Large Mars Globe (75 cm diameter)

[Algebraist]

Dear all

I am in the process of making a large globe of the planet Mars and thought it might be interesting to some people to see how it goes. Since it is a globe of a planet it seemed that PASA was the best place to put the thread (apologies if this is wrong)

Here is a little background to this project.

I have previously made a largish globe of the moon (see below)





It is an enlarge version of Ken West's Moon model. I enlarged by 150% which gave it a diameter of about 50cm. Just to not the model was available for download on ecardmodels before the rebuild, however it is not been uploaded since the rebuild. Hopefully it will reappear there in the not too distant future.

My current project of a 1/24 Saturn V rocket is coming to a close but there was quite some time whilst I could not work on it. So this got me to wanting to start something else, but, I felt like trying something with a lot less parts and more manageable.

I like the finished moon globe and globes in general seem interesting and pleasing to lots of people. So I wondered "just how big could I make a paper globe?"

I settled on 75cm diameter as I thought this was probable the maximum size possible (given the experience of the moon globe) and also the major reason that is the biggest it can be and still fit though the door to remove from my home (an essential criteria my wife told me!)

I considered doing the moon globe even larger than before but 150% is really as much magnification the images can take. So after some hunting around I found something that really grabbed my imagination, namely a globe of Mars and was in very high resolution. This was a really good to me as I am very interested in Mars and think the surface is very visually intersting so makes a really nice globe.

It is on the USGS website https://astrogeology.usgs.gov/search...s_viking_globe

Here is the template



A quick calculation meant I wanted to enlarge 230% a a little test showed that the resolution is still fantastic after this enlargement. I would have to print is off in sections (using the "take a snapshot" option in adobe). In total there would be 123 pieces.

The first piece is the north pole.



As you can see "a piece" is printed on to a sheet of A4 and then cut out. I used 250 gsm paper. Other than the two poles, "a piece" was two "segments" as drawn on the globe (going around the latitude rings, if you get what I mean)

Here is the first piece of the ring joining onto the north pole (which show what I mean)



I started joining the segments using "joiners" as shown



And here is that ring finished



With the previous moon globe it was strong enough to support itself, however if you were to press on it it would "dent" and stay dented. So to get round this problem for the moon globe I inserted and inflatable beech ball inside the globe and pumped it up to a pressure to repel any denting. Of course the beech ball puts some pressure on the joints of the globe (and not necessarily evenly distributed. To strengthen the inside of the moon globe I first covered all the inside with sellotape and then on top of that covered all the inside with duck tape. I decided to use the same system for the Mars globe.

So here is the tapes I use



When adding the sellotape you have to leave some gap for the next ring to join and you also need to leave a gap from the edge of the sellotape to the duct tape (so you can add the next ring of sellotape). So there is a lag between the ring, the sellotape and the duct tape (pictures will make it clear I hope). So here is the sellotape covering the north pole and join of first ring



Next up is the second ring. However by now I have realised that the globe looks just as good without using separate joining tabs and is easier doing it this way. So here is second ring done, then sellotape and then the first of the duck tape can be added



A useful thing I found was to draw a pencil line around the "top" of the current sellotape boundary. This made it easy to see where to overlap the next layer of sellotape too.

Here is the globe up to this point



As you can see it is already getting quite big.

Regards

Kevin

[Butelczynski]

I never did anything like this,I'll see if I can make one page sized model.That site has few moons and Venus models as well but our moon is of much more interest to me.

Looking forward to more of your build.I hope that duct tape won't add too much to weight of completed model.

[Kevin WS]

Interesting.

Clever idea to use the tape for reinforcement.

[mbauer]

Thank you for the link. Downloaded the globe!

Your project is looking fantastic. The Moon globe is incredible, great size!

If you can bring the download into a vector program, found that the detail loss isn't as great as when using a bitmap/raster program.

Mike

[gotham]

Link no work for me 😾

[Algebraist]

Originally Posted by mbauer

Thank you for the link. Downloaded the globe!

Your project is looking fantastic. The Moon globe is incredible, great size!

If you can bring the download into a vector program, found that the detail loss isn't as great as when using a bitmap/raster program.

Mike

Hi Mike

thanks for your comments. for a non techie like me how can I tell if something is in "vector" and can I convert things into vector if they are not?

Thanks

Kevin

[Algebraist]

Originally Posted by Butelczynski

I never did anything like this,I'll see if I can make one page sized model.That site has few moons and Venus models as well but our moon is of much more interest to me.

Looking forward to more of your build.I hope that duct tape won't add too much to weight of completed model.

Glad you are finding it interesting Butelczynski. Actually (based on the evidence of one previous large globe, namely the moon!) the tape layers make no difference in terms of weight. If it hods up without the tape then it will hold up with the tape. if anything the tape slightly helps with this aspect. However the most benefit for the two layers of different type of tape is the following:

The sellotape layer is not very stretchy at all, so (provided firmly joined to the paper) really increases the bond strength of the glued joints. The duct tape layer rally helps with the "denting problem" and is slightly more pliable. in particular, when the beech ball is inflated inside it "spreads out" the force of the ball by sort of acting as a go-between the ball and the sellotape layer.

All in all it worked well on the moon globe. So well, in fact I ,could "bounce it" off the floor!

Regards

Kevin

[Algebraist]

Originally Posted by gotham

Link no work for me 😾

Hi gotham

Try googling "mars globe usgs" which should bring up as a early hit a link entitled "Maps and Globes USGS Astrogelogy Science center". This should be a link to https://astrogeology.usgs.gov/maps/p...aps-and-globes

If that does not work try the sites home page which is

https://www.usgs.gov/

Put "globes" in the sites search box and it should take you to this page

https://www.usgs.gov/science-explorer-results?es=globes

The click on the "maps" tab (there is only one listing, which is this

https://www.usgs.gov/science-explore...sification=map

It has only one link listed called "Maps and Globes and if you click on it you get this page

https://astrogeology.usgs.gov/maps/p...aps-and-globes

Which has a number of globes including "Mars Viking Globe". Click on this link will take you to

https://astrogeology.usgs.gov/search...s_viking_globe

From here you can download the globe (select the "original pdf 3Mb download version to get the globe in the thread)

Hope that helps

Regards

Kevin

[Algebraist]

Originally Posted by Kevin WS

Interesting.

Clever idea to use the tape for reinforcement.

Thanks Kevin. Actually I found that the structural challenges of large globes interesting and the tape idea was motivated by cheapness and something that did not require very high precision cutting of internal parts.

I really recommend Ken west's moon (hopefully) when it returns to ecards.

Regards

Kevin

[Butelczynski]

I found this Making globes of the planets

It might be of interest to someone.