Earth
Science Reference Handbook
[ Missions: Aura ] 101
Aura
Summary
Aura’s four instruments study the atmosphere’s chemistry
and dynamics. Aura’s measurements enable us to inves-
tigate questions about ozone trends, air–quality changes
and their linkage to climate change. Aura’s measurements
also provide accurate data for predictive models and useful
information for local and national agency decision–sup-
port systems.
Instruments
• High Resolution Dynamics Limb Sounder (HIRDLS)
• Microwave Limb Sounder (MLS)
• Ozone Monitoring Instrument (OMI)
• Tropospheric Emission Spectrometer (TES)
Points of Contact
• Aura Project Scientist: Mark Schoeberl, NASA
Goddard Space Flight Center
• Aura Deputy Project Scientist: Anne Douglass,
NASA Goddard Space Flight Center
• Aura Deputy Project Scientist: Joanna Joiner, NASA
Goddard Space Flight Center
Other Key Personnel
• Aura Program Scientist: Phil DeCola, NASA
Headquarters
• Aura Program Executive: Lou Schuster, NASA
Headquarters
• Aura Mission Director: William Guit, NASA
Goddard Space Flight Center
Mission Type
Earth Observing System (EOS) Systematic
Measurements
Launch
•
Date and Location: July 15, 2004, from Vandenberg
Air Force Base, California
• Vehicle: Delta II 7920 rocket
Relevant Science Focus Areas
(see NASA’s Earth Science Program section)
• Atmospheric Composition
• Climate Variability and Change
• Weather
Related Applications
(see Applied Sciences Program section)
• Agricultural Efficiency
• Air Quality
• Public Health
Aura Science Goals
The Aura mission seeks to answer three main science
questions:
• Is the stratospheric ozone layer recovering?
• What are the processes controlling air quality?
• How is Earth’s climate changing?
Key Aura Facts
Joint with the Netherlands, Finland, and the U.K.
Orbit:
Type: Polar, sun–synchronous
Equatorial Crossing: 1:45 p.m.
Altitude: 705 km
Inclination: 98.2º
Period: 100 minutes
Repeat Cycle: 16 days
Dimensions: 4.70 m × 17.37 m × 6.91 m
Mass: 2967 kg (1200 kg of which are in
instruments)
Power: Solar array provides 4800 W. Nickel–
hydrogen battery for nighttime operations.
Downlink: X–band for science data; S–band for
command and telemetry via Tracking and Data
Relay Satellite System (TDRSS) and Deep Space
Network to polar ground stations in Alaska and
Norway.
Design Life: Nominal mission lifetime of 5 years,
with a goal of 6 years of operation.
Contributor: Northrop Grumman Space
Technology
Aura URL
eos–aura.gsfc.nasa.gov/
Earth Science Reference Handbook
102 [ Missions: Aura ]
validate Aura data and to address the science by making
additional measurements.
This strategy emphasizes the strengths of both
focused science campaigns and aircraft measurements.
Campaign instruments make constituent measurements
that are more complete than can be obtained from satel-
lites. Campaign data are also obtained for much smaller
spatial scales and with high temporal resolution compared
to satellite data. Aircraft missions, on the other hand, take
place a few times each year at most and are limited to a
small portion of the globe. The Aura instruments make
global observations throughout the year and provide data
sets that reveal whether or not the campaign observations
are truly representative of the atmosphere’s chemistry.
The Aura validation program also capitalizes on
routine sources of data such as the ozonesonde network
and the Network for the Detection of Atmospheric Com-
position Change (formerly the Network for Detection of
Stratospheric Change, or NDSC). Ground–based radi-
ometers and spectrometers make column measurements
similar to those made by instruments flying on Aura.
Ground–based lidars measure temperature and some
trace–gas constituent profiles. Balloon–borne instruments
measure profiles of stratospheric constituents up to 40 km.
Smaller balloons carry water–vapor instruments in the
tropics to validate Aura’s measurements of this impor-
tant gas. Flights of aircraft, such as the DC–8 (medium
altitude) and WB–57 (high altitude), provide tropospheric
profiles of ozone, carbon monoxide, and nitrogen species.
Aircraft lidars measure profiles of ozone and temperature
for long distances along the satellite track. Scientists
can also compare profiles of stratospheric constituents
from Aura with those from other satellites, including the
NASA Upper Atmosphere Research Satellite (UARS), the
European Space Agency Environmental Satellite (ESA
Envisat), and the Canadian Science Satellite (SCISAT)
and use data–assimilation techniques to help identify
systematic differences among the data sets. The Aura
validation program also includes an instrument develop-
ment program and field campaigns scheduled between
October 2004 and Autumn 2007.
Aura Science Questions
Is the Stratospheric Ozone Layer Recovering?
Ozone is formed naturally in the stratosphere through
break–up of oxygen (O
2
) molecules by solar UV radia-
tion, followed by the uniting of individual oxygen atoms
with O
2
molecules, forming ozone (O
3
) molecules. Ozone
is destroyed when an ozone molecule combines with an
oxygen atom to form two oxygen molecules, or through
catalytic cycles involving hydrogen, nitrogen, chlorine,
or bromine–containing species. For centuries, the atmo-
Aura Mission Background
Aura is the third in the series of large Earth Observing
System platforms to be flown by NASA with international
contributions. Aura, along with Terra (launched Decem-
ber 1999) and Aqua (launched May 2002), provides an
unprecedented view of the global Earth system. The
Aura mission consists of four instruments on a common
spacecraft (the same bus design as for Aqua) designed to
provide the essential services for the instruments.
Aura is part of the A–Train of satellites, which,
when the formation is complete, will include at least four
other NASA missions—Aqua, Cloud–Aerosol Lidar and
Infrared Pathfinder Satellite Observations (CALIPSO),
CloudSat, and the Orbiting Carbon Observatory (OCO)—
as well as a French Centre National d’Etudes Spatiales
(CNES) mission called Polarization and Anisotropy of
Reflectances for Atmospheric Sciences coupled with Ob-
servations from a Lidar (PARASOL). Aura is the trailing
spacecraft in the formation and lags 15 minutes behind
Aqua. While each satellite has an independent science mis-
sion, measurements from the various spacecraft can also
be combined. These complementary satellite observations
will enable scientists to obtain more information than they
could if all the various observations were used indepen-
dently. This offers a new and unprecedented resource for
exploring aerosol–chemistry–cloud interactions. See the
Earth Observing Program section for more details on the
A–Train.
As suggested in part by the name, the objective of
the Aura mission is to study the chemistry and dynam-
ics of Earth’s atmosphere, with emphasis on the upper
troposphere and lower stratosphere (5–20 km altitudes).
Aura’s measurements enable us to investigate questions
about ozone trends and air–quality changes, and their link-
ages to climate change. They also provide accurate data
for predictive models and provide useful information for
local and national agency decision–support systems.
Aura Mission Validation
Aura’s focus on the troposphere and lower stratosphere
presents challenges for validation, because this region
exhibits much more spatial and temporal variability than
the middle and upper stratosphere. To meet these chal-
lenges, the Aura project has adopted a strategy to increase
the scientific return from the validation program. Some
of the validation activities are embedded within focused
science campaigns. These campaigns have been selected
to obtain data needed to unravel complex science ques-
tions that are linked to the three main Aura science goals.
Scientists plan to use the satellite data to understand the
overall chemical and meteorological environment during
the campaigns. Aircraft measurements are used both to