We propose to develop a compact, rugged, and accurate scalar atomic magnetometer suitable for CubeSat missions. The sensor will provide temperature-insensitive measurements of magnetic field magnitude which can be used in conjunction with established fluxgate technology to provide richer information about magnetic fields to further solar and space physics science goals. Potential NASA Applications (Limit 1500 characters, approximately 150 words) Accurate measurements of scalar magnetic fields in space are crucial for the advancement of understanding the sun's outer corona, the solar wind, and the trapped particles in Earth's and other planetary magnetic fields. Magnetic storms are of practical importance because they can cause disruption in our essential communication and navigation systems on Earth. Magnetic field measurements can also contribute to the understanding of the composition of atmospheres and oceans on the planets and their moons. Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words) A compact, rugged and temperature-insensitive scalar atomic magnetometer can find applications outside of NASA in geophysical survey and navigation.