ISS.live is a website that provides access to real-time data from the International Space Station in a user-friendly, informative format.
Data from the ISS is transmitted using the Tracking and Data Relay Satellite System (TDRSS). All data passes through NASA's White Sands Tracking Station in New Mexico, then on to the Johnson Space Center in Houston, Texas.
NASA uses a service called Lightstreamer to proxy the data to the public. Lightstreamer receives data from NASA's servers in Houston, and then broadcasts it to the public.
Some sensors change multiple times per second, while others change less frequently. NASA transmits all sensor changes to the public, so the data is updated as often as possible.
As the ISS orbits the Earth, it experiencies signal handovers between TDRSS satellites. During these handovers, the data is lost for a short period of time. This is usually when Flight Controllers in Houston top-up their coffee and take a break.
As the public data stream is not mission-critical, outages of days to a week are not unexpected. During these outages, Mission Control continue to receive data from the ISS as normal, but the public data stream is not updated.