James E. Graf

The Mars Reconnaissance Orbiter mission

The Mars reconnaissance orbiter (MRO) will be launched in August 2005 by an Atlas V 401 expendable launch vehicle from Cape Canaveral Air Force Station, USA. It will deliver to Mars orbit a payload to conduct remote sensing science observations, identify and characterize sites for future landers, and provide critical telecom/navigation relay capability for follow-on missions. The mission is designed to provide global, regional survey, and targeted observations from a low 255km by 320km Mars orbit with a 3:00 P.M. local mean solar time (ascending node). During the one Martian year (687 Earth days) primary science phase, the orbiter will acquire visual and near-infrared high-resolution images of the planets surface, monitor atmospheric weather and climate, and search the upper crust for evidence of water. After this science phase is completed, the orbiter will provide telecommunications support for spacecraft launched to Mars in the 2007 and 2009 opportunities. The primary mission ends on December 31, 2010, approximately 5.5 years after launch.

NASA Scatterometer Experiment

Abstract Satellite scatterometers are microwave radars capable of measuring near-surface vector winds (both speed and direction) over the oceans under all weather conditions. The data generated from these instruments are used in scientific studies of upper ocean circulation, tropospheric dynamics, air–sea interaction and climate change; in operational meteorology as a means to increase numerical weather forecast skill and the accuracy of storm warning predictions; and in commercial applications such as ship routing. The scatterometer wind measurement technique was demonstrated with the flight of the Seasat Scatterometer in 1978. This paper summarizes the scatterometry measurement technique, describes the design of the NASA Scatterometer (NSCAT) instrument recently launched aboard the National Space Development Agency of Japans (NASDA) Advanced Earth Observing Satellite (ADEOS), presents first results from the NSCAT instrument, and describes the future U.S. program for measuring surface marine wind vectors.

Postlaunch sensor verification and calibration of the NASA Scatterometer

Scatterometer instruments are active microwave sensors that transmit a series of microwave pulses and measure the returned echo power to determine the normalized radar backscattering cross section (sigma-0) of the ocean surface from which the speed and direction of near-surface ocean winds are derived. The NASA Scatterometer (NSCAT) was launched on board the ADEOS spacecraft in August 1996 and returned ten months of high-quality data before the failure of the ADEOS spacecraft terminated the data stream in June 1997. The purpose of this paper is to provide an overview of the NSCAT instrument and sigma-0 computation and to describe the process and the results of an intensive postlaunch verification, calibration, and validation effort. This process encompassed the functional and performance verification of the flight instrument, the sigma-0 computation algorithms, the science data processing system, and the analysis of the sigma-0 and wind products. The calibration process included the radiometric calibration of NSCAT using both engineering telemetry and science data and the radiometric beam balance of all eight antenna beams using both open ocean and uniform land targets. Finally, brief summaries of the construction of the NSCAT geophysical model function and the verification and validation of the wind products will be presented. The key results of this paper are as follows: The NSCAT instrument was shown to function properly and all functional parameters were within their predicted ranges. The instrument electronics subsystems were very stable and all of the key parameters, such as transmit power, receiver gain, and bandpass filter responses, were shown to be stable to within 0.1 dB. The science data processing system was thoroughly verified and the sigma-0 computation error was shown to be less than 0.1 dB. All eight antenna beams were radiometrically balanced, using natural targets, to an estimated accuracy of about 0.3 dB.

An overview of the Mars Reconnaissance Orbiter mission

The Mars Reconnaissance Orbiter (MRO) will be launched in August 2005 by an intermediate-class, expendable launch vehicle from Cape Canaveral Air Station, USA. It will deliver to Mars orbit a payload to conduct remote sensing science observations, characterize sites for future landers, and provide critical telecom/navigation relay capability for follow-on missions. The mission is designed to provide both global and targeted observations from a low 200 by 400 km Mars orbit with a 3:00 P.M. local mean solar time ascending node. During the one Martian year (687 Earth days) primary science phase, the orbiter will acquire visual and infrared high-resolution images of the planets surface. After this science phase is completed, the orbiter will provide telecommunications support for spacecraft launched to Mars in the 2007 and 2009 opportunities. The primary mission ends on December 31, 2010, approximately 5.5 years after launch.

The Mars Reconnaissance Orbiter Mission: From Launch to the Primary Science Orbit

The Mars reconnaissance Orbiter (MRO) was launched from Cape Canaveral Air Force Station, Florida, USA, aboard an Atlas V-401 launch vehicle on August 12, 2005. The MRO spacecraft carries a very sophisticated scientific payload. Its primary science mission is to to provide global, regional survey, and targeted observations from a low-altitude orbit for one Martian year (687 Earth days). After a seven-month interplanetary transit, the spacecraft fired its six main engines and established a highly elliptical capture orbit at Mars. During the post Mars Orbit Insertion (MOI) early check-out period, four instruments acquired engineering-quality data. This was followed by five months of aerobraking operations. After aerobraking was terminated, a series of propulsive maneuvers were used to establish the desired low-altitude science orbit. As the spacecraft is readied for its primary science mission, spacecraft and instrument checkout and deployment activities have continued. After the science phase is completed, the orbiter will provide telecommunications support for future Mars missions. This paper provides a status of the actual mission to date (through October 2006) and briefly describes the planned operations for the upcoming science mission.

Studying Earth in the New Millennium: NASA Jet Propulsion Laboratory's Contributions to Earth Science and Applications Space Agencies

The NASA Jet Propulsion Laboratory (JPL) is a national research facility that carries out cuttingedge earth science missions. JPL developed the first U.S. Earth-orbiting science spacecraft and is a pioneer in the use of remote sensing for science of the oceans, atmosphere, and solid earth. Explorer I was the first U.S. Earth-orbiting spacecraft. It followed the Soviet Sputniks 1 and 2 but carried James Van Allens Geiger counter, which upended space physics with the discovery of the radiation belts now named for him [1]. Explorer I also carried a micrometeoroid detector. JPL developed atmospheric temperature instruments for the Nimbus series of weather satellites, built microwave and infrared instruments to help gain an understanding of stratospheric ozone depletion, ocean circulation, and surface winds, and flew Seasat, which carried the first civilian synthetic aperture radar. This article gives a general overview of recent, current, and near-future earth science missions led by JPL, highlighting a few of the many measurements that are transforming our understanding of the processes governing the Earths atmosphere, oceans, land surfaces, and climate.