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MIDAS - A & B & C

USAF, Early Warning Spacecraft

By © Charles P. Vick 2007 All Rights Reserved


MIDAS-A & MIDAS-B – EW Spacecraft Series – (USAF - Program AFP-239A, 461)

Code name MIDAS-A and MIDAS-B was the first in a long series of Early Warning earth orbit USAF, spacecraft used by the USAF. They were launched by the stretched Atlas- Agena-A, Atlas Agena-B and the final ones in the series were launched by the Atlas Agena-D series booster with a total of at least twelve launch attempts with four failures. The spacecraft were actually nothing more than USAF services specific sophisticated earth orbit space based earth infrared scanning imaging spacecraft. The MIDAS introduced the first infrared scanning imaging sensors with a total spacecraft mass of between 5,000.94 pounds fueled or 4,780 pounds dry for the MIDAS-A series while the MIDAS–B mass was 4,410 pounds fueled with a dry mass of 3,404 pounds. MIDAS’s first launch was a launch failure on February 26, 1960 in the A series followed by a successful launch of the last of the A series on May 24, 1960 and its last launch was for the B series on October 5, 1966. The first launch in the B series was July 12, 1961 and the last launch in the B series was July 18, 1963 followed by the Agena D series first launch on June 9, 1966 The time between the B series launches was a two year hiatus for improvements to the system to reduce false alarms. They were designed to monitor and pick up on ballistic missile launches and jet powered aircraft in flight.

MIDAS-C Series R&D Testing Program

 It would appear that in fact the USAF continued to fly the Midas-C, Agena-D series through 1970 accumulating quite a data base on Soviet and American ballistic missile arsenal test through 1967 until the introduction of the DSP series. In between 1966 and 1970 there were a series of highly classified USAF flights directly related to the flight testing of the new experimental technology ultimately utilized by the DSP program. Circumstantial evidence additionally would tend to indicate that the MIDAS program number 461 IR, BMEUS sensors technology were also placed on the Canyon series. One could also think about the DMSP weather satellites block-4 series as a usable platform for similar sensor deployment.

“During 1966 and 1967, Program 461 collected data on many of the ballistic missiles and space launch vehicles in the Soviet and U.S. arsenals, totaling dozens of test launches. In the course of those observations, Program 461 sensors produced a substantial database on the clutter created by the scanning of the Earth-cloud backgrounds, information also needed for the optimization of the DSP sensors, the development of which was commencing at that time” [read 1968-1970 as highly classified experiments conducted on otherwise unidentified AF satellite programs]. “ Thus were provided the proof of principle for space-based surveillance and a valuable database for the design of the sensors in the national early warning system to follow. “


The MIDAS program was superseded by the DSP Defense Support Program spacecraft series. The MIDAS class sensors in various renditions also appeared on some other SIGINT spacecraft as well as apparently military weather spacecraft.

The technology for these Early Warning spacecraft were brought on line very early in development with the expected problems that only time would resolve but besides providing early warning of potential attacks proved to be an intelligence wind fall to study ballistic missile tests of adversary countries that the follow-on (DSP) Defense Support Satellites series would greatly improve. With time the satellite proved out highly successfully once the technology was perfected. Like any new technology program it had its issues such as false alarm warnings.

Each stabilized spacecraft was about 5 feet in diameter and about 18.8 feet long for the A series while the B series was 5 feet in diameter and longer than the A series with the main part of the spacecraft being the Agena B or Agena D stage. It is presumed that B series of spacecraft carried two solar arrays and one down link communications capability. The launch shroud was essentially a jettisoned nose cap over the infrared scanning sensor .

The A series spacecraft utilized the Agena-A stage placing the spacecraft in an orbital inclination of 33 degrees with a perigee of 484 miles and an apogee of 511 miles with a spacecraft life of just 2 days. This B series spacecraft utilized the five foot diameter by 20.86 foot long Agena-D based stage to place it in earth orbit at an inclination of 88-89 degrees with a perigee of 3,188.4 miles and an apogee of 3,615.8 miles with a spacecraft life of 18 days. The nature of the infrared scanning sensors limited the useful life of the spacecraft systems even in the DSP series though over time this would improve considerably. The Agena-D rocket stage portion of the MIDAS early warning spacecraft packages carried the usual assortment of earth, horizon and solar sensors to orient the spacecraft to orientate its IR sensor to the earth. The spacecraft was able to receive and send the data to several global ground stations via radio beacon antenna signal operated by USAF personnel. The data was then processed and analyzed at for distribution to the Air Force intelligence community.


1 McDowell, Jonathan, U. S. Reconnaissance Satellites Programs, Part 1: Photoreconnaissance, Quest, Vol. 4, No. 2, Summer, 1995, pp.22-33.

Midas Series Early Warning Satellites


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Page last modified: 21-07-2011 13:04:58 ZULU