Discussion on sci.space.science

In article ,
says...

On Wednesday, August 15, 2018 at 7:16:13 AM UTC-4, Jeff Findley wrote:

But, at the same time, terraforming will take hundreds or thousands of
years. Not something we're ever going to watch live on YouTube like a
rocket launch.

One website article I found said more like 100,000 years.

All of us here will no doubt be long gone when the first
Kuiper belt object is dropped on Mars.

Just how do you go about "dropping a Kuiper belt object on Mars?"

An object 1/4 mile in diameter would probably be in the billions
of tons. Where will the energy be found to transfer that to a
Mars solar orbit perigee, then accelerate it up to Mars solar
orbit speed, then decelerate it to Mars surface at a speed that
won't create a massive crater on the scale of the one out in
Arizona?

Nuclear fission or nuclear fusion powered rocket engine using some of
the volatiles from the Kuiper belt object as reaction mass. You'd
almost surely combine that with some gravity assist flybys and the like.
But, as you said before, this would be a very long process.

How many hundreds or thousands of such objects would be needed?

I'd guess many thousands. Terraforming isn't well suited for the
impatient. ;-)

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.

"Scott M. Kozel" wrote on Wed, 15 Aug 2018
13:05:30 -0700 (PDT):

On Wednesday, August 15, 2018 at 7:16:13 AM UTC-4, Jeff Findley wrote:

But, at the same time, terraforming will take hundreds or thousands of
years. Not something we're ever going to watch live on YouTube like a
rocket launch.


One website article I found said more like 100,000 years.


It will take sometime between a week and forever.



All of us here will no doubt be long gone when the first
Kuiper belt object is dropped on Mars.


Just how do you go about "dropping a Kuiper belt object on Mars?"


The same way you move anything else in space.


An object 1/4 mile in diameter would probably be in the billions
of tons. Where will the energy be found ...


Well, the object is essentially MADE of fuel, so you just send out a
tug engine and burn part of the object to get it to Mars. Or you
build a mass driver tug and throw part of the object to move the rest
of it. Or ...


... to transfer that to a
Mars solar orbit perigee, then accelerate it up to Mars solar
orbit speed, then decelerate it to Mars surface at a speed that
won't create a massive crater on the scale of the one out in
Arizona?


Why do you care if it makes a crater and what makes you think it
would? These things are mostly volatiles. They're going to melt on
the way down. Worst case you get something like Tunguska, which made
a big blast but left no crater at all that we can find.


How many hundreds or thousands of such objects would be needed?


Why do you even ask questions like this?


--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn

On Thursday, August 16, 2018 at 12:08:28 AM UTC-4, JF Mezei wrote:

QUESTION:

In theoretical terraforming scenario where lots of CO2 is added, with
so much of atmpsphere very thin and very high, would the CO2 reflect the
heat back to ground level in a significant way? Or would it trap heat at
such a high altitude that ground level would see little change ?

One of the articles that I found, said that if the terraforming process
went awry, that fixing the issues might make the whole process far more
difficult and time consuming than it would be from starting with the
virgin planet.

On Thursday, August 16, 2018 at 12:08:37 AM UTC-4, Fred J. McCall wrote:
"Scott M. Kozel" wrote on Wed, 15 Aug 2018

One website article I found said more like 100,000 years.


It will take sometime between a week and forever.

A week is a bit of a stretch.

Just how do you go about "dropping a Kuiper belt object on Mars?"


The same way you move anything else in space.

So it is an engineering problem. Just like if someone proposed
increasing the diameter of the orbit of Venus by 10 million miles as
part of its terraforming process.

An object 1/4 mile in diameter would probably be in the billions
of tons. Where will the energy be found ...

Well, the object is essentially MADE of fuel, so you just send out a
tug engine and burn part of the object to get it to Mars. Or you
build a mass driver tug and throw part of the object to move the rest
of it. Or ...

You need an oxidizer in addition to the fuel (methane, ethane, other
hydrocarbons).

Why do you care if it makes a crater and what makes you think it
would? These things are mostly volatiles. They're going to melt on
the way down. Worst case you get something like Tunguska, which made
a big blast but left no crater at all that we can find.

Depends on the velocity and angle of entry. Presumably the Tunguska
object entered the atmosphere and a very high velocity but a very
shallow angle. A steep angle might have had the object hit the Earth
mostly intact.

A cubic mile of ices coming in at 20,000 mph and an angle of 70+
degrees to the ground?

JF Mezei wrote on Thu, 16 Aug 2018
00:08:27 -0400:

On 2018-08-15 20:16, Jeff Findley wrote:

Nuclear fission or nuclear fusion powered rocket engine using some of
the volatiles from the Kuiper belt object as reaction mass. You'd
almost surely combine that with some gravity assist flybys and the like.
But, as you said before, this would be a very long process.


Woopty do.


Dipty ****.


When you consider the low gravity of Mars, and that to increase PSI are
ground level, you will need to add a HUGE amount of atmpsophere most of
which will be so high as to be useless, it becomes far more efficient
to just build pressurized shelters (which you need to build anyways) and
just add the atmosphere needed to pressurize the shelters and energy to
heat them.


Except then you're having to work in a high-radiation low-pressure
environment, which is much more difficult and dangerous. Estimates
say if you could melt all the CO2 at the poles it would get you
halfway there without having to dump in anything from outside.


And since such a colony would have limited O2 supply, it is more likely
that the CO2 would get recycled into Carbon and O2 as part of ECLSS of
the habitable volumes. aka: they aren't going to dump CO2 into outside
atmosphere.


Why not? You can always get it back when you want it.


QUESTION:

In theoretical terraforming scenario where lots of CO2 is added, with
so much of atmpsphere very thin and very high, would the CO2 reflect the
heat back to ground level in a significant way? Or would it trap heat at
such a high altitude that ground level would see little change ?


If there is no overcast in the atmosphere you will likely get warmish
days and cold nights (think Denver on a clear winter day).


--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn

"Scott M. Kozel" wrote on Wed, 15 Aug 2018
21:24:54 -0700 (PDT):

On Thursday, August 16, 2018 at 12:08:37 AM UTC-4, Fred J. McCall wrote:
"Scott M. Kozel" wrote on Wed, 15 Aug 2018

One website article I found said more like 100,000 years.


It will take sometime between a week and forever.

A week is a bit of a stretch.

Just how do you go about "dropping a Kuiper belt object on Mars?"


The same way you move anything else in space.

So it is an engineering problem. Just like if someone proposed
increasing the diameter of the orbit of Venus by 10 million miles as
part of its terraforming process.


True, although changing the orbital velocity of something the size of
a planet is just a BIT harder than moving a bunch of comet stuff.

An object 1/4 mile in diameter would probably be in the billions
of tons. Where will the energy be found ...

Well, the object is essentially MADE of fuel, so you just send out a
tug engine and burn part of the object to get it to Mars. Or you
build a mass driver tug and throw part of the object to move the rest
of it. Or ...

You need an oxidizer in addition to the fuel (methane, ethane, other
hydrocarbons).


Part of these things IS water-ice. Plus you can always use something
like nuclear thermal that doesn't 'combust' the fuel in the usual
sense.

Why do you care if it makes a crater and what makes you think it
would? These things are mostly volatiles. They're going to melt on
the way down. Worst case you get something like Tunguska, which made
a big blast but left no crater at all that we can find.

Depends on the velocity and angle of entry. Presumably the Tunguska
object entered the atmosphere and a very high velocity but a very
shallow angle. A steep angle might have had the object hit the Earth
mostly intact.


Unlikely. The Tunguska object was believed to be something more like
a comet than an asteroid (exactly what you'd be throwing at Mars) and
if there was any significant rocky core we'd have found impact
indications.


A cubic mile of ices coming in at 20,000 mph and an angle of 70+
degrees to the ground?


Remember, comet-stuff starts disintegrating from solar pressure...


--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn

On Thursday, August 16, 2018 at 7:00:55 AM UTC-4, Fred J. McCall wrote:
"Scott M. Kozel" wrote on Wed, 15 Aug 2018

So it is an engineering problem. Just like if someone proposed
increasing the diameter of the orbit of Venus by 10 million miles as
part of its terraforming process.

True, although changing the orbital velocity of something the size of
a planet is just a BIT harder than moving a bunch of comet stuff.

You need an oxidizer in addition to the fuel (methane, ethane, other
hydrocarbons).

Part of these things IS water-ice. Plus you can always use something
like nuclear thermal that doesn't 'combust' the fuel in the usual
sense.

I was somewhat tongue-in-cheek about mentioning Venus, as its mass
is millions of times more massive than a comet-like object.

But comets themselves are massive and would take fantastic amounts of
energy to redirect --

"However, what is most likely being asked here is what is the mass
of a typical comet. And the answer to that is: it varies. Cometary
bodies large enough to be detected (i.e. to have both a head and a
discernible tail) can range from less than 6.5 x 10^13 (65 trillion)
kilograms, on up to the mass of Comet Hale-Bopp, which has been
conservatively estimated at 1.3 x 10^16 (13 quadrillion) kilograms,
or what would be more than 28.6 quadrillion pounds if the comet were
to sit somehow on the surface of the Earth."

https://www.quora.com/How-much-does-a-comet-weigh

Depends on the velocity and angle of entry. Presumably the Tunguska
object entered the atmosphere and a very high velocity but a very
shallow angle. A steep angle might have had the object hit the Earth
mostly intact.

Unlikely. The Tunguska object was believed to be something more like
a comet than an asteroid (exactly what you'd be throwing at Mars) and
if there was any significant rocky core we'd have found impact
indications.

The Tunguska object is a mystery. As you suggested a comet-like body
melts and outgasses as it comes closer to the Sun. Usually well underway
within 2 astronomical units from the Sun (Mars being within that). So
the questions outstanding are how did a comet get that close to the Earth
without being sighted, how did it stay intact enough to cause a massive
explosion in the atmosphere.

One theory is that it was a rocky object that came into the atmosphere
at a nearly flat angle and at extremely high velocity (70,000 mph or more)
and traveled several miles in the atmosphere and completely disintegrated
in a multi-megaton explosion to where no significant meteorite remained.
That scenario probably passes the physics test.

Like I said it is still a mystery among scientists that have studied it.
Several good theories but no conclusion.

JF Mezei wrote on Thu, 16 Aug 2018
11:55:47 -0400:

On 2018-08-16 06:53, Fred J. McCall wrote:

If there is no overcast in the atmosphere you will likely get warmish
days and cold nights (think Denver on a clear winter day).


The second you need a pressurized scuba suit when going outdoors, does
it really make a big difference if it is cold or really cold outside?


You appear to have forgotten the whole "increased atmospheric
pressure" thing, Mayfly. At that point you don't need a "pressurized
scuba suit" (which is sort of a conflicting statement in itself, there
being no such thing as a 'scuba suit', much less a pressurized one).
You just need a breathing mask.


The minute your habitats need to be pressurized and insulated, does it
really make such a big difference if it is cold or really cold outside?


If you never go outside, why bother to go at all?


Futhermore, what is the weather impact to increasing air density and
temporature on Mars? could this mean more peaceful weather or
stronger/more frequency wind/sand storms ?


It makes it rain magic pixie dust. Hey, you asked a stupid
question...


--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn

"Scott M. Kozel" wrote on Thu, 16 Aug 2018
10:01:05 -0700 (PDT):

On Thursday, August 16, 2018 at 7:00:55 AM UTC-4, Fred J. McCall wrote:
"Scott M. Kozel" wrote on Wed, 15 Aug 2018

So it is an engineering problem. Just like if someone proposed
increasing the diameter of the orbit of Venus by 10 million miles as
part of its terraforming process.

True, although changing the orbital velocity of something the size of
a planet is just a BIT harder than moving a bunch of comet stuff.

You need an oxidizer in addition to the fuel (methane, ethane, other
hydrocarbons).

Part of these things IS water-ice. Plus you can always use something
like nuclear thermal that doesn't 'combust' the fuel in the usual
sense.

I was somewhat tongue-in-cheek about mentioning Venus, as its mass
is millions of times more massive than a comet-like object.

But comets themselves are massive and would take fantastic amounts of
energy to redirect --

"However, what is most likely being asked here is what is the mass
of a typical comet. And the answer to that is: it varies. Cometary
bodies large enough to be detected (i.e. to have both a head and a
discernible tail) can range from less than 6.5 x 10^13 (65 trillion)
kilograms, on up to the mass of Comet Hale-Bopp, which has been
conservatively estimated at 1.3 x 10^16 (13 quadrillion) kilograms,
or what would be more than 28.6 quadrillion pounds if the comet were
to sit somehow on the surface of the Earth."

https://www.quora.com/How-much-does-a-comet-weigh


Still microscopic when compared to a planet.

Depends on the velocity and angle of entry. Presumably the Tunguska
object entered the atmosphere and a very high velocity but a very
shallow angle. A steep angle might have had the object hit the Earth
mostly intact.

Unlikely. The Tunguska object was believed to be something more like
a comet than an asteroid (exactly what you'd be throwing at Mars) and
if there was any significant rocky core we'd have found impact
indications.

The Tunguska object is a mystery. As you suggested a comet-like body
melts and outgasses as it comes closer to the Sun. Usually well underway
within 2 astronomical units from the Sun (Mars being within that). So
the questions outstanding are how did a comet get that close to the Earth
without being sighted, how did it stay intact enough to cause a massive
explosion in the atmosphere.


Visibility varies based on comet composition. It got so deep because
it didn't soak up enough heat to reach critical temperature until it
was so deep.


One theory is that it was a rocky object that came into the atmosphere
at a nearly flat angle and at extremely high velocity (70,000 mph or more)
and traveled several miles in the atmosphere and completely disintegrated
in a multi-megaton explosion to where no significant meteorite remained.
That scenario probably passes the physics test.





Like I said it is still a mystery among scientists that have studied it.
Several good theories but no conclusion.


"No one knows for sure" doesn't equate to "my niche hypothesis is
correct".


--
"The reasonable man adapts himself to the world; the unreasonable
man persists in trying to adapt the world to himself. Therefore,
all progress depends on the unreasonable man."
--George Bernard Shaw

On Thursday, August 16, 2018 at 4:03:53 PM UTC-4, Fred J. McCall wrote:
"Scott M. Kozel" wrote on Thu, 16 Aug 2018

The Tunguska object is a mystery. As you suggested a comet-like body
melts and outgasses as it comes closer to the Sun. Usually well underway
within 2 astronomical units from the Sun (Mars being within that). So
the questions outstanding are how did a comet get that close to the Earth
without being sighted, how did it stay intact enough to cause a massive
explosion in the atmosphere.

Visibility varies based on comet composition. It got so deep because
it didn't soak up enough heat to reach critical temperature until it
was so deep.

One theory is that it was a rocky object that came into the atmosphere
at a nearly flat angle and at extremely high velocity (70,000 mph or more)
and traveled several miles in the atmosphere and completely disintegrated
in a multi-megaton explosion to where no significant meteorite remained.
That scenario probably passes the physics test.

Like I said it is still a mystery among scientists that have studied it.
Several good theories but no conclusion.

"No one knows for sure" doesn't equate to "my niche hypothesis is
correct".

No, but that is one of the theories.
….

https://science.nasa.gov/science-new...30jun_tunguska
Quote:

"A century later some still debate the cause and come up with different
scenarios that could have caused the explosion," said Yeomans. "But the
generally agreed upon theory is that on the morning of June 30, 1908, a large
space rock, about 120 feet across, entered the atmosphere of Siberia and then
detonated in the sky."

It is estimated the asteroid entered Earth's atmosphere traveling at a speed of
about 33,500 miles per hour. During its quick plunge, the 220-million-pound
space rock heated the air surrounding it to 44,500 degrees Fahrenheit. At 7:17
a.m. (local Siberia time), at a height of about 28,000 feet, the combination of
pressure and heat caused the asteroid to fragment and annihilate itself,
producing a fireball and releasing energy equivalent to about 185 Hiroshima
bombs.

"That is why there is no impact crater," said Yeomans. "The great majority of
the asteroid is consumed in the explosion."