The U.S. space program is rapidly changing from an activity driven by federal government launches to one driven by commercial launches. In 1997, for the first time commercial launches outnumbered government launches at the Eastern Range (ER), located at Cape Canaveral Air Station, Florida. Commercial activity is also increasing at the Western Range (WR), located at Vandenberg Air Force Base, California. The government itself is emulating commercial customers, shifting from direct management of launch programs to the purchase of space launch services from U.S. commercial launch companies in an open, competitive market.
The fundamental goal of the U.S. space program is to ensure safe, reliable, and affordable access to space. Despite the inherent danger of space launches, the U.S. space program has demonstrated its ability to protect the public. No launch site worker or member of the general public has been killed or seriously injured in any of the 4,600 launches conducted at the ER and WR during the entire 50-year history of the space age.
Reliability and affordability have been more difficult to achieve. As the federal government relies more on the commercial space sector to launch government payloads, the vitality, viability, and global competitiveness of the U.S. commercial launch industry are becoming increasingly important. Because range safety costs are an important element of total launch costs, it would be beneficial to streamline safety processes without lowering current safety standards. This study responds to a request from the Air Force Space Command (AFSPC), which operates the ER and WR, to determine if range safety processes can be made more efficient and less costly without compromising public safety. This summary presents six primary recommendations, which address risk management, Africa gates, roles and responsibilities, range safety documentation (i.e., Eastern and Western Range Safety Requirements [EWR 127-1]),1 global positioning system (GPS) receiver tracking systems, and risk standards for aircraft and ships. The main body of the report contains eight other recommendations that would make smaller contributions to achieving the study goals. The report also contains 14 findings that support the recommendations and state the committee’s conclusions in areas where the committee decided recommendations were not warranted.
The statement of task for this study specified three areas of interest:
a top-level, independent review of the Air Force’s safety guidelines and procedures for government and commercial space launches as published in EWR 127-1 to determine if there are alternative approaches to the protection of the general public that are both more efficient and less expensive
an independent assessment of the current and planned range safety and flight termination systems and procedures for government and commercial space launches to estimate the technical feasibility as well as the cost effectiveness of an autonomous GPS flight termination system
an independent examination of the Air Force’s safety guidelines and procedures associated with incursions of aircraft and ships into restricted air space and waters to determine if holds and delays of government and commercial space launches can be reduced while still maintaining an acceptable level of safety
RISK CRITERIA AND RISK MANAGEMENT
With any endeavor, it is generally desirable to increase return or value and reduce risk. This often involves defining an acceptable risk level as a standard to which risk then can be managed. Once this standard has been met, the venture may be considered safe. The fundamental analytical risk standard used by the WR and ER for collective risk to the general public is expressed in terms of casualty expectation (Ec). For each launch, Ec must be less than 30 × 10−6; at a rate of 33 launches per year, this is equivalent to one serious injury or fatality every 1,000 years. The committee considered recommending different risk standards for collective risk and individual risk, Pc (discussed below). The current standards, however, are in line with the level of risk characteristic of many other fields, domestically and internationally, in which the public is involuntarily exposed to risk. Also, the committee determined that the efficiency of range operations could be significantly improved without lowering safety standards and that higher standards are not needed to protect the public. Therefore, the committee supports the continued use of 30 × 10−6 as the collective risk standard for space launches at the ER and WR.
A recurring theme in the findings and recommendations of this report is the importance of managing risk to the accepted standards. Risk management ensures that launch vehicles are manufactured and launch operations are conducted to achieve established safety standards. Risk management also allows weighing the costs and benefits of alternative approaches for meeting risk standards. Currently, commercial operators must comply with federal range safety requirements that are implemented in a way that leads to risk avoidance instead of risk management. The correct goal, however, would be to meet established safety standards in a cost-effective manner that facilitates planned operations, rather than reducing risk to the lowest possible level regardless of the costs or requiring the most conservative application of risk standards throughout the range safety process.
Primary Recommendation on Risk Management. AFSPC should define objective, consistent risk standards (e.g., casualty expectation, Ec, of 30 × 10−6, and individual risk, Pc, of 1 × 10−6) and use them as the basis for range safety decisions. Safety procedures based on risk avoidance should be replaced with procedures consistent with the risk management philosophy specified by EWR 127-1. Destruct lines and flight termination system requirements should be defined and implemented in a way that is directly traceable to accepted risk standards.
Because a launch vehicle may pass over populated landmasses before orbital insertion, strict limits are often provided in the form of “gates” in the impact limit lines (ILLs) and destruct lines that define the range of allowable flight paths. If the vehicle does not pass through the gate, the flight is terminated. The ILLs, destruct lines, and gates are designed to ensure that debris returns to Earth more than 50 miles from the coasts of major populated landmasses. At the ER, the downrange location of gates and destruct lines as well as requirements for downrange coverage by flight termination, telemetry, and tracking systems, are not directly related to accepted risk standards (e.g., Ec of 30 × 10−6 or Pc of 1 × 10−6) but to a risk-avoidance policy that discourages the overflight of inhabited landmasses “whenever possible” (EWR 127-1, paragraph 2.3.6). The committee recognizes that avoiding inhabited landmasses is often the best approach for meeting risk standards. However, using risk standards to evaluate alternate approaches is more rigorous than relying on subjective criteria, such as “whenever possible.”
The positioning of gates is a function of the launch vehicle, flight azimuth, and location of inhabited landmasses. The Africa gates are typically beyond the range of uprange radar tracking facilities and require the use of downrange facilities on the islands of Antigua and Ascension. Moving the Africa gates uprange could reduce the cost of safety-related assets, decrease the complexity of range safety operations, and reduce holds and delays. Based on historical failure data and reliability requirements, moving the Africa gates to within the reach of uprange flight termination systems (FTSs) and tracking systems is unlikely to increase Ec significantly or violate established limits. In addition, the committee knows of no international agreements that would preclude moving the gates uprange. Thus, in terms of range safety there is no clear justification for retaining downrange assets at Antigua and Ascension. It may also be feasible to move other gates uprange and further reduce the need for downrange facilities at the ER. The WR already avoids the use of downrange flight termination, telemetry, and tracking systems by constraining allowable azimuths of orbital launches during the uprange portion of flights to avoid flying over populated areas.
Primary Recommendation on Africa Gates. While other requirements may exist, from the perspective of launch range safety the Air Force should move the Africa gates to within the limits of uprange flight termination and tracking systems; eliminate the use of assets in Antigua and Ascension for range safety support; and conduct a detailed technical assessment to validate the feasibility of moving other gates uprange. If other requirements for downrange tracking exist, AFSPC should validate those requirements and reexamine this recommendation in light of the additional requirements.
ROLES AND RESPONSIBILITIES
AFSPC has transferred to the Air Force Materiel Command (AFMC) responsibility for development, developmental testing and evaluation, and sustaining engineering of
range safety ground systems. Organizational responsibilities for many other range safety processes and procedures, however, are still inconsistent with the current memorandum of agreement between AFSPC and AFMC on spacelift roles and responsibilities. In addition to the operational workforce, each AFSPC range safety office also has an engineering workforce that establishes flight safety system design and testing requirements and certifies that flight safety systems meet safety requirements at the component, subsystem, and system levels. These acquisition-like functions overlap the responsibilities of AFMC.
If properly executed, the complete transfer of range safety development, developmental testing and evaluation, and sustaining engineering to AFMC would increase efficiency and reduce costs without compromising safety by eliminating overlapping responsibilities between the ranges and AFMC, by minimizing differences in range safety policies and procedures applicable to the WR and ER, and by allowing users to deal with a single office when seeking approval to use new or modified systems on both ranges. This transfer could be facilitated by issuing an Air Force Instruction describing the certification of flight safety systems for commercial, civil, and military launches at the ER or WR. The instruction should also describe interfaces among responsible organizations, such as AFSPC, AFMC, the Federal Aviation Administration (FAA), the National Aeronautics and Space Administration, and commercial contractors.
Primary Recommendation on Roles and Responsibilities. The Air Force should fully implement the memorandum of agreement between AFSPC and AFMC on spacelift roles and responsibilities. This would consolidate within AFMC the acquisition-like functions related to safety that are now performed by AFSPC organizations at the Eastern and Western Ranges. These functions include developmental testing and evaluation, sustaining engineering, and certifying that system designs meet safety requirements. To manage the safety aspects of the acquisition-like functions specified in the memorandum of agreement, AFMC should establish an independent safety office. Operational responsibilities, such as generating safety requirements, operational testing and evaluation, and all prelaunch and launch safety operational functions, would be retained by AFSPC.
EWR 127-1 is issued jointly the by 30th Space Wing, which operates the WR, and the 45th Space Wing, which operates the ER. EWR 127-1 specifies in detail how to comply with established risk standards rather than expecting users to develop their own methods of compliance. These detailed requirements create the need for extensive “tailoring” of EWR 127-1 for each new launch vehicle to allow the use of alternate solutions that are more practical than the specified methods of compliance. The committee believes that a more effective approach would be to streamline EWR 127-1 to focus on baseline performance-based requirements and move detailed solutions and lessons learned to a range user’s handbook. This would reduce or eliminate the need for tailoring and draw a clear distinction between non-negotiable performance-based requirements and recommended methods of compliance that can be waived if an equally effective alternative is available and the user accepts the burden of demonstrating its effectiveness.
Primary Recommendation on EWR 127-1. AFSPC should simplify EWR 127-1 so that all requirements are performance based and consistent with both established risk standards for space launch (e.g., Ec of 30 × 10−6) and objective industry standards. The process of revising EWR 127-1 should include the following steps:
Eliminate requirements that cannot be validated.
Remove all design solutions from EWR 127-1.
Establish a range user’s handbook or other controlled document to capture lessons learned and design solutions recognized by the ranges as acceptable means of compliance. (Requirements should be retained in EWR 127-1.)
Form a joint government/industry team to establish procedures for periodically updating EWR 127-1 and ensuring that future requirements are performance based.
Converge the modeling and analysis approaches, tools, assumptions, and operational procedures used at the Western and Eastern Ranges.
GPS FLIGHT ARCHITECTURE
AFSPC plans to implement a GPS-based flight architecture at the ER and WR, which will reduce the cost of upgrading, maintaining, and operating the radar system (see Figure ES-1). A GPS-based tracking system will permit shutting down 11 of the 20 tracking radars currently used to support launch operations at the ER and WR. Three of the remaining radars will be needed only to support launches of the space shuttle.
There are two approaches for implementing a GPS-based tracking system. A GPS translator system would retransmit GPS signals received by a launch vehicle to the ground, where vehicle position and velocity would be computed. This approach would have high bandwidth requirements for communications signals sent from the launch vehicle to ground stations and from ground stations to GPS processor sites.
The alternative would be to use GPS receivers on each vehicle to calculate vehicle position and velocity data, which would then be transmitted to the ground. A GPS receiver system would have low bandwidth requirements and enable an open system architecture compatible with future concepts, such as space-based ranges and autonomous or semiautonomous
FTSs. Autonomous features have already been implemented in current FTSs in the form of inadvertent separation destruct systems, which sense the onset of unplanned vehicle breakups and, in many cases, automatically initiate flight termination. A semiautonomous system could be developed in which the uprange portion of flight is monitored using traditional human-in-the-loop FTS procedures. Then, as the vehicle travels downrange and the risk profile decreases, the FTS could be shifted to a fully autonomous mode. This has the potential to reduce costs, improve responsiveness to unplanned events, and enable ranges to more easily support a broad complement of launch vehicles and mission profiles.
With the incorporation of onboard GPS receivers, fully autonomous FTSs would become technically feasible, but additional research and testing is needed to resolve outstanding issues related to system performance requirements, development and validation costs, and public acceptability. The successful deployment of semiautonomous systems, which would provide operational benefits even if a fully autonomous system is never developed, would help resolve these issues.
Finding. For space launches, an onboard GPS receiver tracking system would be more versatile and have lower total life-cycle costs than GPS translator or radar tracking systems.
Primary Recommendation on GPS Receivers. AFSPC should deploy a GPS receiver tracking system as the baseline range tracking system for space launch vehicles. The transition to GPS-based tracking should be completed as rapidly as feasible.
MARINE AND AIRCRAFT INCURSIONS
Aircraft and marine incursions into restricted airspace and waters have contributed to only a small percentage of launch holds and scrubs at either the ER or WR. However, when they do occur, these delays can be highly disruptive and costly, for both the range and the user. Also, increases in marine and air traffic near the launch area and more frequent space launches are expected to increase the number of boat and aircraft intruders, especially at the ER. An improved
launch communications and notification process would benefit the general public, the Air Force, and range users. Options include making greater use of public media, such as newspapers, radio and television broadcasts, the Internet, notices at public marinas and general aviation airports, and aviation and marine weather broadcasts; reviewing the adequacy of current signs, lights, and other warning devices at marinas and along the coast; and modifying warning devices to increase their effectiveness in deterring marine incursions.
Improving the notification process alone, however, will not completely solve the intruder problem. The committee recommends immediate improvements so that surface and aircraft intruders can be detected earlier and cleared from the launch area more quickly. These improvements should include the use of commercial aircraft equipped with suitable surveillance, navigation, communications, and image recording systems for marine intruders and surveillance systems for aircraft intruders.
AFSPC should also aggressively enforce restrictions against intruders at both ranges to encourage compliance with launch notifications. In cooperation with the U.S. Coast Guard, the FAA, the U.S. Attorney’s Office, and other regulatory and law enforcement agencies, AFSPC should initiate administrative and regulatory changes to facilitate enforcement action against intruders who were afforded ample, timely launch notifications.
All of the actions described above are based on the establishment of hazardous launch areas (e.g., flight hazard and flight caution areas), which extend downrange from the launch site along the intended flight azimuth. The size and shape of these areas are based on calculations of the probability, Pi, of hitting an individual ship or aircraft. The calculations take into account the characteristics of specific launch vehicles and payloads, failure modes and effects (including toxic hazards), and weather considerations.
The individual risk standard for members of the general public is 1 × 10−6. This means that the probability, Pc, that a member of the public at any particular place will be killed or seriously injured shall not exceed 1 × 10−6 for any launch. A different risk standard is appropriate for individual ship-hit probability because hitting a ship with a piece of debris will not necessarily result in casualties.
EWR 127-1 does not specify a risk standard for aircraft incursions. Risk standards are used to manage risk to mission-essential aircraft, but the standards are applied differently at the ER and WR and are not supported by analyses showing that the standards are consistent with other safety criteria used by the ranges. For example, Pi should be calculated differently for aircraft than for ships because even small pieces of debris can endanger aircraft.
The ER and WR use predefined restricted areas to protect public aircraft from launch hazards. These areas are sized to keep aircraft totally away from hazardous operations and are plotted on standard aeronautical charts. Prior to each launch the flying public is warned to remain clear of restricted areas involved in that launch.
If intruder aircraft are in restricted areas prior to launch, the launch could safely proceed if the aircraft will remain clear of the regions of actual hazard. This could be accomplished through the use of buffer zones around each hazard area. The buffer zones should be large enough so that, even if an aircraft outside the buffer zone turns toward the hazard area at the beginning of the launch commit cycle, the aircraft could not reach the hazard area until after the launch vehicle has cleared the area. These buffer zones are not needed for aircraft flying under the direction of air traffic controllers in airways outside the hazard areas.
Primary Recommendation on Risk Standards for Aircraft and Ships. AFSPC should apply the individual ship-hit criterion, Pi, of 1 × 10−5 to the ship exclusion process at the Eastern Range in the same way it is used at the Western Range. EWR 127-1 should be modified to specify an aircraft-hit Pi limit of 1 × 10−6 (properly calculated to include the probability of impact for very small pieces of debris). Prior to each launch, the range should establish aircraft hazard areas (based on the aircraft Pi) and buffer zones (for uncontrolled aircraft in the vicinity of the hazard area). Launches should be allowed to proceed as long as no intruder aircraft are in the hazard area or buffer zone.
Implementation of the committee’s recommendations would streamline range safety processes, resulting in substantially lower costs and higher efficiency without compromising safety. The recommendations and associated findings are grounded on the universal application of the Air Force’s long-established risk management approach to space launch range safety. Implementation of the recommendations would eliminate the overly cautious risk-avoidance practices that have crept into established range safety practices, reform EWR 127-1 to focus on performance-based requirements based on objective risk standards, create a single range safety office under AFMC to consolidate nonoperational range safety activities, greatly reduce the need for downrange safety facilities, reduce launch holds and scrubs caused by aircraft and ship incursions, and upgrade the ranges with GPS receiver tracking systems to reduce costs and pave the way for long-term improvements, such as semiautonomous FTSs and space-based ranges.
The recommendations in this report are consistent with and complementary to many ongoing efforts to modernize space launch infrastructure and procedures. Some of the recommendations can be implemented immediately, while others must be part of longer term upgrades to the infrastructure. All of them will require cooperation among the ranges, other elements of the Air Force, other government agencies
involved in space launches, and range users. If the recommendations are carefully implemented, everyone involved would benefit from a safe, more economical, and more competitive U.S. space launch capability. Together with the results of related studies, the Air Force now has enough information to create timetables, establish priorities, assign responsibilities, and take action to improve U.S. space launch capabilities.
EWR 127-1 (Eastern and Western Range Safety Requirements). 1997. Available on line at: http://www.pafb.af.mil/45sw/rangesafety/ewr97.htm January 20, 2000.
Finn, G., and T. Woods, 1999. Spacelift Range Metric Tracking LCC (Life Cycle Cost) Review: Response to NRC Request. August 10, 1999. Briefing materials prepared by G. Finn, Aerospace Corporation, and T. Woods, Air Force Space and Missile Systems Center, for the Space Launch Range Safety Committee, August 13, 1999.