**Appendix B**

**Capabilities and Technologies (condensed versions)**

**Capabilities**

The following sections discuss the specific capabilities required to
accomplish the missions listed in Appendix A. For each capability, a
description will be provided followed by a status of the current
capability to be contrasted with the required levels. A first-cut
estimate of the mission need for that capability is given for each of
the identified capabilities based on the outcomes of the workshops. If
the capability supported at least half of the missions, it received a
"High" indicator; if it supported at least 25% of the missions, it was
given a "Medium" designation; and the remainder (those supporting less
than 25%) were rated "Low".

**Access to the National Air Space**

**Need: High**

Virtually all of the missions discussed will require access to either
the United States national air space and/or foreign air space at some
point in the flight pattern. Even missions intended for remote areas
require access to get the aircraft to the area. Often, this will require
access not only to United States air space, but foreign air space as
well. Access to the National Air Space can only be obtained through
certification of the aircraft or through a waiver termed a Certificate
of Authorization (COA). There currently exists no method to certify a
UAV through the FAA. Therefore, all UAV flight within the NAS has been
obtained through certificates of authorization thus far. A certificate
of authorization takes up to sixty days to obtain and only permits
execution of a predefined mission flight path on specific dates at
specific times and is typically valid for a very limited time period.
Many of the missions require fast access to the air space; it is not
sufficient to obtain a certificate of authorization because many of the
missions intend to study phenomena which are not predictable sixty days
in advance. The goal is to achieve seamless integration into the NAS
(the so-called "file-and-fly" status) through certification which means
that the flight may begin shortly after the flight plan is filed. This
is the same system used for piloted aircraft. An FAA certification
process must be established to achieve this. Several attributes of the
UAV will likely be required to be assessed before it is granted a
certification. One of these attributes is a method for the UAV to safely
integrate into the air traffic system. This will require the UAV
operator to respond in a timely fashion to commands from air traffic
control. Typically changes to course, altitude, speed, etc. are required
to avoid other air traffic. Another likely system is called contingency
management which allows the vehicle to plan for an alternate course of
action if something goes wrong requiring it to deviate from its original
flight plan. Inherent in contingency management is a vehicle health
management system which is capable of detecting anomalous conditions or
situations. A third attribute is a collision avoidance system which
allows the UAV to detect other aircraft and maneuver around them. In
summary, the UAV must achieve the equivalent level of safety as a manned
aircraft. A significant effort in systems sophistication, aircraft
reliability, and policy/regulation development, including policy on
operator training standards, will be required to accomplish this. The
technologies discussed in Sections through 4.3.2.5 are large
contributors to this effort.

Currently, UAVs cannot fly in the air space in the manner described
here. Developing the ability to provide "file-and-fly" is the goal of
NASA's HALE ROA Access to the NAS project (often called Access 5). This
project is to be accomplished in four steps.

1)  Develop and recommend policy to the FAA for routine UAV flight above
    40000 feet assuming launch and recovery in controlled air space.

2)  Develop and recommend policy to the FAA for routine UAV flight above
    18000 feet assuming launch and recovery in controlled air space.

3)  Develop and recommend policy to the FAA for launch and recovery in
    designated ROA-capable airfields.

4)  Develop the technology (if necessary) for sophisticated contingency
    management handling.

Steps 3 and 4 are currently unfunded. The Access 5 approach towards
achieving these goals is a seamless integration of UAVs into the air
space with little to no additional requirements being placed on existing
piloted aircraft. Before UAVs have file-and-fly capabilities, two other
steps are necessary. Once the policy has been developed and recommended,
it will still require FAA implementation. Finally, UAVs will likely need
the on-board technology to satisfy the policies adopted by the FAA.

**Command and control from an outside entity**

**Need: High**

Typical UAV operations utilize a mission manager programmed during
pre-flight to steer the vehicle around a prescribed course and altitude.
Some mission managers will allow the operator to define new waypoints in
flight. Future mission concepts require an ability for the aircraft's
mission manager to be directed during its mission from a number of
sources, including a ground-based operator or scientist observer, other
aircraft (e.g. formation flying), a payload sensor, or satellites. This
ability to re-direct a flight is instrumental for tracking dynamic
phenomena such as hurricanes or volcanic plume, for adjusting to
unplanned phenomena of interest, and for steering around unplanned
obstacles, such as adverse weather, to meet a mission objective. An
enabling technology to meet this capability is OTH communication, where
a 'sensor web' approach to the mission can easily be achieved. One
consideration is that allowing other entities to take control of the
vehicle provides a mechanism that hostile entities (e.g. terrorists,
hackers) can take advantage of. The system which develops must preclude
takeover by any hostile operations.

Currently some limited command and control authority can be exerted from
a ground-based operator on some UAVs. However, the technology required
for future missions has much broader implications on command and control
in terms of the level of autonomy it interfaces with and the
infrastructure that is implied. One example is in the scenario where the
payload sensor 'drives' the platform.

**Long Range and Endurance**

**Need: High**

Many of the missions conceive of a platform, or series of platforms,
which clearly extend range and endurance beyond the capability of
existing vehicles. These missions require ranges of 10,000 to 13,000
nautical miles (18500 to 24000 km) and endurances between 24 to 72
hours. A few of the missions indicated that endurances up to two to
three weeks would be beneficial, if feasible. In particular the
long-endurance requirements of these missions, as conceived, highlight
the necessity for a UAV platform.

Some existing production UAVs are capable of endurance in the 24 to 36
hour time frame. A few, notably Northrop-Grumman's Global Hawk, have
significant range capability. NASA, in conjunction with several private
companies, is working on the technologies to enhance this capability.
Under the HALE ROA demonstrator project, NASA is developing several new
aircraft with long endurance (one to two weeks) capability. The largest
advances in technologies for these aircraft are expected to come in the
propulsion and power generation areas.

**Increased Platform Availability**

**Need: High**

A key development for enabling future missions will be to increase the
availability of the science platform for collecting data. In other
words, future missions will require that the ratio between the amount of
time the platform is either on a mission or ready to start a mission to
the total time the platform is on deployment be increased. One key
component in increasing availability is the ability to significantly
reduce the amount of time to pre-flight and launch a mission. This not
only increases the availability of the platform for data collection, but
also increases the likelihood of being able turn a mission around to
collect data on dynamic events as they are discovered. Electrical and
power interfaces will have to be standardized. The ability to integrate
varied payloads in a 'plug and play' capability is necessary for quick
deployments and for quick turn-around between missions where a sensor
package may change. Intuitive flight planning tools and pre-flight
processes and an efficient process for downloading and archiving
on-board recorded data will also be key factors in reducing the time on
the ground. And platforms must allow maintenance and pre-flight
procedures to be performed easily and efficiently. Another key component
to increasing availability is increased platform endurance, which allows
the capability to extend mission duration. Analysis of current piloted
Earth Science missions show that significant costs are incurred based on
payload integration and deintegration time, and pre-flight and
post-flight preparation time. An added benefit to increasing
availability is a lower cost per flight hour, as the personnel required
to be on station are reduced.

Current technology assessments indicate limitations on availability are
based on human endurance, turn--around processes, payload, aircraft and
payload maintenance processes, and data downloading and archiving
procedures. Taking the on-board pilot 'out-of-the-loop' and smart
integration of these processes with intelligent vehicle health
management technology, autonomous mission management technology, and the
OTH web-based approach to communication will allow much greater aircraft
availability. For example the ability of the flight planner to interface
with the mission manager at the mission objective level will reduce the
level of human involvement in pre-flight processes. Another example is
the ability of the platform management system to identify when excess
bandwidth exists in the OTH and then to download and archive on-board
recorded data during the mission. This will reduce the level of human
interaction in performing this function post-flight. NASA's Earth
Sciences Capability Demonstration project is working on payload
interface standards to facilitate the "plug-and-play" concept for
payload integration. Much of this type of interface has not been done
before and depends heavily on other technologies such as autonomous
mission management.

**Quick deployment times**

**Need: High**

Several of the missions envisioned a UAV which could deploy within a few
days to an area of interest and launch a mission to collect data on a
dynamic phenomenon as it developed. The capability to quickly deploy
ties together many of the other capabilities previously defined. Key
enabling technologies are those that support access to the NAS, quick
and efficient payload integration, an OTH network available when needed,
and an intelligent mission management system which reduces pre-flight
planning activity.

This capability is strongly linked with platform availability.
Currently, quick and easy access to the NAS is not available but is
being developed by NASA and the FAA. Payload interface standards have
been developed to some degree and will be improved by NASA's Earth
Science Capability Demonstration project. OTH capability will also be
improved by the same project. The intelligent mission management
capability, formerly covered in AuRA, will be developed by NASA's HALE
ROA demonstrator project.

**Terrain Avoidance**

**Need: Medium**

To increase the spatial resolution for some missions, a requirement is
placed on the platform to fly 500 feet (152 m) above ground level or
even lower. The missions envision the use of both MAVs and UAVs in this
capacity and may include flight in mountainous terrain. As such, complex
flight path maneuvering and terrain avoidance is required of the
platform's flight management system.

The technology for terrain avoidance and terrain following has existed
for several years on military vehicles. Commercial airliners have
employed an Enhanced Ground Proximity Warning System for many years.
While the technology is available to implement this capability, the
integration to the platform requirements still exists.

**Formation flight**

**Need: Medium**

A technology related to precision trajectories is the ability to fly a
formation of aircraft maintaining precise distances between them.
Formation flight provides the ability to carry a synchronized set of
scientific sensors on a team of coordinated vehicles. In a flight
formation, one entity would be the "lead"; all other aircraft would fly
relative to the lead. The lead could be another UAV, a piloted aircraft,
or even a satellite. While it is not expected that an aircraft would
keep pace with a satellite, the ability to position the aircraft
relative to the satellite is desirable. Formation flight can be thought
as two separate capabilities. The first is a series of aircraft which
might be hundreds of meters to several miles apart. In this case,
precision is desirable, but sensors would need to work over large
distances. The second capability is close maneuvering wherein a pair of
aircraft would fly relative to each other in close proximity. This
capability would be used to accomplish air refueling as well as a small
aircraft "docking" to a larger one. Proximity sensors for this
requirement would probably be different from large-distance formation
navigation and would require accuracies down to the several-centimeter
level.

Most UAV operations involve one aircraft on a single mission. It is
expected that there will be a significant reduction of human operators
necessary to control a group of UAVs leading to a reduction in cost per
flight hour. The closest system to the "distant" formation is DOD's
station keeping equipment, but accuracies for this capability are far
less than what is desired for precision formation flight. Some
components of the close formation technology have been successfully
flight tested in NASA's Autonomous Formation Flight program and in the
J-UCAS program. These technologies can be leveraged to meet the future
science mission capability for formation flight.

**Monitor/control of multi-ship operations**

**Need: Medium**

Many of the future mission concepts require ground (operator) control of
multi-ship operation and coordination. A key enabling technology which
supports multi-ship missions is the over-the-horizon communication (see
Section ). Since a key motivation for using UAVs as an earth science
platform is reduced cost per flight hour, the ability of one operator to
monitor multiple vehicles significantly reduces the support personnel
required on-station. Also, some of the missions describe coordination
with mini- or micro- air vehicles.

Currently UAV operations involve one aircraft on a single mission. The
concept for future missions, where one operator controls a team of
coordinated vehicles, is just beginning to be developed with MAVs and
J-UCAS. Part of the J-UCAS program is to develop the capability of four
or more UAVs to operate as a coordinated team.

**Precision aircraft state data**

**Need: Medium**

Several missions required the ability to measure attitude data to
relatively high precision (as high as 0.001 degrees). There is an
additional requirement, however, for the aircraft to provide state data
to the sensors or experiment packages. For example, the need for precise
trajectories, accurate sensor pointing, and the onboard real-time
geographically referencing of cameras all require accurate vehicle state
data. The state data might be in the form of aircraft attitudes,
position, ground speed, air speed, etc. While it is possible that each
individual experiment packages might measure their own data, this
approach would be cumbersome, expensive, and inconsistent with the
plug-and-play philosophy. Provisions should be made for the UAV to
accurately measure its state data and make it available to the
experiment package(s).

For the most part, current technology can provide instruments capable of
generating state data to the desired level of precision. Therefore, this
capability exists but must be specified in the requirements for a given
platform, and there will be a cost associated with the requirement.

**High Altitude**

**Need: Medium**

Many of the missions require a platform, or series of platforms capable
of sustained flight at altitudes above 40,000 feet (12 km), with up to
100,000 feet (30 km) being desirable for some missions. A complicating
factor in required aircraft design is performance for an aircraft which
climbs to an altitude and cruises there versus an aircraft that must
traverse wide altitude bands. The latter capability is called vertical
profiling and is discussed in Section . An aircraft that will accomplish
both high altitude and vertical profiling is decidedly more complex.

Although an important capability, the ER-2 and Global Hawk have
routinely flown at most of the altitudes outlined in the future science
missions. Therefore, the ability to fly at relatively high altitudes is
an existing capability that only needs to be defined as a requirement in
the aircraft development. One caveat is that some missions desired
flight in the region of 100,000 ft (30 km) altitude. The Helios aircraft
has flown in that altitude region, but it is considered to be a
prototype and has limited payload capability. The inclusion of the
100,000 ft (30 km) requirement with a significant payload presents an
added level of difficulty.

**All-Weather**

**Need: Medium**

Some of the missions, such as the Hurricane Tracking Mission, indicate
that platforms are required to penetrate severe storms and fly in all
types of weather, including icing conditions, strong wind shears,
lightning, and severe convective environments.

Building a platform rugged enough to withstand flight in severe storms
is within current technology. However this requirement places additional
burdens on flight controls, and potentially platform performance goals,
depending on the design solution of system. For example, it would be
difficult to develop a high altitude, long endurance aircraft (which may
require a "gossamer" design) which would also survive high winds and
turbulence. One design solution for performing these is to launch a
series of rugged MAVs into the storm from a mother ship. The mother ship
can meet performance requirements without the burden of meeting this
requirement. The technology currently exists to build all-weather
aircraft, but the requirement must be stated at the time aircraft is
developed. It is difficult to "retrofit" all-weather capability to an
existing aircraft. All-weather capability will add to the cost of the
aircraft design and construction.

**Vertical Profiling**

**Need: Medium**

Some of the missions depict the collection of spatial data in the
vertical axis above a particular ground station of interest. Although
drop-sondes can be used for a limited set of vertical spatial
measurements, some of the missions envision the entire platform
performing vertical profile maneuvers to collect the data. As such, the
platform must deploy to a region of interest and collect data across a
vertical profile from its altitude ceiling down to 1000 feet above
ground level. This implies that the aircraft has sufficient performance
and power to maintain a reasonable climb rate over the majority of its
envelope which will impact the trade study for efficient climb versus
efficient cruise.

Designing a flight management system to perform vertical profiling
requires no new technology. Many current UAVs are capable of vertical
profiling. However, the combination of vertical profiling and high
altitude, long endurance may tax the aircraft designers.

**Deploy / potentially retrieve**

**Need: Medium**

One of the capabilities required for several of the missions is to have
a UAV act as a mother ship for the deployment of drop-sondes, buoys, or
small UAVs called daughter ships. In the case of the drop-sondes or
buoys, the mother ship would release these at designated locations
(pre-defined or initiated from the ground). The dispensing of
drop-sondes or buoys is relatively simple but suffers from several
drawbacks. First, the drop-sondes or buoys are not controllable; they
are maneuvered only by the wind and gravity. Second, a long mission may
require a large stock of drop-sondes or buoys to adequately cover the
area of interest. This may have some significant consequences on mother
ship payload weight and volume. Third, there are some environmental
concerns about "littering" areas with many drop-sondes or buoys which
may not be recoverable. An alternative to this approach is the use of
daughter ships which would be launched, fly to an area to collect data,
and then would fly back to the mother ship and re-dock. Daughter ship
data would be downloaded to the mother ship and the daughter ship would
be refueled for later use. This has the advantage that the daughter
ships would be re-usable, so the mother ship would not need to carry
nearly as many of them. The daughter ships would also be under the
control of the mother ship so that precise areas for information
gathering could be targeted. Daughter ships would be more complex and,
consequently, more expensive, but their ability to be recovered and used
again may offset the increased cost of purchase.

Deploying aircraft or drop-sondes from a mother ship has been done
previously and does not require new technology developments. However,
retrieving a daughter ship does require some technology development,
principally in the area of precision state data and formation flying.
Also, very little experience has been accumulated with the concept of
re-docking. Lockheed-Martin has made some proposals involving launching
and re-capture of UAVs. The common feeling is that if the technology
exists to autonomously refuel a UAV, that same technology can be used to
re-dock it. The concept of re-docking to a high altitude, long endurance
aircraft is also without precedent.

**Precision trajectories**

**Need: Medium**

Several missions require the location of the UAV to be controlled very
precisely. Flight trajectories within ±5 meters from the prescribed
flight path are desirable. This capability requires both the real-time
knowledge of where the UAV is and the ability to control or maneuver the
UAV to the desired position in the sky. Additionally, some missions have
constraints on the dynamics of the flight path so that high-gain system
may not be suitable.

The development of UAV control systems to maneuver the aircraft
correctly will be largely dependent on the characteristics of the UAV in
question. For years autopilots have been designed that follow a given
trajectory. The issue is whether a particular UAV system can be adjusted
to provide the desired precision. Unfortunately the ability to achieve
the desired precision is dependent on the type of aircraft. Aircraft
with light wing loadings and low speeds are more susceptible to
crosswinds and gusts which may hamper the ability to maintain an
accurate position. Regardless of the controllability characteristics of
the UAV in question, this capability has been demonstrated. The Danish
Center for Remote Sensing has demonstrated flights to approximately
five-meter accuracy using a business jet. NASA's Earth Science
Capability Demonstration project is pursuing the capability to maintain
aircraft position with a 10-meter (or better) tube. However, the
integration to UAVs on a wide scale has yet to be demonstrated.

**Base of operations in remote area**

**Need: Low**

The capability to deploy a small, inexpensive UAV from a remote location
near an area of interest was conceived to obtain specific scientific
data in remote areas. The requirement for this capability is a UAV
platform which requires very little support equipment and minimal
personnel for pre-flight, launch, and recovery. With this capability,
range and endurance requirements on the UAV platform can be reduced.
This concept may also impact the mode of operation for an autonomous
ground station which could pave the way for a planetary-exploring UAV.

Certainly MAVs can be launched with minimal support personnel and
equipment without any advances in technology; however the concept of a
fully automated ground station has not been demonstrated. Using them for
the Earth Science application may depend on payload sensor technology
advances, since payload weight and volume capability is limited. Also,
it is likely that high levels of automated mission management,
intelligent flight control, and health monitoring may not be available
because of the limited computation resources on a MAV. Therefore payload
sensors on a MAV may have to be expendable. The construction of a more
sophisticated, even autonomous, base of operations in a remote area
(even the Moon or another planet) remains in the conceptual state only.

**Covert Operations**

**Need: Low**

A subset of the missions, primarily from the Homeland Security and
wild-life monitoring communities, required platforms with low detection
probability. Implicit in this requirement is low noise emission
propulsion systems and low signal emissions.

Conventional propulsions have undergone low noise emission developments
to support stealth for the military application and airport
considerations for the commercial sector. Although certain propulsion
systems, such as electric motors, provide very low emissions, it is
unclear they can sustain some of the endurance and payload requirements
envisioned in the missions. Development programs to enable more
efficient electric motors are being conducted in both the commercial and
government sectors that may enhance the capability for low noise
operations.

**Technologies**

**Technology Analysis**

The following sections describe each technology in detail, summarizing
development programs and forecasting maturation over the next 10 years.
A determination of when the technology has matured enough to support the
capabilities identified from the missions is provided where appropriate.
More detailed information on the technology development can be found in
Appendix G. Within the title of each technology section, a first-cut
estimate of the need of that technology or capability is given. If the
technology supported at least half of the missions, it received a "High"
rating. If it supported at least 25% of the missions, it earned a
"Medium" rating. The remainder (those supporting less than 25%) were
rated "Low".

**Autonomous mission management**

**Need: High**

A high level of autonomy in the mission management function is required
to take advantage of using a UAV platform to support the missions. Less
direct human interaction in flying the UAV allows less on-station
personnel, less on--station support infrastructure, and one operator to
monitor several vehicles at a given time. These goals must be balanced
with the requirement for the operator and vehicle to respond to air
traffic control in a timely manner. The mission management system should
also allow re-direction of the mission (including activating the
contingency management system) from the ground. This would especially be
useful for moving phenomena which cannot be adequately located prior to
mission initiation. It is envisioned that the human interaction with the
on-board mission manager system will occur at the mission objectives
level. In the ideal scenario, the on-board mission manager, starting
with the mission objectives, would be responsible for pre-flight
planning, real-time flight path adjustments during the mission, and even
real-time mission objective adjustments during the mission based on air
traffic control and contingency management. It is also desired for the
scientist or possibly the payload sensor to interact with the mission
manager, as well as the operator responsible for the mission. Providing
these functions will require a shift in the paradigm of how flight
management software is currently written. The desired system is an open
behavior system. This approach enables much of the capability conceived
in the future missions, such as efficient mission re-tasking, increased
platform availability, efficient contingency management, and coordinated
team formation flying. As such it is highly dependent on the current
condition at the time a behavior is executed and is difficult to
precisely predict. Increasing the complexity is the fact that any intent
to deviate from the original mission plan must be first conveyed to and
approved by air traffic control prior to being executed. The level of
autonomy in the system presents significant human factors challenges to
the operator, who must maintain sufficient situational awareness of the
intention and execution of the platform to fulfill his responsibility.

The level of autonomy in the future mission management function is
significantly more sophisticated then exists with current UAVs.
Additionally, verification and validation of these systems will be a
challenge. Currently the Joint Unmanned Combat Air System program
(J-UCAS) is employing a similar software approach to mission management.
NASA, under the HALE ROA demonstrator program, is also working on a
similar Intelligent Mission Management system. The TRL is estimated at
4, since some components of these methods are modeled in the simulation
environment.

**Collision Avoidance**

**Need: High**

To fly with few restrictions in the NAS, UAVs will require some sort of
collision avoidance system. The intent is to have an "equivalent level
of safety" when compared to piloted aircraft. This system will allow
UAVs to "see" or detect other aircraft (piloted or uninhabited) and
avoid them. The technology for this system is decomposed into two
elements "see" and "avoid". The "see" portion involves the detection of
intruding aircraft through some type of sensor. The "avoid" portion
involves predicting if the intruding aircraft poses a danger and what
course of action should be taken through a software algorithm. For
sensors, the priority should be to detect aircraft at sufficient
distance so that emergency maneuvering can be avoided. The first step in
this development will be to implement a ***cooperative*** sensor for
collision avoidance. Under the cooperative category, aircraft will have
transponders or data links notifying other aircraft of their position.
The second and more difficult portion is ***non-cooperative***
detection. In this case, the "other" aircraft does not share its
position (as would be the case for many general aviation aircraft) and
must be detected with radar or optics. For avoidance, sensor information
must be used to predict future positions of host (ownship) and intruder
aircraft to determine collision potential. If a collision potential
exists, a safe escape trajectory must be derived and automatically
executed if the operator has insufficient time to react.

Some significant work has already been done in this area. The NASA ERAST
project tested both a cooperative and non-cooperative sensor. Also, the
Air Force has completed a project evaluating an avoidance algorithm
coupled to an automatic evasion maneuver. Both cooperative and
non-cooperative sensors were demonstrated in the Air Force project with
promising results. Collision avoidance systems are also being worked
under NASA HALE ROA Access to the NAS project. The overall TRL for this
technology is estimated to be at 6. However, no viable non-cooperative
sensor or sensor suite has been developed to date placing this component
at a TRL of 2.

**Intelligent system health monitoring**

**Need: High**

The ability of a UAV system to reliably identify failures and classify
them according to their impact on vehicle safety and mission success is
a key technology for flying UAVs with an acceptable level of safety.
This technology, generic to any UAV application, allows intelligent
contingency management based on the failed vehicle state and is a
foundation for free access to the air space by UAVs. Additional cost
benefits are accrued by using this system to monitor sub-systems for
maintenance purposes. Identification of sub-systems as they deteriorate
will focus maintenance efforts, decreasing the turn-around times between
missions and reducing costs per flight hour.

Health monitoring concepts and limited systems have been around for some
time, but comprehensive and generic systems have languished due to lack
of funding. Specific systems have been developed and proven,
particularly for new fighter aircraft. Additional work is in progress
under NASA's HALE ROA demonstrator project (previously under the AuRA
program). An overall TRL of 5 is assigned.

**Reliable Flight Systems**

**Need: High**

The ability of a UAV flight system to adapt to system or hardware
failures is a key technology for flying UAVs with an acceptable level of
safety and perhaps the most critical system for the aircraft is the
flight control system (FCS). This technology, generic to any UAV
application, provides for high reliability and is one of the foundations
for unrestricted access to the air space by UAVs. Initial reports from
the FAA regarding UAVs indicate they are looking for "reliability
comparable to a piloted aircraft". The issue of reliability can be
addressed from two viewpoints. The first is basic reliability of the
onboard systems. The second is the reliability of an on-board pilot in
being able to recognize a failure and adapt to the situation (see
Section on Sophisticated Contingency Management). Both of these
viewpoints must be considered in assessing the reliability of UAV flight
systems. This technology is especially important for long endurance
flights in remote areas, where options for recovery are limited.

One approach to system reliability is simply to increase the redundancy
of flight systems. This comes with both an initial cost and an on-going
weight penalty. Another approach would add on-board intelligence to
recognize and remedy a failure. Simulations of adaptive flight control
systems have shown promise for many years, and several methods of
adaptive control have found their way to flight test projects. The
latest of these is a neural-net based system scheduled to fly on an F-15
aircraft at NASA. It is likely that the final solution will be a
compromise or combination of the two approaches. Based on ongoing
intelligent flight control efforts, a TRL of 6 is assigned.

**Sophisticated contingency management**

**Need: High**

UAVs will require some level of contingency management system to all
flight in the NAS. The on-board contingency management system should
react to unforeseen events and failures according to the something like
the following priorities:

> 1\) Minimize expectation of casualty (E~c~)
>
> 2\) Minimize external property damage
>
> 3\) Maximize the chance of aircraft survival
>
> 4\) Maximize the chance of payload survival

For the long term, it will be unreasonable to consider many UAVs as
expendable. In addition to the cost of UAV, the cost of its sensor suite
(which may be one-of-a-kind) must be considered. Loss of the UAV and
payload should only be considered when there is a significant risk to
the general public or property. One of the primary contingencies to be
planned for is the loss of link between the UAV and the operator. In
this case, if the vehicle can not continue on its original mission plan
the vehicle should have the capability to achieve an approved landing
area while considering the priorities above and attempting to
re-establish the communications. During these events, the UAV must have
alternate means to communicate its intended flight plan. However, other
contingencies must also be considered. These might include sensor or
payload failures, aircraft failures, and other communication failures.
The contingency management system should be able to decide, depending on
the nature of the problem whether it should attempt landing at the
airport it was based out of, or a landing at an alternate airport, or
some other impact (ditch) in a remote area. Intelligent contingency
management will also reduce the human oversight required for UAV flight
and contribute to the goal or reducing mission costs.

Contingency management for UAVs at the level described will require a
sophistication that currently doesn't exist. Relatively little
development of this capability has occurred to date although several
promising concepts have been proposed. Global Hawk and Predator have
contingency management systems to some degree, although they lack the
sophistication and intelligence that would be desirable for ease of use.
NASA, under the HALE ROA in the NAS project, is currently working to
define a UAV "code of ethics" and policy regarding contingency
management systems. An overall TRL of 4 is assigned.

**Intelligent Data Handling and Processing**

**Need: High**

As UAV's become more ubiquitous in their use to gather science data or
perform other civilian tasks, the gathering of very large amounts of
data will become an operational hindrance, and provide an opportunity to
the system developer. The ability to intelligently handle and process
large amounts of data, either onboard the air vehicle, or on the ground
immediately after being transmitted from the vehicle, is required.
Technology that would provide this capability would significantly
provide greater efficiency to the operator or payload scientist, and
would help expedite vehicle turn-around, quick deployment, and
multi-ship operations; particularly for long-endurance missions.

If this data analysis capability were to be available on the ground, and
if high-bandwidth communication (probably satellite based, to enhance
the timeliness of the action) is available, the air vehicle could
transmit the data to the mission control center for quick analysis and
possible mid-mission re-tasking.

The ability to process the data onboard goes a step further and becomes
even more useful, because it doesn't require a high-bandwidth satcom
capability. Intelligent onboard data handling and processing would lead
to the use of onboard decision aids and intelligent payload-based
mission management technology, which could result in efficient onboard
mission re-tasking. Alternatively, onboard processing could allow only
low-bandwidth high-order processed data being relayed to the mission
planners for decision-making and mission re-tasking if necessary.

In addition, onboard processing and transmission could allow scientists
quick and easy data retrieval, which could relate to faster post-mission
processing and the beginning turn-around processing, all while the
vehicle is still returning to base.

Intelligent data handling and processing would require technology
innovations in automation and autonomous data analysis systems,
efficient and effective techniques for assembling and processing large
amounts of data, and intelligent searches of large distributed data
sets.

For this technology a TRL of 2 is estimated.

**Over-the-Horizon Communication**

**Need: High**

A key technology that supports almost all of the future missions is the
ability to transmit data over the horizon (OTH). This satellite-based
communication capability is being used by the military today to provide
UAV over-the-horizon C2, FAA air traffic control communication, and
sensor data transmission. Although low-bandwidth OTH communication is
used by civilian UAV's, access to OTH resources for high-bandwidth
civilian use is limited and needs to be expanded. Also, the issue of OTH
communication being non-interruptible, jam resistant, damage tolerant,
and all-weather capability must be addressed. The OTH technology must
also include the ability to pass high bandwidth data from remote areas
or at extreme latitudes such as the poles.

In addition, it will be very valuable to develop a "web-based" network
capability to OTH communication (see Network-Centric Communication
technology section). The vehicle, operator, and payload scientist would
be seen as nodes of the network. For example, this approach means that
an operator in California could control an aircraft flying over the
North Pole while a scientist in Washington, DC was monitoring the
vehicle's science data. Additionally, this network concept for OTH
communication should be configurable based on the data flow requirements
for a given mission. In other words the network should be able to
provide the level of bandwidth required for a given mission so that
missions which don't require high bandwidth communication do not have to
pay for the resources necessary to affect it. This technology will
reduce the cost per flight hour by creating more efficient data handling
and reducing the need for personnel at the base of operations.

However, the concept described here significantly expands the concept of
OTH communications. Adjustable bandwidth's and a 'web-based' use are
concepts that still require significant technology developments. There
is strong interest in this concept from both civilian (NASA) and DOD
agencies. NASA is pursuing this technology under their Earth Sciences
Capability Demonstration project in conjunction with the Integrated
Network Enhanced Telemetry (iNet) efforts. For this technology a TRL of
3 is estimated.

**Network-Centric Communication**

**Need: High**

Network-centric communication is a command and control and sensor data
communication architecture concept that is comprised of multiple
directional, asymmetric links that provide a network communication
approach -- similar to the Internet. This communication architecture is
under development by the military for use between manned and unmanned
air vehicles and personnel within a particular battle space -- but it is
also needed to enhance civilian UAV operations, communications, and
science data flow. For a given mission, key elements within the UAV's
mission are to be considered as a node; data can then flow to and from
any node to any other node. Examples of nodes are the UAV operator, a
scientist observer, the vehicle platform's mission manager, satellites
orbiting overhead, the vehicle's payload, other aircraft, remote command
and control locations, etc.

Although the obvious key benefit is increased command and control and
data routing flexibility, this same flexibility also adds communication
signal protection, allowing entirely different received and transmitted
radio waveforms that can be used to advantage to provide more secure
communication.

In concept, the network should be available with very little interface
required by the mission planning team. Additionally, the network should
be bandwidth configurable based on the data flow requirements for a
given mission. This technology will reduce overall operational cost by
creating more efficient data handling and reducing the need for
personnel at the located at the UAV's primary base of operations.

NASA is pursuing this technology under their Earth Sciences Capability
Demonstration project in conjunction with the Integrated Network
Enhanced Telemetry (iNet) efforts. For this technology a TRL of 3 is
estimated.

**Open Architecture**

**Need: High**

Many civilian UAV mission requirements require quick deployments and/or
quick turn-around times between flights. These requirements have
implications on the UAV's system architecture -- and thus the need for
open architecture.

Open architecture is envisioned as a system design technology that
literally provides a "plug and play" capability within the UAV system.
If a UAV system or its modular payload component has an operational
problem -- ground maintenance personnel can easily and quickly replace
the faulty element. Sensors, sensor systems, and even mission payloads
could be designed as modular components for easy change-out between
storage and air vehicle, or from air vehicle to air vehicle -- in some
cases, even if the air vehicles are different.

Open architecture could encompass the advanced communications systems
network at well. As the air vehicle's communication system moves towards
a more generic network centric design, some vehicle-system communication
elements could be designed with the same quick change-out methodology as
well.

For this technology a TRL of 4 is estimated.

**Power and Propulsion**

**Need: High**

Many missions call for flight to high altitudes, to have long endurance,
or to fly within "dirty" air (such as through the smoke plume of a
forest wild fire). Such missions will require specially designed power
and propulsion technologies.

A high-altitude flight requirement typically dictates the use of turbine
engine propulsion -- or for slower flight, the use of electric
propulsion; each of which are well developed and demonstrated at this
point. If internal-combustion engine technology is desired for this
flight requirement, due to its inherent low cost and relatively low rate
of fuel consumption, a two-stage turbocharger can be used -- and this
has been demonstrated.

For long endurance flight, the propulsion options are varied, and
continue to be developed. Typically, conventionally powered
long-endurance vehicles require a fuel load equal to 40% to 60% of their
gross takeoff weight. This, in turn, provides design and payload
tradeoffs that can limit function. Another method that has been used
with long-endurance UAV's is to use solar power and electric propulsion.
Solar power cells, more technically known as \"photovoltaic (PV)\"
cells, are not very efficient (with modern technology conversion factors
on the order of 18%-21%), and the amount of energy provided by the Sun
over a unit area is relatively modest. This means that a solar powered
aircraft must be lightly built to allow low-powered electric motors to
get it off the ground. Considerable technology development in this area
is required.

Clearly, for long endurance and high altitude flight, electric
propulsion is a key technology and one that hold great promise. New
technology is being developed in many areas: high-efficiency and
high-torque brushless "outrunner" motors, advances in non-silicon
flexible PV technology that could be used as embedded aircraft skin,
advanced standard and regenerative fuel cells, and advances in lithium
polymer battery technology hold great promise. Other relevant
technologies could also enhance long endurance flight with conventional
engines: efficient combustion technology, intermittent combustion,
hydrogen engines, and new efficient power management and distribution
technology are being pursued.

For the advanced technologies discussed, their TRL's are estimated to
vary within the range of 3 and 5.

**Navigation Accurate System Technology**

**Need: Medium**

The need for navigational accuracy within the UAV's onboard system is
required for a number of mission tasks. For example, the need for
precise trajectories, accurate sensor pointing, and the onboard
real-time geographically referencing of EO or IR pictures all require
accurate vehicle position and attitude data.

Such navigation accurate technology can be obtained with current
technology. A vehicle's position can be easily obtained onboard with a
GPS receiver. And the vehicle's 3-axis attitude can be determined with
an onboard inertial measurement unit (IMU).

However, standard GPS data may not be sufficiently accurate. In this
case, the use of differential GPS (dGPS) data, to correct the embedded
random GPS errors, may be necessary. This is available real-time onboard
a UAV by use of a small omni-directional antenna and a subscription to
commercial satellite-based data. Normal computation drift of a miniature
IMU can also be self-corrected by use of the accurate GPS data. NASA's
Jet Propulsion Laboratory (JPL) has flight tested a Global Differential
Global Positioning System (Global DGPS) which advertises accuracies in
the 10 centimeter range over populated land areas and 50 centimeter
range over areas like the North and South Poles.

This navigation and attitude data is then used to either point on
onboard camera to a desired GPS location on the ground; or the reverse,
to calculate the ground location of an object that was visually captured
by the science payload.

All of this is currently being used on large UAV's, but the technology
development required is to miniaturize this technology for use on small
UAV's and thus expand the mission utility to these vehicles.

For application to a small UAV the technology is estimated at a TRL of
4.

**Enhanced Structures**

**Need: Medium**

The flight performance and utility of a UAV designed to fly either, or
both, at high altitude or with long endurance can sometimes be
significantly constrained due to the weight and design limitations
placed on these unique aircraft by the aircraft's structure.
Conventional structural materials provide adverse penalties on vehicle
weight and design flexibility.

The use of advanced low-weight structures, and advanced low-cost
composite manufacturing methods, and active flight elements, will allow
significantly reduced structural weight and the use of bold,
unconventional aerodynamic designs. This, in turn, can significantly
enhance the useable science payload size and weight.

New lightweight material development, flexible structural controls,
"morphing" aircraft airfoil and planform shapes, and active flights
controls for gust alleviation and to maximize performance efficiencies
may have significant impact in this area.

For the advanced technologies discussed, their TRL's are estimated to
vary within the range of 1 and 3.