Explorer 49

  1973-039A

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Because of the problem of terrestrial radio interference, the second RAE, RAE B, was designed to make its observations in lunar orbit, shielded from Earth while it skimmed above the lunar farside. The spacecraft had a velocity control thruster to refine the lunar orbit.

RAE 2 (Explorer 49) was launched at 1413 on 1973 Jun 10 by a Delta 1913 from Cape Kennedy. The Delta stage ignited at 1417:30 and cut off at 1422:30 to place the combination in parking orbit. At 1425 the Delta reignited for 29s to enter a 107.8 min, 182 x 2074 km x 29.3 deg orbit. At 1428 the Star 37D third stage ignited for the 44s translunar injection burn, entering a 182 x 390244 km x 29.1 deg orbit. RAE 2 separated from the Star 37D at 1430. The VCS was used to make a midcourse correction at 1528 on Jun 11. The TE-M-479 (Star 17) solid motor fired at 0721 on Jun 15 to insert RAE 2 in a 241 min, 1123 x 1334 km x 38.3 deg lunar orbit. The Star 17 was jettisoned on Jun 18, and the same day the VCS fired to lower the orbit to 221.2 min, 1053 x 1064 km x 38.7 deg. The 37m dipole antenna was extended on Jun 20.

Another object was cataloged in lunar orbit, probably implying the VCS was also ejected after use.

It was reported in Jun 1973 that on Jul 4 the dipole would be retracted, the VCS used to adjust the orbit, and the two main V antennas would be deployed first to 183m, and then a week later to 229m. Total span is 400m. RAE also has a 190m stabilization boom.

RAE 2 operated in lunar orbit until 1977 Apr 30. After that, engineers performed end-of-life tests retracting and extending the antennas. It probably impacted the lunar surface later in 1977. Orbit according to an internal document was 1058 x 1070 km x 59 deg with a 222 min period; this is presumably the first orbit after VCS sep.

 

Explorer 49
Date	Time	Event	Orbit
1973 Jun 10	1413:00	Launch by Delta 1913	CK LC17B
		T+0:38 SRM 4-9 burnout
		T+0:39 SRM 1-3 on
		T+1:17 SRM 1-3 out
		T+1:25 SRM 1-9 sep
		T+4:29 MECO
		T+4:33 VECO
		T+4:36 St 1 sep
	1417:41	T+4:41 SES-1
		T+4:55 Fairing sep
	1422:31	T+9:31 SECO-1
	1425:57	T+13:57 SES-2 29s
	1426:28	T+14:28 SECO-2	182 x 2074 x 29.3
		T+15:02 Spinup
	1428:05	T+15:05 Stage 2 sep
	1428:19	T+15:17.9 Star 37D burn 44s
	1429:03	T+16:02.7 Star 37D burnout
	1430:43	T+17:43 Star 37D separation	182 x 390244 x 29.1
	1430:45	T+17:45 Star 37D release yo weight
1973 Jun 11	0600?	Pass EL1:4
1973 Jun 11	1528	VCPS TCM
1973 Jun 13	0600?	Enter lunar sphere
1973 Jun 15	0721	Star 17 burn 22s LOI	241.0 1123 x 1334 x 61.4
1973 Jun 18	0725?	Star 17 sep
		Despin to 12 rpm (ACS)
		VCPS lower orbit to avoid LIM	221.2 1053 x 1064 x 61.4
1973 Jun 20		37m dipole extended
1973 Jul 4		Retract dipole?
1973 Jul 9		Final orbit trim
1973 Jul 9?		VCPS separated
1973 Jul		Deploy libration damper
1973 Jul 12		Deploy to 183m
		Experiment turn on
1973 Jul 29		Begin first lunar shadow period
1973 Oct 26		End first shadow period
1973 Nov 8		Upper V extension to 200m
1973 Nov 14		Upper V deploy to 229m
1974 Jan 3		Begin second lunar shadow period
1974 Jan 31			222.0 1059 x 1071 x 62.0
1974 Mar 22		End second shadow period
1974 Jun 10		Begin third shadow period
1974 Aug 28		End third shadow period
1974 Oct 11		One lower-V boom extended to 229m
1974 Nov 6		Second lower-V boom extended to 229m
1974 Nov 17		Fourth shadow period
1975 Feb 1		End shadow period 4
1975 Apr 21		Shadow period 5
1975 Jul 1		Begin new-moon-intensive 50-percent data coverage
1975 Jul 9		End shadow period 5
1975 Dec 24		Resume full time coverage
1976 Apr 17		Reduce to 50 percent coverage again
1976 Oct 19		Resume full time coverage
1977 Apr 30		End of ops