The successful PhoneSat wifi experiment on the Soarex-8 flight

On the 7th July 2015 at 06:15 AM EDT a Terrier/Black Brant sounding rocket left the Earth from the Mid-Atlantic Regional Spaceport on Wallops Island in Virginia. On its 10-minute sojourn across the sky and into the sea it carried the 8th Sub-Orbital Aerodynamic Reentry Experiment (Soarex-8) payload. A description of some of the experimental elements on this payload were presented in last year's paper. The elements described (the exobrake, ZigBee wireless sensor net, and Iridium short message communications) were all successful. Another Soarex-8 experiment is described herein: the successful demonstration of point-to-point IEEE 802.11 (wifi) communications from space. We believe this set a new distance record for wifi as well as being the highest wifi-to-ground link, transmitting from the edge of space. Soarex-8 reached an apogee of 334 km (206 mi). During the flight we sent low frame rate video to a ground station at NASA Wallops Flight Facility from payload ejection until loss-of-signal when Soarex-8 passed over the horizon. The Soarex-8 team did not intend to achieve records in this endeavor. We were attempting to establish a very low cost method to downlink high speed data from small spacecraft. We will repeat this experiment as part of a future small spacecraft launch from the International Space Station in the near future. We will then send low frame rate video from orbit. This paper presents the methodology, process and interfaces of the long haul wifi experiment. We discuss an innovative space camera designed at NASA Ames Research Center (ARC) and the camera/wifi interface. We describe the onboard system, power requirements, hardware specifications, interface to the rest of the Soarex-8 payload and hardware integration. Flight software was written to circumvent the handshaking requirement of wifi links and deal with the image stream from the camera. We describe the ground system including the software and how we were able to use existing antenna at Wallops to track and downlink the wifi signal. Finally we present our plans for future orbital and suborbital flights.