Question
I have had a moon cactus for about 5 years and last night it was knocked over by a racoon. It was broken off directly at the connecting point between the upper and bottom parts. The bottom is the same as the ones in the picture at http://www.cactuscollection.com/faqs/index.html . The top is about 2 inches wide and 9 inches tall with one large arm. It is covered in a thick layer of short and semi soft white spines. The skin of it is a dark green color.
Now is it possible to reconnect the two parts back into one? Or is it possible for the upper part to be potted and grown by itself? Also, if it can be re-attached how long do they survive? It was thriving before it was broken.

Answer
Matt,

I apologize for the delay in answering you, I have been having computer issues. Please see my answers below:

Now is it possible to reconnect the two parts back into one? Yes, but it's not easy. However, here are some detailed instructions: http://www.teessidecacti.org/BCSS/CULTIVAT/grafting.htm

Or is it possible for the upper part to be potted and grown by itself? No. The reason is that the top part is irradiated to get rid of all of it's chlorophyll and plants can not survive with it.
Also, if it can be re-attached how long do they survive? Generally speaking, not very long. The scion (top part) has a limited life span because of the lack of chlorophyll. Even ones that don't get damaged only live for a couple of years.

Hope this helps,

Sincerely,

Greg