When people are first exposed to the potential and possibilities of SBSP, one of the first questions they have is that of Safety. To discuss this, Space Energy asked one of the most qualified and respected experts in the world, Dr. James Logan.Here was his response:
We have over 60 years history of using microwaves in terrestrial environments (radar, telecommunications industry, etc.). It is certainly not 'new', and decades of scientific studies exist verifying the safety of microwaves. Microwaves are part of the electromagnetic spectrum and are considered RF (radio frequency). Microwaves are being constantly broadcast from numerous satellites, terrestrial towers and radar systems. At any given point in a typical city, there are literally thousands of RF signals (microwaves, FM, AM, etc.) passing through people 24hrs a day. The most common forms are: cell phone conversations, air traffic control, police and taxi radios, hundreds of TV & radio channels and dozens of wireless internet signals. Subject to the right receiver, virtually all of these can be accessed and decoded (and are therefore present) by a person just standing in their home.
Microwaves lie just beneath the visual and infrared spectrum and just above broadcast radio waves. Unlike energies further up the frequency spectrum, microwaves are non-ionizing. This means, unlike x-rays or gamma rays, microwaves do not possess energies required to break chemical bonds. International safety standards for permissible exposure limits (with weighted averages) have long been established. These are governed and published by 'OSHA' (Occupational Safety & Health Administration). Obviously, if areas within the receiving antenna exceed the OSHA limits, then personnel entering that area would need to wear protective clothing such as a reflective material. It would be exactly the same as an area where noise exceeding set limits would require people to wear ear defenders.
When Mitsubishi proposed their plan for Space Based Solar Power in 2004 (operation solar bird), they conducted their own microwave safety tests. The results of their studies remain proprietary although they were happy to recommend to the government that they broadcast their power directly over a city. Plans for uninhabited receiving sites [such as those proposed by Space Energy] give even further comfort to safety concerns. With regards to 'drifting', there would be an automatic cut-off facility (based on the ground) that would prevent the satellite from operating if the signal were to 'drift' away from it's receiving site. In addition, the beam would be 'defocused' if the space transmission hardware lost lock on the rectenna.
Dr. Logan is an eighteen-year veteran of NASA. He has avidly studied Space Based Solar Power for almost two decades and is a subject matter expert in the medical/biological aspects of wireless power transmission. His area of expertise is human space operations, space physiology and space medicine. His previous positions held at NASA include: Chief of Flight Medicine, Chief of Medical Operations, Chief of Human Test Support, and Chief of Medical Informatics and Health Care Systems. Mission Control certified, Dr. Logan was Crew Surgeon, Deputy Crew Surgeon and Mission Control Surgeon for 25 space shuttle missions. He served on the original Space Station Skunk Works at Johnson Space Center, as well as the first Space Station Operations Task Force at NASA Headquarters.
For a comprehensive white paper on SBSP safety click here