Dynamics Explorers 1/2

 1981-070A

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Dynamics Explorer 1 (DE 1, DE-A, Dynamics Explorer A) was one of a pair of space science satellites and was designed to study the solar wind, the ionosphere, and the magnetosphere. The 409 kg NASA-GSFC satellite was built by RCA. Both satellites were launched on a single Delta 3913 launch vehicle at 0956 on 1981 Aug 3. The first Delta burn was completed at 1004:39; the stage coasted in parking orbit and then restarted at 1008:28. However the Delta had not been correctly fuelled, and the engine cut off when the tank ran dry at 1010:35, leaving the payload in an unexpectedly low 382 x 969 km x 89.9 deg orbit. DE-B separated at 1011, and at 1037 the DE-A/Star 37N combination separated from the Delta and the Star 37N third stage ignited. The Star 37N was developed for the Japanese N vehicle and this was its only flight on the Delta. DE-A separated from the third stage at 1039, in a 440.0 min, 675 x 24875 km x 90.0 deg orbit. It operated until 1991 Feb 28.

DE-A mass was 424 kg. DE-B mass was 420 kg. DE-A had two 4.0m antennae one 5.8m loop antenna, and two 100m electric field wire antennae (200m tip to tip)

SAI had three optical systems - two in the 3175-6300A range and one in the 1200-1800A range. FOV was 0.3 deg; they had long collimators, and small off-axis focussing mirrors.

DE 1
Date	Time	Event	Orbit
1981 Aug 3	0956:00?	Launch by Delta 3913	CC LC17
		T+0:57 SRM 1-6 burnout
		T+1:00 SRM 7-9 burn
		T+1:18 SRM 1-6 sep
		T+1:58 SRM 7-9 burnout
		T+2:03 SRM 7-9 sep
		T+3:46 MECO
		T+3:59 St 2 SES
	1000:04	T+4:04 Fairing sep
	1004:39	T+8:39 SECO-1	163 x 330 x 90.0
	1008:28	T+14:10s SES-2
	1010:35	SECO-2	(306 x 1300 x 90.0) (plan)
	1015:10?	T+19:10 DE-B sep	301 x 1006 x 90.00
	1018:55	T+22:55 DE-B PAF sep
	1036:37	T+40:37 St 2 sep
	1037:18	T+41:18 St 3 ignition
	1037:59	T+41:59 St 3 burnout
	1039:15	T+43:15 St 3 sep from DE-A	440.0 675 x 24875 x 90.0
	1130?	St 2 depletion?	98.17 380 x 962 x 90.0
1981 Aug?		Booms deployed
1991 Feb 28		DE-A end of tx

Payload:

• RIMS Retarding Ion Mass Spectrometer (MSFC/Chappell)

• EICS Energetic Ion Mass Spectrometer (Lockheed/Shelly)

• HAPI High Altitude Plasma Instrument (SWRI/Burch)

• SAI Spin scan Auroral Imager (Iowa/Frank)

• MAG-A Fluxgate magnetometer (GSFC/Sugiura)

• PWI Plasma wave detector (Iowa/Shawhan)

1981-070B

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DE 2 (DE-B, Dynamics Explorer B) was designed to study the composition of the neutral atmosphere and measure upper atmosphere temperatures, winds, and suprathermal ion flow. The 403 kg satellite was built by RCA. Launched with DE 1 on 1981 Aug 3, it separated from the Delta second stage at 1011 into a 97.66 min, 298 x 996 km x 90.0 deg orbit. It was still transmitting when it reentered on 1983 Feb 19.

The satellite has 6 11-m booms, one 6-m boom.

Payload:

• LANG Langmuir probe (GSFC/Brace)

• RPA Retarding potential analyser (UTD/Hanson)

• IDM Ion drift meter (UTD/Heelis)

• MAG-B Fluxgate magnetometer (GSFC/Sugiura)

• VEFI Vector electric field detector (GSFC/Maynard)

• NACS Neutral atmosphere composition spectrometer (UM/Carignan)

• WATS Wind and temperature spectrometer (GSFC/Spencer)

• FPI Fabry-Perot interferometer (UM/Hays)

• LAPI Low altitude plasma instrument (electrons, ions) (SWRI/Winningham)