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Military Traffic Models

NASA Access to Space Study(1)

This study was undertaken in response to a Congressional request in the NASA FY1993 Appropriations Act. The request coincided with an on-going internal NASA broad reassessment of the Agency's programs, goals, and long-range plans. The launch needs mission model utilized for the study was based upon today's projection of civil, defense, and commercial mission payload requirements. A common mission model was defined that included all US defense, civilian, and commercial user elements covering the period from 1995 through 2030. This model was based on conservative extrapolation of current requirements and planned programs, and did not include major future possibilities such as exploration missions to the Moon and Mars. On the basis of the 1990 Modified Civil Needs Data Base, approximately 90 percent of all future low-Earth orbit payloads are under 20k pounds and are under 20 feet in length. For lack of solid forecasts of future traffic, the model was assumed to be constant through 2030. It was recognized that such a flat model was unlikely to endure over the long term and that excursions would eventually have to be treated as better models became available, as human exploration or other ambitious missions became better focused, or, hopefully, from additional market demand enabled by future reductions in the costs of access to space.

Space Launch Modernization Study(2)

Four major sectors coexist in the national space community: defense, intelligence, civil, and commercial. Each sector has distinct space missions and to a significant degree has developed unique cultures and practices. However, spacelift is a mission that is common to all sectors. The first step in developing a modernization plan for space launch is to understand the needs and perspectives of the principal customers and suppliers of spacelift systems and services.

The defense sector's principal objective is to have efficient and cost-effective space launch capabilities to carry out its warning, surveillance, communication, weather, and navigation missions from space. The evolving National Military Strategy places increased reliance on smaller, more mobile military forces to respond to crises and conflicts around the world. This requires highly capable space force and space launch capabilities with the operability, dependability, and responsiveness to meet operational needs. Because of the increasing costs of launch, the defense sector has generally been pursuing lighter satellites to meet future needs, resulting in a focus on medium lift capabilities. Roughly 6 percent of the DOD budget is spent on space, of which about 20 percent of this funding is spent on space launch -- roughly $2.5 billion.

The intelligence sector provides critical information to national and military decision makers. Their payloads are generally large and expensive, so reliable, heavy lift capability is a top concern. The intelligence sector is also concerned about transition to any new launch vehicle because of experience with transitions from expendable launchers to the Space Shuttle and back to expendables after the Challenger accident. These changes required costly satellite modifications and caused long launch delays. Heavy lift requirements are principally intelligence related, including but not limited to military operational and science and technology (S&T) intelligence requirements. Intelligence needs and technology limit the potential to downsize intelligence satellites, and it is unlikely that any known technologies could enable similar mission success at MLV weights and sizes in the near term.

Human spaceflight and the need to reduce the costs of Space Shuttle operations dominate NASA's needs. Accordingly, NASA's most important requirement is a more cost-effective reusable space launch system. For the near term, NASA plans to meet its Space Station assembly and resupply requirements with the Space Shuttle and Russian Proton and Soyuz boosters. For its scientific, communications relay, and earth observation missions, NASA will rely on a limited number of medium lift expendable boosters. Space activities make up about 93 percent of NASA's budget, with aeronautical activities accounting for the remaining 7 percent. Launch costs account for about 31 percent of NASA's budget -- about $4.3 billion.

Today's commercial space launch requirements are dominated by geosynchronous communications satellites. Both commercial satellite builders and launch service providers want low launch service prices and dependable launch schedules, creating a natural synergy between the needs of the defense and the commercial sectors. Although commercial competitiveness characterizes the dialogue in this sector, the Government is the predominant purchaser of launch products and services, and today there are limited opportunities to significantly expand the space launch market. The small communications satellite market has the potential to drastically change the space launch market, but the actual size and viability of this new commercial sector are still highly uncertain. A recent Department of Transportation, Office of Commercial Space Transportation (OCST) study estimated the size of this market for 1994-2005 at between 4 and 10 medium launches for constellation deployment and between 8 to 12 small launches for constellation sustainment.

The medium/heavy launch market will continue to be dominated by Government launches for the foreseeable future. Launch demand has declined as a result of defense reductions, significantly increasing per flight costs. Future Government mission requirements will not likely increase, and the commercial launch market provides little potential for significant growth or economies. From these trends, the Study Group concluded the United States has too many space launch providers with too much production capacity.

Redesigning satellites to fly on new boosters is extremely costly, delays the satellite program, and often does not improve satellite capability. The movement of payloads onto and then off the Space Shuttle is the case in point, where the payload transition costs were extraordinary. Based upon current plans for future new starts and/or block changes to satellite systems, windows of opportunity for transition of satellites to new launch vehicles occur for heavy lift in the years 2005-2007, 2009 and 2011-2012; for medium lift in 2003-2005; and for the Shuttle in 2006-2010. Any major changes in the industry structure should be timed such that the initial launch capability (ILC) of new spacelift systems occurs at the satellites' transition points.(3)

Commercial Space Transport Study(4)

The government missions market area consists of missions that are predominantly funded by the Federal government budgets. These include existing government missions (primarily DOD, space science, space station, space testbed, asteroid detection, emerging nations, law enforcement, and treaty verification. Most of these missions do not have a commercial customer (the most notable exception is space testbed), although space launch services may be acquired commercially.

A significant amount of information is available for this group of missions. Since many projects have been conducted to study future system requirements, data are readily accessible for both NASA and DoD missions. Typically, future requirements are tabulated databases for near-term activities (present to about 2000) as well as far-term projection (beyond 2000 to 2010 or 2020).

The DOD missions were an updated version of the NLS mission model. The names, destination, launch site, and launch vehicle have been withheld; however, the data are useful to mission capture analyses and launch vehicle requirements definition. The civil missions are a combination of the mixed fleet manifest (present to 1998), midterm (1998 to 2010) captured in the Civil Needs Data Base (CNDB), and placeholders for 2010 through 2020 (also in the CNDB). The combined total mission model includes all US government missions.

Many DOD missions remained intact under the government missions market area because most DOD requirements are unique and divorced from commercial and civil space. There was some recent (late 1993) evidence that the military space role may be changing, allowing both commercial and civil applications to benefit from DOD assets and technologies. This change in DOD philosophy may be incorporated in specific market assessments (e.g., remote sensing), however, the assessment of government missions was based upon the assumption that DOD requires separate assets and capabilities from the civil and commercial needs. The study expected DOD to maintain a steady and sizable space presence.

Few of the DOD missions are covered by other market areas. Those covered in other market areas include GPS, GPS follow-on, and Landsat missions. Defense Meteorological Satellite Program (DMSP) was thought to be different enough from its civil counterpart, NOAA (National Oceanic and Atmospheric Administration) satellites, to keep them separate. All of the other missions are unique to this market area, with the assumption that DOD continues to provide its own weather, surveillance, reconnaissance, communication, and space test assets.

To provide a common basis for comparison, and to accumulate missions requirements across all market areas, the mission model was converted to low Earth orbit/low inclination (28.5 deg) equivalent masses. The result was a 21-year (2000-20) annual average of 240,000 Ib LEO equivalent mass. This result was clearly dependent on the launch vehicle type assumed, especially for missions requiring upper stages. This assessment used equivalence ratios from the National Launch System study, which are typical of two-stage launch vehicles.


1. Adapted from: NASA Headquarters Office of Space Systems Development, Access to Space Study - Summary Report, 27 January 1994.

2. Department of Defense, Space Launch Modernization Plan - Executive Summary, 5 May 1994, pages 3-9, 24.

3. Department of Defense, Space Launch Modernization Plan - Executive Summary, 5 May 1994, pages 25-26.

4. Commercial Space Transport Study Final Report, May 1994, pages 90-95.

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