### Science, Technology, and Earth Applications Satellites

NASA continued to advance its mastery in the areas of advanced technology spacecraft design, along with earth and space science applications. Two more second-generation Landsat satellites were launched (Landsat 4 and 5). They built on the foundations by the previous 4 satellites with greater capabilities to make greater detailed land-use information. The data was used for crop forecasting, vegetation-land usage, and lake and river flood damage reporting. But competition from the French SPOT satellite system began.

Space science once again took the forefront. It included such satellites as the Solar Max Mission (SMM) which was designed to observe sun activities over a wide region of wavelengths and to cover the maximum period of the sunspot cycles. SMM also made history by being the first satellite to be repair by a shuttle crew in 1984. The international Infrared Astronomical Satellite (IRAS) which was sponsored by the United States, Great Britain and The Netherlands had a prime mission of providing a complete infrared map of the observable universe. Earth Radiation Budget Satellite (ERBS) was designed to study solar radiation energy. The Cosmic Background Explorer (COBE) was designed with three instruments to measure diffuse infrared energy that abounds in the universe originating with the Big Band. NASA saved the best to end the 1980s and this was the Hubble Space Telescope (HST). The orbiting telescope was to out perform all ground based telescopes because it did not have to contend with the earth's atmosphere. High hopes were placed on the HST, but when it put on orbit, it was found that a lens aberration had reduced the capability of the system, causing NASA great embarrassment. This difficulty was corrected on a later shuttle repair mission, and HST has become one of the crowning technological accomplishments for NASA as it continues to pierce the secrets of the star-filled heavens.

To help reduce the costs of communicating with satellites, NASA began to close down it world-wide network of tracking stations and replacing them with the Tracking and Data Relay Satellite System (TDRSS). With two operational satellites and one as an on-orbit backup spare, NASA is able to communicate 85% of the time with most of its satellites. Previously with its ground network, it was only able to keep in touch with its space assets 15-20 % of the time. The TDRSS system gave it greater coverage at a lesser cost.

Nicholas M. Short, Sr. email: nmshort@ptd.net
Jim Rosalanka (jrosolanka@worldnet.att.net)