Urban legend or fact?

[makc]

Just a couple of statements I've been hearing here and there, but am too lazy to research if they are true I thought some of you might already know the answer and share it here.

1st, they say Earth axis is stable only because we have our moon, and Mars axis change direction like crazy, hence it doesnt have stable climate. Is it really so? Does Mars have huge precession?

2nd, they say we don't go to Mars because solar radiation is so very high beyond Earth magnetic field. How can that be a problem? I mean here on Earth the only way to feel its magnetic field is to look at compass needle, and some minor quantities of iron ore (not to mention neodymium) can totally mess it up. How come solar radiation is so strong that we can't protect would-be interplanetary spaceship, yet weak Earth field deflects it?

[hstarbuck]

2nd, they say we don't go to Mars because solar radiation is so very high beyond Earth magnetic field.

I think you are referring to the solar wind, which is charged particles not radiation (photons). Charged particles are deflected by Earth's significant magnetic field. The atmosphere takes care of (attenuates) harmful radiation like UVB & C etc.)

The solar wind is a stream of charged particles ejected from the upper atmosphere of the sun. It mostly consists of electrons and protons with energies usually between 10 and 100 eV. The stream of particles varies in temperature and speed over time. These particles can escape the sun's gravity because of their high kinetic energy and the high temperature of the corona.

[Chris Peterson]

1st, they say Earth axis is stable only because we have our moon, and Mars axis change direction like crazy, hence it doesnt have stable climate. Is it really so? Does Mars have huge precession?

Yes, that is basically true, but it isn't a matter of precession. What the Moon does is stabilize the range of angles that the Earth's axis can be at (the obliquity of the equinox). For the Earth this is about 23.5°, and only varies about a degree either way. The axial tilt of Mars is currently about 25°, very close to that of the Earth. But without a stabilizing moon, the tilt of Mars changes by about 40° over millions of years. That certainly has major climatic consequences, although it isn't really correct to say that the Earth has a stable climate over millions of years, either. In fact, Earth's climate is probably much less stable than that of Mars, simply because it is so much more complex.

2nd, they say we don't go to Mars because solar radiation is so very high beyond Earth magnetic field. How can that be a problem? I mean here on Earth the only way to feel its magnetic field is to look at compass needle, and some minor quantities of iron ore (not to mention neodymium) can totally mess it up. How come solar radiation is so strong that we can't protect would-be interplanetary spaceship, yet weak Earth field deflects it?

The Earth's magnetic field is actually pretty strong. Strong enough to deflect most charged particles coming from the Sun. Mars does not have a strong magnetic field, so those particles can reach the ground. Ionizing radiation like that is not a good thing for the human body.

[makc]

the tilt of Mars changes by about 40° over millions of years.

what gives?

The Earth's magnetic field is actually pretty strong.

How come all the devices involving electricity do not interact with it then? Would be nice to see a toaster slowly spinning for no reason

[Chris Peterson]

The Earth's magnetic field is actually pretty strong.

How come all the devices involving electricity do not interact with it then? Would be nice to see a toaster slowly spinning for no reason :)

Think about the field strength necessary to deflect a single subatomic particle over thousands of miles, versus the field strength necessary to spin a toaster in place.

[hstarbuck]

2nd, they say we don't go to Mars because solar radiation is so very high beyond Earth magnetic field.

I think you are referring to the solar wind, which is charged particles not radiation (photons). Charged particles are deflected by Earth's significant magnetic field. The atmosphere takes care of (attenuates) harmful radiation like UVB & C etc.)

I am sorry. I now realize that radiation can refer to other particles besides photons. I guess I thought there was a distinction in general, but electromagnetic radiation was what I was considering radiation. X-rays and gamma rays are ionizing (photons) as well as the electrons and protons from the sun, alpha and beta decay, high energy cosmic rays from elsewhere, etc. Still, because there are effects of the em from the sun and the other particle radiation I would be careful to distinguish between them to avoid confusion.

[makc]

Think about the field strength necessary to deflect a single subatomic particle over thousands of miles, versus the field strength necessary to spin a toaster in place.

I am thinking, and if we have means here to spin a toaster (again... neodymium), I don't understand why can't we employ them to deflect charged particles (not radiation, to make hstarbuck happy;) from spaceships.

[Chris Peterson]

I am thinking, and if we have means here to spin a toaster (again... neodymium), I don't understand why can't we employ them to deflect charged particles (not radiation, to make hstarbuck happy;) from spaceships.

The Earth's magnetic field is tens of thousands of miles deep, as seen by an incoming charged particle. A very small deflection angle is all that is required for the particle to miss the planet. How would you create such a field around a spacecraft? It would require a huge amount of energy. Even very powerful magnets would only produce strong fields over a few meters. There simply wouldn't be time for the particle to be deflected significantly, and it would pass through the ship (and its occupants). Physical shielding is currently the only practical way to protect astronauts.

[BMAONE23]

But how much energy is needed to "Spin a Toaster?"

[makc]

But how much energy is needed to "Spin a Toaster?"

I would say well under 1kJ/s, that's how much your typical drill takes.

[Chris Peterson]

But how much energy is needed to "Spin a Toaster?"

I would say well under 1kJ/s, that's how much your typical drill takes.

That's reasonable. But since we're talking about the Earth's magnetic field, we need to consider what sort of field strength you need to have 4000 miles away from the toaster, in order to achieve that sort of energy density over less than a cubic meter.

[hstarbuck]

There are magnetic field anomalies on Mars which are remnant of an ancient dynamo.
I am wondering if the largest of these would be able to shield ground based earthlings from solar wind particles. 200 nanotesla is ~1/100 the strength of the mag field at Earth's equator according to this:

* 31 µT (3.1×10−5 T) - strength of Earth's magnetic field at 0° latitude (on the equator)
* 5 mT - the strength of a typical refrigerator magnet
* 1 T to 2.4 T - coil gap of a typical loudspeaker magnet
* 9.4 T - Modern high resolution research magnetic resonance imaging system

However, the Mars data is from 400 km and the Earth data is at sea-level (I believe). I have not spent the time to consider total depth etc. on deflection. I think the LHC magnets run at 7-8 Tesla for further comparison--these (will) guide charged particles moving at tremendous velocities.

Also, I bet UV radiation is a concern on Mars for future, possible past, or possible current life as well. Mars gets less light, but has no ozone to shield it. Sunbathing on Mars would be in a pressurized (remember Arnold on Total Recall), UV shielded chamber. The residents might have to get their vitamin D elsewhere.

[wonderboy]

well if mars surface radiation is so bad, how are we going to get astronauts up there in the coming years. apparently we're gonna try and do it. I can't see it happening though.


Paul

[neufer]

Earth's climate is probably much less stable than that of Mars, simply because it is so much more complex.

I've never heard that before. Could you elaborate?

[neufer]

The Earth's magnetic field is actually pretty strong.

How come all the devices involving electricity do not interact with it then? Would be nice to see a toaster slowly spinning for no reason

Think about the field strength necessary to deflect a single subatomic particle over thousands of miles,
versus the field strength necessary to spin a toaster in place.

http://www.youtube.com/watch?v=rjZ8xDHmpb8
http://www.youtube.com/watch?v=iWAUNpmC8zs
http://www.youtube.com/watch?v=sZj66VCZCEE
http://www.youtube.com/watch?v=u14jYLvzuMo
http://www.youtube.com/watch?v=CT7BNGmBqJA
http://www.youtube.com/watch?v=QBB9lT3y7Z8
http://www.youtube.com/watch?v=ckfARbwf8sU
http://www.youtube.com/watch?v=ZOC8sjVTCz4

<<The Brave Little Toaster Goes to Mars is the name of both a children's book by Thomas Disch, as well as the film made from same. Both are sequels to the book and film versions of The Brave Little Toaster. The movie was distributed by Walt Disney Home Video. It was released in 1998.

Summary (Movie)

Rob and Christine have a baby boy named Robbie. At first the appliances all think that they will pay more attention to him but later get used to him. "I see a new you". Later, the Hearing Aid, who was left in a drawer in their new house from the past owner gets out of the drawer and passes everyone who is asleep. Toaster then sees him and follows him up to the attic. Toaster gets very suspicious about him when he was talking to someone in space. The next morning Toaster tells what happened last night then they all agree to stay on watch of the drawer till he comes out. Later when it's midnight everyone falls asleep just when Hearing Aid escapes from the drawer. The "little master", as they call him, awakes to the sound and gets out of his crib and follows Hearing Aid. The appliances awake and find Robbie going up the stairs. Lampy tries to get him down but he is dragged up the stairs and his plug slips out and falls down the stairs. The appliances appear in the room when a big beam of light appears. The appliances chase after Hearing Aid but then Robbie disappears in a bubble through space. After that they all find out that he was sent to Mars.

They get Wittgenstein the old supercomputer to help them and gives them advice. They get the microwave and cheddar cheese popcorn to help them fly, as it's organic, a laundry basket, and the Ceiling fan. They set off in space to go to Mars and find Robbie. During their flight a pack of balloons appear who fly endlessly in space from hands who let them go. "Floating" The appliances crash on Mars and find Robbie. They meet a Christmas angel named Tinselina who was sent to mars with Viking 1. The appliances follow a group of military toasters who'd just arrived to their leader Supreme Commander who is a huge refrigerator. They then learn that they are going to blow Earth up because their old owners threw them out, and Toaster tries to talk them out of it. Inbetween the fight, Robbie is able to push a hand out of his bubble. His hand touches Supreme Commander, and the refrigerator suddenly begins to turn pink. He smiles at the child, before returning his original color. Toaster ends up between an election with Supreme Commander. "Humans". After a while we learn that Toaster wins the election and is the new Supreme Commander. The appliances go into the freezer of Supreme Commander and find another Hearing Aid that is the brother of Hearing Aid. They have not seen each other since sixty years. When asked by Toaster why Surpreme Commander changed his mind about blowing up Earth, he says "the touch of the small boy's hand" reminded him that not all humans are bad. They are all about to return to earth when suddenly Hearing aid's brother forgot to deactivate the rocket. The missile counts down. Toaster jumps off with Hearing Aid's brother and destroys the rocket. Toaster is almost left on Mars but the others come back for him. After Toaster is on board Tinselina gives up her clothes so they can have something organic to get back to earth.

They appliances happily ride back to Earth. "Home Again". The appliances return to Earth just in time as the baby monitor that Ratso, their pet rat, had been restraining all night, finally wakes Rob and Christine up. One day when they're taping Robbie he finds Tinselina in a garbage can and fixes her up. It is a happy ending with Robbie's first word is "Toaster!" and Tinselina's first time on a Christmas Tree. It is a happy ending with the appliances having a happy Christmas with the little master.>>

[wonderboy]

http://www.space.com/scienceastronomy/s ... 10306.html

While Earth's weather may seem tame compared to some of these crazy places, Ingersoll notes one important feature -- a scientific fact -- that forecasters still wrestle with every day: Our planet has the most unpredictable and inexplicable weather in the solar system.

Climate wise we are unpredicatable and sometimes inexplicable according to the above; therfore it is reasonable to deduce that, more so than any other planet, our climate is the most unstable. It is not by any means the most harsh or deadly (at least to us) as the article proves, with some wind speeds getting up to supersonic levels due to them skirting with the vacuum of space.


Hope that helps Neufer



Paul

[Chris Peterson]

well if mars surface radiation is so bad, how are we going to get astronauts up there in the coming years. apparently we're gonna try and do it. I can't see it happening though.

Shielding astronauts on the surface of Mars is fairly easy. The challenge is shielding them on the way- a problem that doesn't yet have any well developed solution. I agree, an actual manned mission to Mars doesn't seem likely to happen any time in the near future (decades).

[Chris Peterson]

Earth's climate is probably much less stable than that of Mars, simply because it is so much more complex.

I've never heard that before. Could you elaborate?

The Earth has a vastly more complex climate system than Mars. We have a high pressure atmosphere, comprised of many gases. We have both land and oceans, and a complicated heat transport system in the atmosphere as well as the sea. We are tectonically active, leading to many long term climate effects. Mars has a very thin atmosphere consisting almost entirely of one gas. It has only a weak energy transport system and is tectonically stable.

I think that if you wanted to develop a climate model for Mars, it would be much simpler than that of the Earth. There is evidence that the Martian climate is stable for billions of years, while Earth's changes significantly over multiple time scales, from decades to eons.

[neufer]

Earth's climate is probably much less stable than that of Mars, simply because it is so much more complex.

I've never heard that before. Could you elaborate?

The Earth has a vastly more complex climate system than Mars. We have a high pressure atmosphere, comprised of many gases. We have both land and oceans, and a complicated heat transport system in the atmosphere as well as the sea. We are tectonically active, leading to many long term climate effects. Mars has a very thin atmosphere consisting almost entirely of one gas. It has only a weak energy transport system and is tectonically stable.

I think that if you wanted to develop a climate model for Mars, it would be much simpler than that of the Earth. There is evidence that the Martian climate is stable for billions of years, while Earth's changes significantly over multiple time scales, from decades to eons.

By why can't complexity mean more stable (; e.g., a la Gaia theory).

(Besides...Milankovitch cycles on Mars must be wild.)

[Chris Peterson]

By why can't complexity mean more stable (; e.g., a la Gaia theory).

I think you perhaps meant to link here. Certainly, the Gaia hypothesis (theory is probably too strong a word) is wrong if it suggests that the Earth has a stable climate system; it obviously does not. At best, it proposes a complex system of feedback mechanisms that keep it more stable than it would be without a biosphere.

(Besides...Milankovitch cycles on Mars must be wild.)

Why? The thing is, Mars doesn't have much of a climate system to be affected. So while such cycles on Earth produce huge variations, what happens on Mars? It gets a little colder or warmer? There is a subtle change in dust storm patterns? What exactly constitutes "wild" in terms of Martian weather or climate? It brings to mind the "wild" climate on the Moon due to long term orbital variations.

[wonderboy]

By why can't complexity mean more stable (; e.g., a la Gaia theory).

(Besides...Milankovitch cycles on Mars must be wild.)

I get what your saying Neufer and I quite like the idea that our complex atmosphere actually makes for a perfect atmosphere.

For example

We rely on a lot of things our atmosphere provides in order to live here, i.e. Water, Wind, Heat, Fire (providing oxygen e.g.)

What we don't need, is tornados, and hurricanes etc, this is the downside of our atmosphere.

However, as we go more green and rely on solar, turbine and even the undulating nature of sea waves in scotland to provide energy, it is maybe the case that our complex atmosphere is becoming more perfect by the day.


Paul.