and information systems directorate. The standards being adopted as a basis for the IPN are the result of work done by both the IETF and the Consultative Committee for Space Data Systems (CCSDS; www.ccsds.org). The protocols that underlie the IPN will need to share many of the capabilities that the earth's Internet has required (which are embodied in TCP/ IP). The IPN will work somewhat like e-mail, where information can be stored and forwarded to any hub on the system. This delay-tolerant network will provide an always-on connection between planets, spacecraft, and the terrestrial Internet. The IPN's store-and-forward approach will help minimize problems that arise due What's Next on the Internet the vast distances involved, such as high error rates and latency rates that are min- utes or even hours long (versus the fractions of a second we experience on the earth-based Internet). In early 2004, a pioneering demonstration of communications between the U.S. National Aeronautics and Space Administration (NASA; www.nasa.gov) Mars Exploration Rover Spirit and the European Space Agency (ESA; www.esa.int) Mars Express orbiter succeeded. On February 6, 2004, while Mars Express was flying over the area Spirit was examining, the orbiter transferred commands from earth to the rover and relayed data from the robotic explorer back to earth. This was the first time we had had an in-orbit communication between ESA and NASA space- craft, and it was also the first working international communications network around another planet, both of which are significant achievements. As of 2005, NASA had cancelled plans to launch the Mars Telecommunications Orbiter in September 2009; that orbiter had had the goal of supporting future mis- sions to Mars and would have functioned as a possible first definitive Internet hub around another planetary body. Still, while earth-bound Internet and mobile phone users won't be surfing the IPN any time in the near future, the research that goes into the IPN is very likely to spark exciting innovatio