Second Landsat Science Team Meeting

--Darrel Williams, Darrel.Williams@gsfc.nasa.gov
Landsat-7 Project Scientist
Goddard Space Flight Center

The second Landsat Science Team meeting was held April 15-17, 1997, at the Lockheed Martin Missiles and Space (LMMS) facilities in Valley Forge, Pennsylvania. The meeting was chaired by Landsat Science Team Leader, Samuel Goward (University of Maryland), and Project Scientist, Darrel Williams (GSFC). The 49 attendees included delegates from all 14 science investigations, as well as representatives from NASA HQ, the NASA Landsat Project Office, and the NOAA Landsat Commercialization Office.

The meeting commenced with a status report on the Landsat project by Phil Sabelhaus, the Landsat Project Manager. At that time, Sabelhaus reported that the project remained on schedule for a late May 1998 launch despite some lingering problems with the ETM+ instrument delivery from the Hughes SBRS fabrication facility. These problems included some bad wiring harnesses and faulty power supplies, both of which resulted in unacceptable noise levels, primarily in the 15-m panchromatic band. Since the Science Team meeting, additional problems associated with scan mirror start-up have also been encountered. The net result is that delivery of the instrument to the LMMS plant is not expected until mid-October, making it nearly impossible to meet a late May launch date. In a recent development, NASA and the Air Force have agreed to swap their respective Delta launch dates at Vandenberg AFB next year. Landsat-7 is now slated for a mid-July launch. On a more positive note, Sabelhaus stated that initial tests at SBRS indicated that noise levels for the seven spectral bands meet requirements and are significantly lower than those of Landsat-6.

Art Azarbarzin and Robert Menrad (NASA GSFC) presented overviews of spacecraft integration and ground system status, respectively. The Landsat-7 spacecraft is currently being assembled at the LMMS plant in Valley Forge. Spacecraft integration and test activities were proceeding smoothly, with power and electrical systems being checked out at the time of the meeting. The solid-state recorder was in the final stages of integration, although minor performance issues remained unresolved. After lunch, the meeting attendees were given a guided tour of the LMMS integration facilities for both Landsat-7 and the EOS AM-1 spacecraft.

The Landsat-7 ground system consists of a Command and Control Group, including the Mission Operations Center (MOC) at NASA GSFC, and a Data Processing Group, including the Landsat Processing System (LPS), a Level-1 Product Generation System (LPGS), and an Image Assessment System (IAS). The LPS, LPGS, and IAS will be located at the EROS Data Center (EDC) in Sioux Falls, South Dakota, along with the primary X-band receiving station. Hardware installation at EDC is proceeding on-schedule (the X-band antenna was installed in mid-May), and all ground system software development tasks are proceeding smoothly. R.J. Thompson presented a summary of activities at the EDC DAAC, which will be responsible for archiving and distributing Landsat-7 data, while Daniel Devito gave a status report on the EOS Data and Information System (EOSDIS) project. Current plans call for the EOSDIS Core System (ECS) to support management and distribution of Level 0R data at launch (Release B.0), with retrieval of fixed WRS-scene subsets. Floating scene and band subsetting and distribution of Level 1 products will be supported by Release B.1 approximately 7 months after launch. To provide additional schedule contingency, EOSDIS project management has authorized funding for an "Emergency" Landsat backup archive and limited distribution system. Jim Ellickson of the NOAA Landsat Commercialization Office presented a preview of NOAA Mission Operations, which will be transferred to NOAA from NASA 90 days after launch. Ellickson stated that although NOAA has responsibility for long-term Landsat operations, no money has been allocated to NOAAÍs budget by OMB/Congress for that purpose. As a result, NOAAÍs current plans call for making up the operational budget from a license fee levied on each International Ground Station (IGS). A number of Science Team members expressed concern that: (1) Landsat operations were, in effect, being jeopardized by placing funding of day-to-day operations at the whim of IGS participation in the program, and (2) by placing a hefty acquisition fee on the IGSs, they might be less likely to willingly participate in assisting the U.S. in creating and refreshing a seasonal, global archive. Team Leader Goward took an action item to write a letter expressing these concerns to key administrators at NASA, NOAA, and USGS. [NOTE: This letter was sent, and the issues summarized in the letter are actively being worked by representatives of all three agencies.]

Terry Arvidson (Lockheed Martin) and Samuel Goward discussed acquisition strategies and limitations for the ETM+ sensor. Arvidson pointed out that the on-board Solid-State Recorder has a capacity of ~100 scenes. Depending on the number of daily opportunities for direct downlink to U.S. ground stations, the number and spatial distribution of possible acquisitions may be limited during certain World-wide Reference System (WRS) orbits, but we can still meet the Level-1 requirement of acquiring 250 scenes per day. Goward presented plans for a Long-term Acquisition Plan (LTAP), designed to optimize coverage for global change and land-use/land-cover change studies. The LTAP seeks to incorporate vegetation phenology, cloud cover climatology, and gain sensitivity into an algorithmic acquisition strategy that can be used to optimize Landsat-7 operations.

On the second day, the team heard a briefing by Project Scientist Darrel Williams on preliminary ideas for a Landsat-7 follow-on mission. Williams indicated that thermal infrared (TIR) coverage in future Landsat sensors was doubtful, since accommodation of TIR capability significantly increases sensor development costs, mid-morning orbits are not ideal for making thermal measurements, and the Landsat TIR Band 6 data have been the least used. Williams further stated, however, that the improved 60-m single TIR band on the Landsat-7 ETM+, and the multispectral, 90-m TIR data to be acquired by ASTER, would create a larger user community and demand for TIR data. He suggested that a stand-alone TIR sensor, placed in a more ideal early afternoon orbit, should be seriously considered. However, during last yearÍs first wave of New Millennium Project (NMP) proposals, it was determined that there was no new technology yet available that would substantially reduce the cost of building such a TIR sensor. Following the presentation by Williams, additional ideas for next-generation imagers were presented by Steve Ungar, Mission Scientist for the NMP Earth Orbiter-1 (EO-1) mission. When launched in 1999, EO-1 will test innovative ideas in high-resolution, broad-area-coverage and low-cost hyperspectral imaging.

Following status briefings on individual science investigations, the Science Team meeting concluded with reports from two working groups which had initially met the afternoon prior to the Team meeting. The first working group addressed the need for a Landsat-7 Science Plan, recommending that it be released in stages during the next several years. The group also edited and ratified the Science Team charter. The second working group addressed ETM+ performance and calibration. The group expressed concern that schedule pressures were compromising the robustness of calibration tests and made several recommendations to modify or reinstate calibration tests to insure the scientific quality of Landsat-7 data. Williams subsequently presented these concerns to Landsat Project management, and mutual agreements were reached on the instrument test schedule during the remainder of the development and integration phases of the Project.

The next Landsat Science Team meeting is scheduled for October 21-23, 1997, at, or near, Goddard Space Flight Center in Greenbelt, Maryland.

More information on the Landsat Science Team is available through the Team WWW page: www.geog.umd.edu/landsat7.
Mail may be directed to Science Team Leader: Sam Goward at sg21@umail.umd.edu; a "cc" copy to Darrel Williams, Landsat Project Scientist, would also be appreciated at Darrel.Williams@gsfc.nasa.gov.