ASI W9600578r1.1

Moon Miners' Manifesto

#93 March 1996

Section the Artemis Data Book

MMM#93 Mailbox column

Is Mars more impact prone than Moon?

It would seem to me that settlers on Mars could be more exposed to meteorite bombardment than pioneers on the Moon. Mars weighs in some 5 times heavier than the Moon, giving it more gravity [3/8ths vs. 1/6th Earth-standard] and hence a bigger/wider/deeper gravity well. This means it will "catch" more asteroidal and cometary debris, and impose on it higher velocities of acceleration prior to impact.

Mars's tenuous atmosphere will burn up the micrometeorite stuff, so that the Martian surface is not subject to the steady "rain" that the lunar surface undergoes. It would follow that the dust on Mars comes from weathering, rather than impact "gardening". But the larger stuff will not be stopped and much will get through that incinerates in Earth's much thicker atmosphere.

We should not be misled by visual and photographic comparisons of the Martian and Lunar surfaces at various resolutions. Unlike the Moon, Mars experiences real weather (wind, and scattered freeze-thaw cycles) and formerly underwent major episodes of volcanic activity. This gives its surface a deceptively younger, less impact-scarred look.

Not to scare anyone away. The heavy lunar bombardment we see happened mostly more than 3 eons [3 billion years] ago, and danger to pioneers will be less than us terrestrials face in volcanic eruptions, earthquakes, hurricanes, tornadoes, lightning, avalanches, landslides and other catastrophes from Earth's active geology and weather systems. The same should be true on Mars.

- Thomas Heidel, Milwaukee, Wisconsin

EDITOR: Thanks Tom. You have summed up the situation accurately.

Why the boxes and bars filled with random dots?

For a long time, you have been closing articles [on the printed version of MMM] written by you with "MMM" in a box filled with random dots. This same kind of dot-filled box has appeared as bars in the masthead, and now bars in the footers at the bottom of each page, as well as in the "state" bars preceding the various chapters in the chapter news section. What is the symbolism here?

- Simon Cook, Phoenix, Arizona

EDITOR: The symbolism, I had hoped, would be clear. The random dots stand for "regolith", that is the lunar (and asteroidal, and Martian) soil composed of fine and coarser particles of rock and glass. This inorganic soil covers these worlds with a blanket inches to meters thick and consists mostly of bombardment debris and meteoritic material. In the case of Mars, regolith also includes wind-deposited products of weathering. For me, the regolith is the very quintessence of the frontier, its mineral makeup posing early limits to what pioneers can do by way of self-reliance and "living off the land", and setting the scope of the challenge for frontier settlements. I should have made this clear at the outset.

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