Which other planets can you see humans on? - Within our solar system at one point

Mark · 2003-12-27 19:51:26

Which other planets within our solar systems, or moons for that fact, can you see humans on at one point in the future, even if it is past our lifetimes. How would you rank your choices?

Of course, there is Mars which seems to come in at number 1, but I've seen some other people mentioning even Mercury(the dark side away from the sun where temperatures are below zero).

Bill White · 2003-12-27 21:45:40

Which other planets within our solar systems, or moons for that fact, can you see humans on at one point in the future, even if it is past our lifetimes. How would you rank your choices?
Of course, there is Mars which seems to come in at number 1, but I've seen some other people mentioning even Mercury(the dark side away from the sun where temperatures are below zero).

<1> Mars

<2> Asteroid - - Main Belt

<3> Moons of Jupiter and Saturn

After that I say robot mining operations on Mercury (scientists might visit the dark side) and atmospheric probes into Venus. The surface will be inhospitable for a long, long time.

Anyway - - for a few centuries at least - - Mars and the asteroids will be where all the serious action will be. IMHO.

~Eternal~ · 2003-12-27 23:06:47

Mercury Polarized Domes
Venusian Sky Colonies
Luna Polarized paraterraformed Domes
Mars & Phobos, possibly Deimos
Large asteroids
Galliliean moons
Titan
Triton
Mimas
Pluto & Charon
Oort Cloud objects
And Orbitting colonies still in the heliosheath

Yeah I have BIG plans for humanity.

Shaun Barrett · 2003-12-28 07:01:51

I'm getting the impression that some people think Mercury keeps the same side toward the Sun all the time.
This is not the case. It rotates once on its axis every 59 days (Earth days, that is) but takes 88 days to orbit the Sun. This peculiar situation gives rise to the fact that if you arrived on the surface at local sunrise, and stayed where you were, you'd have to wait 176 Earth days for the next sunrise. You could actually walk away from the rising sun quite easily, even at the equator, and stroll back into the darkness!
In fact there was a science fiction story about a settlement on rails on Mercury, which kept pace with the daylight/darkness terminator as it moved across the landscape. In this way, it was possible to maintain an even temperature inside the settlement by avoiding the thermal extremes of midday and midnight. I think Arthur C. Clarke may have written the story but I can't be sure.

Mark · 2003-12-28 07:10:20

What is the pressure like on Mercury?

Say humans landed on the dark side(at the time), what things would they otherwise need to combat(apart from low temperatures)? Infact, landing on the darkside of Mercury would be tougher than landing on Mars?

Also, does anyone know much about the moons of Uranus or Neptune, are there any interesting ones there that could *possibly* be landing sites for human exploration in the future?

Stu · 2003-12-28 07:21:32

In fact there was a science fiction story about a settlement on rails on Mercury, which kept pace with the daylight/darkness terminator as it moved across the landscape. In this way, it was possible to maintain an even temperature inside the settlement by avoiding the thermal extremes of midday and midnight. I think Arthur C. Clarke may have written the story but I can't be sure.

I think that's one of Kim Stanley Robinson's ideas, first described in his pre-R/G/B Mars novella "THE MEMORY OF WHITENESS" and then returned to later, I think, in BLUE MARS.

Stu

Stu · 2003-12-28 07:25:34

Also, does anyone know much about the moons of Uranus or Neptune, are there any interesting ones there that could *possibly* be landing sites for human exploration in the future?

Miranda, one of Uranus' moons, has a bewildering landscape of valleys, grooves, plains and enormous scarps, or cliffs. There's one range of cliffs which is truly huge, dwarfing even the escarpment which forms the supporting base of Olympus Mons. The figure of an almost 10km sheer drop springs to mind from somewhere, but can't swear to it.

Triton, Neptune's moon, has geysers which gush out dark material which then forms sooty streaks on the surface, which would be pretty cool to see. We also think Pluto might resemble Triton in someways, so it would definitely be worth going to.

Stu

atitarev · 2003-12-28 10:09:41

I venture to add to this, as it is my favourite topic.

I must be the most optimistic about this, although I am not so technically equipped in terraformation area and in creation of life support system.

Humans are very ingenious when they have to achieve something, especially if they have too.

I believe Venus will be fully terraformed (or at least) in the far future, with or without changing its rotation. If a dense wet atmosphere is created on Venus (2.5 bars, 90% nitrogen, 8% oxygen, 2% water) it may be good enough to support steady climate during its 55 day diurnal period (not 243 - its rotational period!). I put Venus as number 3 candidate after Mars and the Moon.

The Moon might be partially terraformed with larger ice asteroids thrown at its poles and its atmosphere would be topped up from time to time. Its atmosphere would be much thinner than Earth's, although enough to make use of parachutes and pressurized tents (not domes).

Mercury is too close to the Sun but polar regions are good candidates for settlement. I still believe that shifting it further from the Sun is possible and if moved to 90-95 mln km orbit would be in the safe distance from Venus and far enough from the Sun to support hot but tolerable atmosphere.

I am in favour of settling the Jovian moons and beyond, although good sources of energy will be required or huge lenses.

Happy New Year everyone and good luck with Beagle 2!

Palomar · 2003-12-28 15:23:07

Miranda, one of Uranus' moons, has a bewildering landscape of valleys, grooves, plains and enormous scarps, or cliffs. There's one range of cliffs which is truly huge, dwarfing even the escarpment which forms the supporting base of Olympus Mons. The figure of an almost 10km sheer drop springs to mind from somewhere, but can't swear to it.

*My god!

How marvelous and mind-boggling.

--Cindy

Stu · 2003-12-28 16:18:19

*My god!
How marvelous and mind-boggling.
--Cindy

Indeed... even more mind-boggling is the possibility that Miranda has actually been shattered in the distant past by impacts with asteroids or comets, and the Miranda we see today has actually re-assembled from the pieces. The whole moon is like a huge jigsaw puzzle, or a rocky and icy Rubiks Cube, with scarps and cliffs and ridges sticking out all over the place...

Then you've got Miranda, one of Saturn's smaller moons, which has a massive crater called Herschel dominating one whole hemisphere, making it look like the Death Star from STAR WARS. Stand on Herschel's central peak and look back at Saturn, and you'd see the rings cutting it it half vertically like a massive sword. That's got to be one of the best views in the solar system... :-)

Stu

Stu · 2003-12-28 16:28:48

Correction - the cliffs on Miranda are "only" 5km high..!!

And a cool pic of Mimas and its 120km wide crater Herschel can be seen here:

http://seds.lpl.arizona.edu/nineplanets … mimas.html

Stu

Mark · 2003-12-28 17:42:00

That sounds like an awesome view indeed. Do you have anymore info on that moon? I wonder if the Cassini will fly-by and do analysis on that moon..

Palomar · 2003-12-28 19:04:57

Correction - the cliffs on Miranda are "only" 5km high..!!
And a cool pic of Mimas and its 120km wide crater Herschel can be seen here:
http://seds.lpl.arizona.edu/nineplanets … mimas.html
Stu

*Stu, that's a really good link. I visited the main site, wanted to see a pic or two of Miranda (wild!!).

And while I was at it, I checked out this guy (have researched it before at different sites):

http://www.seds.org/nineplanets/ninepla … petus.html

You all may know/recall the Arthur C. Clarke originally set the key action of _2001: A Space Odyssey_ (I love the novel, can pass on the movie) on Iapetus...it was host to the Monolith (the 2nd in the story, which was alerted/awakened by the "cosmic trigger" of the Monolith on the moon) which Dave Bowman approached before tumbling into his ultimate life-altering journey. When the first up-close photos (Voyager) of Iapetus were released years later, Clarke was a bit tickled and astounded at the coincidence of a rectangular-shaped dark blotch on Iapetus (only peripherally visible in the pic above). IIRC, he mentioned this in the Foreward to 2010. A pic which shows this feature a bit more:

http://www.metaresearch.org/solar%2....tus.jpg

Anyway, terrific site, and I see it is very current (last update 28 July 2003).

Maybe we can add Iapetus to our aspirations (in the Satellite Category).

Shaun wrote (about Mercury): " It rotates once on its axis every 59 days (Earth days, that is) but takes 88 days to orbit the Sun. This peculiar situation gives rise to the fact that if you arrived on the surface at local sunrise, and stayed where you were, you'd have to wait 176 Earth days for the next sunrise..."

*Huh? How so? Earth comparison: 24 hours to rotate on axis, 365 days to orbit the sun (as we know)...no matter where I am on Earth, it's only going to take 24 hours (or, if we want to split hairs, 23.59 hours!) to see another sunrise (orbit around our sun not a consideration except as seasons go)...provided I'm standing in the same area as the day prior. Aside from the obvious differences in axis rotational time and sun orbiting time between Earth and Mercury...am I misreading something in your post, Shaun? Help?

Shaun: "You could actually walk away from the rising sun quite easily, even at the equator, and stroll back into the darkness!
In fact there was a science fiction story about a settlement on rails on Mercury, which kept pace with the daylight/darkness terminator as it moved across the landscape..."

*Whoa Nellie. That is so cool. I'd like to read that story. You think it may have been Clarke who wrote it; Stu seems certain it was Robinson. Well, I'm interested.

Someone hurry up and invent a Do-It-Yourself Spaceship Kit.

--Cindy

Mad Grad Student · 2003-12-28 20:52:38

no matter where I am on Earth, it's only going to take 24 hours (or, if we want to split hairs, 23.59 hours!) to see another sunrise (orbit around our sun

Nope, actually it takes 24 hours to go from sunrise to sunset every day of the year BUT ONLY AT THE EQUATOR. The 23.9 hour day you mention is refered to as a sidreal day, or the time it takes for Earth to turn 360 degrees once. This is useful to astronomers because it is the time it takes for any star (Excluding the sun due to its proximity to Earth) to return to it's origional position. The two are different because as Earth turns it also goes around the sun, and Mercury's days are so wacky because it moves so fast around the sun it practically outruns it when the planet is at its perigee.

Where do I think we'll go after Mars? The migration of humans off of Earth will likely be like that of humans out of Africa, slow and glacial rather than speedy. It will be influenced by the commodities we can more readily get on the system's various moons and planets. Eventually they will be so desired that people just quit the hassle of running back to Earth every few years and just start self-sustaining cities on the planets.

For example, astronomers will colonize Mercury fairly early on because it's an excellent place to have a telescope. There is practically zero atmosphere and no sun for 176 days of the year, then sun for the next 176 days, a perfect place for both celestial and helispheric observatories.

The Moon will likely be the first place to be permenently colonized, becasue it will be a much cheaper place to manufacture goods than Earth and close enough that residents won't have to part with that pale blue dot. It turns out that money makes space go round, too, not just the world. Because of its proximity to Earth, I feel that the majority of space-borne goods will come from the Moon, not the asteroid belt.

Europa could easily become a colony once we get more advanced radiation sheilding. I've heard that the radiaton there would kill an unsheilded person in 20 minutes, definately an obstacle. If there's life there people will come very soon after and likely set up a colony on the surface or under the ocean (20 km of free sheilding is a nice bargain) to study it and Jupiter.

Ah, Saturn. Titan will be colonized before anything else, with smaller settlements in the rings to mine minerals. What makes Titan so appealing is that it's very faithful to the conditions Earth was under when it first came up with life, which makes it a nice science target. Interesting places always attract people, you have to admit.

Unfortunately, Uranus is kind of uninteresting, at least according to Voyager. However, I've heard of planes before to mine exotic elements like Deuterium in the gas giants, and Uranus it the best target for this.The reason to pick Uranus is that it has the lightest gravity of any gas giant, making it the easiest to go to Earth from.

Finally, Neptune/Triton would be colonized, well, just because. It's a spectacular planet with a spectacular moon, by the time we have the ability to colonize it, people would want it. Additionally, Trition is a very interesting little moon, it's geologically active and has a nice little atmosphere. Pluto, too will be colonized, but it's too early to tell why. When the New Horizons probe flyby's it we'll learn much more aobut the oddball world.

Palomar · 2003-12-28 22:23:24

no matter where I am on Earth, it's only going to take 24 hours (or, if we want to split hairs, 23.59 hours!) to see another sunrise (orbit around our sun
Nope, actually it takes 24 hours to go from sunrise to sunset every day of the year BUT ONLY AT THE EQUATOR. The 23.9 hour day you mention is refered to as a sidreal day, or the time it takes for Earth to turn 360 degrees once.

*Okay...I'm with you.

But back to the original point I was trying to make:
The length of our orbit around the sun *doesn't* factor into sunrise (or sunset) and length of days.

I don't understand how Mercury's orbit around the sun is somehow factored into the story which Shaun relates, pertaining to sunrise.

Sidereal time, near the equator, near the pole...whatever. It's still the rotation of a planet upon its own axis which creates sunrise and sunset, day and night. Our orbiting of the sun has nothing to do with those particular matters. How could it be different on Mercury?

I'm sure this is mostly a communication gap of sorts...

--Cindy

::EDIT:: It's that figure of "176" (pertaining to Mercury) which is throwing me.

Mark · 2003-12-28 22:36:09

On the topic of Mars, I've read somewhere where it was suggested to perhaps build a station on one of Mars' moons, Phobos, what's the thought about that moon, what kind of conditions does it have. I can't remember where I read this or who suggested it, but the basic idea was to setup a station on Phobos to learn more about Mars(primarily), but also it's moons, and the station could be used as a stop-over for any manned missions to Mars.

RobS · 2003-12-29 00:23:34

I've seen a proposal somewhere to put a base on Deimos. I'm not sure why (as opposed to Phobos). They seem to be about the same; if you aerobrake into a Mars orbit, Phobos is easier to reach because the delta-vee to circularize your orbit is smaller, but on the other hand, Deimos offers a slightly lower delta-vee to fly back to Earth. Both moons have a few ten thousandths of a gee of gravity; dusty regoliths covering carbonaceous chondrite bedrock; both are irregular in shape, with craters almost up to the size of fragmentation; and both share the same inclination of axis as Mars, so neither has permanent sun at its poles.

-- RobS

Mark · 2003-12-29 00:35:37

So setting up some kind of station or outpost on those moons wouldn't be totally out of the question at some point? and it would perhaps help make manned or unmanned missions to Mars a bit easier?

Shaun Barrett · 2003-12-29 02:06:54

Hi Cindy!
Just popped in to attempt a quick explanation of something which takes a little bit of chewing over to really understand.
Mercury is gravitationally locked into a rotational ratio whereby it rotates three times on its axis for every two revolutions around the Sun. This a stable tidal relationship in the same way that the one-to-one ratio of our Moon's rotation and revolution about Earth is stable.
This is why sunrise to sunrise, at the same spot on Mercury's surface, takes exactly the same time as two Mercurian years.

This peculiar anomaly is difficult to understand from our terrestrial perspective because Earth rotates hundreds of times for each revolution around the Sun, whereas Mercury's 'day' and its year are much closer to the same duration.
The mechanics of it may be easier to grasp if you consider what has been mentioned here already. Our Earthly day is 24 hours long from noon to noon, but only 23 hours and 56 minutes long from 'celestial noon' to celestial noon' - not much difference because Earth's rotation rate is so high. But it takes Mercury so long to rotate once on its axis that a significant proportion of its year (2/3rds) passes in the same period of time.
Get a tennis ball and move it around a light source twice, while rotating it exactly three times. If you do it right, you should see why there are two Mercurian years between sunrises!

It is quite difficult to conceptualise, I admit, but I hope that helps!

Mark · 2003-12-29 05:36:15

Also, if it takes 6 months with current technology to get to Mars, how long would it take to get to any of Jupiter's moons where humans could possibly land on, like Callisto for instance or Saturn's moon Titan?

Shaun Barrett · 2003-12-29 06:48:15

If the Voyager probes are anything to go by, reaching the Jupiter system might take 18 months to two years.
And the Saturnian system is upwards of 3 years away.

A crewed mission, though, would surely be conducted with a little more haste than that, so as to avoid mental deterioration etc. Perhaps a nuclear thermal engine or the Vasimir engine could cut down on transit times and make the trip more manageable.

Mark · 2003-12-29 07:48:15

If that time period could be cut down by at least more than half, that would prove to be a more tolerable flight, but even by half, getting to the Saturnian system would still take around 1.5 years. Time is the biggest problem for us, we need more speed.

Palomar · 2003-12-29 10:38:11

Hi Cindy!
Just popped in to attempt a quick explanation of something which takes a little bit of chewing over to really understand.
...
It is quite difficult to conceptualise, I admit, but I hope that helps!

*Thanks for the explanation Shaun. Yes, difficult to conceptualize...but it opens a new door of understanding.

I appreciate you.

--Cindy

Shaun Barrett · 2003-12-29 19:01:04

It's always nice to be appreciated, Cindy! But that explanation was rather perfunctory and scrappy due to time restrictions. I now have a little more time available and would like to attempt a better explanation, as much for completeness in my own mind as anything else (just humour me and keep smiling! ). It is quite a fascinating situation on Mercury, after all.

In order to get a grip on what's happening, let's separate Mercury's rotation from its orbital revolution.
Let's start by supposing that Mercury has no sidereal rotation at all. In other words, no matter where Mercury is in its orbit about the Sun, the same stars sit motionless above your head as you stand on the equator. But Mercury is still orbiting the Sun, anticlockwise as seen from above the Sun's north pole, once every 88 days (Earth days).
If you imagine yourself standing on the equator at noon facing due north (carrying a parasol and wearing 15,000+ sun-block!! ), as time passes you would notice the Sun moving slowly toward the eastern horizon. In fact, after 22 days, or 1/4 of a Mercurian year, you would notice the Sun setting on the eastern horizon, having moved 90 degrees from the zenith. Remember, none of this movement is due to any rotation of the planet; it's all due simply to its revolution around the Sun.

But now, let's stop Mercury revolving around the Sun! Let's imagine we can persuade it it to remain motionless in space relative to the Sun without falling into the nuclear fires. And let's now re-introduce Mercury's slow west-to-east rotation, which turns it 360 degrees every 58.646225 days (Earth days again).
Let's start at the same point we did before. In the same 22 days you've been standing on the equator facing north, Mercury's W-to-E rotation would appear to make the Sun move 22/58.646225 times 360 degrees to the west, as it's supposed to do on any self-respecting planet! i.e. 135 degrees to the west.

So, in the same 22 day period, we have Mercury's revolution around the Sun trying to cause the Sun to move 90 degrees to the east, while Mercury's rotation is trying to cause it to move 135 degrees to the west! Which movement wins? Obviously, the larger westward movement predominates.
The overall effect is to cause you, still standing on the equator facing north(! ), to see a net movement of the Sun 45 degrees (135 - 90) to the west.
This 45 degree westward motion of the Sun in the Mercurian sky has occurred during 22 days, which is 1/4 of a Mercurian year of 88 days. So, over a full year, the Sun would move westward by 4 times 45 degrees, or 180 degrees. This places it on the other side of Mercury, directly beneath your feet; in other words, you'll now be standing on the equator at midnight, wishing you'd brought thermal underwear with you!
If you stay put for another 88 days, you'll notice the Sun has now returned to its original position directly overhead, a total of 176 days after you began your lonely and uncomfortable vigil.

So noon to noon (or dawn to dawn, or dusk to dusk) on Mercury is a period of 176 days, which is exactly 2 Mercurian years.
A very peculiar situation, but there it is!

[And there are other anomalies to the Sun's apparent movement on Mercury, too, which relate to its marked orbital eccentricity. This eccentricity causes Mercury to move much faster at certain times in its orbit and leads to 'double dawns' and 'double sunsets' on occasions. In other words, the Sun can set, then appear to rise above the horizon again before finally sinking out of sight. And it can do the opposite at dawn; appearing, dropping back, then rising once more above the horizon.
But that's a whole different ball game and I'm not even going to try to explain that one!!]
:laugh:

atitarev · 2003-12-30 02:37:13

It was a discovery for me to learn that Venusian solar day is so much different from its rotational day. It's the same reason as with Mercury, only Venus is rotating very slowly in the direction opposite to other planets. That makes its solar day (day and night) much shorter than the rotation around its axis. On Earth both are the same - 24 hours.

On Venus rotational period is 224.8008 Earth days, and the solar day is 116.8 Earth days long. It's still a long day (58 days sunlight/58 days night).

As for Miranda (Stu, you mistyped it as Saturn's moon the second time). Why would you start settling Miranda (diameter 472 km) before Titania (1578 km), Umbriel (1170 km) and Ariel (1158 km) - the larger Uranus' satellites. Miranda looks cool but it's pretty tiny.

New Mars Forums

Announcement

#1 2003-12-27 19:51:26

Re: Which other planets can you see humans on? - Within our solar system at one point

#2 2003-12-27 21:45:40

Re: Which other planets can you see humans on? - Within our solar system at one point

#3 2003-12-27 23:06:47

Re: Which other planets can you see humans on? - Within our solar system at one point

#4 2003-12-28 07:01:51

Re: Which other planets can you see humans on? - Within our solar system at one point

#5 2003-12-28 07:10:20

Re: Which other planets can you see humans on? - Within our solar system at one point

#6 2003-12-28 07:21:32

Re: Which other planets can you see humans on? - Within our solar system at one point

#7 2003-12-28 07:25:34

Re: Which other planets can you see humans on? - Within our solar system at one point

#8 2003-12-28 10:09:41

Re: Which other planets can you see humans on? - Within our solar system at one point

#9 2003-12-28 15:23:07

Re: Which other planets can you see humans on? - Within our solar system at one point

#10 2003-12-28 16:18:19

Re: Which other planets can you see humans on? - Within our solar system at one point

#11 2003-12-28 16:28:48

Re: Which other planets can you see humans on? - Within our solar system at one point

#12 2003-12-28 17:42:00

Re: Which other planets can you see humans on? - Within our solar system at one point

#13 2003-12-28 19:04:57

Re: Which other planets can you see humans on? - Within our solar system at one point

#14 2003-12-28 20:52:38

Re: Which other planets can you see humans on? - Within our solar system at one point

#15 2003-12-28 22:23:24

Re: Which other planets can you see humans on? - Within our solar system at one point

#16 2003-12-28 22:36:09

Re: Which other planets can you see humans on? - Within our solar system at one point

#17 2003-12-29 00:23:34

Re: Which other planets can you see humans on? - Within our solar system at one point

#18 2003-12-29 00:35:37

Re: Which other planets can you see humans on? - Within our solar system at one point

#19 2003-12-29 02:06:54

Re: Which other planets can you see humans on? - Within our solar system at one point

#20 2003-12-29 05:36:15

Re: Which other planets can you see humans on? - Within our solar system at one point

#21 2003-12-29 06:48:15

Re: Which other planets can you see humans on? - Within our solar system at one point

#22 2003-12-29 07:48:15

Re: Which other planets can you see humans on? - Within our solar system at one point

#23 2003-12-29 10:38:11

Re: Which other planets can you see humans on? - Within our solar system at one point

#24 2003-12-29 19:01:04

Re: Which other planets can you see humans on? - Within our solar system at one point

#25 2003-12-30 02:37:13

Re: Which other planets can you see humans on? - Within our solar system at one point

Board footer