The International Telecommunications Union: Orbital Parking Enforcement
Earlier this month, on a picturesque summer evening, SpaceX successfully launched Intelsat 35e communications satellite to geostationary orbit. To date, this satellite represents the heaviest orbital payload that SpaceX has ever launched. In fact, the fuel requirements were so great that the Falcon 9's first stage used for this launch was unrecoverable since not enough fuel remained to safely guide it back down.
Reading up on this launch, I became curious about the rules, procedures, and policies surrounding and governing satellite launches into geostationary orbit. Below is what I have uncovered.
Background: Geostationary Orbit & Slots for Satellites
Geostationary Orbit, or the Geosynchronous Equatorial Orbit ("GEO"), is about 22,200 miles or 35,800 km above the earth's equator, and is a special type of a Geosynchronous Orbit. What makes this orbit unique is that an object in GEO will appear to stay in a fixed position relative to a spot on earth. This is because an object in GEO has an orbital velocity of 1.91 mi/s or 3.07 km/s with an orbital period (how long it takes an object to orbit around another object) around Earth of 23.93 hours, which is very closely equal to the Earth's rotational period (how long it takes Earth to complete one spin around its axis). So, the Earth and the object appears stationary to each other similar to how a driver and a passenger looks to each other in the same fast-moving car.
Due to this "stationary" nature, many satellites are launched to GEO because the satellite antennas on the ground do not need to rotate and track these satellites once they arrive at a "locked-in" position in the GEO. These satellites, fixed in on a position above the earth, are also perfect candidates to track changes in specific points on earth (e.g. the Geostationary Ocean Color Imager). The idea of launching satellites into and using the GEO for telecommunications purposes was popularized by Sir Arthur Clarke, and hence, GEO is also recognized as the Clarke Orbit.
With a circumference of about 165,000 miles or 265,000 kilometers, the GEO is not limitless. While some maintenance and orbital station-keeping is necessary to keep an object, such as a satellite, in GEO from the effects of solar wind, radiation pressure, longitude drift, and etc., the lifetime of a satellite in GEO tends to be long. But, with only a limited amount of space in the GEO ring and spacing requirements needed to prevent interference of satellites on one another's working frequencies, there are only a certain number of "parking spots" available for satellites. So, an entity can't just willy nilly launch a satellite into GEO without some form of cooperation and collaboration among the other entities who also have satellites in GEO.
This is where the International Telecommunications Union ("ITU"), or what I like to call Orbital Parking Enforcement, comes into play. The ITU is an agency of the United Nations that is responsible for assigning and allocating "parking spots" or orbital slots on the GEO for satellites. Headquartered in Geneva, it's also the primary agency responsible for resolving any disputes related to frequency interference among different global entities. The rules and regulations governing these GEO orbital slots are laid out in its Radio Regulations. Below, I have summarized and simplified the most pertinent sections dealing directly with the rules of parking on the GEO.
Radio Regulations: GEO Satellite Parking Spots
The Radio Regulations ("RR"), as promulgated by the ITU, serves as a set of international regulations governing the use of radio communication and frequencies. In that vein, RR is also used to govern access and allocation of satellites in the GEO. Since ITU is an international organization, it's responsible to many different stakeholders, some that have more advanced space-faring technologies than what others have. Due to this diversity in ITU's membership, the RR's policies regarding allocation and assignment of satellites reflects ITU's attempt to create a balance between equitable access and efficient use of telecommunications services in geostationary orbit. Most of the frequencies used by and the allocation of telecommunication satellites in GEO operates on a "first come first served" basis; this is essentially a posteriori plan in which various national entities would apply for/confirm their satellites' positioning in the GEO with the ITU. But, a small number of frequencies are reserved by ITU under a priori plan, in which certain national entities are allocated certain parking spots for their satellites in the GEO even if they have no immediate plans of launch. These allocation plans, FSS Plan and BSS and the associated feeder-link Plans, are described in detail in Appendices 30, 30A, and 30B to the RR.
For entities that are requesting orbital slots on the GEO, they (or the national administrations representing them) will need to follow the procedures that ITU has laid out in Articles 9 and 11 of the Radio Regulations. From my own analysis of these Articles, below are, at a high level but including the applicable time periods, the relevant procedures:
Step One (Article 9): Determination of whether the proposed satellite(s) and operational frequencies will affect other satellites' operations. The applicant administration will determine the existence of any harmful interference of its proposed satellite system/network via criteria that are listed in Appendix 5 to the RR.
If no harmful interference exists: No coordination is needed (defined below).
Between 2 to 7 years of the proposed satellite system's launch, the applicant administration would submit to the ITU certain information regarding the proposed satellite network/system as required by Appendix 4 to the RR (e.g., identification of the satellite network, date of bringing into use, nominal geographical longitude, hours of operation, satellite antenna beam, and etc.).
The ITU will examine the application for completeness, and upon payment of appropriate fees and within 3 months of the date of receipt, ITU will publish certain information related to the proposed satellite system in a special section of the International Frequency Information Circular ("BR IFC").
Any other country's administration in charge of satellite operations has 4 months from the date of publication to object to any unacceptable interference that might result from the proposed satellite launch. These objections will be communicated to the applicant administration and the ITU.
All parties involved will work together to resolve these difficulties. If need be, ITU will provide assistance during this process.
If there is a potential for harmful interference: Coordination is required. Coordination is the "process of seeking an agreement of other administrations." RR at A.9.II.2. During this process, the applicant administration will need to adequately address/resolve the interference that the proposed satellite system will have on the operations of the other satellites.
The applicant administration will notify and send ITU and those affected administrations certain information (e.g., information listed in Appendix 4, projected transmission, reception diagrams, and etc.) related to the proposed satellite system. If requested, ITU can help facilitate this process.
The ITU will examine this coordination notice for completeness, and upon payment of appropriate fees and within 4 months of the date of receipt, ITU will publish certain notice information, including information on coordination requests, in the BR IFC.
Any other country's administration that believes it should have been or should not have been included in the coordination request has 4 months from the date of publication to notify the ITU. The ITU will study the notification and include or exclude the administration as needed and publish a special section including a list of administrations and satellite networks for which coordination is needed.
The administration receiving the request for coordination is responsible for the following:
Acknowledgment: the affected administration must acknowledge the request within 30 days. If the requesting administration does not hear back within this time frame, it will send a telegram requesting acknowledgment, and if there is still no response 15 days after the transmission of the telegram, ITU will get involved in the notification process and notify the affected administration as well. If there is no response to ITU's request within 30 days, ITU will send another request, and if there is no response within 15 days of this final request, then a failure to acknowledge event will have occurred. The affected administration will be deemed to have (1) made no complaints regarding any harmful interference affecting its own assignments from the proposed satellite system and (2) acknowledged that the use of its own assignments will not cause any harmful interference to the proposed satellite system. So it's highly in the interest of the affected administration to respond.
Evaluation: The affected administration will examine the information received and respond within 4 months of either, as applicable, the date of the publication of the original BR IFIC notice or the subsequent coordination notice on the proposed satellite system. The affected administration can (1) inform its disagreement to the solution proposed and propose its own suggestions, (2) inform that it has existing or planned terrestrial stations that might be affected by the planned satellite system, or (3) agree to the proposed coordination. If the affected administration fails to respond within 4 months, then ITU will request a decision, and if the affected administration does not respond within 30 days of this request, ITU will send out a final request. If there is still a failure to respond with an evaluation after 15 days of this final request, then the affected administration will have deemed to give up its rights and the above abandonment results will occur.
Continued Disagreement: If there is continued disagreement among the different administrations involved, the applicant administration will delay its proposed satellite system submission for 6 months to resolve these differences. If after 6 months, there is still disagreement, the ITU will examine the issue and resolve it on ITU's authority.
Step Two (Article 11): Examination and Recordation of Frequency Assignment
Along with information regarding the planned satellite system/network, the applicant administration will also send the ITU a notice regarding the frequencies that will be assigned to such satellite system/network. For GEO satellites, these notices, containing the characteristics as listed in Appendix 4, must reach the ITU no earlier than 3 years before the assignments are "brought to use." (explained below).
Once ITU receives such a completed frequency notice, it will publish in the BR IFIC within 2 months of the date of receipt, this assignment notice which will include contents from the notice, diagrams, and maps.
The ITU will examine and analyze the frequency assignment notice/application (e.g., conducting its determination of probability of harmful interference, analysis of the coordination information, and etc.) and render its decision on the notice:
If ITU finds everything is in working order, the assignment is recorded in the Master International Frequency Register ("Master Register) with an indication that such assignment notice has a favorable finding.
If ITU does not find everything to be in working order, it will either (1) return the notice with an indication of appropriate actions or (2) if the proposed frequency is technically sound but would impact or is a part of an Allotment Plan (e.g., FSS Plan above) that is not assigned to applicant administration, ITU will record such assignment in the Master Register but with an indication that this frequency should not cause harmful interference with a frequency that is part of an Allotment Plan or otherwise in the Master Register with a favorable finding.
Step Three: Bringing into Use
Now that the applicant administration has its frequency and satellite approved and recorded, it must comply with a "bring to use" requirement. Essentially, once the applicant administration gets its orbital slot, in order to keep it, the administration must be using it or risk the possibility that ITU will assign it to someone else.
The Radio Regulations govern this via the "bringing into use" rule in Article 11. For satellites, the "notified date of bringing into use" must be within 7 years of the date of ITU's receipt of the applicant administration's frequency notice in Step Two above.
For a satellite system, it "shall be considered as having been brought into use when a space station in the geostationary-satellite orbit with the capability of transmitting or receiving that frequency assignment has been deployed and maintained at the notified orbital position for a continuous period of 90 days." RR at A.11.44.B. And the "notified date of bringing into use" will be the commencement date of such 90-day period. The ITU will also make the "notified date of bringing into use" publicly available once the applicant administration notifies the ITU within the last 30 days of this 90-day period.
So, if the applicant administration has not launched its satellite into orbit before its notice to the ITU, it has 7 years from the date its frequency notice was received by the ITU to ensure that its satellite is launched into GEO and operates for 90 continuous days.
But, if the ITU receives the applicant administration's notice more than 120 days after the applicant administration had already launched its satellite into GEO, then the satellite would be considered "brought into use" if the applicant administration confirms that the satellite has been deployed and maintained for a continuous period of time from the "notified date of bringing into use" to the date of receipt of the notice information by the ITU.
One of my takeaways from this rule is that, while it's not polite, the rule does not forbid an applicant administration from parking/launching its satellite in GEO before the administration even start the application process for the "proposed" satellite. But I guess satellite launches tend to be expensive, and any interference caused to other satellites will likely to have a harmful impact on the applicant administration's satellite, so random unplanned satellite launches into GEO probably rarely occurs due to self-policing and practical reasons.
If the applicant administration does not bring a satellite into use within this 7-year period, the ITU will notify the applicant administration at least six months prior to the expiration of this period but will then cancel the registration. So, if the applicant administration snoozes and never uses the parking spot it worked so hard in getting assigned, then it will lose the parking spot. And if you don't think this should be a concern, just look at this story about "Tonga Maneuvers to Save Slot."
Future Challenges to These Rules
And there you have, these are the rules and regulations governing the assignment of satellite "parking spots" in the GEO; at least according to my understanding. But, these rules and regulations are not without future challenges. For instance, some critics believe 7 years is too long of a time period for an entity to reserve an orbital slot in the GEO without actually having a satellite to "bring into use" that frequency assignment. Another concern, which mainly impacts satellites in non-GEO orbits, is that telecommunication entities are increasingly reserving a large number of frequency allocations and orbital slots for their huge array/system of satellites by launching just one small satellite to satisfy the "bringing into use" requirement. Critics worry that this will eventually clog up the Master Register and make it harder for future companies to reserve slots, even though some reserved slots might not be in use for years to come.
But, to leave on an optimistic note, I would say have no fear, quantum communications might be just around the corner and help to save us from this potential orbital traffic jam. But until then, I am buzzing off before the traffic hits.
Radio Regulations: http://www.itu.int/pub/R-REG-RR-2016/en