TRW/AESC LS-3 DSP
The Integrated Missile Early Warning System (IMEWS) or Defense Satellite Program (DSP), was an operational system of military early warning satellites. Built by TRW, the satellites were equipped with television cameras and infrared sensors operating through a Schmidt telescope which was offset from the main axis of the telescope by 7.5° so that, with the satellite spinning at 6 rpm, a conical scanning pattern was achieved. Over several scans this allowed observers to distinguish between a stationary heat source, such as a forest fire, and a moving heat source, such as a missile.
Also known as Code 647 and LS-3A, the first generation of satellites is believed to have carried an array of 2000 infrared sensors whereas the second generation carried 6000 such sensors. The satellites are believed to have had a length of 7.01 m, a diameter of 2.78 m and a mass of 1100 kg. The operational system consisted of five satellites of which three were operational and two in-orbit spares. The locations which have been mentioned in subsequent reference sources included 36°W, 70°W, 85°W, 105°W, 134°W, 72°E and 75°E and it is suggested that satellites were periodically shifted to other locations.
|Photo: Author's collection|
IMEWS-4 (1973 040A)
IMEWS-10, IMEWS-11 and IMEWS-12 incorporated significant modifications to improve their performance and were designated as LS-3B.
|Photo: Author's collection|
IMEWS-21 (2001 033A)
The third generation, commencing with IMEWS-14 comprised nine satellites. They had a length of 10 m, a diameter of 4.15 m and a mass of 2500 kg. The operational system consisted of three satellites in geostationary orbit over the Atlantic, Pacific and Indian Oceans. The satellites were equipped with an improved telescope and 6000 infrared sensors with future versions having a capacity of 24,000 sensors. Some or all of the satellites in the series also carried a magnetospheric plasma analyser to measure low-energy ions and plasma, as well as a particle analyser, to measure energetic particles.
|IMEWS-1||1970 093A||6-Nov-1970||Also known as Ops-5960; failed to achieve correct orbit|
|IMEWS-2||1971 039A||5-May-1971||Also known as Ops-3811|
|IMEWS-3||1972 010A||1-Mar-1972||Also known as Ops-1570|
|IMEWS-4||1973 040A||12-Jun-1973||Also known as Ops-6157|
|IMEWS-5||1975 118A||14-Dec-1975||Also known as Ops-3165|
|IMEWS-6||1976 059A||26-Jun-1976||Also known as Ops-2112|
|IMEWS-7||1977 007A||6-Feb-1977||Also known as Ops-3151|
|IMEWS-8||1979 053A||10-Jun-1979||Also known as Ops-7484|
|IMEWS-9||1981 025A||16-Mar-1981||Also known as Ops-7350|
|IMEWS-10||1982 019A||6-Mar-1982||Also known as Ops-8701|
|IMEWS-11||1984 037A||14-Apr-1984||Also known as Ops-7641|
|IMEWS-12||1984 129A||22-Dec-1984||Also known as USA-7|
|IMEWS-13||1987 097A||29-Nov-1987||Also known as USA-28|
|IMEWS-14||1989 046A||14-Jun-1989||Also known as USA-39|
|IMEWS-15||1990 095A||13-Nov-1990||Also known as USA-65|
|IMEWS-16||1991 080B||25-Nov-1991||Also known as USA-74|
|IMEWS-17||1994 084A||22-Dec-1994||Also known as USA-107|
|IMEWS-18||1997 008A||24-Feb-1997||Also known as USA-130|
|IMEWS-19||1999 017A||9-Apr-1999||Also known as USA-142; failed to achieve correct orbit|
|IMEWS-20||2000 024A||8-May-2000||Also known as USA-149|
|IMEWS-21||2001 033A||6-Aug-2001||Also known as USA-159|
|IMEWS-22||2004 004A||14-Feb-2004||Also known as USA-176|
|IMEWS-23||2007 054A||11-Nov-2007||Also known as USA-197|
Launch dates of the IMEWS series
The launches of the last two IMEWS satellites, IMEWS-24 and -25, were cancelled.
The primary objective of the early warning satellite development was to fill the gaps in the coverage provided by the land based Ballistic Missile Early Warning System utilised by the United States to provide an early detection of a missile attack. The system initially consisted of a chain of three large radar stations which observed the USSR.
The Missile Detection And Surveillance (Midas) series of experimental military early warning satellites tested the feasibility of complementing the land based Ballistic Missile Early Warning System. The spacecraft were built by Lockheed and were based on the Agena upper stage. The satellites were equipped with infrared sensors developed by IT&T, which could detect missiles as soon as they would be launched. These sensors had only a limited capability and were not successful.
The first two satellites in the series were placed in relatively low orbits, which was all that could be achieved for the 2000 kg satellite in combination with the Atlas Agena A launch vehicle. Subsequent satellites were lighter (1600 kg) due to the use of solar cells instead of batteries, and did use the Atlas Agena B combination, allowing them to be placed in a higher orbit of about 3500 km, commencing with Midas-3. Midas-2 also carried a magnetometer, a micrometeorite detector and an ion and electron detector as ancillary instruments.
It is believed that the programme was only partially successful due to the limited capability of the sensors that were carried. The Midas series of satellites were also used to place ancillary satellites of a technology nature in orbit, whilst Midas-4 and Midas-7 conducted the Project Westford experiments in communications.
|Midas-1||---||26-Feb-1960||---||Failed to orbit|
|Midas-4||1961 αδ1||21-Oct-1961||Used in Project Westford|
|Midas-6||---||17-Dec-1962||---||Also known as Ops-5201; failed to orbit|
|Midas-7||1963 014A||9-May-1963||Used in Project Westford|
|Midas-8||---||12-Jun-1963||---||Also known as Ops-1240; failed to orbit|
|Midas-9||1963 030A||19-Jul-1963||Failed to separate from ERS-10|
Launch dates of the Midas series
The sensor development undertaken as part of the Midas programme led briefly to a satellite proposal identified as Code 461. This programme was cancelled in favour of the Code 266 programme which the author has labelled as Improved Midas. The three satellites in this series are believed to have tested the use of television cameras in conjunction with the infra-red detectors but may have been unsuccessful.
|Photo: Author's collection|
|Improved Midas-2 (1966 077A)|
|I. Midas-1||1966 051A||9-Jun-1966||3-Dec-1966||Also known as Ops-1960 and FTV-1351|
|I. Midas-2||1966 077A||19-Aug-1966||Also known as Ops-0856 and FTV-1352|
|I. Midas-3||1966 089A||5-Oct-1966||Also known as Ops-1920 and FTV-1353|
Launch dates of the Improved Midas series
For some years it was thought that a series of six satellites launched between 1968 and 1975 were the Ballistic Missile Early Warning System (BMEWS) series to replace the earlier Midas system of military early warning satellites. Also referred to as Code 949, the satellites were thought to have been built by TRW and were reported to be equipped with infrared sensors developed by Aerojet and a television system developed by RCA. Information gathered since then have identified the satellites as part of the Canyon and Rhyolite series of intelligence gathering satellites.
Last Updated: 18 January 2008