The disadvantage is that it takes a full survey. Equipment and to assist in the exploration of the very people making the survey of the area is less than the VES. Need a space to explore and survey equipment is expensive.
The downside is that it takes a long time and a lot of surveys and needs help in the exploration of space exploration has made much less than the VES. Require a lot of space to explore and survey equipment is expensive.
The disadvantage is spent long survey equipment a lot and need help in exploring the many survey area was less than a VES. Need space survey and surveying equipment is expensive.