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Chang'e 4 farside landing mission
Phil Stooke
post Jun 6 2017, 04:15 PM
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Chang'E 4 landing site:



https://www.chinaspaceflight.com/satellite/.../CE-4/CE-4.html


Landing area - 45.5 degrees south latitude, 178 degrees east longitude

This is on the flat floor of the large crater Von Karman, with a bit of ejecta from the relatively young crater Finsen. Until now most indications had been for a landing near the Apollo basin at about 42 south, 157 west (203 east).


Phil


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Phil Stooke
post Jun 11 2017, 08:24 PM
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Here's a couple of maps showing the CE4 area.

Phil

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antipode
post Jun 12 2017, 04:37 AM
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Phil

I take it Von Karman's walls are sufficiently lofty to be visible in any surface imagery taken from inside that box?

p
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Explorer1
post Jun 12 2017, 05:35 AM
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I wouldn't be so sure; the horizon is really close in the Chang'E 3 surface images. We shouldn't expect huge vistas anymore than we get them on Mars; cool terrain is by definition hazardous!
I would welcome being pleasant surprised to see anything more than a few km away, of course.
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Phil Stooke
post Jun 12 2017, 05:16 PM
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Short answer - I think some relief will be visible. Von Karman is about 3500 m deep and some distant topography should show up.

I will post something on the Chang'E 3 thread about distant topography. There are distant hills to the north and west at distances of 10 to 15 km, protruding above closer topography. To the east the horizon is about 4 km from the lander.

Phil

EDIT: OK, I posted in the other thread. That was a very flat site, but local high spots can be seen about 10 km away. I would expect that either the central peak of Von Karman or the SE wall of the crater should be visible from the lander, and possibly both will be, as well as small crater rims closer to the landing site. Not high mountains like Taurus-Littrow, but distant features should be visible, appearing as low hills.


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Phil Stooke
post Jul 6 2017, 06:01 PM
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More information on site selection for CE4. This image:

https://www.chinaspaceflight.com/usr/upload...53834140857.jpg

from this site:

https://www.chinaspaceflight.com/satellite/.../CE-4/CE-4.html

shows a number of sites at about 45 degrees north or south. I am preparing something on this topic, so I will post a map later. Some sites are in mare-type areas of the SPA basin or the large craters in that area, but the northern sites are all in or between large craters in the highlands (Mare Moscoviense is not one of these areas).

This is from a presentation at the German Aerospace Centre DLR, where China and Germany have just agreed to cooperate on the mission, Germany joining several other countries.

Phil


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Phil Stooke
post Jul 7 2017, 12:22 AM
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Here is a map of those sites from the slide linked to above.

Phil

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JRehling
post Jul 7 2017, 01:32 AM
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Probably everyone knows this, but on the Moon, the horizon is inherently closer than from a similar vantage point on Earth or Mars. Though the bowl of a crater may make the global curvature locally moot.
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Phil Stooke
post Jul 7 2017, 06:00 PM
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That's true, of course, but the distance to the ideal horizon is not as important as the height and distance of significant relief features. Von Karman is about 160 km across and up to 4 km deep (wall height varies quite a bit). A good comparison might be with Flamsteed P, the flooded crater which Surveyor 1 landed in. It is 80 km across, but mostly filled with lava and with hills 1500 m high protruding above the plains. Hills 20 km away were visible in the Surveyor 1 panorama. Scaling up, I am confident there will be some relief on the CE4 horizon. Maybe if the landing is in exactly the worst place for viewing relief there would not be much, but from many areas some features will be visible.

Phil


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