Space-Based Solar Power

a public discussion sponsored by the Space Frontier Foundation

Obtaining Orbital Parking Slots and Frequencies

Posted by Coyote on August 31, 2008

I was asked two interesting questions yesterday by people interested in commercial development of space-based solar power (SBSP):

  1. How would a company obtain a geostationary parking slot for a SBSP satellite?
  2. How would a company obtain a license to broadcast power from space over radio frequencies?

Excellent questions. Here are the answers that I slapped together from the Internet. (Special thanks to Maldivian Digital, and Wikipedia for having some well researched info posted on their sites!) Please check my work and let me know if I’ve embarrassed myself in public (again):

  1. How does a company obtain a geostationary parking slot for a SBSP satellite?
    • Parking slots are allotted internationally, by the International Telecommunications Union (ITU).
    • However, the ITU only allocates orbital slots to countries, and not to private sector companies.
    • Companies must negotiate with countries who hold the rights to orbital slots of interest. They must establish an agreement whereby space-based solar power satellites can thereafter occupy the countries’ allocated orbital slot(s).
    • This is a common and standard practice by companies operating communications satellites in the geostationary belt. Space-based solar power companies will follow these routine and well established procedures to acquire orbital parking slots.
    • When satellites are located close to each other, their up-link and downlink frequencies and polarisations are to be coordinated, so that there is no interference. Sometimes this requires that existing frequencies or polarisations be altered by existing satellites, to accommodate a new entrant.
    • The ITU which allocates the orbital slots (to countries who in turn may grant use of their slots to commercial ventures) requires that all players coordinate their frequencies so that there is no disruption of service. The new entrant is obliged to ensure that their transmissions will not disrupt existing services.
    • Frequency coordination is a technical matter, and not easily resolved, particularly in regions over India, where practically every orbital slot is occupied by one or more satellites.
  2. How would a company obtain a license to broadcast power from space over radio frequencies?
    • Space-based solar power companies most likely will broadcast power from space to Earth using radio frequencies in the industrial, scientific, and medical (ISM) radio bands originally reserved internationally for the use of RF electromagnetic fields for industrial, scientific, and medical purposes other than communications. In general, communications equipment must accept any interference generated by ISM equipment.
    • ISM bands are defined by the ITU-R in 5.138, 5.150, and 5.280 of the Radio Regulations. Individual countries’ use of the bands designated in these sections may differ due to variations in national radio regulations. Because communication devices using the ISM bands must tolerate any interference from ISM equipment, these bands are typically given over to uses intended for unlicensed operation, since unlicensed operation typically needs to be tolerant of interference from other devices anyway. In the United States of America, ISM uses of the ISM bands are governed by Part 18 of the Federal Communications Commission (FCC) rules, while Part 15 Subpart B contains the rules for unlicensed communication devices, even those that use the ISM frequencies. Thus, designers of equipment for use in the United States in the ISM bands should be familiar with the relevant portions of both Part 18 and Part 15 Subpart B of the FCC Rules.
    • Specifically, space-based solar power companies will broadcast energy from space to Earth at 2.45 GHz, or 5.8 GHz
    • In recent years these bands have also been shared with license-free error-tolerant communications applications such as wireless LANs and cordless phones in the 0.915 GHz, 2.45 GHz, and 5.8 GHz bands. Because licensed devices already are required to be tolerant of ISM emissions in these bands, unlicensed low power uses are generally able to operate in these bands without causing problems for licensed uses.
    • SBSP companies must engage with the International Telecommunications Union (ITU) to secure general approval for the use of these frequencies.
    • SBSP companies must also engage with customer countries’ agencies responsible for national radio regulations (eg, the Federal Communications Commission (FCC) in the US) to obtain approval to use either 2.45 GHz or 5.8 GHz for power broadcasts in their country.
    • If these radio frequencies are unavailable, SBSP companies might pursue power beaming using lasers at 1.0 micron or 0.86 micron wavelengths. This removes the need for any frequency approval, as lasers are not regulated as radio frequencies.
    • SBSP companies must also engage with national aviation agencies (eg, the Federal Aviation Administration (FAA) in the US) to establish no-fly zones around radio or laser energy corridors between the satellite and its ground-based receivers, as may be required by national or local laws.

There’s a lot that goes into building space-based solar power systems. Let’s get it out on the table so we can take a look at all that goes into it and think together about how to grease the tracks of progress.




6 Responses to “Obtaining Orbital Parking Slots and Frequencies”

  1. Coyote

    Good job – spot on – preventing harmful interference while enabling the use of frequencies is the key.

    One thought is to look at how the Geostationary Satellite Operators work their filings today – a mixture of US and other Flag carriers via the ITU. Satellite operators (themselves at the heart of an existing $150 billion plus annual industry) could either be great proponents of SBSP or great opponents.

    If it is a US commercial venture then the FCC would be the first port of call. If Governmental, then of course the NTIA in the USA.

    It’s a big world out there and lots of options.

    The Isle of Man (via ManSat) today work satellite filing issues and would be most interested in working SBSP filings.


  2. Not forgetting of course the business base involved in the filings as well – filings aren’t just filings, they also bring added considerations on regulatory, fiscal, and legal consequences for investors, financing of the projects, and profitability of the projects, etc.

    Something else to consider.


  3. Coyote said

    Chris Stott: Very insightful! Contributions like yours make this sight a total learning experience for those who read and participate here. I have a question; what is the NTIA? How should we approch them? Please feel free to add to any and all other postings, threads, and comments. You have a great deal to add! (when will you be in London next?)



  4. hartzell said

    It seems to me that the ISM bands should be reserved for communications, and do have some power restrictions.

    A commercial SBSP venture should be required to license spectrum, as they will be possibly profiting from activity.

  5. J. Armes said

    Focusing on ISM bands is not the way to go here. A lead application through the FCC (Federal Communications Commission) and NTIA (National Telecommunications & Information Administration) requesting a (very nominal) spectrum allocation will ultimately result in a dedicated allocation for operation of power satellites in the Americas. By this means, interference with other communications networks can be avoided, and the entire geostationary arc opened up for satellites that only operate on power satellite frequencies.

  6. The 2.45 and 5.8Ghz frequency areas are really the only good places for WPT to occur (if one is transmitting microwaves that is) Atmospheric absorption gets too high outside of these windows. Naturally, that same atmospheric transparency draws terrestrial users. The difference is one of power level. If you shift WiFi up to 3 Ghz or so, power can be increased with literally no environmental impact to compensate for the increased absorption. (Battery life would suffer somewhat) On the other hand, shifting the powersat WPT frequency to 3Ghz substantially impacts the power delivered, and the amount of energy absorbed by the atmosphere. In my technical estimation, WPT should have priority in the high-transparency windows. Communications users can incrementally increase power with little impact. WPT cannot.

    William Maness

    Full Disclosure…
    WilliamManess (at) PowerSat (dot) com

    PS. Col. Smith, drop me a line at the above email address if you would. I can’t seem to find your direct line. 🙂

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