FR-1 was the second French satellite. Planned as the first French satellite, it was launched on 6 December 1965—ten days after the actual first French satellite, Astérix—by an American Scout X-4 rocket from the Western Range at Vandenberg Air Force Base. The scientific satellite studied the composition and structure of the ionosphere, plasmasphere, and magnetosphere by measuring the propagation of very low frequency (VLF) waves and the electron density of plasma in those portions of the Earth's atmosphere. FR-1's VLF receiver operated until 26 August 1968. FR-1 remains in orbit as of 2023.
Background
FR-1 was the first step of an ambitious French plan to launch six FR-series satellites, each meant to study a different aspect of the Earth's atmosphere. FR-1 was generally designed to study the Earth's magnetic and electric fields in the ionosphere and magnetosphere. The satellite Astérix—ultimately France's first satellite, launched ten days before FR-1—was initially conceptualized as the second FR satellite under the name FR-2. Like FR-1, FR-2 would study the ionosphere. FR-3 was to be a "scaled-up" version of FR-2, with FR-4 to carry instruments measuring hydrogen distribution in the upper atmosphere, FR-5 to study "magnetic impulses" and serve as a platform for future research, and FR-6 to be a solar-stabilized spacecraft with final payload to be determined based on experimental results from its antecedents.
The French space agencies Centre national d'études spatiales (CNES) and Centre national d'études des télécommunications (CNET) were developing FR-1 concurrent with Astérix as early as 1963. That year, a model of FR-1 was displayed at the 25th Paris Air Show. Payload tests launched from NASA's Wallops Flight Facility (WFF) were planned for autumn 1963. Initial plans called for a late 1964 or early 1965 launch of FR-1 at the Pacific Missile Range, today's Western Range, with Astérix'''s launch scheduled for early 1965. Astérix was orbited prior to FR-1 because Charles de Gaulle and CNES wanted France to become the third space power by launching an independently-developed satellite on a French launcher, a propaganda coup for French exceptionalism during the Cold War.
Spacecraft design
FR-1 was a joint American-French project. CNES and CNET collaborated with the Goddard Space Flight Center (GSFC) on and received funding from NASA's Office of Space Science and Applications for the satellite's design, development, and construction. Xavier Namy of CNES and Samuel R. Stevens of GSFC served as project managers. Dr. Llewelyn Robert Owen Storey of CNET (later NASA) was the primary designer of the satellite's scientific instruments, working in concert with Dr. Robert W. Rochelle of GSFC. French scientists C. Fayard of CNET and Jean-Pierre Causse also worked on the project. French aerospace contractor Nord Aviation helped build the satellite.
The design, construction, and launch of FR-1 and Astérix went relatively quickly thanks to three related factors: postwar knowledge gained from Nazi scientists and their work on the V-2 rocket, France's independent development of nuclear IRBM launchers including the Saphir and Diamant rockets, and France's collaborative civilian research with the United States (through NASA) and other European countries (through CERN and ESRO).
FR-1 consists of two truncated octagonal pyramids, joined at their bases by an octagonal prism measuring across from corner to corner and about high. Solar cells cover the satellite's exterior. A probe for measuring local electron density extends downward from the base of this octagonal structure. A high magnetic field antenna and its supporting tube extend upward from the top of the structure. Four telemetry antennas extend diagonally upward and out from the base of this supporting tube. Four long electric field antenna booms extend outward from the base of the octagonal prism. During its operational lifespan, the spacecraft was spin-stabilized, with altitude and spin determination made from sun sensor and three-axis fluxgate magnetometer observations. Depending on the source, the satellite's launch mass is cited as , , or .
The mission objective was to study the composition and structure of the ionosphere, plasmasphere, and magnetosphere by measuring the propagation of very low frequency (VLF) waves and the local electron density of plasma in those atmospheric layers. For the VLF wave experiments, stations located on land in Seine-Port, France (at the Sainte-Assise transmitter), and Balboa, Panama, transmitted signals at 16.8 kHz and 24 kHz, respectively, while the satellite's magnetic and electric sensors orbiting about away analyzed the magnetic field of the received wave.