TERRIERS

 1999-026A

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The Tomographic Experiment using Radiative Recombinative Ionospheric EUV and Radio Sources (TERRIERS) is a UNEX (STEDI) explorer built by AeroAstro/Herndon for PI institution Boston University to study the ionosphere. TERRIERS is based on the HETE bus. Terriers is 0.5 dia x 1.0 long, 125 kg. Terriers and MUBLCOM are separated by an adapter cone of 19 kg, 0.2 x 1.0m.

The Terriers and MUBLCOM satellites were launched on May 18 by an Orbital Sciences Corp. Pegasus XL/HAPS vehicle. The L-1011 Stargazer aircraft took off from Vandenberg's runway 30/22 at 0412 UTC on May 18 and headed to the drop box over the Pacific at 36.0N 123.0W. Stargazer dropped the Pegasus at 0509 UTC and the first stage solid motor ignited five seconds later. At 0518 UTC the third stage motor (cataloged as 1998-26C) burned out and separated, leaving the payload stack in a 405 x 548 km x 97.7 deg orbit. The PRIMEX HAPS-Lite stage then made the first burn of its hydrazine engine and entered a 540 x 553 km x 97.7 deg orbit. The box-shaped Terriers satellite was deployed at 0520 UTC. A minute later the conical Payload Adapter Fitting (1998-26E) was jettisoned, leaving the disk-shaped MUBLCOM satellite attached to HAPS. The second HAPS burn at 0522 UTC raised apogee to 775 km, followed by a third, apogee burn at 0610 UTC which circularized the orbit. MUBLCOM was deployed to a 769 x 776 km x 97.7 deg orbit. The final HAPS burn then placed the depleted HAPS stage (1998-26D) in a lower 388 x 722 km x 97.1 deg disposal orbit.

TERRIERS is a University Explorer (UNEX), part of NASA's Student Explorer Demonstration Initiative (STEDI). It was to be operated by the space physics group at Boston University for ionospheric studies, and carries TESS, a set of extreme ultraviolet (EUV) spectrographs to get electron density and thermospheric emission profiles. The GISSMO instrument will measure the solar EUV flux. The spacecraft was built by AeroAstro and based on HETE.

After orbit insertion, TERRIERS failed to orient itself correctly and lack of solar power depleted the spacecraft battery.

Terriers
Date	Time	Event	Orbit
1999 May 18	0412	T/O Vandenberg RW30/22
	0509:36	Drop
		T+00:05 Pegasus F-27 Stage 1 burn
		T+01:15 Stage 1 BO
		T+01:31 Stage 1 sep
		T+01:31 Stage 2 burn
		T+2:09 Fairing sep
		T+2:43 Stage 2 burnout
	0516:34	T+6:58 Stage 2 sep
	0516:43	T+7:09 Stage 3 burn
	0517:53	T+8:17 Stage 3 cutoff	94.60 447 x 550 x 97.7 (ILAM)
	0518:53	T+9:17 HAPS 1 burn
	0519:06	T+9:30 HAPS 1 cutoff
	0520:07	T+10:31 Terriers sep	95.66 549 x 551 x 97.7 (ILAM)
	0521:07	T+11:31 Adapter cone sep	95.60 541 x 553 x 97.7
	0522:06	T+12:30 HAPS 2 burn
	0522:25	T+12:49 HAPS 2 cutoff	97.75 649 x 652 x 97.7 (ILAM)
	0611:22	T+1:01:46 HAPS 3 burn
	0611:40	T+1:02:04 HAPS 3 cutoff
	0612:20	T+1:02:44 MUBLCOM sep	100.34 773 x 775 x 97.8 (ILAM)
	0614:20	T+1:04:44 HAPS CCAM
	0614:21	T+1:04:45 HAPS cutoff	460 x 775 x 97.8
	0643:01	T+1:33:25 HAPS depletion	95.62 390 x 706 x 97.1 (ILAM)