chapter 19. heritage of earth orbit orbital debris - its mitigation and cultural heritage

381

19 Heritage of Earth Orbit: Orbital Debris—Its Mitigation and Cultural Heritage

Alice Gorman

CONTENTS

Introduction ............................................................................................................ 381Orbital Debris ......................................................................................................... 382Managing Orbital Debris ...................................................................................... 385

Design and Operational Mitigation ............................................................. 385Earth-Based Removal Programs .................................................................. 385Intervention Missions .................................................................................. 385

Archaeology and Heritage of Orbital Objects ...................................................... 386Vanguard 1 ............................................................................................................. 387

Aesthetic ....................................................................................................... 388Historic ......................................................................................................... 388Scientifi c ....................................................................................................... 389Social ............................................................................................................ 389

Survey of Early Satellites in Orbit .........................................................................390Risk Assessment .................................................................................................... 391Conclusions ............................................................................................................ 394Further Reading .................................................................................................... 395References .............................................................................................................. 396

INTRODUCTION

Since the launch of Sputnik 1 in 1957, human material culture in the form of satellites, launch vehicle upper stages, mission-related debris, and “space junk” has prolifer-ated in Earth orbit. There are now signifi cantly more than 10,000 trackable objects circling the Earth between low Earth orbit at around 200 km and the “graveyard orbit” around the geostationary ring at 35,000 km above the surface of the Earth.

© 2009 by Taylor and Francis Group, LLC

382 Handbook of Space Engineering, Archaeology, and Heritage

Only a small portion of this material is operational spacecraft; the rest is classed as orbital debris. Space industry is now at the stage where collision with orbital debris is a serious threat for the continued provision of satellite-based services, such as navigation, telecommunications, meteorology, and earth observation.

This situation constitutes an environmental management problem for space indus-try. In the short term, measures to control the proliferation of debris have included changing mission design and operation practices as recommended the U.S. National Aeronautics and Space Administration (NASA), the European Space Agency (ESA), and the United Nations.1,2,3 However, it is widely recognized that more active mea-sures to remove debris from orbit will be required in the future. Proposals have included the destruction of debris using ground- and space-based lasers and inter-vention missions by specialized spacecraft.

While the necessity of some active management is accepted by all, the problem is slightly more complex than a consideration of the technical diffi culties suggests. As discussed in Chapter 16, orbital space constitutes an organically evolved cultural landscape as defi ned by the World Heritage Convention.4 Objects now classed as orbital debris may have social, historical, aesthetic, and scientifi c signifi cance for nations, communities, groups, and individuals who will have an interest in decisions made about their long-term survival. It is not just the threat of collision that needs to be managed: proposals for orbital debris cleanup must also consider how to manage the cultural values of the orbital spacescape.

This does not mean that everything must be saved. In this chapter, I look at some of the issues that can help us make well-grounded decisions about what to preserve in situ and what to let go. There are two facets to this: an assessment of the risk posed to space operations by different debris classes, and the assessment of the signifi cance of orbital objects according to the categories of the Burra Charter, Australia’s pri-mary heritage management document.5 The Charter, while designed specifi cally for Australia, has been recognized as a simple and powerful set of heritage management guidelines that sets standards worthy of being emulated at an international level. To demonstrate how signifi cance can be assessed as the basis for sound manage-ment decisions, I look at the oldest surviving human object in orbit: the Vanguard 1 satellite.

ORBITAL DEBRIS

Orbital debris has been defi ned as any human-manufactured object in orbit that does not currently serve a useful purpose and is not anticipated to in the foreseeable future.6 Approximately 4,200 launches have occurred since 1957, leaving more than 10,000 trackable objects larger than 10 cm in orbit (Figure 19.1).7 Only 7% of these are operation spacecraft; 52% are decommissioned satellites, upper stages, and mis-sion-related objects, and 41% are debris from the fragmentation of orbital objects.

Operational and decommissioned spacecraft include scientifi c and telecommu-nications satellites, weather and earth observation satellites, navigation and surveil-lance satellites, satellite constellations, and military satellites. Upper stages include the durable Agena, in use from the time of the Gemini program to the mid-1980s, and those of the Ariane family of rockets, fi rst launched in 1979.


Heritage of Earth Orbit 383

Mission-related debris derive from deployments and separations of spacecraft, which typically involve the release of items such as separation bolts, lens caps, fl y-wheels, nuclear reactor cores, clamp bands, auxiliary motors, launch vehicle fair-ings, and adapter shrouds.8 Solid rocket motors used to boost satellite orbits have contributed other objects, such as motor casings, aluminum oxide exhaust particles, nozzle slag, motor-liner residuals, solid-fuel fragments, and exhaust cone bits result-ing from erosion during the burn, to the debris population.

Fragmentation debris are derived primarily from the explosion of satellites and launch vehicle upper stages, both of which tend to remain in orbit after the comple-tion of their mission.9 Explosion can occur when residual liquid fuel components accidentally mix, or when fuel or batteries become over-pressurized. There are also cases where spacecraft have been deliberately detonated, to prevent reentry and/or to conceal their presence or purpose. More than 124 breakups have been verifi ed so far, and the rate of breakup increases each year. Another major source of debris is material degradation from a range of environmental effects, resulting in the produc-tion of particulates, such as fl akes of paint and insulation. Figure 19.2 shows the “energy fl ash” when a projectile launched at speeds up to 27,000 km/h impacts a solid surface at the Hypervelocity Ballistic Range at NASA’s Ames Research Center in Mountain View, California. This test is used to simulate what happens when a piece of orbital debris hits a spacecraft in orbit.

Debris is concentrated in the orbital confi gurations most commonly used in space operations, defi ned by altitude above the earth’s surface, inclination, and eccentric-ity. The orbit employed depends on the purpose of the satellite and the location of the launch site. Most objects are in the nominally circular orbits, low Earth orbit (LEO)

FIGURE 19.1 This computer-generated image shows the thousands of satellites, spent rocket stages, and breakup debris in low Earth orbit. (Courtesy of NASA.)



or geosynchronous Earth orbit (GEO).10 Medium Earth orbits are less widely used, to avoid the Van Allen radiation belts.

In low Earth orbit, aerodynamic drag acts as a “natural cleansing mechanism,” causing objects to reenter the atmosphere and (mostly) burn up.11 At 400 km or below in altitude, it may take only a few months for objects to reenter. However, above 600 km, objects can remain in stable orbits for a few decades up to thousands of years. Satellites in GEO are beyond the reach of atmospheric affects although still subject to the vagaries of the space environment.

Within these orbital regimes, there are areas of higher debris density. In low Earth orbit, debris builds up near polar inclinations from sun-synchronous satellites and at altitudes near 800, 1,000, and 1,500 km.12,13 There are an estimated 70,000 pieces of debris about 2 cm in size at the 850–1,000 km altitude.14 Objects in geosynchronous and Molniya orbits and constellations of navigation satellites cause another peak in density at 25,000 km. The highest peak is at 42,000 km, consisting of objects at or near the geostationary ring.15 Within the GEO region, peaks of debris occur at the following:

The equatorial inclination• 28.5°, due to the latitude of the main U.S. launch site at the Kennedy Space • Center63°, from Molniya and GLONASS satellites•

Modeling the debris environment is reliant on data collected from optical and radar tracking. Debris over 10 cm is tracked by U.S. Space Command (USSPACECOM), using twenty-fi ve land-based radars and optical telescopes in the Space Surveillance Network. Over the former USSR’s territory, debris is tracked by the Russian Space

FIGURE 19.2 Energy fl ash of an orbital debris hit. (Courtesy of NASA.)



Surveillance Centre,16 ESA maintains the DISCOS database of space debris. Only debris above a certain size can be tracked in this way, and visibility depends on altitude: in GEO, an object must have a diameter of 1 m to be visible, while in LEO, radar can detect pieces as small as 5 mm. The population of debris below this size is estimated on the basis of impacts on returned spacecraft surfaces.17

MANAGING ORBITAL DEBRIS

Mitigation strategies for orbital debris can be broadly divided into three types: (1) design and operational solutions, (2) Earth-based removal programs, and (3) inter-vention missions.

DESIGN AND OPERATIONAL MITIGATION

This strategy is aimed at controlling the amount of new debris that enters the system by designing spacecraft and missions to minimize mission-related debris and the potential for fragmentation. Design solutions include using tethered lens caps and bolt catchers, shielding or augmenting components to withstand impact, and the use of operating voltages below arc thresholds.

Operational measures include postmission maneuvers to place the spacecraft within the range of aerodynamic drag or in a graveyard orbit and expelling remain-ing propellants and pressurants to prevent accidental explosion.18 The NASA guide-lines for limiting orbital debris recommend that an object should not remain in its mission orbit for more than 25 years.19,20

EARTH-BASED REMOVAL PROGRAMS

Other proposals have examined the prospect of removing debris between 1 and 10 cm in diameter in LEO by ground-based lasers (e.g., NASA’s Project Orion and Electro-Optical Systems).21,22 The laser ablates particles from the surface of the debris, creat-ing enough thrust to edge it into reentry.23 Space-based laser removal has also been considered, for example, to move debris out of the path of the International Space Station, but is considered too costly in time and energy to be feasible at this stage.

INTERVENTION MISSIONS

Intervention missions include the use of specialized spacecraft that actively remove objects from orbit. A study undertaken by QinetiQ investigated scenarios for remov-ing decommissioned satellites in GEO using a reorbiting spacecraft, concluding that this was plausible if not yet feasible.24 For LEO, a Royal Melbourne Institute of Technology group has proposed the use of space-based electrodynamic tethers to capture and remove debris.

At this point in time, only design and operational mitigation is used on space mis-sions. Before any active debris mitigation measures are implemented, the question of whether spacecraft currently classed as debris have any cultural heritage value needs to be addressed. What do we want to save for future generations? Should signifi cant



spacecraft be left in situ or removed to Earth for curation and display? If we accept that orbital space is a cultural landscape, the most appropriate management response is to leave spacecraft where they are. But this raises a critical question: can cultural heritage values be managed without compromising safety or service delivery?

ARCHAEOLOGY AND HERITAGE OF ORBITAL OBJECTS

The primary concern of archaeology is to understand role of material culture in human social and environmental engagement. Despite popular perceptions, archae-ology is not necessarily concerned only with the ancient: there is much to be learnt from contemporary material culture, particularly as it brings with it the added dimen-sions of extensive documentation and personal memories. It is often in the disjunc-tions between these that the most interesting stories wait to be told.

Space objects fall into the fi eld known as historical archaeology or postmedi-eval archaeology, which is concerned with the global expansion of industrialized European nations, the growth of capitalist economies, and interactions with indig-enous people in the colonies. Within this broad fi eld, there are subdisciplines, such as military archaeology and contemporary archaeology, which have useful theoreti-cal perspectives.

Spacecraft can be regarded as archaeological artifacts, the material record of a particular phase in human social and technological development. They have research potential in terms of understanding human interaction with the space environment. But they also more than this. Material culture can be regarded as heritage: objects from the past that have meaning in the present and that are important to the identity and well-being of communities.

We know that people see the material culture of space exploration as important: for example, of all the Smithsonian institutions in Washington, D.C., the most popu-lar is the National Air and Space Museum. The attraction is actually seeing the artifacts such as the Gemini capsule, spacesuits, and pieces of Skylab.25 One can read books and documents, watch fi lm footage, and view photographs, but nothing can convey the same information or meaning as the actual object itself. So we know that at least some people in some places value these objects. The question we need to address in managing heritage values during orbital debris mitigation is for whom are they signifi cant, and why?

The signifi cance of space material culture is often assumed to be self-evident. One of the most commonly cited rationales for space exploration, referred to in countless books, documentaries, and museum displays, is that space exploration is the natural outcome of an innate human urge to explore. Thus, space objects are perceived to have a globally understood meaning that appeals to our common human nature.26 Space exploration is seen as the most recent manifestation of a fundamental curiosity that led humans out of Africa, across the seas from the Old World to the New World, and inevitably into space.

Another popular model for understanding the signifi cance of space material culture is what I have called the Space Race model.27 In this formulation, objects and places have signifi cance for their contribution to the Cold War confrontation between the United States and the USSR. This model focuses on these two states,



ignoring the achievements of other countries, such as France, Britain, China, Japan, and Australia, and the contributions made by “developing” nations who often hosted launch sites, ground stations, and so forth. The Space Race model emphasizes com-petitiveness rather than cooperation in space, with an implicit Darwinian overtone: spacefaring nations (mostly imperial, industrial, and white) demonstrate technologi-cal fi tness by their success in space enterprises. The relationship of space explora-tion to inequalities between the developed and developing world is unexplored, and indeed unproblematic, in the Space Race scenario.28

Of course, these approaches do capture something meaningful about the sig-nifi cance of space material culture, but it is far from the whole story. To obtain a deeper and more inclusive understanding of heritage signifi cance, I turn to the guidelines adopted by the Australian National Committee of the International Council on Monuments and Sites in the Burra Charter.29 As well as providing a methodology for assessing signifi cance, the Burra Charter sets out principles for preservation and conservation. Its main tenet is “Do as much as is necessary and as little as possible” in order to retain the cultural signifi cance of a place or object.

The Burra Charter outlines four different categories of signifi cance:

1. Aesthetic: considerations of form, scale, color, texture, material, smells and sound, and setting

2. Historic: association with historic fi gures, events, phases, or activities 3. Scientifi c: importance in terms of rarity, quality, representativeness, and the

degree to which a place can contribute further substantial information 4. Social: the qualities for which a place has become a focus of spiritual, polit-

ical, national, or other cultural sentiment to a majority or minority group

The Burra Charter also stresses that signifi cance may be multivocal, and Article 6.3 states that the “co-existence of cultural values should be recognized, respected and encouraged, especially in cases where they confl ict.”

These kinds of signifi cance are used successfully as the basis for museum col-lections of space artifacts around the world and have been used in nominating space sites on Earth for heritage listing. In the next section I want to apply them to the old-est artifact in Earth orbit: the Vanguard 1 satellite.

VANGUARD 1

The Vanguard 1 satellite, launched successfully on March 17, 1958, is now the old-est manufactured object in orbit (Figure 19.3). It is in a highly stable LEO orbit with every prospect of remaining there for perhaps another 600 years.

Unlike Sputnik 1 and Explorer 1, Vanguard was launched using scientifi c sounding rockets rather than missile technology to avoid a military “taint.” As the launch was part of the International Geophysical Year program, the Vanguard team recruited a network of volunteers across the world to carry out visual tracking in Project Moonwatch.30 This community involvement played an important role in con-fi guring the project as scientifi c, cooperative, and inclusive.



In terms of the Burra Charter’s categories of signifi cance, we might attempt an assessment along the following lines.

AESTHETIC

In design, Vanguard 1 is spherical, with antennae attached at right angles to the body, made of silver aluminum. It was renowned for its small size, being dubbed the “grapefruit satellite” by Khrushchev. The size and the design refl ect the cost of placing material in orbit and perhaps also mutual infl uence with USSR designs—Vanguard and Sputnik are remarkably similar. Satellites are no longer manufactured to a spherical design, so this shape is indicative of an early phase, where satellites were seen not so much as an earth-circling spaceship as a miniature moon (bébé lune, or baby moon). The spherical shape continued to be used in the USSR for crewed shariks (descent capsules), but by 1960 this design was becoming rare.

HISTORIC

Vanguard 1 is associated with the Cold War and the International Geophysical Year of 1957–1958. It was the third satellite to be successfully launched and the second U.S. satellite. It represents the fi rst experimental phase of space explora-tion. Analysis of Vanguard’s orbital perturbations revealed that the Earth was “pear-shaped.” Vanguard represents the confl icting motivations and rationales for space exploration in the critical period of the 1950s, when the United Nations also fi rst moved to set up the principles of the Outer Space Treaty. Although it was designed as a peaceful scientifi c satellite, it was also an ideological weapon, a “visible display

FIGURE 19.3 Vanguard 1 satellite. (Courtesy of NASA.)



of technological prowess” aimed at maintaining the confi dence of the free world and containing Communist expansion.31,32 Vanguard’s design and mission refl ect the competing models of cooperation and confrontation in space, at a time when there were no rules, laws, or guidelines to structure the human-orbital interaction.33

SCIENTIFIC

There are three aspects to the scientifi c signifi cance of Vanguard 1.

Representativeness: • Vanguard 1 is the sole survivor of all satellites launched in 1957–1958, and one of the 23% of satellites remaining in orbit from 180 launches between 1957 and 1963 (the fi rst successful geosynchronous launch, Table 19.1). As such, it is unique: there is no equivalent satellite if Vanguard should be destroyed.Relevance to space research: There is no other object that has been in space • as long as Vanguard 1; hence it is the only artifact that can inform us of the long-term impact of the space environment on human materials.Relevance to archaeological research: Although there is extensive docu-• mentation about the history of Vanguard 1, this does not convey the same information as the object itself and its relationship to other artifacts in Earth orbit. A recording of the physical features of Vanguard 1 (when this is pos-sible) may reveal discrepancies between documentation and reality, and aspects of technological processes that are not longer in use.

SOCIAL

The satellite represents the expectations that the United States would be fi rst in space, and its failure to be so caused nationwide doubt and panic. At the time, the community esteem in which Vanguard was held was very low, and it was the butt of jokes in both the United States and the USSR. Nevertheless, the staff of the Naval Research Laboratory responsible for the project and the international network of Project Moonwatch volunteers must have had considerable emotional investment in

TABLE 19.1Satellites in Earth Orbit (1957–1963)

Year Number of Launches Number of Satellites Remaining Country of Origin

1957 2 0 USSR

1958 8 1 United States




1962 61 10 Canada, United States




its success. With the passage of time, Vanguard’s social signifi cance has changed. Later assessments have acknowledged as Project Vanguard as “the progenitor of all American space exploration today.”34 The satellite has Internet-based fan groups, including one that tracks its location in real time. It is now actually considered to be a “vanguard.” It is esteemed at an international level as the oldest human artifact in space, at a national level as oldest U.S. artifact in space, and at the local level by the space-buff communities who follow its progress.

This cursory signifi cance assessment demonstrates how the Burra Charter prin-ciples can be applied to orbital objects. Following the guidelines, signifi cance assess-ment should then be used as the basis for management. So what then is the best management policy to preserve the cultural signifi cance of this satellite? Options include destruction as part of an active debris mitigation program, removal to the safekeeping of a terrestrial museum as soon as practicable, or—simply nothing.

As is clear from the assessment of signifi cance above, Vanguard does have high cultural signifi cance, so destruction is not an appropriate option. It is also clear that part of Vanguard’s scientifi c and social signifi cance is its presence in orbit. Two Burra Charter principles can be applied here: fi rst, that we should do as much as is necessary and as little as possible, and second, that the setting of an object or place should be retained as part of its cultural signifi cance. Removal to Earth would diminish the cultural signifi cance of the satellite and should not be considered appro-priate management unless this would prevent its destruction.

SURVEY OF EARLY SATELLITES IN ORBIT

Vanguard 1 is not the only satellite that may have heritage signifi cance from the early years of space exploration. The following is a brief survey of other whole satellites still in low and medium Earth orbits from the period between the launch of Sputnik 1 in 1957 to the launch of the fi rst geosynchronous satellite, Syncom 1, in 1963.

Data come from a publicly available database of objects tracked by USSPACECOM. The information presented here focuses on satellites that had been launched intention-ally into Earth orbit rather than toward the Moon, sun, or other planets. Spacecraft that have been lost or deliberately deorbited, landed, or decayed, as well as rocket bodies, mission-related debris, and fragmentation debris, have been excluded.

Of 180 satellites launched between 1957 and 1963, 41 remain in Earth orbit (23%). All except the Canadian Alouette 1 originated from the United States (Figure 19.4; Table 19.1). They occupy low Earth orbit at both equatorial and polar inclinations, sun-synchronous orbits, and medium Earth orbit. The function of the satellites is not always clear-cut: many scientifi c and other missions were undertaken for military applications, and information about others is still classifi ed, but even in this early period, the satellites cover the range of functions that are still predominant today, with a fairly even distribution among scientifi c, meteorological, navigation, commu-nications, and defense-related missions.35

There are only a small number of satellites still in orbit from this early period, and each one could be argued to demonstrate an aspect of developing space technology. They include Vanguard 1, 2, and 3; Explorer 7; TIROS 1, the fi rst weather satellite; Transit 4A and 4B, which carried the fi rst nuclear power sources on a spacecraft;



Telstar 1, the fi rst active telecommunications satellite (Figure 19.5); and the Westford needles and their release capsule.36 In this range we can see technological trajecto-ries: from nuclear power to solar power, from passive telecommunications to active, from spherical baby moons to more diverse designs, increasing size, and increasing height above Earth’s surface.37 The material is dominated by U.S. spacecraft: how might this be interpreted by archaeologists of the future? What can we learn about the early space programs by what is left in orbit, as opposed to the documentary record? We cannot anticipate future research directions, but one day orbital objects will tell their own stories, if they survive.

RISK ASSESSMENT

If signifi cant spacecraft are left in orbit, does this merely contribute to the orbital debris problem? The next step is to assess the actual risk posed by heritage space-craft to operational spacecraft. This involves a consideration of the damage caused by different size classes of debris, and the actual probability of collision.

Orbital debris can be divided into three size classes.

Large: diameter greater than 10 cm. Large debris can be optically tracked. • Medium: diameter between 1 mm and 10 cm. Tracking depends on size • and altitude. Small: diameter less than 1 mm. This is the largest population of orbital • debris, and these items cannot be tracked.

FIGURE 19.4 Alouette 1. (Courtesy of NASA.)



The results of collision with a piece of debris include mechanical damage, material degradation, and, occasionally, catastrophic breakup of operational spacecraft. Even tiny particles can cause signifi cant damage because the impacts occur at hyperve-locity (i.e., when the magnitude of the impact velocity is greater than the speed of sound in the impacted material).38 In LEO, the average relative velocity of space debris at impact is 10 km/s (36,000 km/h).39 Average relative velocities in GEO are much lower, about 200 m/s (720 km/h), but collisions at this speed can still cause signifi cant damage. In terms of impact, a 10-cm fragment in geosynchronous orbit has roughly the same damage potential as a 1-cm fragment in LEO. A 1-cm geosyn-chronous fragment is roughly equivalent to a 1-mm low Earth orbit fragment.40

Collision with an object in the large size class (>10 cm) can cause fragmentation and breakup, a signifi cant source of new orbital debris. Impact from the medium debris class, 1 mm to 10 cm, can cause signifi cant damage and mission failure.41 Penetration by a debris fragment 1 mm to 1 cm in size, through a critical component, can result in the loss of the spacecraft. Fragments greater than 1 cm can penetrate and damage most spacecraft.42 Although objects in the small size class rarely cause catastrophic breakup, they can erode sensitive surfaces, such as payload optics.43

However, it is also necessary to consider the frequency with which such collisions occur for the different size classes. There is a direct relationship between the num-bers of debris in each size class, the relative velocities in different orbital regimes, and the probability of impact.

FIGURE 19.5 Telstar 1. (Courtesy of NASA.)



In LEO, the population of large debris is much lower than the medium and small classes, but the severity of impact is much greater when collision does occur because of the high relative velocity.44 Despite this, collisions with large objects over 10 cm are rare, and there are only a few recorded breakups due to catastrophic collisions.45 The density of the small debris class, however, is such that spacecraft in LEO experi-ence continuous bombardment by very small particles.

Lower relative velocities and greater distances between objects in GEO signifi -cantly reduce the probability of collision.46 Because of the increasing use of disposal orbits after mission completion, the rate of debris accumulation is slower than in LEO. Approaches between operational spacecraft and tracked objects can be pre-dicted and evasive maneuvers undertaken to avoid collision. Because most objects in the geosynchronous ring move along similar orbits, objects in GEO are more likely to collide with a meteoroid than with debris.47 However, untracked debris in GEO is not as well modeled as that in LEO.48

Table 19.2 illustrates the mean time between collisions with objects in the three size classes in different orbits. This table also demonstrates that the great-est risk of impact derives from the small debris size class in LEO. The larger the piece of debris and the higher the orbit, the less likely it is that a collision will occur. However, the medium debris class, 1 mm to 10 cm, is the most destructive. Medium debris are far more numerous than the large class, have a higher risk of collision, and can cause signifi cant damage and mission failure.49 Apart from indicating that any active orbital debris mitigation program should target this size class rather than large objects, this also suggests that costly intervention missions aimed at removing large decommissioned spacecraft will have minimal impact on the debris problem.

In the fi rst instance, then, preserving orbital debris larger than 10 cm, which includes whole but defunct satellites, upper stages, and mission-related debris such as the famous glove lost by Edward White in 1965 (currently tracked by Electro-Optical Systems50) in their orbital locations can be done without compromising the safety and operation of crewed and uncrewed missions. If an object, such as

TABLE 19.2Mean Time between Impacts on a Satellite with a Cross-Section Area of 10 m2 in Low Earth Orbit

Height of Circular Orbit (km)

Mean Time between Collisions (Years)

Objects 0.1–1.0 cm Objects 1–10 cm Objects >10 cm

500 10–100 3,500–7,000 15,000

1,000 3–30 700–1,400 20,000

1,500 7–70 1,000–2,000 30,000

Source: Courtesy of United Nations, Technical Report on Space Debris, United Nations, New York, 1999.



Vanguard 1, has been identifi ed as having heritage value, then it can be excluded from any future debris mitigation projects that involve deorbiting. Potentially cata-strophic approaches can be avoided by on-orbit maneuvers. As any active debris mitigation proposal must be designed to exclude operating spacecraft, it should sim-ply be a matter of appropriate planning to avoid objects of cultural signifi cance.

It is also possible that debris in other size classes may have cultural signifi cance, particularly with regard to its representativeness. An initial reaction may assume that any signifi cance will be extremely low, but this cannot be determined without a systematic investigation, which I will not attempt here.

CONCLUSIONS

Early conceptions of the Space Age imagined it as technological utopia, constructed of clean, metallic surfaces buffering the population from the disorder of a messy, organic past. In the contemporary world, it is acknowledged that continuity and connection to the past are vital in maintaining the well-being of communities, as the world becomes increasingly globalized. The destruction of cultural heritage has accelerated with the growth of population, development, and industrialization, and UNESCO, through the World Heritage Convention, recognizes that “that deteriora-tion or disappearance of any item of the cultural or natural heritage constitutes a harmful impoverishment of the heritage of all the nations of the world.”

There is also a growing interest in the archaeology and cultural heritage of the more recent past, covering events and phases such as the two world wars, the nuclear indus-try, and the Cold War.51,52 Heritage authorities around the world are now protecting landscapes shaped by these events. It would be wrong to assume that simply because a place or object is “recent” we know all about it: rapid technology change and military and commercial secrecy may, in some cases, mean that we understand even less about a Cold War site than an Iron Age hill fort. Space places and objects are no exception.

To date, all considerations of the orbital debris problem have focused on the risk posed to satellite services and crewed missions. The potential for space debris miti-gation to impact on cultural heritage values has not been examined. In this discus-sion, I have argued that orbital debris can have cultural heritage signifi cance, and preserving signifi cant orbital objects in the large size class in situ does not add to the risk posed by orbital debris to space missions. From this, it follows that the implementation of active debris mitigation strategies, such as deorbiting into the atmosphere or into graveyard orbits, should consider what impact this will have on the cultural landscape of orbital space and on the object as part of that landscape.

In the absence of legal instruments, cultural heritage in orbit could be protected by agreed guidelines. In 1999, an environmental symposium at the UNISPACE conference recommended that the concept of international environmental impact assessments be developed for all proposed space projects “that might interfere with scientifi c research or natural, cultural and ethical values of any nation.”53 Although cultural impacts were identifi ed primarily as affecting the night sky as seen from Earth, this could apply equally to orbital debris.

Following terrestrial models such as those used in Australia, an environmental impact assessment for an orbital enterprise might include the following:



Identifi cation of objects of signifi cance at international, national, and • agency levelsIdentifi cation and consultation with stakeholders (designers, scientists, gov-• ernment, industry, clients, and users of the service) Signifi cance assessment, including aesthetic, historic, scientifi c, social, or • spiritual value for past, present, or future generations54

Identifi cation of impacts on orbital heritage (e.g., damage, destruction, • alteration of current orbit, increased risk of collisions)

Management options may include undertaking no active measures, monitoring of the position of signifi cant objects, changing the orbit of the signifi cant object to reduce the risk of damage, or redesigning the mission to avoid impacts on the signifi cant object.

Before active debris mitigation strategies are implemented, there is an opportu-nity to assess the nature of the material record in orbit and ensure that objects of signifi cant cultural heritage value are not lost. What would future generations of space tourists think if they found that Vanguard 1 was destroyed needlessly through lack of forethought?

FURTHER READING

Belk, C.A., Robinson, J.H., Alexander, M.B., Cooke, W.J. and Pavelitz, S.D. 1997 Meteoroids and Orbital Debris. Effects on Spacecraft. NASA Reference Publication 1408. Huntsville, AL: NASA.

Campbell, J.W. 1996. Project Orion: Orbital Debris Removal Using Ground-Based Sensors and Lasers. NASA-TM-108522. Huntsville, AL: NASA.

Centre for Orbital Reentry and Debris Studies. http://www.aero.org/capabilities/cords.Chapman, S. 1959. IGY: Year of Discovery. The Story of the International Geophysical Year.

Ann Arbor, MI: University of Michigan Press.Clark, P.S. 1994. Space Debris Incidents Involving Soviet/Russian Launches. Journal of the

British Interplanetary Society 47(9): 379–391.Cocroft, W., and Thomas, R. 2003. Cold War: Building for Nuclear Confrontation 1946–1989.

London: English Heritage.Crowther, R. 1994. The Trackable Debris Population in Low Earth Orbit. Journal of the British

Interplanetary Society 47(4): 128–133.European Space Agency. 2006. Robotic GEostationary orbit Restorer (ROGER). http://www.

esa.int/TEC/Robotics/SEMTWLKKKSE_0.html.European Space Operations Centre. 2003. Space Debris Spotlight. http://www.esa.int/

SPECIALS/ESOC/SEMHDJXJD1E_0.html.Gorman, A.C. 2005. The Cultural Landscape of Interplanetary Space. Journal of Social

Archaeology 5(1): 85–107.Gorman, A.C. 2007. Leaving the Cradle of Earth: The Heritage of Low Earth Orbit 1957–

1963. Paper presented at the Australia ICOMOS Conference: Extreme Heritage, July 19–21, Cairns, Australia.

Gorman, A.C., and O’Leary, B.L. 2007. An Ideological Vacuum: The Cold War in Space. In A Fearsome Heritage: Diverse Legacies of the Cold War, ed. J. Schofi eld and W. Cocroft, 73–92. Walnut Creek CA: One World Archaeology, Left Coast Press.

Green, C.M., and Lomask, M. 1970. Vanguard: A History. NASA SP-4204. The NASA Historical Series. Washington DC.

Hypervelocity Impact Test Facility. http://www.wstf.nasa.gov/Hazard/Hyper/Default.htm.ICOMOS Australia. 1999. Burra Charter. http://www.icomos.org/australia.



NASA. NASA Management Instruction 1700.8—Policy for Limiting Orbital Debris Generation. Washington, DC: Offi ce of Safety and Mission Assurance.

NASA. NASA Safety Standard 1740.14—Guidelines and Assessment Procedures for Limiting Orbital Debris. Washington, DC: Offi ce of Safety and Mission Assurance.

Osgood, K.A. 2000. Before Sputnik: National Security and the Formation of US Outer Space Policy. In Reconsidering Sputnik: Forty Years since the Soviet Satellite, ed. R.D. Launius, J.M. Logsdon, and R.W. Smith, 197–229. Amsterdam: Harwood Academic Publishers.

Smith, B. 2004. It’s the Artifacts, Stupid! The Mineralogical Record 35(2): 106–107. Sullivan, W. 1999. Report on the Special IAU/COSPAR/UN Environmental Symposium:

Preserving the Astronomical Sky (International Astronomical Union Symposium 196). http://www.iau.org/IAU/Activities/environment/s196rep.html.

United Nations. 1999. Technical Report on Space Debris. New York: United Nations.UNESCO Intergovernmental Committee for the Protection of the World Cultural and Natural

Heritage. 2005. Operational Guidelines for the Implementation of the World Heritage Convention. World Heritage Centre. http://whc.unesco.org/archive/opguide05-en.pdf.

Woodford, J. 2004. A Blast from the Past. Sydney Morning Herald, July 10.

REFERENCES

1. NASA. NASA Management Instruction 1700.8—Policy for Limiting Orbital Debris Generation. Washington, DC: Offi ce of Safety and Mission Assurance.

2. NASA. NASA Safety Standard 1740.14—Guidelines and Assessment Procedures for Limiting Orbital Debris. Washington, DC: Offi ce of Safety and Mission Assurance.

3. United Nations. 1999. Technical Report on Space Debris. New York: United Nations. 4. UNESCO Intergovernmental Committee for the Protection of the World Cultural

and Natural Heritage. 2005. Operational Guidelines for the Implementation of the World Heritage Convention. World Heritage Centre. http://whc.unesco.org/archive/opguide05-en.pdf.

5. ICOMOS Australia. 1999. Burra Charter http://www.icomos.org/australia/. 6. Crowther, R. 1994. The Trackable Debris Population in Low Earth Orbit. Journal of the

British Interplanetary Society 47(4): 128–133. 7. European Space Operations Centre. 2003. Space Debris Spotlight. http://www.esa.int/

SPECIALS/ESOC/SEMHDJXJD1E_0.html. 8. Belk, C.A., Robinson, J.H., Alexander, M.B., Cooke, W.J., and Pavelitz, S.D. 1997

Meteoroids and Orbital Debris. Effects on Spacecraft. NASA Reference Publication 1408. Huntsville, AL: NASA.

9. Crowther 1994 (note 6). 10. Crowther 1994 (note 6). 11. Crowther 1994 (note 6). 12. Crowther 1994 (note 6). 13. Belk et al. (note 8). 14. Centre for Orbital Reentry and Debris Studies. http://www.aero.org/capabilities/cords/. 15. Crowther 1994 (note 6). 16. Clark, P.S. 1994. Space Debris Incidents Involving Soviet/Russian Launches. Journal of

the British Interplanetary Society 47(9): 379–391. 17. Belk et al. (note 8). 18. Osgood, K.A. 2000. Before Sputnik: National Security and the Formation of US Outer

Space Policy. In Reconsidering Sputnik: Forty Years since the Soviet Satellite, ed. R.D. Launius, J.M. Logsdon, and R.W. Smith, 197–229. Amsterdam: Harwood Academic Publishers.

19. NASA (note 1). 20. NASA (note 2).



21. Woodford, J. 2004. A Blast from the Past. Sydney Morning Herald, July 10. 22. Campbell, J.W. 1996. Project Orion: Orbital Debris Removal Using Ground-Based

Sensors and Lasers. NASA-TM-108522. Huntsville, AL: NASA. 23. Ibid. 24. European Space Agency. 2006. RObotic GEostationary orbit Restorer (ROGER). http://

www.esa.int/TEC/Robotics/SEMTWLKKKSE_0.html. 25. Smith, B. 2004. It’s the Artifacts, Stupid! The Mineralogical Record 35(2): 106–107. 26. Gorman, A.C. 2005. The Cultural Landscape of Interplanetary Space. Journal of Social

Archaeology 5(1): 85–107. 27. Ibid. 28. Ibid. 29. ICOMOS Australia 1999 (note 5). 30. Chapman, S. 1959. IGY: Year of Discovery. The Story of the International Geophysical

Year. Ann Arbor, MI: University of Michigan Press. 31. Green, C.M., and Lomask, M. 1970. Vanguard: A History. NASA SP-4204. The NASA

Historical Series. Washington DC. 32. Osgood 2000 (note 18). (see specifi cally p. 216). 33. Gorman, A.C., and O’Leary, B.L. 2007. An Ideological Vacuum: The Cold War in

Space. In A Fearsome Heritage: Diverse Legacies of the Cold War, ed. J. Schofi eld and W. Cocroft, 73–92. Walnut Creek CA: One World Archaeology, Left Coast Press.

34. Ibid. 35. Gorman, A.C. 2007. Leaving the Cradle of Earth: The Heritage of Low Earth Orbit

957–1963. Paper presented at the Australia ICOMOS Conference: Extreme Heritage, July 19–21, Cairns, Australia.

36. Ibid. 37. Ibid. 38. Hypervelocity Impact Test Facility. http://www.wstf.nasa.gov/Hazard/Hyper/Default.

htm. 39. Belk et al. (note 8). 40. Crowther 1994 (note 6). 41. Belk et al. (note 8). 42. Crowther 1994 (note 6) (see specifi cally Fig. 11). 43. Crowther 1994 (note 6). 44. United Nations 1999 (note 3). 45. Crowther 1994 (note 6). 46. United Nations 1999 (note 3). 47. Belk et al. (note 8). 48. United Nations 1999 (note 3). 49. Belk et al. (note 8). 50. Woodford 2004 (note 21). 51. Gorman and O’Leary 2007 (note 33). 52. Cocroft, W., and Thomas, R. 2003. Cold War: Building for Nuclear Confrontation

1946–1989. London: English Heritage. 53. Sullivan, W. 1999. Report on the Special IAU/COSPAR/UN Environmental Symposium:

Preserving the Astronomical Sky (International Astronomical Union Symposium 196). http://www.iau.org/IAU/Activities/environment/s196rep.html.

54. UNESCO 2005 (note 4).


chapter 19. heritage of earth orbit orbital debris - its mitigation and cultural heritage

Documents