Aura (satellite)

Aura (satellite)
NASA · Public domain · source
Name	Aura
Mission type	Earth observation
Operator	NASA
Cospar id	2004-035A
Satcat	28391
Manufacturer	Northrop Grumman
Launch mass	2,270 kg
Launch date	15 July 2004
Launch rocket	Delta II 7920-10L
Launch site	Vandenberg Air Force Base
Orbit reference	Geocentric
Orbit regime	Sun-synchronous
Orbit inclination	98.2°
Apsis	gee

Aura (satellite) is a NASA Earth observation satellite launched in 2004 as part of the Earth Observing System to study atmospheric chemistry and climate processes. Operated by the Goddard Space Flight Center in coordination with mission partners, the spacecraft carries multiple instruments to measure trace gases, aerosols, and ozone with global coverage. Aura contributes to long-term time series used by agencies, research centers, and international programs for air quality, climate, and stratospheric studies.

Mission overview

Aura was developed under NASA's Earth Observing System program to investigate the chemistry of the upper and lower atmosphere, focusing on stratospheric ozone recovery, tropospheric composition, and pollutant transport. The mission complements spacecraft such as Terra (satellite), Aqua (satellite), and the OCO-2 mission by situating instruments in a sun-synchronous polar orbit for morning overpass observations. Managed by the Goddard Space Flight Center with industry partners including Northrop Grumman and scientific collaboration from institutions like the Jet Propulsion Laboratory, Aura's design emphasized synergistic measurements from ultraviolet to microwave wavelengths to address questions raised by programs including the World Meteorological Organization and the United Nations Environment Programme assessments of ozone.

Spacecraft design and instruments

The Aura platform integrates a stabilized bus derived from previous EOS assets and accommodates four primary instruments: the Ozone Monitoring Instrument (OMI), the Microwave Limb Sounder (MLS), the High Resolution Dynamics Limb Sounder (HIRDLS, lost functionality later), and the Tropospheric Emission Spectrometer (TES). OMI, developed by the Netherlands Agency for Aerospace Programmes and Finnish Meteorological Institute partners with NASA, performs ultraviolet-visible spectrometry for ozone and aerosols. MLS, contributed by NASA and Jet Propulsion Laboratory teams, uses microwave limb-sounding to profile temperature, water vapor, chlorine species, and ozone in the stratosphere. HIRDLS, developed at NASA Goddard, targeted high vertical resolution limb radiances before partial failure affected its performance. TES, led by researchers at the California Institute of Technology and Jet Propulsion Laboratory, performed infrared Fourier-transform spectroscopy to retrieve tropospheric trace gases including ozone, carbon monoxide, and methane. The instrument complement enables cross-validation among teams at institutions such as NCAR, NOAA, University of Maryland, and Harvard University.

Launch and orbital operations

Aura was launched aboard a Delta II 7920-10L vehicle from Vandenberg Air Force Base on 15 July 2004 into a sun-synchronous near-polar orbit with an inclination of about 98.2°. The orbital configuration synchronized morning equatorial crossing times with the EOS constellation, enabling coordinated observations with Terra (satellite) and Aqua (satellite). Routine operations and ground contacts are handled via the Ground Network and mission control at Goddard Space Flight Center, with calibration and validation campaigns coordinated through field sites and airborne programs like NASA ER-2 flights and DC-8 science missions. Anomalies, including degradation of HIRDLS and instrument calibration drifts, were managed through mission operations, software updates, and coordinated validation by laboratories at Scripps Institution of Oceanography and University of Colorado Boulder.

Scientific objectives and key findings

Primary objectives included quantifying stratospheric ozone recovery, characterizing tropospheric ozone production and transport, assessing aerosol distributions and direct radiative effects, and measuring greenhouse gas precursors and pollutants. Key findings from Aura data contributed to improved understanding of stratospheric chlorine and bromine decline following the Montreal Protocol measures, documented trends in global tropospheric ozone burden linked to emissions and atmospheric circulation, and revealed seasonal and interannual variability in water vapor and temperature in the upper troposphere–lower stratosphere. Aura observations informed studies on transboundary pollution episodes affecting regions identified by European Space Agency and Intergovernmental Panel on Climate Change assessments, refined emission inventories used by International Energy Agency, and supported satellite data assimilation systems at European Centre for Medium-Range Weather Forecasts and NOAA for air quality forecasting.

Data processing and availability

Data from Aura instruments are processed through science teams at NASA Goddard and distributed via NASA data centers, including the Goddard Earth Sciences Data and Information Services Center and the NASA Earthdata portal, using standardized products for research and operational use. Level 1 radiances, Level 2 retrievals, and gridded Level 3 climatologies are produced with algorithm development led by academic groups at University of Oxford, Massachusetts Institute of Technology, and Columbia University in partnership with federal labs. Validation activities include comparisons with ozonesonde networks coordinated by the World Meteorological Organization and aircraft campaigns organized with NCAR and NOAA facilities. Open-access policies facilitated use by international modelers and policy analysts at institutions such as the International Institute for Applied Systems Analysis.

International collaboration and impact

Aura exemplifies international cooperation through instrument contributions, joint science teams, and validation networks spanning agencies like European Space Agency, Netherlands Agency for Aerospace Programmes, and national meteorological services including the UK Met Office and Finnish Meteorological Institute. Its datasets have underpinned multinational assessments by the IPCC and WMO and informed regulatory and mitigation strategies shaped by the Montreal Protocol and regional air quality directives. The mission fostered capacity building through data-sharing partnerships with research centers in China, India, Brazil, and South Africa, influencing satellite mission design and atmospheric chemistry research worldwide.

Category:NASA satellites Category:Earth observation satellites