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  #61  
Old August 18th 18, 03:11 PM posted to sci.space.policy
Alain Fournier[_3_]
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On Aug/18/2018 at 8:36 AM, Jeff Findley wrote :
In article ,
says...

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).


No you don't. You need a very hot heat source. That can be fission
(today) or fusion (just 5 or so years away, if you believe the fusion
proponents).

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.


These objects will be under power. Hopefully we'll be able to hit Mars
at the desired trajectory.

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


I'm sure some of it will go "boom" when it hits. So what? Mars already
has craters. What's a few more? Just don't hit anywhere near your
"HAB" domes.


And keep in mind, with Mars' lower gravity the definition of "anywhere
near" isn't the same as on Earth. Debris will fly much further away on
Mars than on Earth. In fact if the object hitting Mars is big enough
debris can very well go halfway around the planet. You should limit the
size of the objects you through at Mars accordingly.


Alain Fournier
  #63  
Old August 19th 18, 08:49 AM posted to sci.space.policy
Fred J. McCall[_3_]
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JF Mezei wrote on Sat, 18 Aug 2018
12:48:30 -0400:

On 2018-08-18 10:04, Alain Fournier wrote:

CO2 is quite transparent to visible light. Sun light will go right
through and hit the ground where it will be transformed into heat. CO2
is much less transparent to infra-red radiation. So heat at ground level
will have a somewhat hard time escaping to space. It will do so by
heating the atmosphere a little higher which will then heat the
atmosphere again a little higher etc.


When you have a thick , compressed and compact atmosphere, when the
ground emits infrared, the CO2 captures it at an altitude that is part
of the weather and thus warms the atmopsphere people on the ground feel

But if most of the heat is captured by CO2 that is very very very high
up and far away from "weather" atmosphere, then the heat at that
altitude may not benefit the atmpsphere on the ground.


So Venus obviously isn't hot because most of the CO2 is 'up high' due
to lower gravity? Mayfly, meet reality.


You may get better efficiency placing black panels at ground level to
heat the low altitude atmosphere instead of moving celestial bodies to
impact Mars to add CO2 to it.

Or heck, a nuclear power plant does put out large quantities of heat day
and night.


Again you've forgotten that the point is increased atmospheric
pressure and radiation shielding, not just to make it a little warmer.


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




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