NASA has selected a new launch date of April 15, 1999, for the Landsat-7 Earth science satellite. The launch, originally scheduled for December 1998, will take place from Vandenberg Air Force Base, CA, on a Delta II launch vehicle.

The Enhanced Thematic Mapper Plus (ETM Plus), the science

instrument on Landsat-7, will continue a database of high-

resolution Earth imagery begun in 1982 by the Landsat-4 thematic

mapper. As changes occur on the Earth's surface due to natural or

human-induced events, scientists will be able to use the archive

of imagery from the Landsat missions to better understand the

behavior of the global environment. Landsat images provide

information meeting the significant and diverse needs of business,

science, education, government and national security.

Applications for Landsat-7 imagery will include agricultural crop

planning, timber issues in the Northwest, and information about

population change and water quality.

Landsat-7 will add to the global archive of sunlit,

substantially cloud-free images of the Earth's land surfaces. The

spacecraft contains several technological improvements over

previous Landsat satellites and their instruments. These

improvements include better instrument calibration and a solid-

state data recorder capable of storing 100 individual ETM Plus

Earth images. This capability will enable Landsat-7 to update a

complete global view of the Earth's land surfaces seasonally, or

approximately four times per year. The Landsat series has

provided the longest record of the Earth's continental surfaces as

seen from space.

"The launch delay of Landsat-7 was caused by a need for

changes in the design of the electrical power-supply hardware for

the spacecraft's instrument," said Phil Sabelhaus, Landsat-7

project manager at NASA's Goddard Space Flight Center, Greenbelt,

MD. During instrument-level thermal vacuum tests beginning in

December 1997, a power supply on the ETM Plus instrument failed

twice. These technical challenges have been resolved and Landsat-

7 is on track for launch. "We're satisfied that our design

concerns have been met, and we're ready for a springtime launch of

the spacecraft."

Landsat 7 will continue the legacy of the first U.S. Earth

Resources Technology Satellite (ERTS-1), launched in 1972, by

building upon the only global data record captured from space.

The ETM Plus was designed and built by Raytheon (formerly

Hughes) Santa Barbara Remote Sensing, Santa Barbara, CA. Lockheed

Martin Missiles and Space built the Landsat-7 spacecraft, with

integration of the instrument and spacecraft conducted at the

company's facility in Valley Forge, PA.

NASA is developing in parallel to the Landsat-7 mission the

next generation Landsat instrument and spacecraft technologies

through the New Millennium technology demonstration program. This

follow-on technology development effort will enable future

measurements to be made by a sensor that is one-fourth the mass of

the ETM Plus. A new sensor enabled by this development will use

only 20 percent of the electrical power currently needed, while

reducing the overall mission cost by 60 percent. The next

generation Landsat flight demonstration is expected to launch in

late 1999.

NASA intends to operate Landsat 7 and the flight

demonstration spacecraft in the same orbit, but separated from

each other by approximately one minute in distance. Such a flying

formation will allow for observing the same area of Earth by both satellites, providing validation of the new imaging technologies being demonstrated. The advanced Landsat technology mission is intended to mitigate technological risk, improve future Landsat performance by a factor of four, and reduce overall mission development time by half.

Landsat is the central pillar of the national remote sensing capability. The Landsat 7 spacecraft was built to complement the research of NASA's Earth Science Enterprise, a long-term research program designed to study Earth's land, oceans, atmosphere, ice and life as a total integrated system. NASA's Goddard Space Flight Center manages the development of Landsat for the Earth Science Enterprise, NASA Headquarters, Washington, DC.