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Landing on Mercury on equator at perihelion
Bob Shaw
post May 10 2006, 05:58 PM
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John:

The trouble with Mercury is, that although the environment *could* be coped with at a pinch, the sheer cost in terms of rocketry is worse than enormous. Getting to Mercury at all other than (slowly) by way of multiple Earth-Venus gravity assists is hideously impractical - and landing on it is literally the 'worst-case' scenario in the entire Solar System, what with it's reasonably high gravity and no atmosphere for braking purposes.

To put men there is even more difficult as you'd almost certainly want to do it *quickly* because of Solar flares!

To get to Mercury you really need some major set of breakthroughs in propulsion technology, even above and beyond the few speculative technologies we have some promise of!

Bob Shaw


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RNeuhaus
post May 10 2006, 07:06 PM
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A comparative view of Sun between Mercury and Earth.
Attached Image
Attached Image

I would be most impressed to view the Sun from Mercury at 1/3 closer than Earth.

Rodolfo
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jsheff
post May 10 2006, 07:27 PM
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I know how horrendous the delta-vee requirements are for landing on Mercury, but they're not, even with present technology, impossibly high. If you remember, the lander portion of Beppi-Columbo was not nixed for technological reasons - it was simply deemed too expensive for the program's budget!

I agree that manned landings, when they happen, will probably not occur within our technological horizon, i.e., this century, and only as a "mopping-up" exercise after the rest of the solar system has been thoroughly explored.

I remember as a kid reading a SF novel by Alan E. Nourse, called, I think, "Brightside Crossing" (You might want to look it up, Rem31, if you can find a copy; it might answer your questions). It may even have been written before Mercury's true rotation period was known. His characters mounted a surface-crawling manned expedition to traverse Mercury's dayside, timed to arrive at the center right when the planet was at perihelion! The expedition was mounted not for the sake of science, but for the glory, as it was "the last great challenge left in the solar system". This was science-fiction, I know, but I wonder ...

Today you have people willing to pay $60,000 and put their lives at great risk to climb Mt. Everest. They do it not for science, nor for the sake of being as high up as they can. (You can, after all, get higher in a aircraft or spacecraft!) They do it for the sheer challenge of it, "because it was there". So the fact that Mercury is, as you say, the most difficult place in the solar system to get to, may not repel people, but may be precisely what makes it an irresistable draw for some. Funny things, these humans...
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JRehling
post May 10 2006, 08:27 PM
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QUOTE (jsheff @ May 10 2006, 12:27 PM) *
The expedition was mounted not for the sake of science, but for the glory, as it was "the last great challenge left in the solar system".
...
So the fact that Mercury is, as you say, the most difficult place in the solar system to get to, may not repel people, but may be precisely what makes it an irresistable draw for some. Funny things, these humans...


I've heard the phrase "last great challenge" before referring to various challenges, but never accurately.

Millionaires try to do various things in balloons or on mountains, which is fine, but when they frame some accomplishment in narrow definitions and call it the last great challenge, I laugh. I bid them to accomplish whatever they want, but if they want to have it proven that it wasn't the last great challenge, I'll donate 30 seconds of my time and pitch them one much harder than what they actually accomplished.

Mercury subsolar at perihelion? OK, try going to the center of Mercury. Jupiter. The Sun. Rigel.

Sail around the world in a balloon? OK, try it on an over-the-poles route. Try going around Venus in a balloon. Neptune. The Sun.

Climb Everest without oxygen? OK, try it naked. Try it in 24 hours. Try it walking backwards. Try it on one foot. Try it in January. Olympus Mons. In 24 hours.

Swim the English Channel? OK, swim the Pacific. Swim from Anchorage to Venice. Without coming up for air.

This whole "last challenge" thing is about using a superlative where a comparative would be accurate. Unless by "last" they mean "latest"... but I think they mean "final".
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Bob Shaw
post May 10 2006, 08:39 PM
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QUOTE (JRehling @ May 10 2006, 09:27 PM) *
This whole "last challenge" thing is about using a superlative where a comparative would be accurate. Unless by "last" they mean "latest"... but I think they mean "final".


Somehow, I think most of those challenges would be not so much 'final' for the participants as 'terminal'!

Personally, I'll stick to walking backwards for Christmas, across the Irish Sea!

Less chance of ending up deaded, even if you *do* end up fallen in de water!

(exits stage left bearing photograph of 10/- note)

Bob Shaw


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helvick
post May 10 2006, 08:50 PM
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Absolutely agree with you on this but people are strange as Jsheff pointed out. At some stage some human will just do it so they can say they did it first.
QUOTE (JRehling @ May 10 2006, 09:27 PM) *
Climb Everest without oxygen? OK, try it naked. Try it in 24 hours.

Reinhold Messner has climbed Everest in 4 days, solo and without oxygen in the Monsoon season which isn't quite as extreme as you suggest since he took a bit long and thankfully he wasn't naked as far as we know but it does go to show just how mad people can be.
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Guest_BruceMoomaw_*
post May 10 2006, 09:11 PM
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Well, all the way back in the 1950s -- when he was still an unabashed hack SF writer rather than a fairly good stylist -- Robert Silverberg wrote a story about an attempt to drive all the way across Mercury's dayside (which ends in failure and the deaths of a couple of the participants). More recently we've had stories about a guy deliberately jumping into that gigantic cleft on Miranda (20 km deep, if I remember correctly), and -- so help me God --another one about the first successful bungee jump from orbit into the atmosphere of Jupiter.
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ilbasso
post May 18 2006, 05:47 PM
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QUOTE (Bob Shaw @ May 10 2006, 04:39 PM) *
Somehow, I think most of those challenges would be not so much 'final' for the participants as 'terminal'!

Personally, I'll stick to walking backwards for Christmas, across the Irish Sea!

Less chance of ending up deaded, even if you *do* end up fallen in de water!

(exits stage left bearing photograph of 10/- note)

Bob Shaw


Bob, you are obviously a member of the East Finchley Wolf Cubs. If you see Blue Bottle, tell him to come home - his mum has found his knees.


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ljk4-1
post May 18 2006, 05:52 PM
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QUOTE (helvick @ May 10 2006, 04:50 PM) *
Absolutely agree with you on this but people are strange as Jsheff pointed out. At some stage some human will just do it so they can say they did it first.

Reinhold Messner has climbed Everest in 4 days, solo and without oxygen in the Monsoon season which isn't quite as extreme as you suggest since he took a bit long and thankfully he wasn't naked as far as we know but it does go to show just how mad people can be.


And quite recently a double amputee scaled Everest:

http://msnbc.msn.com/id/12811777/

We're hardly done with new goals to achieve.


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indeed much harder than a rock. From hard, coarse, insensible men with whom I have
no sympathy, I go to commune with the rocks, whose hearts are comparatively soft."

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Rem31
post Jun 17 2006, 09:00 PM
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Do you need also Solarheat and radiation protection when you land on Mercury when it is at (aphelion)? greatest distance from the Sun. I know that you need protection when landing at perihelion ,closest to the Sun. And what will be the best place on Mercury to put a lander down on the Surface?
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dvandorn
post Jun 18 2006, 11:52 PM
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I don't have detailed numbers for you, but my gut feeling is that the proximity of the Sun is such, aphelion or perihelion, that you'd run into a similar harshness of environment (and need about the same level of protection) either way.

After all, what difference does it make if the heat outside is just about enough to melt lead, or just more than enough to melt lead? Well, except for maybe needing lead-pond floats on your spacecraft... smile.gif though I will note that there is no evidence of liquid-ponding of *any* materials in the Mariner 10 images.

-the other Doug


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RNeuhaus
post Jun 19 2006, 12:46 AM
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In spite of the fact Mercury has extermes temperatures between day and night: 427C and -173 C and its mean surface temperature of 179 C, the best place for human supervivence is on the poles. At the poles might have some water ices. But, the problem is that every 44 days (one orbital period is close to 88 days), the North and the South of poles will have alternate soft summer and winter due to its small orbital inclination of 7 degrees.

However, Mercury has own a small magnetic field that is 1% as strong as Earth. This does not help much to protect from solar wind and energetic particles.

Finally, Mercury's Perihelion is 46,001,272 km and Aphelion is 69,817,079 km, difference of 23.8 millions kilometers is much difference than the Earth with its about 3 millions kilometers. That will induce, I seems, a small greater variations of temperatures between the seasons.

All at all, Stephen Hawking recently has told to the press that there is no any an adequate biosphere place for human in our solar system unless we have to travel inter-stars searching for a similar Earth biosphere.

Rodolfo
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ermar
post Jun 20 2006, 08:09 PM
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QUOTE
every 44 days (one orbital period is close to 88 days), the North and the South of poles will have alternate soft summer and winter due to its small orbital inclination of 7 degrees.


Actually, the orbital inclination is irrelevant - what matters is the tilt of the planet's rotation axis with respect to the plane of its orbit. Because Mercury's axial tilt is a miniscule 0.01 degrees, the sun will hardly be seen to move above or below the ecliptic at any point in the year. Any "seasons," then, will be due to the eccentricity of its orbit.

And, interestingly enough, even Mercury's weak magnetic field is enough to deflect the solar wind (at least, most of the time).

Just a few thoughts.
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RNeuhaus
post Jun 21 2006, 03:04 AM
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Good tought ermar!

I haven't percated that its 7 degree inclination orbital implies a 0.01 degree for sol inclination orbital. Hence, the poles might have some permanent ice since they might be always in the shadow. Not yet sure if there are any volcan or mountain on the poles. Anyway, the climate of Mercury is similar to Moon only for the night side and much harsh for the day side.

Rodolfo
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Rem31
post Jun 22 2006, 09:11 PM
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Here is one of the most beautifull photographs of Mercury i can found on the web Taken by the Mariner 10. Mercury was at near (ap)helion ,its greates distance from the Sun. You can see the sharp dark shadows on the picture. One thing is sure ,it will be hot on the dayside areas on the time the pictures were taken. I hope that the link works
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