yes, it is very possible to do this... it is called mounting.... alot of orchids are sold and kept in this fashion....
the tricky part is keeping mounted orchids thriving in a terrarium.... they need humidity, but, 90 percent or better humidity like in most terrariums, usually is not good.... also, they do need a bit of air movement which is hard to get in a terrarium and still keep a balance...
the lighting part can be tough as well.... check out tropiflora or black jungle for
plants more suited for a terrarium environment....
thank you