2.2.0 spase://SMWG/Observatory/IMP IMP Spacecraft Series 2010-10-06T18:37:16Z The IMP spacecraft series. Prelaunch, the 10 IMP's were called IMP's A-J. 8 of them were intended for geocentric orbits (A-C, F-J) and 2 for selenocentric orbits (D,E). Prelaunch, the latter two were also called Anchored IMPs (AIMPs) A and B. After launch, the 8 intended for geocentric were also called IMPs 1-8 and the 2 intended for lunar orbit were called AIMP 1 and 2. Only IMP E = AIMP B = AIMP 2 achieved lunar orbit; IMP D = AIMP A = AIMP 1 went into a geocentric orbit. The mapping of prelaunch IMP letters to postlaunch Explorer numbers and IMP numbers was +-----------------------------------------------+ | IMP (prelaunch) | IMP (postlaunch) | Explorer | |-----------------------------------------------| | A | 1 | 18 | | B | 2 | 21 | | C | 3 | 28 | | D | | 33 | | E | | 35 | | F | 4 | 34 | | G | 5 | 41 | | H | 7 | 47 | | I | 6 | 43 | | J | 8 | 50 | +------------+ spase://SMWG/Person/Jan.Merka MetadataContact Heliosphere.NearEarth Earth.Magnetosphere