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Landing on Mercury on equator at perihelion
Rem31
post Mar 21 2006, 12:18 AM
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How will it be to make a manned landing at Mercury at its closest to the sun (perihelion) on its equator when the sun is in the zenith ,what are the dangers of a landing then? Do we need to be protected against the sunheat and radiation then? How strong is the heat and radiation of the sun then ,and is it dangerous when the solaractivity is high then? What kind of spacesuits do we need then? Better protected suits than we have used on the apollo moonlandings i think. Can you explain how a landing on Mercury will be when it is at perihelion and land on its equator with the sun directly overhead? I hope it will ever happen. Lets start discuss about it.
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Guest_BruceMoomaw_*
post Mar 21 2006, 04:25 AM
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A manned landing on Mercury at perihelion -- or an unmanned one, for that matter -- would be difficult as Hell (which may be appropriate). The problem wouldn't be as severe as that on a Venus lander, but it would be plenty hard -- you would not only need to have an extremely efficient reflecting shield to fend off the heat radiation from the Sun, but also another to deal with that being reflected and emitted from Mercury's surface. (This, in fact, is one reason why the Messenger orbiter will be put into a highly elliptical orbit around Mercury: to give it time to cool off again from each of its low-altitude periapses over Mercury's surface.) As for the design of any EVA walking suit that could cope with that heat: I shudder even to think about the problem. The high-energy particle radiation and X rays from the Sun at that range would also pose a very difficult problem for any manned mission that close to the Sun -- we'll have enough danger from those during long-duration manned trips to Mars and near-Earth asteroids.

However, temperature-wise, there are plenty of other places that either an unmanned or manned lander could touch down on Mercury that would be a cinch. Its near-polar regions are quite tolerably cool -- which is why it has ice as its poles -- and its nightside very quickly cools down after sunset, stays cold, and even stays within modest temperature ranges for a short time after sunrise again.

A polar or nightside landing on Mercury is entirely feasible with the technology we have right now. The trouble, as usual, is simply money. Europe's BepiColombo, which consists of a large and low-altitude European orbiter and a small secondary Japanese one for magnetospheric studies, was originally also supposed to include a very small lander to touch down within about 3 degrees of the pole -- but, since Mercury is an airless world with a gravity field considerably stronger than the Moon's (and therefore requiring a larger mass of braking fuel), in the end the cost and mass of the lander was just too much for ESA's already-strained budget to endure and they cut it out of the mission. At some point it certainly will be done by someone; Mercury's surface almost certainly looks almost indistinguishable from the Moon's, but there are a great many interesting geophysical and compositional instruments they could land there on even a single lander. But that's likely to be a couple of decades off (at least), just for monetary reasons.
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JRehling
post Mar 21 2006, 10:02 PM
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QUOTE (BruceMoomaw @ Mar 20 2006, 08:25 PM) *
A polar or nightside landing on Mercury is entirely feasible with the technology we have right now.
[...]
At some point it certainly will be done by someone; Mercury's surface almost certainly looks almost indistinguishable from the Moon's, but there are a great many interesting geophysical and compositional instruments they could land there on even a single lander. But that's likely to be a couple of decades off (at least), just for monetary reasons.


A good bang-for-the-buck mission might avoid a high-latitude constraint by making a night landing and carrying a strobe light for imaging the vicinity. Because the surface will not cool immediately after sundown, it would be best not to land in daytime just before sunset. To allow a mission plenty of duration for seismic (or, alternately, lifetime for a rover), it could land about 10-20% of the way into local night, study the vicinity for about 45 days (night on Mercury is 54 Earth days), and then get a sunrise panorama of the background before sunlight cooks the craft.

Another approach would come from the unique fact that the Sun shows retrograde motion on Mercury because the revolution at perihelion overtakes the rate of rotation. A carefully-targeted lander could alight somewhere that was in night, then experienced a very brief "day" of a sunrise-then-sunset. So long as the engineering team could set the lander down precisely, the length of that day could be arbitrarily brief, and a rotatable "parasol" could mean that the craft would take no direct solar heating while the ground would experience only trivial heating in the short run. A lander aimed at just the right longitude could thus experience a short sol (for imaging) and go on to run other studies during a few more Earth days of nighttime before a longer sol cooked the craft.

And of course, there is the polar option. Conceivably, a lander could be sent into an area of eternal night, and never face a thermal constraint at all (except during cruise), but such a landing site would be idosyncratic (and therefore interesting, but differently interesting than just a generic Mercury landing site).
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Guest_BruceMoomaw_*
post Mar 21 2006, 11:57 PM
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QUOTE (JRehling @ Mar 21 2006, 10:02 PM) *
A good bang-for-the-buck mission might avoid a high-latitude constraint by making a night landing and carrying a strobe light for imaging the vicinity. Because the surface will not cool immediately after sundown, it would be best not to land in daytime just before sunset. To allow a mission plenty of duration for seismic (or, alternately, lifetime for a rover), it could land about 10-20% of the way into local night, study the vicinity for about 45 days (night on Mercury is 54 Earth days), and then get a sunrise panorama of the background before sunlight cooks the craft.

Another approach would come from the unique fact that the Sun shows retrograde motion on Mercury because the revolution at perihelion overtakes the rate of rotation. A carefully-targeted lander could alight somewhere that was in night, then experienced a very brief "day" of a sunrise-then-sunset. So long as the engineering team could set the lander down precisely, the length of that day could be arbitrarily brief, and a rotatable "parasol" could mean that the craft would take no direct solar heating while the ground would experience only trivial heating in the short run. A lander aimed at just the right longitude could thus experience a short sol (for imaging) and go on to run other studies during a few more Earth days of nighttime before a longer sol cooked the craft.

And of course, there is the polar option. Conceivably, a lander could be sent into an area of eternal night, and never face a thermal constraint at all (except during cruise), but such a landing site would be idosyncratic (and therefore interesting, but differently interesting than just a generic Mercury landing site).


I already thought of Idea #1. (Pause for misguided snickers from Alex.) If you want to set up a good multiple-lander seismic network on Mercury -- and a mission with several tiny Mercury landers, which could be very productive scientifically, is on the Decadal Survey's list of longer-range New Frontiers candidates -- then just putting two seismometers at the poles, although they could survive indefinitely there, would be lousy for trying to locate seismic events on the planet. You'd want a third lander (or maybe just a second one) at low latitude, and the only way to get that would be the nighttime lander plan. (Also keep in mind that, given today's instruments, any searchlight that a nighttime lander needed for photos and near-IR maps could be very low-powered -- Huygens' was about as strong as a nightlight. But, to the extent that the payload of a Mercury lander would be seriously limited by mass and data rate, the very first thing I'd throw out would be the camera. It's good for PR, but low-value for science.)

As for the polar landing: except for the possibility that it might be able to study one of the polar ice (or sulfur) deposits, there's nothing particular unusual geologically about Mercury's poles -- which made them the perfect spot for the ESA's planned first-time Mercury lander.


QUOTE (ljk4-1 @ Mar 21 2006, 10:22 PM) *
Clarke also wrote an SF story in the 1950s about astronauts who
land in the "Twilight Zone" of Mercury - back when its day was still
thought to equal its year of 88 Earth days.

I can recall their encounter with a spindly crab-like creature that
caught prey and defended itself by throwing rocks. It threw a rock
at one of the astronauts, puncturing his spacesuit and causing a
scramble back to the ship.


Yeah, that was his Winston kids' SF novel "Islands in the Sky". Poor Arthur -- the Solar System has turned out to be SO much less interesting than he hoped it would be. (Note, though, that the guy whose suit was damaged -- with the result that his legs froze solid and had to be amputated -- then happily made a life for himself on a space station, since legs are actually something of an encumberance in 0-G. That idea has been floating around in the SF world ever since, usually in connection with genetic engineering of humans. As Jack Vance points out, obese people would also be a lot happier living in orbit.)

While we're on the subject of misguided SF predictions about Mercury, the prize-winner surely has to be Larry Niven's very first SF story, "The Coldest Place", in which the same two astronauts we'd later meet in "Becalmed in Hell" have just landed triumphantly on "the coldest place in the Solar System", and encountered a helium II-based lifeform. The story neatly suckers the reader into assuming that they're on Pluto, until the last sentence reveals it to be the permanent nightside of Mercury instead. Poor Niven got this story published exactly three months before the radar discovery that Mercury's rotation was not synchronous.
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Posts in this topic
- Rem31   Landing on Mercury on equator at perihelion   Mar 21 2006, 12:18 AM
- - antoniseb   QUOTE (Rem31 @ Mar 20 2006, 07:18 PM) How...   Mar 21 2006, 12:25 AM
- - RNeuhaus   QUOTE (Rem31 @ Mar 20 2006, 07:18 PM) How...   Mar 21 2006, 02:25 AM
|- - Rem31   But how will a (hypothetical) manned landing on Me...   Mar 21 2006, 03:42 AM
|- - RNeuhaus   QUOTE (Rem31 @ Mar 20 2006, 10:42 PM) But...   Mar 22 2006, 01:35 AM
- - BruceMoomaw   A manned landing on Mercury at perihelion -- or an...   Mar 21 2006, 04:25 AM
|- - JRehling   QUOTE (BruceMoomaw @ Mar 20 2006, 08:25 P...   Mar 21 2006, 10:02 PM
|- - BruceMoomaw   QUOTE (JRehling @ Mar 21 2006, 10:02 PM) ...   Mar 21 2006, 11:57 PM
|- - JRehling   QUOTE (BruceMoomaw @ Mar 21 2006, 03:57 P...   Mar 22 2006, 05:46 PM
- - Richard Trigaux   QUOTE (Rem31 @ Mar 21 2006, 01:18 AM) How...   Mar 21 2006, 06:09 AM
- - edstrick   Exploring Mercury is difficult. While it's re...   Mar 21 2006, 08:49 AM
|- - Richard Trigaux   At least, and orbiter with high resolution mapping...   Mar 21 2006, 09:08 AM
- - edstrick   Robert Strom (I think) and subsequent researchers ...   Mar 21 2006, 10:26 AM
|- - Richard Trigaux   hey, that is interesting, and fairly different of ...   Mar 21 2006, 11:06 AM
- - Richard Trigaux   An interesting job too for a probe would be sensin...   Mar 21 2006, 11:18 AM
|- - ljk4-1   Come on, guys - just land at night! How about...   Mar 21 2006, 03:20 PM
|- - JRehling   To summarize what other posters have written: Merc...   Mar 21 2006, 05:37 PM
- - BruceMoomaw   Even Arthur C. Clarke, the Keeper of the Holy of H...   Mar 21 2006, 09:42 PM
|- - ljk4-1   QUOTE (BruceMoomaw @ Mar 21 2006, 04:42 P...   Mar 21 2006, 10:22 PM
|- - Rem31   Are there space artist impressions to find on the ...   Mar 21 2006, 11:42 PM
- - RNeuhaus   The Mercury atmospheric composition: CODEHelium 4...   Mar 22 2006, 01:59 AM
- - BruceMoomaw   It has stupendously less than that -- its atmosphe...   Mar 22 2006, 03:40 AM
- - edstrick   Niven may or may not have been aware of the really...   Mar 22 2006, 07:04 AM
- - BruceMoomaw   He surely wasn't aware of that, or he wouldn...   Mar 22 2006, 07:37 AM
- - edstrick   I'm assuming he wasn't. It was pretty obs...   Mar 22 2006, 08:15 AM
|- - BruceMoomaw   QUOTE (edstrick @ Mar 22 2006, 08:15 AM) ...   Mar 22 2006, 08:25 PM
- - Richard Trigaux   There was in another thread a discution on the pos...   Mar 22 2006, 08:37 AM
- - edstrick   A long lived Mercury lander would have decidedly d...   Mar 22 2006, 11:12 AM
- - Richard Trigaux   An ion drive would do well on a trajectory to Merc...   Mar 22 2006, 07:26 PM
|- - ljk4-1   QUOTE (Richard Trigaux @ Mar 22 2006, 02...   Mar 22 2006, 08:09 PM
|- - antoniseb   QUOTE (ljk4-1 @ Mar 22 2006, 03:09 P...   Mar 22 2006, 08:45 PM
||- - Richard Trigaux   QUOTE (antoniseb @ Mar 22 2006, 09:45 PM)...   Mar 22 2006, 09:40 PM
|- - JRehling   QUOTE (ljk4-1 @ Mar 22 2006, 12:09 P...   Mar 22 2006, 09:27 PM
|- - ljk4-1   QUOTE (JRehling @ Mar 22 2006, 04:27 PM) ...   Mar 22 2006, 09:41 PM
- - edstrick   Mariner 10 did have a tiny infrared radiometer. I...   Mar 23 2006, 09:33 AM
- - Rem31   What kind of experience will it (possibly) be when...   Apr 28 2006, 09:47 PM
- - BruceMoomaw   All I can say is you like hot weather a lot more t...   Apr 28 2006, 09:53 PM
|- - Rem31   What are the kind of dangers of a (manned) landing...   May 10 2006, 12:06 AM
- - BruceMoomaw   God, yes. We've mentioned all this before. A...   May 10 2006, 08:43 AM
|- - Bob Shaw   QUOTE (BruceMoomaw @ May 10 2006, 09:43 A...   May 10 2006, 11:00 AM
|- - JRehling   QUOTE (BruceMoomaw @ May 10 2006, 01:43 A...   May 10 2006, 01:35 PM
|- - JRehling   QUOTE (JRehling @ May 10 2006, 06:35 AM) ...   May 10 2006, 05:08 PM
- - Rem31   And on a manned landing on Mercury at (perihelion)...   May 10 2006, 11:28 AM
|- - helvick   QUOTE (Rem31 @ May 10 2006, 12:28 PM) And...   May 10 2006, 12:19 PM
- - jsheff   As I recall, Mariner 10's discovery of a magne...   May 10 2006, 03:52 PM
|- - Bob Shaw   John: The trouble with Mercury is, that although ...   May 10 2006, 05:58 PM
- - RNeuhaus   A comparative view of Sun between Mercury and Eart...   May 10 2006, 07:06 PM
- - jsheff   I know how horrendous the delta-vee requirements a...   May 10 2006, 07:27 PM
|- - JRehling   QUOTE (jsheff @ May 10 2006, 12:27 PM) Th...   May 10 2006, 08:27 PM
|- - Bob Shaw   QUOTE (JRehling @ May 10 2006, 09:27 PM) ...   May 10 2006, 08:39 PM
||- - ilbasso   QUOTE (Bob Shaw @ May 10 2006, 04:39 PM) ...   May 18 2006, 05:47 PM
|- - helvick   Absolutely agree with you on this but people are s...   May 10 2006, 08:50 PM
|- - ljk4-1   QUOTE (helvick @ May 10 2006, 04:50 PM) A...   May 18 2006, 05:52 PM
- - BruceMoomaw   Well, all the way back in the 1950s -- when he was...   May 10 2006, 09:11 PM
- - Rem31   Do you need also Solarheat and radiation protectio...   Jun 17 2006, 09:00 PM
- - dvandorn   I don't have detailed numbers for you, but my ...   Jun 18 2006, 11:52 PM
- - RNeuhaus   In spite of the fact Mercury has extermes temperat...   Jun 19 2006, 12:46 AM
|- - ermar   QUOTE every 44 days (one orbital period is close t...   Jun 20 2006, 08:09 PM
- - RNeuhaus   Good tought ermar! I haven't percated th...   Jun 21 2006, 03:04 AM
- - Rem31   Here is one of the most beautifull photographs of ...   Jun 22 2006, 09:11 PM
|- - helvick   QUOTE (Rem31 @ Jun 22 2006, 10:11 PM) I h...   Jun 22 2006, 11:40 PM
|- - JRehling   QUOTE (helvick @ Jun 22 2006, 04:40 PM) N...   Jun 23 2006, 04:10 PM
|- - Rem31   QUOTE (JRehling @ Jun 23 2006, 04:10 PM) ...   Jun 24 2006, 11:09 PM
- - edstrick   Note that we *DO* know there's polar volatile ...   Jun 23 2006, 10:50 AM
- - edstrick   I note that that page has ONE (the first) of the M...   Jun 24 2006, 10:24 AM
- - efron_01   about Mercury having been a moon of Venus.. I have...   Nov 12 2006, 03:44 PM
- - nprev   As I recall, the Arecibo radar images of Mercury...   Nov 13 2006, 02:11 AM
- - Alan S   This might be a topic for a new thread, but since ...   Jan 8 2007, 06:21 AM
- - edstrick   The helium 3 is a fraction (in very approximate pr...   Jan 8 2007, 12:43 PM
|- - Bob Shaw   QUOTE (edstrick @ Jan 8 2007, 12:43 PM) T...   Jan 8 2007, 10:32 PM
- - ljk4-1   Dr. Robert Bussard of the Bussard ramjet interstel...   Jan 8 2007, 02:52 PM
|- - JRehling   QUOTE (ljk4-1 @ Jan 8 2007, 06:52 AM...   Jan 8 2007, 07:16 PM
- - nprev   I think that JR's analysis was right on, if ni...   Jan 9 2007, 02:25 AM
- - edstrick   "...what minerals might the planet have ......   Jan 9 2007, 08:39 AM


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