"RIPE Atlas is a global network of probes that measure Internet connectivity and reachability, providing an unprecedented understanding of the state of the Internet in real time." (from RIPE Atlas website)
Anyone can host a probe free of cost. You should simply fill in a request form on RIPE Atlas website and wait them to send to you by mail. RIPE Atlas is however trying to expand the measurement framework to regions and Autonomous Systems that they yet have limited coverage. South America is one of these regions.
I am a RIPE Atlas ambassador for Brazil. Therefore, if you reside in South America, specially in Brazil, and you are interested on hosting a RIPE Atlas probe, fell free to contact me on r.schmidt (at) utwente.nl and I will be glad to walk you through the procedure to get one (or more) Atlas probes. Note that a probe can be hosted anywhere, from home to campus to enterprise networks. It is important though that the probe is placed within a stable connection, so that it is available for measurements (at least most of the time).
More information about RIPE Atlas on RIPE Atlas.