Louise Veilleux

The tandem-L mission proposal: Monitoring earth's dynamics with high resolution SAR interferometry

Tandem-L is a proposal for an innovative interferometric and polarimetric radar mission that enables the systematic monitoring of dynamic processes on the Earth surface. Important mission objectives are global forest height and biomass inventories, large scale measurements of millimetric displacements due to tectonic shifts, and systematic observations of glacier movements. The innovative mission concept and the high data acquisition capacity of Tandem-L provide a unique data source to observe, analyze and quantify the dynamics of a wide range of mutually interacting processes in the bio-, litho-, hydro- and cryosphere. By this, Tandem-L will be an essential step to advance our understanding of the Earth system and its intricate dynamics. This paper provides an overview of the Tandem-L mission concept and its main application areas. Performance predictions show the great potential of Tandem-L to acquire a wide range of bio- and geophysical parameters with high accuracy on a global scale. Innovative aspects like the employment of advanced digital beamforming techniques to improve performance and coverage are discussed in detail.

The NASA-ISRO SAR mission - An international space partnership for science and societal benefit

The National Aeronautics and Space Administration (NASA) in the United States and the Indian Space Research Organisation (ISRO) have embarked on the formulation of a proposed Earth-orbiting science and applications mission that would exploit synthetic aperture radar to map Earths surface every 12 days. The missions primary objectives would be to study Earth land and ice deformation, and ecosystems, in areas of common interest to the US and Indian science communities. To meet demanding coverage, sampling, and accuracy requirements, the system would require a swath of over 240 km at fine resolution, using full polarimetry where needed. To address the broad range of disciplines and scientific study areas of the mission, a dual-frequency system was conceived, at L-band (24 cm wavelength) and S-band (10 cm wavelength). To achieve these observational characteristics, a reflector-feed system is considered, whereby the feed aperture elements are individually sampled to allow a scan-on-receive (“SweepSAR”) capability at both L-band and S-band. In the partnership, NASA would provide the instrument structure for both L- and S-band electronics, the L-band electronics, the reflector and associated boom, and an avionics payload to interface with the radar that would include a solid state recorder, high-rate Ka-band telecommunication link, and a GPS receiver. ISRO would provide the spacecraft and launch vehicle, and the S-band radar electronics.

The proposed DESDynI mission - From science to implementation

The proposed DESDynI mission is being planned by NASA to study earth change in three distinct disciplines - ecosystems, solid earth, and cryospheric sciences. DESDynI would provide unique and unprecedented capabilities to the science community, with an imaging L-band radar proposed to include new modes and observational techniques, and a first-of-a-kind multi-beam lidar for measuring canopy height metrics at fine spatial resolution. Under current planning scenarios, DESDynI could be ready to launch in 2017. In this paper, we describe the science objectives, how these lead to the measurements that achieve these objectives, and how these requirements lead to a mission design. The properties of the radar are then described, including a number of new radar modes and capabilities such as “SweepSAR” scan-on-receive techniques and split-spectrum acquisitions in single and multipol configurations.

Digital calibration system enabling real-time on-orbit beamforming

Real-time On-orbit digital beamforming, combined with lightweight, large aperture reflectors, enable SweepSAR architectures, which promise significant increases in instrument capability for solid earth and biomass remote sensing. These new instrument concepts require new methods for calibrating the multiple channels, which are combined on-board, in real-time. The benefit of this effort is that it enables a new class of lightweight radar architecture, Digital Beamforming with SweepSAR, providing significantly larger swath coverage than conventional SAR architectures for reduced mass and cost. In this paper we will present the current development of the digital calibration architecture for digital beamforming radar instruments, such as the proposed D-SAR instrument. This proposed instruments baseline design employs SweepSAR digital beamforming, requiring digital calibration. We will review the overall concepts and status of the system architecture, algorithm development, and the digital calibration testbed currently being developed. We will present results from a preliminary hardware demonstration. We will also discuss the challenges and opportunities specific to this novel architecture.

A P-band radar mission to Mars

Large regions of Mars are covered by dust that obscures geological evidence for fluvial channels, the extent of volcanic flows, and features associated with near-surface ground ice. We describe a Mars orbiting mission carrying a P-band SAR to map these hidden surface features. Mapping would be carried out in HH and VV polarizations, with the comparison of the two expected to yield a distinction between surface echoes and subsurface features beneath up to 5 m of dust. Repeat-pass interferometry data would also be collected to characterize volatile migration at the poles, aeolian shifting of the dust mantle, and possible volcanic deformation. This work describes the technical design of a P-band SAR for global mapping of Mars, and the characteristics of the proposed mission.

Design considerations of GeoSAR

The primary purpose of GeoSAR is to demonstrate the feasibility of interferometric topographic mapping through foliage penetration. GeoSAR should become a commercially viable instrument after the feasibility demonstration. To satisfy both requirements, we have designed a dual frequency (UHF- and X-band) interferometric radar. For foliage penetration, a lower frequency (UHF) radar is used. To obtain better height accuracy for low backscatter areas, we proposed a high frequency (X-band) interferometric system. In this paper, we present a possible GeoSAR system configuration and associated performance estimation.

Shuttle imaging radar-C: a system integration and test perspective

The Shuttle Imaging Radar—C(SIR---C) is a synthetic aperture radar(SAR) designed to fly on the Space Shuttle as a payload instrument in the Shuttle Radar Laboratory(SRL). To fly together with SIR-C are the German/Italian X-band SAR(X-SAR) and the Data Processing Subsystem (DPS), built by the Applied Physics Laboratory of John Hopkins University. The first mission is scheduled in mid-April, 1994, for an 8-day duration, with one follow-up mission in planning. The instrument itself — its inheritance, mission profile, potential scientific advances, design and performance — has been published earlier2