NASA selected ‘Terra’ as the winning name for the EOS AM-1 spacecraft after a competition to come up with a new, more descriptive, name for this flagship Earth Observing System mission to observe the entire planet from the unique vantage point of space. Terra will enable new research into ways the Earth’s lands, oceans, atmosphere, ice, and biological ecosystems interact as a whole climate system. It is currently scheduled for launch on July 28 from Vandenberg Air Force Base, California (see article on page 10).
A small, low-cost Total Solar Irradiance Mission (TSIM) to study the Sun’s solar radiation input to the Earth-atmosphere system has been selected as part of the second phase of the EOS program. The competitively selected science team will have full responsibility and authority to accomplish this mission, including acquiring a spacecraft, integrating the instruments and spacecraft together, integrating the spacecraft with a government provided launch vehicle, operating the spacecraft during the life of the mission, and analyzing the data. The TSIM, led by Dr. Gary Rottman of the Laboratory for Atmospheric and Space Physics, University of Colorado, seeks to learn more about global climate change through precise measurements of both the spectral and total irradiance from the sun. Solar radiation is the dominant energy input into the Earth’s ecosystem, and even small changes in the sun’s output can produce significant changes in the Earth’s climate and environment. The possibility of combining the SOLSTICE (Solar Stellar Irradiance Comparison Experiment) instrument, also led by Dr. Rottman, with TSIM on one spacecraft, is currently under study. There is scientific synergy and programmatic benefit to combining these two instruments onto a single platform.
On March 2, Dr. Ghassem Asrar, Associate Administrator of the Office of Earth Science, announced the selection of four concepts for a six-month study as candidates for the Earth Observing 3 (EO-3) mission. One of these concepts will be selected as the third in a series of Earth Observation-focused New Millennium Program (NMP) technologies aimed at identifying, developing, and validating key instrument and spacecraft technologies that can lower cost and increase the performance of science missions in the 21st century.
The concepts selected for further study all focus on geostationary or geosynchronous orbits, and include: (i) Active large-aperture optical systems to provide high-resolution thermal imaging from geosynchronous orbit, proposed by Del Jenstrom, Goddard Space Flight Center; (ii) Geostationary synthetic-aperture microwave sounder, proposed by Dr. Bjorn Lambrigtsen, Jet Propulsion Laboratory; (iii) Geostationary imaging Fourier transforming spectrometer, proposed by Dr. William L. Smith, Langley Research Center; and (iv) Geostationary tropospheric trace-gas imager, proposed by Dr. Jack Fishman, Langley Research Center, who will work with Dr. James F. Gleason, Goddard Space Flight Center.
These NMP concepts were selected from 24 proposals submitted in response to a NASA Research Announcement released in September 1997. The selection process included evaluations of each proposal by external science and technology peer reviewers, along with two panel sessions with leading NASA scientists and technologists to categorize each proposal.
The first New Millennium Program Earth-orbiting mission, Earth Observing-1 (EO-1), is scheduled for launch in December 1999. It will demonstrate an Advanced Land Imager (ALI) and hyperspectral imaging technologies (Hyperion) that may eventually replace the current measurement approach used by Landsat satellites. Earth Observing-2 will fly an infrared coherent Doppler lidar in the cargo bay of the Space Shuttle to demonstrate the capabilities of a space-based lidar to accurately measure tropospheric winds from the Earth’s surface to a height of about 16 km. This flight, known as the Space-Readiness Coherent Lidar Experiment (SPARCLE), is scheduled for launch in early 2001.
The Geoscience Laser Altimeter System (GLAS), SOLSTICE, and EOS Chemistry science teams have developed Algorithm Theoretical Basis Documents (ATBDs) that are currently being reviewed by the international scientific community.
Following these written evaluations, an oral review will be conducted on April 29 for GLAS, and May 18-19 for TES, HIRDLS, MLS, and SOLSTICE. A total of 7 ATBDs will be reviewed during the first week by a visiting committee chaired by Prof. Pat McCormick of Hampton University, and 9 ATBDs will be reviewed during the second week by a committee chaired by Mr. Larry Gordley of GATS, Inc. These documents, developed for each data product, consist of a detailed physical and mathematical description of the algorithm, variance or uncertainty estimates, and practical considerations, such as calibration and validation, exception handling, quality assessments, and diagnostics. These documents will be posted on the World Wide Web following revisions that result from the written reviews as well as panel report recommendations.
This peer review process is extraordinarily valuable to the science teams and engages the larger scientific community, both nationally and internationally, in the process of providing feedback on approaches to routine data analysis from EOS sensors. At present, 17 of the 19 algorithm teams of EOS have gone through at least one of these peer review processes, with only Jason-1 to follow at an appropriate point in the future. Landsat 7 Enhanced Thematic Mapper Plus (ETM+) does not have any standard data products and hence will not be required to develop any ATBDs in the future.
I am happy to report that AMSU-A (Advanced Microwave Sounding Unit-A) has been delivered to TRW, Inc., Redondo Beach, California, for integration on the EOS PM-1 spacecraft. This instrument provides atmospheric temperature measurements above the Earth’s surface which, when combined with the Atmospheric Infrared Sounder (AIRS) and Humidity Sounder for Brazil (HSB), allow precise estimates of both temperature and moisture profiles from the Earth’s surface to 100 hPa.
Finally, the table below lists the launches planned for Earth Science payloads throughout 1999. This looks to be a significant year for major satellite launches of interest to the Earth science research community as well as policy makers, applications specialists, and educators
| Date | Launch Site | Vehicle and Provider | Payload & Owner |
|---|---|---|---|
| April 15 | Vandenberg Air Force Base, Calif. | Delta II, Boeing Co. | Landsat 7, NASA |
| May 16 | Vandenberg Air Force Base, Calif. | Titan II, Lockheed Martin | QuikSCAT, NASA |
| July 28 | Vandenberg Air Force Base, Calif. | Atlas IIAS, Lockheed Martin | Terra, NASA |
| September | Baikonur Cosmodrome, Kazakhstan | Zenit-2, Yuzhmash, Ukraine | Meteor-3M(1)*/ SAGE III, NASA |
| October 27 | Vandenberg Air Force Base, Calif. | Taurus, Orbital Sciences Corp. | ACRIMSAT**, NASA |
| December 15 | Vandenberg Air Force Base, Calif. | Delta 7320, Boeing Co. | EO-1***, NASA |
| *Russian meteorological spacecraft provided by Russian Space Agency
**Co-manifested with KOMPSAT (Korea) ***Co-manifested with SAC-C (Argentina) | |||