The P-code is reserved for military use, while the C/A is open to the public. Instead of placing many magnetic satellites close to Mars to artificially generate a magnetic field to protect Martian colonists from harming radiation, we could place a magnetic satellite at Lagrangian point L1. Called Lagrange point 1, or simply L1, this halo like orbit is a neutral gravity point, requiring fewer orbital corrections, allowing DSCOVR to use less fuel and remain in its operational location for much longer. The L1 signal is the oldest GPS signal.
The magnetic field does not need to be as strong to deflect the solar wind enough, since the deflection takes place over millions of km before reaching the planet. At L1, the gravitational forces between the sun and Earth balance the centrifugal forces of a satellite to provide a quasi-stable orbit point requiring fewer orbital corrections (and therefore reducing fuel consumption) for the spacecraft to remain in its operational location for a longer period of time. DSCOVR, NOAA’s first deep space satellite, occupies a special orbit. It has two parts: the Coarse/Acquisition Code (C/A) and the Precision Code (P-code). The ESA/NASA solar watchdog spacecraft, the Solar and Heliospheric Observatory (SOHO), remains at the L1 point, orbiting the Sun at the same rate as the Earth. From this position, SOHO constantly monitors the Sun and, as well as conducting scientific studies, SOHO is also an early warning spacecraft. The L1 signal uses the frequency 1575.42 MHz.