news/2018-08-scientists-mineral-co2-atmosphere.html

To be clear, any terraforming is engineering on a crazy scale.  But there’s more crazy and there’s less crazy.  My two cents is that mining enough hydrogen from a gas giant in the outer solar system to seed entire oceans and shipping it to the atmosphere of Venus is more crazy than bombarding Venus with inner solar system asteroids to activate the massive but unused geological CO2 sinks that exist just beneath its surface.  The fact that we are uncovering catalytic processes through carbon sequestration research that can accelerate the carbon sink process from thousands of years to tens of days makes it even more reasonable than the alternative.  I’m not claiming that this terraforming scheme will work.  I’m not claiming that any terraforming scheme is sensible.  I’m just groping through degrees of insanity and saying this scheme seems somewhat less insane than this other one.

In general, my belief is that terraforming schemes that can create a runaway effect by kicking a planet’s existing chemical or physical disequilibria downhill will probably work better, faster, and more affordably than more brute force methods.  But since we are talking about changing extremely large and complex systems on scales humanity has never purposefully attempted, I’m qualifying that as a belief, not an observation.  At some point, any conversation about terraforming methods becomes angels on the head of a pin.

 

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