Explorer 31

 1965-098B

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DME-A (Direct Measurements Explorer A), built by APL, was part of the ISIS-X (International Satellite for Ionospheric Studies) program, and was launched together with Alouette 2 on 1965 Nov 29 by a Thor Agena B from Vandenberg. DME-A was launched inside an adapter, below Alouette. Orbit of Explorer XXXI was 121.4 min, 505 x 2978 km x 79.8 deg. It operated until 1969 Jun 9. Explorer 31 was 98 kg, 0.9m dia, 0.64m high, with a 0.5m boom giving span of 1.2m.

Payload:

• Retarding Potential Analysers (Te,ne,Tion,nion)

• Energetic electron current monitor (GSFC/Donley) (high flux)

• Energetic electron current monitor (GSFC/Maier) (low flux)

• Electron wake studies

• Ion mass spectrometers

• A1 Thermal Ion Experiment (GSFC/Donley)

• B1 Thermal Electrons (GSFC/Donley)

• C1/C2 Electrostatic Probe (GSFC/Brace)

• E Electron Temperature (UCL/Willmore)

• F Spherical Ion Mass Spectrometer (UCL/Willmore)

• D High Resolution Ion Mass Spectrometer (NRL/Hoffman)

DME-A
Date	Time	Event	Orbit
1965 Nov 29	0448:47	Launch by Thor Agena B	V 75-1-1
	0451:16	Thor MECO (T+2:29)
	0451:25	Thor VECO (T+2:38)
	0451:32	Thor sep (T+2:45)
	0451:56	Agena burn (T+3:09)
		T+3:20 Fairing sep
	0455:48	Agena MECO (T+7:01)	-100? x 500 x 79.8
		T+49:59 Agena MES-2
	0538:58	T+50:11 Agena MECO-2	121.40 500 x 2980 x 79.80 (VCR)
	0543:23	T+54:36 Alouette sep
	0544:04	T+55:17 Adapter petals sep
	0544:31	T+55:44 DME-A sep	121.4 505 x 2978 x 79.8
1969 Jun 9		End of ops