PDA

View Full Version : Why is Mars so low in mass?



Inclusa
2015-Dec-15, 06:06 AM
I keep wondering, while the size of Mars may be roughly half of Earth, its mass is only 10% of Earth.
The puny mass of Mars renders it rather unsuitable for terraforming (unless we can generate gravity in the Dragonball Z way.)

Noclevername
2015-Dec-15, 06:24 AM
Mars's core is made of lighter materials, mainly iron sulfide, with less heavy metals.

https://en.wikipedia.org/wiki/Mars#Internal_structure


Like Earth, Mars has differentiated into a dense metallic core overlaid by less dense materials.[37] Current models of its interior imply a core region about 1,794 65 kilometers (1,115 40 mi) in radius, consisting primarily of iron and nickel with about 16–17% sulfur.[38] This iron(II) sulfide core is thought to be twice as rich in lighter elements than Earth's core.[39

Shaula
2015-Dec-15, 06:33 AM
Mass is proportional to volume and Mars' volume is about 0.15 times that of Earth. So while the radius difference may appear large in volume terms it is not so dramatic.

Noclevername
2015-Dec-15, 07:55 AM
The puny mass of Mars renders it rather unsuitable for terraforming

We don't know what the human tolerance for Martian gravity is yet, and how it would affect childhood development.

eburacum45
2015-Dec-15, 05:15 PM
We don't know what the human tolerance for Martian gravity is yet, and how it would affect childhood development.

The low gravity causes worse problems for would-be terraformers than poor human tolerance of a low-gee environment. Mar's low gravity would allow the atmosphere to escape over time; slowly, it seems, but steadily, and over very long timescales Mars would become uninhabitable again. The lack of a magnetic field would also cause problems for the inhabitants.

Perhaps some sort of paraterraforming would be the best option; put a roof over Mars.
ftp://www.fourmilab.ch/web/entrenous/worldhouse/wh1.html

Noclevername
2015-Dec-15, 05:26 PM
The low gravity causes worse problems for would-be terraformers than poor human tolerance of a low-gee environment. Mar's low gravity would allow the atmosphere to escape over time; slowly, it seems, but steadily, and over very long timescales Mars would become uninhabitable again. The lack of a magnetic field would also cause problems for the inhabitants.


A terraformed Mars would simply require ongoing maintenance. And a magnetic field is more of a luxury than a necessity; I've been informed that a thick enough atmosphere provides a perfectly adequate radiation shield, and a GPS satellite net can substitute for a compass.



Perhaps some sort of paraterraforming would be the best option; put a roof over Mars.


Paraterraforming might be a natural outgrowth of expanding numbers of sealed habitats. Eventually, if the Martian population grows large enough, dome compartments will simply cover most of the planet.

chornedsnorkack
2015-Dec-15, 09:57 PM
How long did Mars have flowing rivers?

Jerry
2015-Dec-17, 04:56 PM
The mass of Mars is low given the surface constituents and reasonable expectations of interior materials and structure. But a much larger peculiarity is the calculated distribution of mass densities on the Martian surface.

On the Earth, uplifted regoth is generally lighter than the surrounding terrain; while the floors of oceans are significantly denser than landed crust. This only makes sense, so that even though the surface terrain varies, the net gravimetric state is very relaxed.

But the exact opposite is true for the calculated densities of Martian regoth: The highest mountains appear to be made of more dense material than the surrounding terrain, and chasma are less dense. The scale of these enigmas is dramatic. Mars may not have the water we do to serve as a leveling agent, but one still needs an explanation why more dense materials ended up on higher ground in the first place.

I am of the opinion that this is the single greatest inexplicable anomaly in the solar system...other than the red mountains on Pluto.

dtilque
2015-Dec-17, 05:50 PM
As for the question in the subject line, the Grand Tack (http://www.armaghplanet.com/blog/the-grand-tack.html) model is the best explanation so far for why Mars is so small.

DaveC426913
2015-Dec-17, 09:44 PM
But the exact opposite is true for the calculated densities of Martian regoth: The highest mountains appear to be made of more dense material than the surrounding terrain, and chasma are less dense. The scale of these enigmas is dramatic. Mars may not have the water we do to serve as a leveling agent, but one still needs an explanation why more dense materials ended up on higher ground in the first place.

I am of the opinion that this is the single greatest inexplicable anomaly in the solar system...other than the red mountains on Pluto.
Surely this is due to whatever can of fast-moving whoopass created the Hellas Basin in the South and - directly antipodal to it - the Tharsis bulge with its huge volcanoes and the crustal split that is Valles Marineris, not to mention the great disparity in altitude and surface makeup between Northern and Southern hemispheres.