The Threat of Meteors

Palomar · 2002-09-28 09:19:25

*I was thinking last evening about our occasional meteor showers here on Earth. They're very spectacular to behold, thanks to our thick atmosphere, which protects us as we pass through the tail of a comet or what-have-you.

But Mars has a thin atmosphere. I can't believe it, too, doesn't occasionally pass through the tail of a comet. The astronauts in their year-long stay on Mars will be sitting ducks for meteors. And settlements? How will settlers be protected from potential meteor showers on Mars? Unless and until the Marsian atmosphere is considerably thickened, they too will be sitting ducks.

Sorry to sound "doomsdayish," but I was thinking along these lines last evening. Perhaps Dr. Z has already discussed this in _Case for Mars_, and I forgot (I do so much reading). If this topic has come up before, my apologies; I don't recall it discussed at length.

Just curious. Like usual.

--Cindy

Byron · 2002-09-28 10:09:39

I've flipped through Zubrin's -Case for Mars-, and I don't see any reference to meteor impacts. I don't think that the risk of meteor impacts is as great as you think. As thin as Mars' atmosphere is, I do believe it does offer protection against the tiny, sand grain-sized comet tail meteors that are so commonly seen in meteor showers. Anything that burns up at 120,000 feet or higher on Earth will also burn up in Mars' atmosphere.

I think the biggest risk is from pea-sized and larger meteorites, which would make it to the Martian surface and pose a risk to human habitats, but those are thankfully much less common, and the overall risk would be quite low. If a dome or hab does get hit, I'm sure there would be quick-patch kits scattered about for people to place over the hole in case of emergency, or perhaps this could be performed by semi-intelligent robots.

In light of all the other hardships of living on Mars, the risk from meteors probably wouldn't even be in the top ten of the very long list of things to worry about...

B

Palomar · 2002-09-28 11:08:50

In light of all the other hardships of living on Mars, the risk from meteors probably wouldn't even be in the top ten of the very long list of things to worry about...
B

*I have to say I ::would:: be worried about it...particularly the larger ones that wouldn't burn up completely in that thin Marsian atmosphere...particularly if Mars were to pass through the tail of a comet while I'm there.

Thanks for answering, Byron.

--Cindy

Lil_vader · 2002-09-28 20:59:07

I have suggested elsewhere that the habs be made of self-sealing material in case they're punctured, whether its by a meteorite or something else.

That said, I think it would more likely be the something else.

Shaun Barrett · 2002-10-01 06:30:27

Byron has, as usual, hit the nail on the head with his response to Cindy's question.
The whole thing was so interesting, and so relevant to early colonisation, I looked into it a little further.

The vast majority of meteors are tiny and apparently Earth's atmosphere stops them at between 50 and 100 kilometres above the surface. As Byron pointed out, Martian air at ground level is about as dense as Terran air at an altitude of 38 kilometres. So, most meteors entering the Martian atmosphere will be stopped a good dozen or so kilometres above the ground.
This ignores the beneficial effect of Martian gravity, which gives Mars a 'taller' atmosphere. i.e. It's density tails off less abruptly with height. This factor should mitigate in our favour, meaning more protection for our colony than the above arithmetic seems to show.

Of course, there's no guarantee of safety here at home either! There are two recorded incidents involving meteorites and personal injury: The first involved a dog, killed in a street somewhere in Egypt. The second involved a woman in America, badly bruised when a meteorite crashed through the roof of her house! I believe there was also a case of a car being struck, causing moderate damage to the bodywork of the vehicle but none to the owner.

In reality, the chances of being killed by a meteorite on Mars are probably considerably less than the chances of being killed by lightning here on Earth. And we don't waste a lot of time worrying about that, do we?

I think Byron is absolutely right in suggesting we'll have lots of other more important things to worry about when we get there.

RobS · 2002-10-03 14:13:52

My information on this is twenty years old and may need updating, but I believe the Martian surface has no craters smaller than about 100 meters across, which means meteorites that can make smaller craters are destroyed by the atmosphere. At any rate, close examination of the surface will tell us what sizes of meteorites are stopped.

One of the main differences between the surfaces of the moon and Mars is particle size. Mars seems to be one giant rock field. The moon, on the other hand, seems mantled in beach sand and gravel. The reason is because micrometeorites pulverize the lunar surface, but not the Martian surface.

I'm pretty sure habs are as safe from falling space debris on Mars as they are on Earth.

-- RobS

Palomar · 2002-10-03 15:15:50

The moon, on the other hand, seems mantled in beach sand and gravel. The reason is because micrometeorites pulverize the lunar surface, but not the Martian surface.

*And the moon has huge impact craters. Which makes me wonder how anyone can be serious about human settlements on the moon, considering it has zero atmosphere and thus no protection from any size of meteor whatsoever. I can't remember the exact analogy, but I read in _Lost Moon_ by Jim Lovell -- when discussing the hazards meteors pose to spacecraft -- that a meteor the size of a grain of sand, traveling at a certain velocity, would have the same damaging impact as a bowling ball speeding along at 100 miles per hour.

Even if lunar settlements would be situated deep in the ground, there is still serious danger posed by meteors...again, some of those craters are deep. I suppose lunar settlements could be buried way down deep into Luna...that is, if everyone wants to live like moles all the time.

--Cindy

Phobos · 2002-10-03 18:10:31

Even if lunar settlements would be situated deep in the ground, there is still serious danger posed by meteors...again, some of those craters are deep. I suppose lunar settlements could be buried way down deep into Luna...that is, if everyone wants to live like moles all the time.
--Cindy

Most of the big craters on the Moon (and probably Mars to) are very ancient. The probability of a big one coming down and smacking a space colony is probably about the same as Earth, not impossible, but nothing that we should let scare us from building lunar and Martian establishments. Anyways, if micro-meteorites are all we have to worry about those are easily stopped by good shielding. RobS's observation of the lack of smaller craters on Mars seemed encouraging but I wonder if such craters could have been filled in or eroded away fairly quickly. In any case the Martian surface doesn't appear to be inundated with small craters which means it probably hasn't had much recent history of small meteorites smacking into its surface since it would still take a long time to fill in the craters or erode them away with Mar's thin atmosphere.

RobS · 2002-10-04 08:26:53

The danger from anything larger than a grain of sand is miniscule anyway because they are so rare. The Earth is hit by objects a meter or more across just once a year or so. When they had functioning Apollo seismometers on the moon, they deteched only one impact in the kilogram-range (and that was over a few years).

The surface of the moon is safer than low earth orbit because of all the orbiting space junk in the latter domain. A Space Shuttle window was pitted once by an impact; they concluded the object was about the size of a fleck of paint. It would have come from a spacecraft. A French satellite was once crippled by a space collision and they later determined it had hit an old French third-stage booster from a launch several years earlier. There are now protocols about not losing small objects; a wrench (spanner) dropped by an astronaut constructing ISS could come around and punch a hole in it a year later (because orbits change over time, it could hit hard, too). Third stage boosters used to explode a few days after launch because left-over cryogenic fuel would vaporize in the tanks and burst them. Now there are pressure vents, so the stage stays intact and doesn't get disintegrated into lots of small pieces. The Space Shuttle orbits the earth with its main engines pointing forward, so if the vehicle gets whacked, they take the punch and not the crew quarters. The ISS modules are all armored (which is one reason it costs more than Mir and Skylab, launched in less debris-filled times).

But on the moon, all you have to do is bury your habs under a few meters of regolith or sandbags (regolithbags?). You'll have micrometeoroid protection and radiation protection to boot.

-- RobS

RobS · 2002-10-05 01:31:25

I just found a number: nothing smaller than 1 kilogram in mass reaches the Martian surface and makes a crater because of the Mars atmosphere. The references is Peter Cattermole, *Mars: The Mystery Unfolds* (Oxford: Oxford Univ. Press, 2001), page 48. This is quite a good book, by the way, about what we know about the Martian surface, atmosphere, and interior, with chapters about the moons as well.

-- RobS

Mace · 2005-07-17 17:37:40

I find it amazing how ants work to build their nest. Perhaps something of the like could be used to build a massive network or deep mines on another planet. The shear amount of dirt as a wall will protect anyone from most dangerous "falling stones."

Also we could put in those doors that they have on ships. If a compartment leaks after being hit, pressure causes the door to slam shut thus saving the rest of the colony. People themselves should naturally live only in the deepest chambers. Bad luck for anyone who happens to be in the compartment, but it will minimize any further damage.

Mars_B4_Moon · 2023-02-20 09:15:21

Fragment of meteorite that exploded over the English Channel recovered in France

https://www.spacedaily.com/reports/Frag … e_999.html

A small, 1-meter-wide (3-foot) asteroid, dubbed 2023 CX1, previously known as Sar2667, lit the sky after entering the Earth's atmosphere at around 3 a.m. CST on February 13 over the English Channel. Due to its size, it does not pose a threat. It was visible from across southern England and Wales and as far south as Paris, France.

We might be due a hit

Some of them say every 90 years to 1,200 years Tunguska sized event happens

The Tunguska incident is part of modern 'conspiracy' but it is believed that the explosion had been caused by a giant-ish meteorite impact airbursting about the size of a 747 jumbo jet, and it was 12-megaton explosion that occurred in 1908. The area was not very well populated and the people had a basic lifestyle, the explosion happened over the sparsely populated Eastern Siberian it flattened an estimated 80 million trees over an area of 2,150 km2 830 sq miles of forest, and eyewitness reports suggest that at least three people may have died in the event. In 1930, the British meteorologist and mathematician F. J. W. Whipple suggested that the Tunguska body was a small comet. A comet is composed of dust and volatile, such as water ice and frozen gases, and could have been completely vaporized by the impact with Earth's atmosphere, leaving no obvious traces. The Barringer Crater, a meteorite impact crater about 37 mi (60 km) east of Flagstaff and 18 mi (29 km) west of Winslow in the desert of northern Arizona, United States was a smaller meteor but made impact with the ground while Tunguska is thought now to have exploded mid air. A smaller air burst occurred over a populated area on February 2013, at Chelyabinsk in the Ural district of Russia. The exploding meteoroid was determined to have been an asteroid that measured about 17–20 metres (56–66 ft) across. It had an estimated initial mass of 11,000 tonnes and exploded with an energy release of approximately 500 kilotons. In June 2007, scientists from the University of Bologna identified a lake in the Tunguska region as a possible impact crater from the event. They do not dispute that the Tunguska body exploded in mid-air, but believe that a 10-metre (33 ft) fragment survived the explosion and struck the ground. Lake Cheko is a small bowl-shaped lake approximately 8 km (5.0 mi) north-northwest of the hypocentre.
https://doi.org/10.1111%2Fj.1365-3121.2007.00742.x

Last edited by Mars_B4_Moon (2023-02-20 09:26:57)

Mars_B4_Moon · 2023-10-29 12:05:02

An explosion in the atmosphere February 2013 exploded with 400–500 kilotons of TNT the shockwave injured people and smashed windows, it was thought to be a mix of stones, irons, they found meteoric iron, and sulfides. The Russian meteor is thought to have been 17 m or 55 feet slightly longer than an average sized US school bus but less wide than the tail of a Boeing 747, for a moment it was much brighter than the Sun.

An Asteroid Came Uncomfortably Close to Earth in July. Could we Have Stopped it?
https://www.universetoday.com/163956/an … topped-it/

In July of this year, an asteroid roughly 30 to 60 meters across passed Earth to within one-quarter of the distance to the Moon. It posed no threat to our world, but if it had struck Earth it would have created a blast three times greater than the 2013 Chelyabinsk impact. And we only noticed it two days after it passed. It’s a good example of how sizable asteroids still miss detection.

Last edited by Mars_B4_Moon (2023-10-29 12:05:26)

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#1 2002-09-28 09:19:25

Re: The Threat of Meteors

#2 2002-09-28 10:09:39

Re: The Threat of Meteors

#3 2002-09-28 11:08:50

Re: The Threat of Meteors

#4 2002-09-28 20:59:07

Re: The Threat of Meteors

#5 2002-10-01 06:30:27

Re: The Threat of Meteors

#6 2002-10-03 14:13:52

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#7 2002-10-03 15:15:50

Re: The Threat of Meteors

#8 2002-10-03 18:10:31

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#9 2002-10-04 08:26:53

Re: The Threat of Meteors

#10 2002-10-05 01:31:25

Re: The Threat of Meteors

#11 2005-07-17 17:37:40

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#12 2023-02-20 09:15:21

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#13 2023-10-29 12:05:02

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