1066 IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 44, NO. 5, MAY 2006 Overview of the EOS Aura Mission Mark R. Schoeberl, Anne R. Douglass, Ernest Hilsenrath, Pawan K. Bhartia, Reinhard Beer, Joe William Waters, Michael R. Gunson, Lucien Froidevaux, John C. Gille, John J. Barnett, Pieternel F. Levelt, and Phil DeCola Abstract—Aura, the last of the large Earth Observing System observatories, was launched on July 15, 2004. Aura is designed to make comprehensive stratospheric and tropospheric composition measurements from its four instruments, the High Resolution Dy- namics Limb Sounder (HIRDLS), the Microwave Limb Sounder (MLS), the Ozone Monitoring Instrument (OMI), and the Tro- pospheric Emission Spectrometer (TES). With the exception of HIRDLS, all of the instruments are performing as expected, and HIRDLS will likely be able to deliver most of their planned data products. We summarize the mission, instruments, and synergies in this paper. Index Terms—Atmospheric composition, Aura, Earth Ob- serving Sytem (EOS), remote sensing, satellites. I. INTRODUCTION T HE Earth Observing System (EOS) program began in the late 1980s with the selection of a large number of earth science instruments and interdisciplinary science teams. Originally conceived to fly on two very large platforms (EOS A and B), budget constraints forced the redesign of the EOS program. EOS now consists of three core platforms, Terra, Aqua, and Aura and several smaller satellites such as SORCE and ICESAT. Terra (formerly EOS AM), launched in late 1999, focuses on land processes. Aqua (formerly EOS PM) focuses on the atmosphere’s hydrological cycle and was launched in early 2002. Aura (Latin for breeze, formerly EOS CHEM) concen- trates on atmospheric composition. Aura was launched July 15, 2004 into an ascending-node 705-km sun-synchronous polar orbit with a 98 inclination with an equator-crossing time of min. The design life is five years with an operational goal of six years. Aura flies in formation about 15 min behind Aqua. The Cloud-Aerosol Lidar and Infrared Pathfinder Satel- lite Observation (CALIPSO, http://www-calipso.larc.nasa.gov) and Cloudsat (http://cloudsat.atmos.colostate.edu), to be launched together in April 2006 [22] will fly a few minutes behind Aqua. This group of satellites, including the CNES PARASOL satellite (http://smsc.cnes.fr/PARASOL/GP_mis- sion.htm) which was launched in December 2004, and the ESSP Orbiting Carbon Observatory (OCO, http://oco.jpl.nasa.gov), Manuscript received April 29, 2005; revised August 1, 2005. M. R. Schoeberl, A. R. Douglass, E. Hilsenrath, and P. K. Bhartia are with the NASA Goddard Space Flight Center, Greenbelt, MD 20771 USA (e-mail: mark.r.schoeberl@nasa.gov). R. Beer, J. W. Waters, M. R. Gunson, and L. Froidevaux are with the Jet Propulsion Laboratory, Pasadena, CA 91109 USA. J. C. Gille is with the University of Colorado, Boulder, CO 80309 USA. J. J. Barnett is with the Oxford University, Oxford, OX1 2JD, U.K. P. F. Levelt is with the Royal Dutch Meteorological Institute (KNMI), KS/AS, 3730 AE De Bilt, The Netherlands. P. DeCola is with the National Aeronautics and Space Administration, Wash- ington, DC, 20546 USA. Digital Object Identifier 10.1109/TGRS.2005.861950 Fig. 1. Model of the Aura spacecraft showing the location of the four instruments, HIRDLS, MLS, OMI, and TES. TABLE I AURA INSTRUMENTS AND MEASUREMENTS scheduled for launch in 2008, are referred to as the “A-Train.” The measurements from Aura will be within 30 min of these other platforms. The A-Train can be thought of as an extended instrument package focusing on climate change. Fig. 1 shows the Aura spacecraft and its four instruments (Table I): the High Resolution Dynamics Limb Sounder (HIRDLS), the Microwave Limb Sounder (MLS), the Ozone Monitoring Instrument (OMI), and the Tropospheric Emis- sion Spectrometer (TES). These instruments were selected because of: 1) their complementary measurements; 2) their technological heritage; and 3) the new capabilities they bring to measuring the Earth’s atmosphere. Below we describe the objectives and science strategy of the Aura mission. Fig. 2 graphically shows the vertical range of the various Aura mea- surements and the instrument that provides them. 0196-2892/$20.00 © 2006 IEEE