In HughesNet’s terms:
Every remote [computer] uses the HughesNet turbo page servers, which only use HughesNet DNS.
The “turbo page servers” are the proxy which HughesNet uses to limit the latency imposed by satellite connnections.
There is one workaround, but it doesn’t sound like an improvement, and no one (not Hughes, not me) recommends it. Still…for curious technical folks, you may choose to not use the HughesNet turbo page servers. If you do that, then you may use an alternate DNS provider, including OpenDNS. However, given the latency of satellite broadband, I can’t imagine that faster DNS will counteract slower download speeds, as much as I might hope it would.
I don’t have official answers/confirmation from other satellite ISPs, but I expect the story is similar.