This chapter addresses the capabilities of space systems without
regard to their
general application in an operational setting as was
done in Chapter 3. Here, they are considered within the major
functional areas of communications, reconnaissance, intelligence,
surveillance, and target acquisition, weather, terrain, and
environmental monitoring, position and navigation, and missile
warning. These capabilities reinforce the importance of space systems
as force multipliers, increasing the effectiveness and efficiency of the
force. The advantages gained through the use of space systems are
vital and integral to the success of any Army operation; however, the
limitations associated with the use of space systems must also be
Space system capabilities increase the effectiveness and efficiency of
Army forces, whether training, supporting MOOTW, or conducting combat
operations. Army planners must optimize the use of space capabilities to
enhance land operations. Generally, the CINC, or in the case of most
contingency operations, the Army service component commanders
(ASCCs), develop operational requirements and then forward them to the
Department of the Army staff for resolution. Requirements vary, depending on
the specific area of operations, the mission, the maturity of the theater,
and the situation. However, space systems may satisfy many of these
requirements. The CINC, through apportionments from the JCS, decides what
space support is available or can be made available to the ASCC. Generally,
space capabilities enhance the Army's ability to--
- Accurately assess the current situation.
- Adapt to the demands of the situation, that is, to modify plans.
- Anticipate enemy actions.
- Act and react faster than the enemy.
- Exploit opportunities and enemy
- Identify targets for fire support systems.
- Command and control its forces.
However, access to and availability of space capabilities depend to a
degree on the echelon of command. The staff's responsibility is to know
what capabilities are available and to optimize them. As forces are
tailored to satisfy mission requirements, space system user terminals
may have to be redistributed and space support teams created. To ensure
adequate space support for the deploying force, a USARSPACE ARSST can
form the nucleus of a tailored space support team.
Each space system consists of three segments: a space segment--the
satellites; a control segment--ground control stations and managers; and
a user segment--the equipment necessary to receive the satellite signals
(see Figure 4-1). Following is a general discussion of space systems and
associated terminals available to support the Army.
High ground has always played an important role in effective military
communications. Communicating with forces dispersed across the battlefield or
deployed great distances from their home bases has always been a major
challenge. The importance of communications increases as the Army's mission
becomes more complex and force levels decrease. Combat net radios for
ultrahigh frequency (UHF) and very high frequency (VHF) are limited by line
of sight (LOS) and have to rely on radio relays located on high ground to
overcome terrain restrictions. Satellite communications systems are less
hampered by LOS restrictions and can significantly enhance Army
communications capabilities by extending ranges and reliability. Satellites
offer an effective means of overcoming the physical limitations of LOS
radios, extending the range of terrestrial communications systems, such as
MSE, throughout the area of operations.
Communications satellites are the cornerstone of the Army's battle
command architecture. They operate in a wide band of radio frequencies
and provide the link between theater and CONUS for split-based
operations and range extension between subordinate commands in the
theater (see Figure 4-2). UHF satellite communications systems, such as
the FLTSAT and AFSATCOM systems, are used to support battle command
requirements for high-priority users, to include EAM dissemination, force
direction, and JCS/CINC netting. SHF communications systems, such as the
DSCS, support worldwide, long-haul, secure-voice and high-data-rate
communications for battle command, early warning, crisis management, and
internetting between the NCA/JCS and the combatant commanders. Milstar,
the next generation military satellite communications system, is an EHF
system capable of jam-resistant secure worldwide communications during
all levels of conflict.
The modern battlefield is volatile and requires synchronization of
operations throughout its depth. Success on the battlefield demands
flexible, highly mobile, responsive, reliable, secure, jam-resistant,
and survivable communications, unhindered by terrain masking or other
LOS constraints. Currently, satellites are used primarily to augment
ground-based communications systems, providing communications links not
only to forces employed in an area of responsibility, but also to
deploying forces while en route. However, during deployments to
contingency areas having little or no infrastructure to support command
and control, satellites will become the primary means of communications.
Satellite communications provide the following advantages, which make
them ideal for force projection operations:
- Greater freedom from siting restrictions.
- Extended range, capacity, and coverage.
- Real-time and store-and-forward capabilities.
- Stand-alone capability and reduced
logistical support on the battlefield.
- Freedom from rigid network configurations.
- Mobility and rapid emplacement.
- Extremely high circuit reliability.
Military and commercial satellite communications systems are invaluable
assets that can be used at all echelons of command. Military battle
command nets are usually routed through military satellites due to the
low probability of intercept and the increased communications capability
(for example, to pass higher data rates and imagery) that they afford.
Administrative and logistics networks may use either military or
commercial satellites, which routinely support force projection and
split-based operations around the world. These same systems may also be
available to support selected training exercises. Military satellite
communications systems, however, are considered joint assets and are
controlled by the JCS, who allocate the resources based on need. JCS
Memorandum of Policy 37 specifies access priorities. More often than
not, demand exceeds the capabilities of the systems; therefore, access
to military satellite channels is at a premium and closely monitored.
Consequently, Army forces must clearly define and articulate their
requirements for critical battle command connectivity. The Army also
must consider the use of commercial satellites, such as the INTELSAT and
the INMARSAT terminals, as an alternative means of satisfying their
communications requirements. Space is not the panacea for all
communications shortfalls; however, it is an important element of the
flexible, responsive. and integrated battle command system required for
POSITION AND NAVIGATION
The NAVSTAR GPS satellite is a space-based, all-weather,
continuous-operation radio navigation system that provides military
users highly accurate worldwide position and location data, as well as
velocity information and precision time. While GPS receivers do not
replace the map and compass or some of the other navigation systems
currently available, these lightweight man-portable systems satisfy more
of the Army's requirements than other available systems. GPS receivers
provide the soldier much useful information, such as positioning and
timing data; however, some other advantages to using the GPS are equally
- First, because GPS receivers do not
transmit any signals, they are not
- Second, the number of simultaneous GPS
users is unlimited.
- Third, although the accuracy of GPS is
subject to certain influences, it does not
vary over time as does the accuracy of
inertial navigation aids. Ongoing technical
refinements promise to strengthen the
robustness and reliability of the GPS
signal. GPS can quickly regain precision
accuracy after momentary disruptions
without further operator actions.
GPS greatly improves the commander's ability to locate units and to
control them on the battlefield, facilitating situational awareness and
improving agility and the ability to synchronize forces. GPS receivers
increase the ability to accurately locate assets and to move them long
distances over difficult terrain, especially during poor weather or
lighting conditions. The GPS, when used in conjunction with maps or
image products, can assist in all-weather, day-or-night rendezvous at
designated points and times under radio silence. Accurate positioning
data on friendly troops and on the location of minefields emplaced by
friendly units can simplify the passage of lines and reduce fratricide.
GPS output can be in any one of the three commonly used coordinate
systems: geographic, universal transverse mercator, or military grid
reference. Joint and combined operations benefit from a common user
grid. This grid allows units to use their specific coordinate position
system and then to convert it rapidly to common coordinates or into
similar systems used by other services or nations. Common positioning
also reduces the minimum separation distance requirements for artillery,
naval fire support, or close air support. The GPS's inherent accuracy
increases the accuracy of requested fires, reducing the expenditure of
ammunition as well as the risk of casualties caused by friendly fire.
The commander can also use GPS to manage critical assets that support
the battle, to include weapon convoys, fuel, and ammunition supply
points. The true value of POS/NAV equipment is that, for the first time,
ground forces have access to small, lightweight navigational tools--that
is, the SLGR and its replacement, the PLGR, AN/PSN-11--that are capable
of providing very accurate information. This capability can provide
POS/NAV information under most terrain and weather conditions. It will
also profoundly influence azimuth determination, air traffic control,
munitions guidance, and gun-laying operations.
The Army also has a limited number of commercial off-the-shelf (COTS)
geodetic-quality receivers that provide positioning accuracies within
millimeters. While engineers primarily use these systems to support
terrain analysis and mapping requirements, they can also be used to
support battle command and targeting. The cost and the necessity for
specially trained operators limit the use of these receivers.
SURVEILLANCE, AND TARGET ACQUISITION
Space-based sensors have the advantage of unrestricted access over
battlefields and other areas that are difficult to observe due to
political or military reasons. Space systems allow the commander to see
his area of operations and battle space, often far better than
terrestrial systems, and permit near-real-time exploitation of favorable
situations. This capability improves the agility, flexibility, and
synchronization of the force--important aspects of current Army
doctrine. Commanders can receive deep operations information as quickly
and as accurately as close operations information. When information
derived from space-based RISTA sensors is merged with information from
ground and airborne systems through the ASAS, IPB is enhanced,
situational awareness improved, and uncertainty reduced.
The Army's TENCAP Program, as executed by the ASPO, focuses on tactical
applications of national space systems. The program provides Army
commands with equipment (see Figure 4-3) that can receive and process
data from these systems. The result has been the development and
fielding of limited production equipment as operational systems that
provide a valuable adjunct to organic sensors.
The commander benefits from access to data on enemy troop movements,
lines of communications, and terrain conditions. He can use such
information to determine the enemy's intent through direction and mass
of enemy movement. The favored avenues of approach and the direction of
the main attack can point to the most effective time and location for
targeting friendly fires. Such information also offers opportunities for
target damage assessment after deep attack by fire. See The Joint
Tactical Exploitation of National Systems (J-TENS) manual for further
information on the TENCAP Program and system capabilities. The J-TENS
manual contains the procedures tactical commanders follow to obtain
The DSP offers an early warning missile surveillance capability during
operations. The DSP satellite constellation recognizes the launch of
strategic and certain tactical missiles using infrared sensors to detect
heat from missile plumes. Warning information consists of an assessment
of the time and place of launch, the type of missile launched, and the
missile's estimated course/direction. This information is provided to
supported CINCs via voice and data communications. SATCOM is used to
disseminate voice warning, and the TERS is used for data. The TERS is a
worldwide distribution system currently made up of the Tactical and
Related Applications (TRAP), Tactical Information Broadcast Service
(TIBS), and Joint Operation Tactical System Communications Network. This
launch warning data is communicated to Army forces within a theater to
support TMD operations. Today, warning information is both centrally
processed in CONUS and transmitted to the user via JTAGS prototypes that
are actively serving tactical users with direct in-theater downlinks
today. They will be replaced by van-mounted objective systems in the near
WEATHER, TERRAIN, AND ENVIRONMENTAL MONITORING
Detailed analysis of the environment, that is, weather and terrain, is a
critical step in the IPB process. Weather and terrain conditions impact
on friendly and enemy capabilities to move, shoot, and communicate. To
optimize the capabilities of modern weapons systems, the tactical
commander requires real-time weather and terrain information about his
battle space. Satellites with weather and terrain monitoring sensors are
a vital component in the information collection system. Weather and
terrain information must be collected and downlinked to a ground
processing unit where it can be used to prepare tailored products to
support decision making by tactical commanders.
Military and civil weather satellites provide worldwide, near-real-time
weather information. DMSP satellites obtain comprehensive information on
weather phenomena and atmospheric data. They can image weather phenomena
in both visual and infrared spectral bands. Simultaneously, they record
the temperature and moisture data throughout the swath width and at
various altitudes. Large DMSP receiver systems, known as Air Force Mark
IV vans, normally deploy to rear areas in mature theaters where they
receive data and relay products to corps and division SWOs via
facsimile. There it is analyzed and combined with other local weather
information that may be received through the IMETS to forecast
conditions throughout the battle space.
Civil geostationary satellites such as the GOES provide a hemispherical
view of weather patterns, while polar-orbiting satellites, such as the
television infrared observation satellite
(TIROS), provide a low earth view of the weather as they pass overhead.
Wraase weather receivers receive weather facsimile (WEFAX) and automatic
picture transmission images from US, Russian, Japanese, and European civil
weather satellites. They do not receive DMSP or other data, for example,
atmospheric temperatures and moisture content, transmitted by civil
satellites. Using the Wrasse weather receiver to exploit near-real-time
satellite-gathered weather data and making it available down to division
level has significantly improved forecasting at the tactical level of
operations. The public and private sectors have jointly made great advances
in exploiting space technologies, resulting in the rapid accumulation and
dissemination of weather data in immediately usable form to Army forces.
Understanding the limitations and opportunities of terrain is a
fundamental military skill. Terrain forms the natural structure of the
battlefield. Commanders must recognize the its drawbacks and potential
to protect friendly operations and to put the enemy at a disadvantage.
Terrain analysis is critical to current and projected operational uses
of specific terrain.
Much of the world is not adequately mapped to support Army operations.
Satellites collecting MSI can provide reasonably accurate,
medium-resolution data (see Figure 4-4) to aid in mapping and terrain
analysis. The DMA and some engineer topographic (TOPO) units can create
MSI maps primarily to be used as map substitutes in areas of the world
that are not adequately mapped to large scale. Satellite image mapping
capabilities can provide the most current data worldwide.
Terrain-sensing satellites using MSI can provide accurate 5-to-80-meter
resolution terrain data to support mapping and other analytical
requirements. In the near future, satellites will be capable of
providing HSI data that will further enhance map-producing capabilities.
The Army may establish purchasing accounts through the DMA to obtain
MSI/HSI data from sources outside the US, such as data from France's
SPOT earth resources satellite or Japan's MOS-1. This data will normally
be delivered to the requesting unit. The primary source of data for Army
units is collected with the earth imaging satellite Landsat, which is
channeled through the DMA through theater mapping, charting, and geodesy
channels. However, several other Army organizations (Topographic
Engineering Center [TEC] and USARSPACE) have been funded to procure
Landsat imagery. DOD involvement in the Landsat program and the creation
of a worldwide data base will vastly increase the availability and use
of MSI data within DOD. Using digital map data as a base, satellite
images can be fused to provide information, often only days old, that is
invaluable to commanders. Today, the Army's organic MSI manipulation and
analytical capabilities are just getting established. The ARSST at
USARSPACE is equipped and trained to bring COTS processors with these
capabilities to deploying units. Topographic support teams at the corps
and division levels manipulate MSI data using these processors. These
products can be used to support military engineering requirements and
IPB by identifying--
- Vegetation characteristics--cover and
- Snow/ice characteristics.
- Fording locations--water depth.
- Energy resources/facilities.
- Urban and cultural features
Merging MSI data with digital TOPO data and digital terrain elevation
data produced by the DMA provides three-dimensional perspective views.
These views highlight observation and fields of fire from both the
aerial and ground perspectives. A rough analysis of these images will
show potential ingress and egress routes and aid in the development of
trafficability assessments. This information could include soil
trafficability, mobility corridors, and perspective views of denied
areas, including enemy-controlled territory, contaminated areas,
minefields, smoke, forest fires, and many other conditions that may
arise in the operational environment that may critically impact battle
space awareness. In the IPB process, MSI is useful in determining
maneuverability and possible areas of enemy concealment and operations.
While satellites can provide the Army many valuable capabilities,
planners and users must understand some of their general limitations.
Though not all-inclusive, the following limitations represent areas that
must be considered when planning and requesting space support.
Launch operations are complex, time-consuming, manpower-intensive, and
costly. For these reasons, military satellites are national resources
supporting the NCA, CINCs, other services, and tactical users. As a result,
requirements may exceed system capacity and capabilities. A validation
process to determine what requirements will be satisfied is based on priority
and system availability. Potentially, this process limits the Army's
accessibility to satellite capabilities. Not only are these systems limited,
most are owned, controlled, or dedicated to exclusively supporting other
missions and may not be available to support Army requirements. Furthermore,
many satellites do not provide direct links to the ultimate user, often
requiring significant processing time by a third party to convert data into
usable media. This conversion further delays distribution to Army users. As a
result of having limited access, Army planners should explore the use of
commercial space systems when developing military operations plans.
Satellites are designed to survive the harsh space environment and have
a degree of hardiness that many ground systems do not have. While in
orbit, they may be affected by temperature extremes, radiation, solar
flares, meteoroids, and space debris. Imaging systems used for
reconnaissance can be affected by clouds, fog, and smoke.
METT-T affects employment of satellite ground terminals. They are also
affected by line-of-sight disruptions such as high foliage areas, low
take-off angles, placement in fringe areas of coverage, high usage in
small and close areas, and susceptibility to whatever military
capability--such as destruction, denial, disruption--an enemy force may
have to use against any other ground system in the area of operation.
The ground control and user segments represent the most likely targets
for an adversary. When planning the use of satellite systems, the
planner must consider alternatives in the event these systems are lost.
Satellites can be attacked, but they are not easy targets. Russia has
demonstrated a limited capability to attack and destroy satellites in
low earth orbit. Jamming satellite systems or the link between the
satellite and the ground segment of the system is also a threat. Not
lost on Operations Desert Shield/Storm observers was how much dependence
was placed on the use of satellite systems. Therefore, jam-resistant
satellite capabilities such as Milstar must become the backbone of our
satellite systems. Also imperative is that the Army should place more
emphasis on influencing their design and survivability. Military use of
commercial satellites must be expanded; however, risk as well as
benefits must be considered, given the vulnerability of these systems.
Operationally, the Army is dependent upon systems currently in orbit,
although these systems may or may not be suited to a particular Army
mission. Many satellites do not provide continuous coverage; for
example, Landsat sensors revisit equatorial points on the earth
approximately every 16-18 days. Moving a satellite to a more
advantageous orbit or position takes time and is limited to the amount
of fuel on board since satellites cannot be refueled. Satellites are
normally built with a high degree of survivability and redundancy, but
once damaged or having experienced component failure, their utility and
reliability are degraded. Furthermore, they are difficult to repair.
Generally, the orbital characteristics of a space system are related to
the function of the satellite (see Figure 4-5). Satellites may be at a
relatively fixed altitude (circular orbits) or vary in altitude
(elliptical orbits). Low orbits, being closer to the earth, best support
sensing requirements. The disadvantage of a low orbit is a limited view
of the earth and a relatively short time over any particular location.
As altitude increases, the field of view increases, but the ability to
resolve small objects decreases.
Another factor affecting the use of satellites is inclination--the angle
the satellite's orbital plane makes with the earth's orbital plane. A
higher inclination generally means that more of the earth is covered.
For example, a satellite in polar orbit (90 degrees inclination) will
observe the entire globe as the earth rotates through the orbital plane.
Inclinations from 0 to 90 degrees cover increasingly higher latitudes
for low-altitude satellites. The length of time between satellite
coverage of a particular location (that is, revisit time) depends upon
the number of satellites in a constellation and the capabilities of the
payload, such as direct versus slant view, type of frequency, band
width, data transmission rates, and sensor footprint size.
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