SCIENTISTS HAVE identified seven primary research areas, specifically for the EOS programme, to understand the Earth's climate more fully and the effect the human race has had on it:
the role of clouds, radiation, water vapour and rain;
the productivity of the oceans, their circulation and effect on the atmosphere;
sources and levels of "greenhouse" gases and their effect on the atmosphere;
changes in land use, land cover, productivity and the water cycle;
the role of polar ice sheets and sea level;
the coupling of ozone chemistry with the climate and biosphere;
the role of volcanoes in climate change.
THE SPACECRAFT
EOS-AM 1 June 1998. Intermediate-class. From Van denberg AFB, California, on an Atlas 2AS booster. The EOS-AM 1 will be the only large space platform in the series. Originally, like other EOS spacecraft, it was to have been even larger. Built by Lockheed Martin, this craft will collect data on clouds, radiation and aerosols - particles which enter the atmosphere naturally, such as those from volcanoes, or from human sources, such as fossil-fuel burning; the surface temperature of land and oceans; vegetation and ocean phytoplankton; global biological productivity; and the chemistry of the troposphere. The EOS-AM 1 will carry three US instruments and one each from Canada and Japan. The AM designation results from its planned Sun-synchronous, 98.2°-inclination, 705km circular orbit, descending from the north to reach the equator at 10.30 in each pass, during 14.5 orbits per day, achieving full global coverage with the same latitude-longitude pass every 16 days, or 233 orbits. The spacecraft weighs 4,600kg. The EOS-AM 2, a smaller-class spacecraft, will be launched in June 2004 and the AM 3 in June 2010.
EOS-COLOUR September 1998. Small class. Data will be collected on ocean colour, phytoplankton, biological production in the sea, on afternoon equatorial passes from polar orbit. The probable launcher is the Pegasus. It is the first in a planned series of Flight of Opportunity (FOO) missions for specific instruments.
EOS-ALT 1 September 1999. Medium class. The EOS-ALT 1 is the first of two planned spacecraft series in what was originally a one-spacecraft mission. The craft will provide radar altimetry of ocean circulation. An EOS Laser ALT series is planned to study sea-level ice-sheet mass balance; land-surface topography; and cloud layering, using laser radar. The EOS-ALT is to be launched into 66°-high-inclination orbit. The first series mission will probably be flown as the US-French TOPEX-Poseidon Follow-On, or the US Navy's Geosat Follow-On spacecraft. A second mission is planned for 2004. The EOS Laser ALT will be flown in 94°-inclination, non-Sun-synchronous orbits, in 2003.
ACRIMSAT September 1999. Small class. This is the first in a series of flights of the Active Cavity Radiometer Irradiance Monitor flying piggyback on a Pegasus launcher. It will be used to study the varying radiation levels from the variable star, the Sun, in a study of its effect on changes in the climate.
FOO-CERES June 2000. Instrument only. The Clouds and the Earth's Radiant Energy System (CERES) instrument may be flown on the Japanese Atmos B spacecraft. Flights of the SAGE instrument are also called for FOO missions. Later FOO missions include the Solstice, a craft to take measurements of solar ultra-violet irradiance, to be launched in 2003.
EOS-PM 1 December 2000. Intermediate class. This covers clouds, rain and radiative balance; snow and sea ice; sea-surface temperatures; land and sea biological and vegetation productivity; and atmospheric temperature and moisture. The spacecraft is to be built by TRW, with the EOS-CHEM 1, under a contract, with options for two more craft (the AM2 and PM 2) to 2012, with a potential total value of $668 million, using a common spacecraft bus called the AB1200. The contract was competed for against Lockheed and Hughes, which had filed protests with the General Accounting Office (GAO) - claiming that TRW's $400 million estimate for the EOS-PM 1 and EOS-CHEM 1 was unrealistically low. The GAO has now overruled these protests. The EOS-PM 1 (passing over the equator at 13.30 daily, in its polar orbit) will carry up to seven instruments and weigh about 3,175kg. The probable launcher is the Delta 2. An EOS-PM 2 is planned for launch in December 2006 and the PM 3 launch is set for December 2012.
EOS-CHEM (December 2002). Intermediate class. Chemistry of the troposphere and stratosphere; data on aerosols in atmosphere; and solar radiation will be studied. To be built by TRW (see EOS-PM 1). Up to seven instruments will weigh about 3,175kg. Polar orbit will be made, with an afternoon pass over the equator at 13.45. The probable launcher will be the Delta 2. The EOS CHEM 2 and 3 are scheduled for launches in 2008 and 2014.
Source: Flight International
