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#1 2004-04-08 08:24:52

REB
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From: Houston, Texas
Registered: 2004-04-07
Posts: 555
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Re: Cycler Spaceships - Ships going between Earth and Mars

[color=#000000:post_uid0]Cycler Spaceship

I had thought of a similar idea, and I thought it was unique, until a friend pointed me to that web page. Buzz Aldrin beat me to it.

I was thinking what a waste of energy it would be to slow a ship down from Mars, just to drop people and supplies off, just to pick up more people and supplies and accelerate back to Mars.

At first, I was wondering if there would be a ways for an incoming ship to transfer its energy to an outgoing ship. Basically they switch their speed and course. Somehow, they would have to join and then switch places, and I have no idea how that could be engineered.

In the old days of Steam Engines, trains would grab mailbags hanging by the track. This saved energy, otherwise the train would have to slow down, stop, pick up the mail, and then start up again. It also saved time.

Back to our Earth/Mars ship, just have the main mass in a constant orbit between Mars and Earth. Why waste energy slowing it down, just to waste more energy speeding it up? Ferry people and supplies out to it in smaller taxies. Sure, the smaller ships would have to use energy to catch the Earth/Mars ship, but we are talking much less mass, and so less energy.

But Buzz already thought of this sad Oh well. I am glad someone is seriously thinking about it.[/color:post_uid0]


"Run for it? Running's not a plan! Running's what you do, once a plan fails!"  -Earl Bassett

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#2 2004-04-08 08:28:35

Bill White
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Registered: 2001-09-09
Posts: 2,114

Re: Cycler Spaceships - Ships going between Earth and Mars

[color=#000000:post_uid0]Why have a cycler "spaceship" - - build your L5 style cities in free return orbits, every time you pass by Earth or Mars add a few new buildings.  :;):

Choose a free return orbit and over the centuries perhaps hundreds of thousands of people could come to live in this travelling city.[/color:post_uid0]

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#3 2004-04-08 08:31:26

John Creighton
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From: Nova Scotia, Canada
Registered: 2001-09-04
Posts: 2,401
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Re: Cycler Spaceships - Ships going between Earth and Mars

[color=#000000:post_uid0]

Why have a cycler "spaceship" - - build your L5 style cities in free return orbits, every time you pass by Earth or Mars add a few new buildings.   

Choose a free return orbit and over the centuries perhaps hundreds of thousands of people could come to live in this travelling city. [/quote:post_uid0]

Cool[/color:post_uid0]

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#4 2004-04-08 08:41:55

dicktice
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From: Nova Scotia, Canada
Registered: 2002-11-01
Posts: 1,764

Re: Cycler Spaceships - Ships going between Earth and Mars

[color=#000000:post_uid0]Bill White: Please don't divert Reb's and Buzz's ideas re. Cycler spaceship service to and from  Mars. Your theme should go under Space Colonies--not this one.
While I'm all in favour of your premise (but not its dependence upon Earth's resources for ongoing expansion, because plenty of inner Solar System resources exist to supply microgravity manufacturing). So, enough already.
Let's hear it from the supporters of Space Cyclers between Earth and Mars, and (most rewarding, for want of previous detailed discussions) the orbital mechanics infrastructure for supporting them.[/color:post_uid0]

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#5 2004-04-08 08:54:58

Bill White
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Registered: 2001-09-09
Posts: 2,114

Re: Cycler Spaceships - Ships going between Earth and Mars

[color=#000000:post_uid0]At one time I had thought that in the short and medium term, cycler ships might well be the equivalent of the 19th century American railroads. Yet with "Martin Lo" trajectories and nuclear or solar ion propulsion, I do not know if cycler ships make sense anymore, except if combined with substantial life support for a human crew.

The advantage of cyclers (IMHO) is the ability to deploy a very large mass in a free return orbit, which allows a much smaller mass (passengers) to travel in comfort and rely on the gravitational momentum to avoid the need to accelerate anything other than a tiny crew capsule.

Visualize a CEV "grabbing a tether" left dangling behind a massive cycler for crew transfer purposes.

But for cargo, "Martin Lo" trajectories using areobraking or direct entry seems more efficient[/color:post_uid0]

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#6 2004-04-08 09:11:43

RobS
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From: South Bend, IN
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Re: Cycler Spaceships - Ships going between Earth and Mars

[color=#000000:post_uid0]Near as I can tell, there is no such thing as a zero energy orbit between planets, only between lagrange points in the same system (in our case, the Earth/sun/moon system). But That's neither here nor there.

Transportation between the Earth and Mars is shaped by several points worth considering:

1. Are the vehicles heading for Mars sufficiently reliable that we can be sure we can launch them at a precise second on a certain day. Since cyclers don't slow down and wait for you, you MUST launch a taxi to them at a certain time. If our Earth departure vehicles are like the current space shuttle, whose launch must be delayed because of safety concerns again and again for weeks at a time, then cyclers are not practical. I see cyclers as a mature technology; something used not for the first missions to Mars, but for later missions involving settlement of the place.

2. Are the vehicles heading for Mars made out of materials the settlers will need on the surface of the planet. If so, you may not need a cycler because the entire trans-Mars vehicle may be heading for the surface of the planet in pieces. In my Mars novel, for example, I postulate the eventual development of inflatable habitats about ten meters in diameter and ten meters (four stories) high. Each habitat has a heat shield, an outer anti-micrometeoroid shell, and three inner air-tight shells (for redundancy). Each transports 12 people under snug conditions (25 square meters per person). The habs fly in pairs so they can counterbalance each other for artificial gravity, and pairs fly together in pairs as well so that if there is an emergency, there are three habs into which the inhabitants of the fourth can be evacuated. After arriving in Mars orbit by aerobraking and docking to a station there, the residents remove all furniture, life support equipment, and solid objects from the habs, then deflate the inner shell and add air pressure to the next shell out, thereby squeezing the inner shell into minimum volume ("shrink-wrapping" it). It is removed through an airlock and stored in the cargo hold of a reusable shuttle that has flown up from the surface. Then the second and third shells are similarly compressed to minimum size and removed, leaving the kevlar micrometeoroid shell and heat shield. Any cargo returning to the earth is placed inside and strapped down, and then the shell is sent back to Earth using a stage fueled from Phobosian propellant. Several shuttle flights transport the people, furniture, life support equipment, and the three pressure membranes to the surface, where the latter are set up separately inside a dome to provide 75 square meters of living and working space per arrival.

Under these circumstances a cycler might not be needed, except to provide roomier transport between planets, and possibly to provide heavy radiation shielding.

3. How many people are returning from Mars? If the number equals those going to Mars, a cycler is more useful. If not, a cycler may be empty most of the time.

4. Orbits chosen and propulsion systems used. These effect the maintenance costs of the cyclers immensely. For example, a cycler on a 26-month orbit betwen the planets will take six months to go to Mars and twenty months to return to Earth. No one will want to use it for the return trip, obviously, so you will need a second cycler on a complementary orbit (six months to Earth, twenty back to Mars). Will someone have to crew the cyclers when there are no passengers on board? How will you maintain the systems when it is empty? How will you make money on your investment when it is occupied only a quarter of the time? What do you do if the propulsion system malfunctions when the ship is passing Mars? Mars's gravity is not strong enough to send the cycler back to Earth; you need some sort of propulsion system to supplement the gravity slingshot, preferrably when the cycler is deep in Mars's gravity well. But that's the very point when the Mars-bound passengers have already left and the Earth-bound passengers have not yet arrived. An ion engine may be the alternative.

So there are concerns with cyclers that have to be addressed.

         -- RobS[/color:post_uid0]

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#7 2004-04-08 09:25:33

REB
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From: Houston, Texas
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Re: Cycler Spaceships - Ships going between Earth and Mars

[color=#000000:post_uid0]I see your point, Bill. Cycler ships would be great for people, but for cargo, they don’t make a lot of sense. With cargo, your mass is with the cargo, the engines and the fuel. People, on the other hand, need a lot of extra mass. I like Buzz’s idea of these cycler ships being luxurious hotels

I don’t know if a cycler ship would be practical to get people to the Moon and then back to Earth. I am reminded of the luxury transatlantic liners of the early 1900’s.

People could travel in style, like in a nice hotel. So why don’t we have those today? Because an airplane can get you across the Atlantic in less than a day. People prefer speed over luxury.

If we can get a ship to the Moon in a day, people will not want to ride in a luxery hotel that takes a couple of days.[/color:post_uid0]


"Run for it? Running's not a plan! Running's what you do, once a plan fails!"  -Earl Bassett

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#8 2004-04-08 10:32:35

Bill White
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Registered: 2001-09-09
Posts: 2,114

Re: Cycler Spaceships - Ships going between Earth and Mars

[color=#000000:post_uid0]

I like Buzz’s idea of these cycler ships being luxurious hotels.[/quote:post_uid0]

I like this idea also. Very much because a large cycler can offer facilities that reduces the dangers of interplanetary travel.

= = =

RobS is accurate as usual, and that is why I tend to see cyclers as starting points for actual cities rather than primarily as a means for transportation. A luxury hotel is a good starting point for a village, which can grow and eventually afford massive radiation shields, such as [b:post_uid0][i:post_uid0]feet[/i:post_uid0][/b:post_uid0] of polyethylene or water rather than inches.[/color:post_uid0]

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#9 2004-04-08 19:24:09

dicktice
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From: Nova Scotia, Canada
Registered: 2002-11-01
Posts: 1,764

Re: Cycler Spaceships - Ships going between Earth and Mars

[color=#000000:post_uid0]Reb: Re. ". . . If we can get a ship to the Moon in a day, people will not want to ride in a luxery hotel that takes a couple of days."
   Speaking for yourself, you mean? Because for me the trip through space would be what I'd be paying for between Earth and Moon![/color:post_uid0]

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#10 2004-04-08 21:05:11

John Creighton
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From: Nova Scotia, Canada
Registered: 2001-09-04
Posts: 2,401
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Re: Cycler Spaceships - Ships going between Earth and Mars

[color=#000000:post_uid0]

Near as I can tell, there is no such thing as a zero energy orbit between planets, only between lagrange points in the same system (in our case, the Earth/sun/moon system). But That's neither here nor there.[/quote:post_uid0]

What are the useful orbits? I think I recall seeing an orbit that some commits take from Juperter L1 to L4 to L5 back to L1. So if we took a similar trajectory from mars, would we come anywhere near earth? And if we did how fast would we be going, what direction would we be going by earth at and how might the gravity of earth affect these Martian orbits?[/color:post_uid0]

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#11 2004-04-09 12:53:15

RobS
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From: South Bend, IN
Registered: 2002-01-15
Posts: 1,701
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Re: Cycler Spaceships - Ships going between Earth and Mars

[color=#000000:post_uid0]I think the reference to Jupiter and comets referred to the Jupiter/sun lagrange points, not the Earth/sun or Earth/moon Lagrange points. There are similar things orbiting the sun in roughly the same orbit as the Earth. One of them may actually be a discarded Saturn V third stage! These objects loop around the sun in such a way that, relative to Earth, they gradually approach the earth (they are in a slightly lower orbit), then turn and retreat from it (they move into an orbit slightly higher than the Earth's because of the Earth's gravitational effect), then when they catch up with the Earth from the other side of the orbit (350 degrees around) they switch and retreat from it in the other direction instead (by dropping back into the lower orbit). Two of Saturn's moon do this, too; one is in a slightly higher orbit than the other, and when they finally come into opposition with each other they perturb each other's paths and switch orbits, so the higher one ends up in the lower orbit and vice versa! I think the comets were doing something similar.

                  -- RobS[/color:post_uid0]

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#12 2004-04-13 21:20:36

PLIND
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From: Canada
Registered: 2004-04-13
Posts: 18

Re: Cycler Spaceships - Ships going between Earth and Mars

[color=#000000:post_uid0]There is one argument for having cyclers in the very early stages of Mars exploration. They could be used very much like oasis are used in the dessert. Many years before the astronauts get headed for Mars we could have a number (say five for example) of these cyclers at different locations between Earth and Mars. Two would be cruising from Earth to Mars, two more would be headed back and one (for good measure) would be circling Mars.
The astronauts could hook up to these 'drive ins' on their way to/from Mars. Because they have been in motion for years they could be travelling at very high speed. In addition, because we have been dropping off materials as they pass Earth they would be stock full of goodies. Finally, they would be, or could be, excellant shelters against the high radiation threat.
I see cyclers as an essential part of getting humans to Mars, refreshed and alive.

What do you think?[/color:post_uid0]

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#13 2004-04-14 06:15:58

bolbuyk
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From: Utrecht, Netherlands
Registered: 2004-04-07
Posts: 178

Re: Cycler Spaceships - Ships going between Earth and Mars

[color=#000000:post_uid1]I think that´s part of the idea: Enough room to live quite easy in space. Movements from/to this cycler could bee done by a Apollo-like capsule or maybe some kind of shuttle that both cn land on Mars and Earth.

What about the ffrequency?  The cyclers have to resonate with both Earth and Mars. Because this is not strictly  obtaineble, you have to put one resonance and to correct ffor the alteraations off the position. I cam by a very useful design by  using a 8:15 reesonance, Mars would orbit about 8 times the  sun while Earth does this 15 times. The total period of this systeem will be 15 years minus some days. The route of the cycler will turn slightly to the west.

When 7 cyclers are used, every launch-window is taken. When you let them cycle with a period of 1.5 year, the Earth-Mars transfer is about 8 months, the traansffer back will be about 28 months, because the cycler´reaches it´s perihelium (at the same distaant as Earth)  when  Earth is in conjunction.

For every fruitful flight, the orbits 4 times fruitless. It passes Earth every 3 year and by an Earth-flyby (about 2 million km) it will alter it´s orbit.

Maybe it´s an idea to use some  asteroid for this purpose. tongue[/color:post_uid1]

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#14 2004-04-15 09:12:21

REB
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From: Houston, Texas
Registered: 2004-04-07
Posts: 555
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Re: Cycler Spaceships - Ships going between Earth and Mars

[color=#000000:post_uid0]bolbuyk, The thought of using asteroids crossed my mind, except that I wouldn’t feel comfortable with an asteroid coming that close to the Earth. If we could ensure the safety of Earth and Mars, then an asteroid would make a great cycler base/ship.[/color:post_uid0]


"Run for it? Running's not a plan! Running's what you do, once a plan fails!"  -Earl Bassett

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#15 2004-04-15 15:44:33

bolbuyk
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From: Utrecht, Netherlands
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Posts: 178

Re: Cycler Spaceships - Ships going between Earth and Mars

[color=#000000:post_uid1]REB, it passes by a distance of 2 million km. Is that something to worry about? For Mars even a far bigger distance can be used.[/color:post_uid1]

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#16 2004-04-20 11:49:39

REB
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From: Houston, Texas
Registered: 2004-04-07
Posts: 555
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Re: Cycler Spaceships - Ships going between Earth and Mars

[color=#000000:post_uid0]bolbuyk, I don't know what a safe range would be for asteroids. It would need to be in a stable cycle, and there would need to be all kinds of fail-safe plans in case it was ever a threat to Earth, Mars or the Moon.[/color:post_uid0]


"Run for it? Running's not a plan! Running's what you do, once a plan fails!"  -Earl Bassett

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#17 2004-04-20 18:26:37

Hop
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From: Ajo
Registered: 2004-04-19
Posts: 146
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Re: Cycler Spaceships - Ships going between Earth and Mars

[color=#000000:post_uid0]There are 3 cycler orbits I've heard of

Niehoff VISIT 1 has a period of 1.25 years. This can rendesvous with earth every 4 periods or 5 years. 1.25/1.881 = .6646 which is very close to 2/3 of the Mars orbit. It can rendesvous with Mars every third period or 3.75 years. But since .6646 doesn't exactly equal 2/3, there is a drift, 2.2 degrees each rendesvous by my calculations.

Niehoff VISIT 2 has a period of 1.5 years. This can rendesvous with earth every 2 periods or 3 years. 1.5/1.881 = .7976 which is very close to 4/5 of the Mars orbit. It can rendesvous with Mars every fifth period or 7.5 years. But since .7976 doesn't exactly equal 4/5, there is a drift, 4.4 degrees each rendesvous.

Both the Niehoff orbits aren't very far from a Hohmann orbit (1.4174 year period) and the Delta vee isn't very much greater.

The Aldrin orbit is about 2.2 years and intersects earth's orbit in 2 places. After it leaves the descending earth crossing, it miss this crossing 2.2 years later but passes through near earth space at the ascending crossing at a time = 2.1354 years (Mars synodic period) after the first crossing. At that point it uses it's own delta vee plus an earth gravity assist to rotate it's line of apsides. The Aldrin cycler crosses Mars orbit at a substantial angle. Delta vee for Aldrin to Mars shuttles are about 12 km/s. I guess this is considered acceptable because the tiny shuttles would be only a fraction of the cycler's mass.

I thought I had sent a message earlier. Apologies if something like this shows twice.[/color:post_uid0]


Hop's Orbital Mechanics Coloring Book - For kids from kindergarten to college.

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#18 2004-04-21 17:12:29

Hazer
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From: Texas/Oklahoma
Registered: 2003-10-26
Posts: 173

Re: Cycler Spaceships - Ships going between Earth and Mars

[color=#000000:post_uid8]Well if you want to use an asteroid, how big of an asteroid are we talking about here?  Moreover, how many big-bombs will it take to pound it into dust?
I see a practical application here for a self-destruct mechanism.[/color:post_uid8]


In the interests of my species
I am a firm supporter of stepping out into this great universe both armed and dangerous.

Bootprints in red dust, or bust!

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#19 2004-04-21 17:24:23

bolbuyk
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From: Utrecht, Netherlands
Registered: 2004-04-07
Posts: 178

Re: Cycler Spaceships - Ships going between Earth and Mars

[color=#000000:post_uid1]Interesting, this last topic. I found the Niehoff VISIT 2 scenario by calculating. I assumed some resonance and calculated the deviation with the real situation. Mars and Earth resonate in a 8:15 with a deviance of .3 %. When a cycler is placed in this system with a resonance of 10 this solution is found. It resonates with Earth as 2:3 and with Mars as 5:4. Because of the regression of the apsides the whole period is not 15 year, as could be assumed from the 15, but 14.9464 year. Then I come to a regression of 3.86 degree retrograde each Earth-flyby, close to the 4.4 mentioned by Hop.
Every 10 orbits of the cycler, there is one fast 'to' one slow 'to' one fast 'from' and one slow 'from' , the slow taking about 21 months, the fast just 9.

BTW: I didn't realize 10 resonates with 8 until I read this last reply tongue[/color:post_uid1]

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#20 2004-04-22 22:55:39

Hop
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From: Ajo
Registered: 2004-04-19
Posts: 146
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Re: Cycler Spaceships - Ships going between Earth and Mars

[color=#000000:post_uid0]Bolbuyk, here is an asteroid that is already quite close to being a Niehoff VISIT 2 cycler:
http://clowder.net/hop/2000YJ11.html
You will notice a little further down the page is a schedule. The dates are a little weird. 2002.205339 works better in my spread sheet than March 17, 2002. I've colored those events when 2000 YJ11 passes within 10 degrees of Mars or Earth. You can see passes through near Earth space can occur every 3 years and passes through near Mars space every 7.5 years.
Orbital elements are from jpl Horizon ephemeris.
If you'd like to search for other possible cyclers you may go to:
http://neo.jpl.nasa.gov/cgi-bin/neo_elem
This page allows you to sort by period so it's easy to find ~1.25 and 1.5 year period asteroids.
Also look for low inclination: High inclination adds delta v and physical distance between asteroids and destination planets.
It's believed a large fraction of asteroids are carbonaceous chondrites which range from 10 to 20% water. I agree with an earlier poster that water is a very valuable resource. It can be used to drink, for radiation shielding, reaction mass with nuclear thermal or solar thermal rocket engines, or its hydrogen and oxygen components can be used for chemical rocket fuel.
It is also suspected that many asteroids are extinct comets (like Wilson Harrington comet/1979 VA asteroid). Extinct comets are believed to have water ice beneath their insulating mantles.[/color:post_uid0]


Hop's Orbital Mechanics Coloring Book - For kids from kindergarten to college.

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