Description: NASA is interested in electromagnetic sounding of ionospheric and magnetospheric plasma density structure at radio frequencies from kilohertz to MHz region. The majority of such soundings rely on passive sensing, i.e., they use either naturally occurring radiation or using transmitters of opportunity such as global navigation satellite system or ground-based transmitters used by world’s navies to transmit commands to submarines. Active sensing using the injection of ELF/VLF (300Hz -30kHz) frequency band electromagnetic waves into the Earth’s magnetosphere have played an important role in discovering and elucidating wave-particle interactions in near-Earth space. Efficient generation of low frequency waves, however, requires physically large antennas which essentially precludes their deployment in space. CRG is working to develop a completely novel type of transmitter for active sensing in the ionosphere and magnetosphere based on the induced transitions between highly excited Rydberg-atom energy levels. The advantage of such a transmitter is based on the fact that an atom makes an efficient electrically small radiator. Dr. Latypov of CRG first proposed it as a solution to the long-standing problem of submerged submarine communication with the air/space platforms (Latypov, 2022). Now, CRG considers its potential applications in space. The scope of this project is to evaluate the Rydberg atom-based technologies for potential NASA applications. The environment in space is significantly different from the environment on Earth’s surface and can vary depending on the location and other factors. Therefore, performance of the transmitter in space may significantly differ from its performance on the ground. CRG therefore will also review how the space conditions affect the performance of conventional antennas and investigate their possible impact on the Rydberg atom-based low frequency radiator.

Benefits: Low frequency transmitter for space applications Geophysical surveying using low frequency electromagnetic waves Underwater surveying using low frequency electromagnetic waves

• Submerged submarine communications • Near field LF communication for Internet of Things • VLF for space platforms to probe ionosphere and magnetosphere • VLF injection for controlled precipitation of radiation belt electrons • Beyond line of sight communication • Geophysical surveying using LF electromagnetic waves • Through-the-earth communication for mining applications