Geology topics

Grant R. Mah

Publications and source records attributed to Grant R. Mah.

3 recordsLinked to original sources

USGS2012

Design and implementation of the next generation Landsat satellite communications system

The next generation Landsat satellite, Landsat 8 (L8), also known as the Landsat Data Continuity Mission (LDCM), uses a highly spectrally efficient modulation and data formatting approach to provide large amounts of downlink (D/L) bandwidth in a limited X-Band spectrum allocation. In addition to purely data throughput and bandwidth considerations, there were a number of additional constraints based on operational considerations for prevention of interference with the NASA Deep-Space Network (DSN) band just above the L8 D/L band, minimization of jitter contributions to prevent impacts to instrument performance, and the need to provide an interface to the Landsat International Cooperator (IC) community. A series of trade studies were conducted to consider either X- or Ka-Band, modulation type, and antenna coverage type, prior to the release of the request for proposal (RFP) for the spacecraft. Through use of the spectrally efficient rate-7/8 Low-Density Parity-Check error-correction coding and novel filtering, an XBand frequency plan was developed that balances all the constraints and considerations, while providing world-class link performance, fitting 384 Mbits/sec of data into the 375 MHz X-Band allocation with bit-error rates better than 10-12 using an earth-coverage antenna.

Conference Paper↗

USGS2000

Follow-ons to the KidSAT/EarthKAM student remote sensing program

The KidSAT/EarthKAM program is a NASA educational initiative that allows students to develop and operate a remote sensing space program. The first phase of the program consisted of a student developed camera that is flown on Space Shuttle missions in the nadir window. A network of students develop a series of image acquisition requests, based on approved science proposals, that are combined into a set of instrument commands that are uplinked to the space shuttle. Acquired images are downlinked and archived for student access in completing their research. The International Space Station provides a unique platform for the next generation of KidSAT/EarthKAM instruments, which will allow more students to participate in the program and enable development of more sophisticated instruments. Follow-on instruments consist of Earth-looking multispectral digital sensors mounted in the optical window and on the express pallet, and radar instruments located on the express pallet. Use of the International Space Station will allow routine data acquisition and enable the instrument to be part of regular science curricula unconstrained by the Space Shuttle launch schedule.

Conference Paper↗

USGS2000

Landsat 5/Landsat 7 underfly cross-calibration experiment

There was a one-time opportunity to obtain nearly coincident coverage from both Landsat 5 and Landsat 7 as Landsat 7 drifted to its final orbital position during the initialization and verification phase following launch. During the underfly period, Landsat 7 Enhanced Thematic Mapper Plus (ETM+) data were collected using the U.S Landsat 7 ground station network and the solid-state recorder, while agreements were established with Space Imaging/EOSAT and various international ground stations to collect corresponding Landsat 5 Thematic Mapper (TM) data. Approximately 750 coincident scenes were collected during the underfly from 1-3 June 1999. Underfly data are intended to play a major role in developing cross-calibrations to bridge the results derived from historical Landsat 5 TM data with research performed with current Landsat 7 ETM+ data. The purpose of this paper is to provide an overview of the underfly experiment, and to provide some early comparative results between Landsat 5 and 7 data sets. Initial results indicate that products produced using TM and ETM+ data are very similar.

Conference Paper↗