Spacenet rhymes with:
sassnet, allnet, arpanet, avnet, bayonet, bissonnette, cellnet, dragnet, driftnet, ethernet, filenet, imnet, instinet, internet, investnet, massenet, raynet, robinette, rudnet, sassnet, selectnet, seniornet, telenet, tymnet, usenet
Spacenet sounds like:
subcommittee, subsequent, sufficient