The Interplanetary Monitoring Platform (IMP) was launched in 1963 and involved a network of eleven Explorer satellites designed to collect data on space radiation in support of the Apollo program. The IMP program was a major step forward in spacecraft electronics design, as it was the first space program to use integrated circuit (IC) chips and MOSFETs (MOS transistors). The IMP-A (Explorer 18) in 1963 was the first spacecraft to use IC chips, and the IMP-D (Explorer 33) in 1966 was the first to use MOSFETs. +List of Interplanetary Monitoring Platform (IMP) missionsMissionPhotoSatelliteLaunch DateDecay DateNotesExplorerIMPIMP-1frameless|180x180pxExplorer 18IMP-A27 November 1963, 02:30 UTCDecember 30, 1965First use of integrated circuits in a spacecraft. First satellite in IMP-A/-B/-C design series.IMP-2frameless|180x180pxExplorer 21IMP-B4 October 1964, 03:45 UTCJanuary 1, 1966Second satellite in IMP-A/-B/-C design series.IMP-3frameless|180x180pxExplorer 28IMP-C29 May 1965, 12:00 UTC4 July 1968Third satellite in IMP-A/-B/-C design series.AIMP-1frameless|180x180pxExplorer 33IMP-D1 July 1966, 16:02 UTCIn orbitFirst use of MOSFET integrated circuits in a spacecraft, similar design to IMP-E. Originally intended to orbit the Moon, but placed in an elliptical high orbit instead.IMP-4frameless|180x180pxExplorer 34IMP-F24 May 1967, 14:05 UTCMay 3, 1969Similar design to IMP-G.AIMP-2frameless|180x180pxExplorer 35IMP-E19 July 1967, 14:19 UTCAfter June 24, 1973Similar design to IMP-D. Positioned in Selenocentric orbit.IMP-5frameless|180x180pxExplorer 41IMP-G21 June 1969, 08:47 UTCDecember 23, 1972Similar design to IMP-F.IMP-6frameless|180x180pxExplorer 43IMP-I13 March 1971, 16:15 UTCOctober 2, 1974First spacecraft in IMP-I/-H/-J series.IMP-7frameless|180x180pxExplorer 47IMP-H23 September 1972, 01:20 UTCIn orbitSecond spacecraft in IMP-I/-H/-J series.IMP-8frameless|180x180pxExplorer 50IMP-J26 October 1973, 02:26 UTCIn orbitThird spacecraft in IMP-I/-H/-J series, remained in service until 2006 Over the following two decades, NASA has launched over 50 Explorer missions, some in conjunction to military programs, usually of an exploratory or survey nature or had specific objectives not requiring the capabilities of a major space observatory. Explorer satellites have made many important discoveries on: Earth's magnetosphere and the shape of its gravity field; the solar wind; properties of micrometeoroids raining down on the Earth; ultraviolet, cosmic and X-rays from the Solar System and beyond; ionospheric physics; Solar plasma; solar energetic particles; and atmospheric physics. These missions have also investigated air density, radio astronomy, geodesy, and gamma-ray astronomy.
the interplanetary monitoring platform (imp) was launched in 1963 and involved a network of eleven explorer satellites designed to collect data on space radiation in support of the apollo program the imp program was a major step forward in spacecraft electronics design as it was the first space program to use integrated circuit (ic) chips and mosfets (mos transistors) the imp-a (explorer 18) in 1963 was the first spacecraft to use ic chips and the imp-d (explorer 33) in 1966 was the first to use mosfets +list of interplanetary monitoring platform: (imp) missionsmissionphotosatellitelaunch datedecay datenotesexplorerimpimp-1frameless|180x180pxexplorer 18imp-a27 november 1963 0230 utcdecember 30 1965first use of integrated circuits in a spacecraft first satellite in imp-a/-b/-c design seriesimp-2frameless|180x180pxexplorer 21imp-b4 october 1964 0345 utcjanuary 1 1966second satellite in imp-a/-b/-c design seriesimp-3frameless|180x180pxexplorer 28imp-c29 may 1965 1200 utc4 july 1968third satellite in imp-a/-b/-c design seriesaimp-1frameless|180x180pxexplorer 33imp-d1 july 1966 1602 utcin orbitfirst use of mo:sfet integrated circuits in a spacecraft similar design to imp-e originally intended to orbit the moon but placed in an elliptical high orbit insteadimp-4frameless|180x180pxexplorer 34imp-f24 may 1967 1405 utcmay 3 1969similar design to imp-gaimp-2frameless|180x180pxexplorer 35imp-e19 july 1967 1419 utcafter june 24 1973similar design to imp-d positioned in selenocentric orbitimp-5frameless|180x180pxexplorer 41imp-g21 june 1969 0847 utcdecember 23 1972similar design to imp-fimp-6frameless|180x180pxexplorer 43imp-i13 march 1971 1615 utcoctober 2 1974first spacecraft in imp-i/-h/-j seriesimp-7frameless|180x180pxexplorer 47imp-h23 september 1972 0120 utcin orbitsecond spacecraft in imp-i/-h/-j seriesimp-8frameless|180x180pxexplorer 50imp-j26 october 1973 0226 utcin orbitthird spacecraft in imp-i/-h/-j series remained in service until 2006 over the following two decades nasa has launched over 50 explorer missions some in conjunction to military programs usually of an exploratory or survey nature or had specific objectives not requiring the capabilities of a major space observatory explorer satellites have made many important discoveries on earth's magnetosphere and the shape of its gravity field; the solar wind; properties of micrometeoroids raining down on the earth; ultraviolet cosmic and x-rays fr,om the solar system and beyond; ionospheric physics; solar plasma; solar energetic particles; and atmospheric physics these missions have also investigated air density radio astronomy geodesy an.d gamma-ray astronomy