NASA/TM-2009-214647

NASA Global Hawk: A New Tool for Earth 

Science Research

J. Chris Naftel

NASA Dryden Flight Research Center

Edwards, California

May 2009
NASA STI Program ... in Profile

Since its founding, NASA has been dedicated

to the advancement of aeronautics and space

science. The NASA scientific and technical

information (STI) program plays a key part in

helping NASA maintain this important role.

The NASA STI program operates under the

auspices of the Agency Chief Information

Officer. It collects, organizes, provides for

archiving, and disseminates NASA’s STI. The

NASA STI program provides access to the NASA

Aeronautics and Space Database and its public

interface, the NASA Technical Report Server,

thus providing one of the largest collections of

aeronautical and space science STI in the world.

Results are published in both non-NASA channels

and by NASA in the NASA STI Report Series,

which includes the following report types:

• TECHNICAL PUBLICATION. Reports of

completed research or a major significant

phase of research that present the results of

NASA Programs and include extensive data

or theoretical analysis. Includes compilations

of significant scientific and technical data and

information deemed to be of continuing

reference value. NASA counterpart of peerreviewed formal professional papers but has

less stringent limitations on manuscript length

and extent of graphic presentations.

• TECHNICAL MEMORANDUM. Scientific

and technical findings that are preliminary or

of specialized interest, e.g., quick release

reports, working papers, and bibliographies

that contain minimal annotation. Does not

contain extensive analysis.

• CONTRACTOR REPORT. Scientific and

technical findings by NASA-sponsored

contractors and grantees.

• CONFERENCE PUBLICATION. Collected

papers from scientific and technical

conferences, symposia, seminars, or other

meetings sponsored or co-sponsored

by NASA.

• SPECIAL PUBLICATION. Scientific,

technical, or historical information from

NASA programs, projects, and missions,

often concerned with subjects having

substantial public interest.

• TECHNICAL TRANSLATION. Englishlanguage translations of foreign scientific

and technical material pertinent to

NASA’s mission.

Specialized services also include creating

custom thesauri, building customized databases,

and organizing and publishing research results.

For more information about the NASA STI

program, see the following:

• Access the NASA STI program home page

at http://www.sti.nasa.gov

• E-mail your question via the Internet to

help@sti.nasa.gov

• Fax your question to the NASA STI Help

Desk at 443-757-5803

• Phone the NASA STI Help Desk at

443-757-5802

• Write to:

NASA STI Help Desk

NASA Center for AeroSpace Information

7115 Standard Drive

Hanover, MD 21076-1320

This page is required and contains approved text that cannot be changed.
NASA/TM-2009-214647

NASA Global Hawk: A New Tool for Earth 

Science Research

J. Chris Naftel

NASA Dryden Flight Research Center

Edwards, California

May 2009

National Aeronautics and

Space Administration

Dryden Flight Research Center

Edwards, California 93523-0273
NOTICE

Use of trade names or names of manufacturers in this document does not constitute an official

endorsement of such products or manufacturers, either expressed or implied, by the National Aeronautics 

and Space Administration.

Available from:

NASA Center for AeroSpace Information

7115 Standard Drive

Hanover, MD 21076-1320

(301) 621-0390
ABSTRACT

Scientists have eagerly anticipated the performance capability of the National Aeronautics and Space 

Administration (NASA) Global Hawk for over a decade. In 2009 this capability becomes operational. 

One of the most desired performance capabilities of the Global Hawk aircraft is very long endurance. The 

Global Hawk aircraft can remain airborne longer than almost all other jet-powered aircraft currently flying, 

and longer than all other aircraft available for airborne science use. This paper describes the NASA Global 

Hawk system, payload accommodations, concept of operations, and the first scientific data-gathering 

mission: Global Hawk Pacific 2009.

NOMENCLATURE

ACTD	 	 Advanced Concept Technology Demonstration

APCS	 	 airborne payload C3 system

ATC	 	 air traffic control

BLOS	 	 beyond line of sight

C2	 	 command and control

C3	 	 command, control, and communications

COA	 	 certificate of authorization

DFRC	 	 Dryden Flight Research Center

EAFB	 	 Edwards Air Force Base

EIP	 	 experiment interface panel

FAA	 	 Federal Aviation Administration

FOR	 	 flight operations room

GHOC	 	 Global Hawk Operations Center

GPCS	 	 ground payload C3 system

GPS	 	 global positioning system

HALE	 	 high altitude long endurance

LOS	 	 line of sight

NAS	 	 National Airspace System

NASA	 	 National Aeronautics and Space Administration

NGC	 	 Northrop Grumman Corporation

NOAA	 	 National Oceanic and Atmospheric Administration

nm	 	 nautical miles

POR	 	 payload operations room

Satcom		 satellite communications

SER	 	 support equipment room
UAS	 	 unmanned aerial system

UHF	 	 ultra high frequency

USAF	 	 United States Air Force

VHF	 	 very high frequency

INTRODUCTION

The National Aeronautics and Space Administration (NASA) Dryden Flight Research Center (DFRC) 

(Edwards, California) acquired two Advanced Concept Technology Demonstration (ACTD) RQ-4A Global 

Hawk (Northrop Grumman Corporation, Los Angeles, California) aircraft from the United States Air Force 

(USAF). These pre-production Global Hawk aircraft are being used to support NASA and the National 

Oceanic and Atmospheric Administration (NOAA) science customers as well as additional customers 

who require access to a high-altitude, long-endurance system. The DFRC and the Northrop Grumman 

Corporation (NGC) have entered into a five-year Space Act Agreement that includes the development and 

operation of the NASA Global Hawk system. The NGC is providing technical, engineering, maintenance, 

and operations support, as well as the ground control station. The DFRC is providing facilities; flight 

approval responsibility; flight operations coordination; and maintenance, operations, and project staffing. 

The NGC and NASA will share equal access to the NASA Global Hawk system.

NASA GLOBAL HAWK SYSTEM DESCRIPTION

The DFRC is located within Edwards Air Force Base (EAFB) and is 65 miles northeast of

Los Angeles, California. It is from the DFRC facilities that the two Global Hawk unmanned aircraft are 

being operated. This section describes the aircraft, the DFRC facilities, and operational and payload-related 

features, including those features that are unique to the NASA Global Hawk system.

The NASA Global Hawk Aircraft

The NASA ACTD Global Hawk aircraft have the same geometry and similar performance

characteristics as the USAF RQ-4A (Block 10) air vehicles. The Global Hawk aircraft provides a unique 

combination of high-altitude and long-endurance performance capabilities that can meet many demanding 

payload and mission requirements. The Global Hawk aircraft has demonstrated the capability to carry more 

than 1,500 lb of payload to 65,000 ft with mission endurance of over 31 hr and a total range in excess of 

11,000 nm. With this total range capability, the aircraft can fly down range 2,000 nm from the operations 

base, remain on station for 20 hr, and return to the same operations base. For example, the aircraft can fly 

from EAFB to the Arctic region, collect scientific data for over 7 hr, and return to EAFB. 

The Global Hawk is a mid-wing, long-range, long-endurance, single-engine unmanned jet aircraft 

that typically operates as a fully autonomous vehicle using a comprehensive pre-loaded mission plan. The 

execution of the mission plan begins when the aircraft is commanded to taxi onto the runway and ends when 

the aircraft rolls to a stop after touchdown. 
The typical flight profile of the aircraft consists of a rapid climb to approximately 55,000 ft; a subsequent 

climb at a lower, steady rate as fuel is expended until the aircraft reaches its maximum operational altitude 

of 65,000 ft; and flight at maximum operational altitude until the aircraft returns to the operations base and 

descends for landing.

Ground Facilities

Both of the NASA Global Hawk aircraft reside in a hangar located within DFRC. A joint DFRC/

NGC team maintains the aircraft, integrates the payloads, and conducts ground operations. Within the same 

hangar, a dedicated payload work area is available for visiting customers. This customer workspace is both 

climate and access controlled, and is available for all payload-related activities, including payload buildup 

and payload checkout. Before integration into the aircraft, the payload is connected to a payload test bench 

in the hangar for verification of power and data connections, and to verify that the payload is capable of 

providing health status through the Global Hawk payload communications system.

The Global Hawk Operations Center (GHOC) is located within a building at DFRC. The GHOC is 

used to support all ground testing, training, and worldwide flight operations of the NASA Global Hawk 

aircraft. The GHOC consists of consoles used for the command and control (C2) of the aircraft, monitoring 

of the aircraft systems, air traffic control (ATC) coordination, mission planning, and all payload-related C2 

and data display functions.

The GHOC consists of three rooms: the flight operations room (FOR), the payload operations room 

(POR), and the support equipment room (SER). The FOR has workstations for the pilot, flight support 

engineer, mission director, GHOC operator, and a range safety officer. The POR has workstations for up to 

14 customers. Each POR workstation is connected to the aircraft payload network via an Iridium (Bethesda, 

Maryland) satellite communications (Satcom) link. The SER contains the racks of equipment that support 

the workstations located in the FOR and POR. The SER also serves as an observation area while missions 

are being conducted.

A combination pilot trainer and mission simulator is located at DFRC near the GHOC. The software 

and pilot interfaces are identical to the software and interfaces in the GHOC. This facility is used for pilot 

training when the GHOC itself is not available for training.

Communications Between the Global Hawk Operations Center and the Aircraft

Although the Global Hawk system consists of an autonomous aircraft that is fully capable of executing 

a pre-programmed mission plan, communication links are active between the DFRC GHOC Center and the 

aircraft at all times during a mission. These links permit the pilot to send commands and receive system 

status information from the aircraft’s mission computers, and to conduct two-way audio communications 

with ATC via radios on board the aircraft. Separate and fully independent communications links are used 

for command, control, and data communications with the payloads on board the aircraft.

The NASA Global Hawk is operated in two distinct regions: line-of-sight (LOS) and beyond

line-of-sight (BLOS) of the ultra high frequency (UHF) ground antennas located at DFRC. The 


communications link used for aircraft LOS C2 is a UHF-band link. The primary communications links 

used for aircraft BLOS C2 are a primary Iridium Satcom link and a redundant Iridium Satcom link. An 

International Maritime Satellite Terminal Satcom link provides a backup aircraft C2 communications 

capability. The BLOS ATC bi-directional audio communications between the pilot located in the GHOC 

and the aircraft are conducted using a primary Iridium Satcom link and a redundant Iridium Satcom link. 

The aircraft has an onboard UHF/VHF radio set that is used to transmit and receive voice communications 

between the aircraft and ATC. The use of the Iridium system for aircraft C2 and ATC communications 

provides complete global coverage, including the Polar regions. 

The NASA Global Hawk payload communications links are fully independent of the communications 

links used to operate the aircraft. Four dedicated Iridium Satcom links are used for continuous narrow band 

communications between the GHOC and the payloads on the aircraft. This narrow band communications 

capability allows customers to send payload commands from dedicated payload workstations in the payload 

operations room of the GHOC, and receive real-time status and low-rate data from their instruments 

throughout the duration of the mission. The flight crew uses two additional Iridium links to monitor power 

consumption by individual payloads, and to control features such as lasers and dropsonde dispensing. A 

wide-band payload data telemetry link will be added to the NASA Global Hawk system in the near future.

PAYLOAD ACCOMMODATIONS

The NASA Global Hawk aircraft can carry payloads with a total weight of up to 1,500 lb in 

compartments with a total approximate volume of 336 ft3. Two types of payload spaces are available: 

pressurized compartments, which are conditioned during the flight by the environmental control system 

of the aircraft, and non-environmentally controlled compartments, which will experience the ambient 

temperature and pressure conditions present during a flight.

Payload Command, Control, and Communications System

The core element of the NASA Global Hawk payload capability is the new Global Hawk payload 

command, control, and communications (C3) system, which consists of the airborne payload C3 system 

(APCS) and the ground payload C3 system (GPCS). The C3 system enables every payload in the aircraft 

to be constantly monitored and controlled throughout the mission by payload principal investigators and 

controllers located in the GHOC.

The airborne and ground Global Hawk payload C3 system is an integrated, TCP/IP based, 

communications network. This system permits a payload operator, working at a payload workstation in 

the GHOC POR, to communicate with their airborne payload instrument interface, which is similar to 

communicating with another IP address on a local wireless network.

When a payload is connected to the APCS on the aircraft, it will have access to the complete

functionality of the Global Hawk payload system including: AC and DC electrical power; real-time 

communication with the ground payload workstation for command and control, and global narrowband 

data transmissions; real-time aircraft state and air data; access to APCS-based auxiliary data storage; access 

to GPS and IRIG-B data signals; and connectivity to a safety-interlock circuit. 


Payload Integration

For payload integration into the aircraft, the NASA Global Hawk project provides a single point of 

contact so that the process is consistent and convenient for the customer. The customer has two options for 

mounting a payload to the NASA Global Hawk aircraft: payloads may be attached directly to mounting 

points in the payload bays; or mounted onto a pallet, which is then attached to mounting points in the payload 

bay. The modular feature of the payload pallets allows for sensor development, integration, checkout, and 

maintenance at the customer’s facility before the payload/pallet is delivered to DFRC.

For electrical integration, the Global Hawk project provides two cables to the customer for their 

payload. One cable connects the payload to the experiment interface panel (EIP); the other cable connects 

the payload to an Ethernet switch. The EIP provides AC and DC power, a safety enable circuit, a GPS 

signal, and the aircraft state data. The Ethernet switch provides access to the aircraft data telemetry system 

and permits the customer to interact with their payload.

Some payloads may require viewing ports, external probes, hatches, radome fairings, and other payloadspecific accommodations. The DFRC and NGC teams provide assistance with the design, fabrication, and 

installation of all payload-specific systems.

MISSION PLANNING AND CONDUCT

Mission planning for unmanned aircraft is typically more complex and requires longer lead-time than 

does mission planning for manned aircraft, especially for flights outside of the EAFB restricted airspace in 

the National Airspace System (NAS). The Federal Aviation Administration (FAA) has developed a policy 

that allows unmanned aircraft to fly in the NAS through the issuance of a certificate of authorization 

(COA), which is a waiver process that requires a thorough review of the planned mission. The Global Hawk 

project provides all coordination for flight clearances and the development of COAs. 

Missions within the EAFB restricted airspace require coordination with EAFB airspace, airfield, and 

frequency management. There are typically no altitude or chase aircraft requirements for flying in this 

restricted airspace. Specific requirements are determined for each mission. The FAA regulations do not 

apply in restricted airspace. 

When conducting flights in the NAS, coordination with the FAA is required for all Global Hawk 

missions. For each COA application, DFRC will develop and submit a detailed documentation package to 

the FAA. Included in the COA request are the flight profiles with the number and frequency of the planned 

flights.

The time required to gather and process the required information for the COA request, and to coordinate 

flight activities with the FAA, could be extensive. The amount of time needed will depend on the location, 

altitude, and frequency of the specific flights. Missions that require coordination across multiple states and 

air route traffic control centers may require up to six months lead time to coordinate airspace usage with 

the FAA.


The NASA DFRC is responsible for all flight safety aspects of the NASA Global Hawk aircraft, 

and therefore also the flight approval process. The NASA Global Hawk project office will coordinate the 

airworthiness process for a customer mission; including identification, categorization, and mitigation of 

specific risks and hazards that may exist. 

Prior to a NASA Global Hawk mission, the customer team, and the NASA Global Hawk ground and 

flight operations team will develop procedures covering pre-flight, flight, and post-flight. In addition, the 

combined team will conduct mission rehearsals and simulations prior to flight.

On the day of the flight, the ground operations team will prepare the aircraft and the payload team 

will complete pre-flight payload preparations. The flight operations team for the aircraft and payload will 

occupy the GHOC several hours before takeoff in order to conduct pre-flight activities. The aircraft is towed 

to a staging area near the runway, where the final aircraft checkouts are completed and the engine is started. 

At this point, control of the aircraft is transferred from the ground operations team to the pilot in the GHOC. 

The pilot commands the aircraft to begin executing the mission plan. After landing, the ground operations 

team will conduct post-flight activities and assist the payload team in gaining access to their instruments 

and sensors on board the aircraft. The FOR and POR will be occupied throughout the mission.

GLOBAL HAWK PACIFIC 2009

The initial scientific campaign utilizing the NASA Global Hawk system has been designated Global 

Hawk Pacific 2009 (GloPac). GloPac flights will begin and end at EAFB, and are expected to encompass 

the entire offshore Pacific region and the USA-controlled Arctic region. A total of six flights, ranging from 

12 to 30 hr in duration will be flown. GloPac flights are currently planned for June-July 2009.

Scientific Objectives

The GloPac flights are designed to address various scientific objectives, including:

Validation and scientific collaboration with NASA earth-monitoring satellites, principally the Aura 

satellite,

Observations of stratospheric trace gases in the upper troposphere and lower stratosphere from the

mid-latitudes into the tropics,

Sampling of polar stratospheric air and the break-up fragments of the air that move into the

mid-latitudes,

Measurements of dust, smoke, and pollution that cross the Pacific from Asia and Siberia,

Measurements of streamers of moist air from the central tropical Pacific that move onto the west coast 

of the United States (atmospheric rivers).

1.

2.

3.

4.

5.


Scientific Instruments

The scientific payload suite for the GloPac missions consists of a combination of in situ and 

remote-sensing instruments. The majority of these instruments have flown on other airborne platforms, 

most notably the NASA ER-2 (Lockheed Martin Corporation, Bethesda, Maryland) research aircraft. The 

twelve GloPac instruments include:

Airborne Compact Atmospheric Mapper (ACAM),

Autonomous Modular Sensor (AMS),

Cloud Physics LIDAR (CPL),

Meteorological Measurement Systems (MMS),

Microwave Temperature Profiler (MTP),

Miniature Visual Imaging System (MVis),

Nuclei Mode Aerosol Size Spectrometer (NMASS),

Focused Cavity Aerosol Spectrometer (FCAS),

Global Hawk UAS Ozone Photometer (Ozone),

UAS Chromatograph for Atmospheric Trace Species (UCATS),

Ultra-High Sensitivity Aerosol Spectrometer (UHSAS),

UAS Laser Hygrometer (ULH).

Science teams from the NASA Ames Research Center (Moffett Field, California), NASA Goddard 

Space Flight Center (Greenbelt, Maryland), NASA Jet Propulsion Laboratory (Pasadena, California), 

NOAA Earth System Research Laboratory (Boulder, Colorado), the University of Denver, and Droplet 

Measurement Technologies (Boulder, Colorado) are providing these instruments.

Mission Description

The final flight path for a specific GloPac flight will not be chosen until several days prior to flight. 

Nominally, baseline flight paths will be determined 48 hr prior to flight and coordinated with the appropriate 

FAA organization. It is expected that the project will fly one flight per week during the campaign for a total 

of six flights.

Additionally, there will be other meteorological, volcanic, and climactic phenomena that will be of 

interest for investigation during the GloPac flights. Sampling of these phenomena will be requested in 

real time as deviations from the filed flight plan or modifications to the 48-hr coordinated flight track. 

The modifications will be determined 6-12 hr prior to flight using short-term meteorological forecasts. 

Long-range meteorological forecasts (greater than 12 hr) are too inaccurate to adequately specify the 

location of these phenomena.

In addition to the standard flight conditions flown by Global Hawk aircraft to date, a new flight 

condition, known as a vertical profile, will be used during GloPac missions. A vertical profile is a straightahead descent from maximum cruise altitude (greater than 55,000 ft, down to 43,000 ft, and then a climb 

back up to the current maximum cruise altitude. The aircraft will remain at 43,000 ft altitude up to 15 

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.


minutes to accommodate payload sampling. The vertical profiles will be coordinated with ATC, in real 

time, to avoid any potential conflict with other air traffic. Approximately 3-5 vertical profiles per flight will 

be requested.

SUMMARY

The National Aeronautics and Space Administration (NASA) Global Hawk system will become 

operational in 2009. A partnership between NASA and the Northrop Grumman Corporation (Los Angeles, 

California) has been established. This partnership has enabled the rapid development of the NASA Global 

Hawk capability and provides customers with efficient payload integration options as well as streamlined 

mission preparations. Flight operations are scheduled to begin in Spring 2009 and initial customer flights 

in June 2009.
REPORT DOCUMENTATION PAGE Form Approved

OMB No. 0704-0188

1. REPORT DATE (DD-MM-YYYY)

01-05-2009

2. REPORT TYPE 

Technical Memorandum

 4. TITLE AND SUBTITLE

NASA Global Hawk: A New Tool For Earth Science Research

5a. CONTRACT NUMBER

 6. AUTHOR(S)

J. Chris Naftel

 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

NASA Dryden Flight Research Center

P.O. Box 273

Edwards, California 93523-0273

 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration

Washington, DC 20546-0001

 8. PERFORMING ORGANIZATION

 REPORT NUMBER

H-2951

10. SPONSORING/MONITOR'S ACRONYM(S)

NASA

13. SUPPLEMENTARY NOTES

Naftel, NASA Dryden Flight Research Center. Also presented at the 33rd International Symposium on Remote Sensing of 

Environment, Stresa, Italy, May 4-8, 2009.

12. DISTRIBUTION/AVAILABILITY STATEMENT

Unclassified -- Unlimited

Subject Category 43 Availability: NASA CASI (301) 621-0390 Distribution: Standard 

19b. NAME OF RESPONSIBLE PERSON

STI Help Desk (email:help@sti.nasa.gov)

14. ABSTRACT

Scientists have eagerly anticipated the performance capability of the National Aeronautics and Space Administration (NASA) Global Hawk for

over a decade. In 2009 this capability becomes operational. One of the most desired performance capabilities of the Global Hawk aircraft is very 

long endurance. The Global Hawk aircraft can remain airborne longer than almost all other jet-powered aircraft currently flying, and longer

than all other aircraft available for airborne science use. This paper describes the NASA Global Hawk system, payload accommodations,

concept of operations, and the first scientific data-gathering mission: Global Hawk Pacific 2009.

15. SUBJECT TERMS

Earth science, Global Hawk, High altitude, Long endurance, Remote sensing, Unmanned aerial system

18. NUMBER

 OF 

 PAGES

13

19b. TELEPHONE NUMBER (Include area code)

(301) 621-0390

a. REPORT

U

c. THIS PAGE

U

b. ABSTRACT

U

17. LIMITATION OF 

 ABSTRACT

UU

Prescribed by ANSI Std. Z39-18

Standard Form 298 (Rev. 8-98)

3. DATES COVERED (From - To)

5b. GRANT NUMBER

5c. PROGRAM ELEMENT NUMBER

5d. PROJECT NUMBER

5e. TASK NUMBER

5f. WORK UNIT NUMBER

11. SPONSORING/MONITORING

 REPORT NUMBER

NASA/TM-2009-214647

16. SECURITY CLASSIFICATION OF:

The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing 

data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or 

any other aspect of this collection of information, including suggestions for reducing this burden, to Department of Defense, Washington Headquarters Services, 

Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware 

that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a 

currently valid OMB control number.

PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS.