This is a short term effort to conduct initial orchestrated coherent scatter and scintillations experiments utilizing the RAX II spacecraft together with ground based incoherent scatter radar and heating facilities. The Radio Aurora Explorer (RAX) satellite was the first NSF Cubesat mission to be selected and flown. It was launched in November 2010 and successfully executed two radar experiments in coordination with NSF's Poker Flat Incoherent Scatter Radar (PFISR). Shortly after, the solar power system degraded, and the mission prematurely terminated. The recent NASA launch of the backup flight spacecraft (RAX II) in October 2011 offers the opportunity to continue the RAX mission. The additional experiments that this opportunity enables are the subject of this RAPID project
The RAX mission is a ground-to-space bi-static radar remote sensing experiment designed to measure meter-scale ionospheric turbulence that occurs during strong auroral disturbances. Five globally distributed UHF Incoherent Scatter Radar facilities will be used to illuminate natural/artificial ionospheric field-aligned irregularities (FAI). The RAX UHF radar receiver measures coherent backscatter at multiple points along the satellite track, from which on can quantify the plasma wave energy distribution parallel to the geomagnetic field lines. RAX II experiments will be conducted for both naturally occurring and artificially generated ionospheric irregularities in mid to high latitudes. RAX I was planned to address natural ionospheric irregularities; with RAX II, the experimental scope is expanded to address new HF heater generated effects. The goals are to capture (1) coherent scatter from natural and artificial ionospheric irregularities, and (2) the amplitude and phase distortions of UHF signals passing through naturally and artificially generated irregularities. Ionospheric irregularity backscatter experiments will be coordinated with megawatt-class narrow-beam UHF incoherent scatter radars to provide high spatial and temporal resolution mapping of ionospheric irregularities (between the altitudes of 80-400 km) for a wide range of conditions for the ionospheric electric field, currents, and plasma density gradients. In addition to studying the properties of naturally occurring plasma turbulence, we will run experiments to measure artificial ionospheric irregularities generated by high-power HF heating of the ionospheric E and F regions. Currently, two heater facilities are available for this purpose: HAARP and SPEAR. The Modular UHF Incoherent Scatter Radar (MUIR) and the EISCAT Svalbard Radar (ESR), respectively, will be the ISRs operating in conjunction with RAX II for diagnostics of the artificially generated plasma turbulence. Ionospheric scintillation of UHF signals will be measured using the raw data acquisition mode of the RAX UHF payload receiver.
Better understanding of ionospheric irregularities and their role in ionospheric dynamics is an important space weather research objective because plasma structures in the ionosphere can have an adverse effect on communications via satellite, HF and VHF radio and as well as an adverse effect on navigation, tracking, and positioning. The project will promote education and learning in that graduate undergraduate students from University of Michigan will perform the majority of the satellite operations and data handling.
This grant provided funding to perform novel space weather measurements with the RAX-2 satellite, the second satellite from the Radio Aurora Explorer mission. RAX-2 was successfully launched by the NASA CubeSat Launch Initiative in October 2011. It was built by students at the University of Michigan in the Michigan Exploration Laboratory (MXL) and contained a payload developed by SRI International. The primary mission of RAX-2 was to perform measurements ionospheric disturbances caused by space weather. These disturbances are known to impact space-based communication and navigation capabilities. RAX-2 used a novel bistatic radar system that included a radar receiver onboard the satellite and radar transmitters on the ground. Transmitters in Alaska and Canada were used to probe the ionosphere. Similar to terrestrial weather maps made by Doppler radar, the RAX-2 radar system was able to remotely monitor ionospheric disturbances. Initial results have provided fundamentally new insight into basic space weather processes. RAX-2 has provided unprecedented clarity and insight, thereby helping scientists to better understand space weather. Additionally, over fifty engineering students participated in the RAX project and gained valuable hands on training while making fundamental contributions to the mission. Over seven peer-reviewed journals have been published along with over twenty conference proceedings. RAX-2 has helped pave the way for additional NSF-sponsored CubeSats to explore space weather.
