Galaxy 10

 1998-F03

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Galaxy 10 was a Hughes HS-601HP satellite built by Hughes/El Segundo for Panamsat. The satellite carried 24 C-band and 24 Ku-band transponders to provide US/Caribbean coverage, and was to have replaced the aging SBS-5 satellite at 123 deg West. Launch mass of Galaxy 10 was 3876 kg; BOL mass 2115 kg. I haven't been able to find its dry mass. Replenishing the Galaxy/PAS constellation was a high priority for Panamsat following the loss of Galaxy 4 and problems with Galaxy 7.

Dimensions are 26m span, 5.9m x 2.7m x 3.6m stowed.

Galaxy III was on the first Delta III 8930 launch vehicle, lost 80 seconds into flight on 1998 Aug 26. Boeing Expendable Launch Systems (formerly McDonnell Douglas) builds the Delta III at Huntingdon Beach, California with final assembly in Pueblo, Colorado. The standard Delta II model is widely regarded as one of the world's most reliable launch vehicles, and I expect that the Delta team will recover from this failure and eventually bring the new rocket up to the same standard. However, the loss of the initial vehicle is certainly a major blow for Boeing and for the US space launch industry; although it represents less money than the recent Titan failure, it will probably have a wider impact. The Delta III consists of:

- Nine Alliant GEM-46 solid strapon motors, a scaled up version of the GEM-40 motors used on the Delta II 7925. The graphite-epoxy case motors use HTPB solid propellant. The motors are built in Alliant's Bacchus, Utah factory; Alliant was formerly known as Hercules Powder and built the upper stage for the first Delta back in 1960.

- The Delta III First Stage, similar to the Delta II first stage, but with the fuel tank at the top reshaped to fit with the wider upper stage. It uses the same LOX/kerosene RS-27A main engine as the Delta II.

- The Delta III Second Stage. This is an entirely new stage, and the first entirely new high energy upper stage developed in the US since the 1960s. It uses a Pratt and Whitney LOX/liquid hydrogen RL10B-2 engine with a long extensible nozzle built by SEP of France. The RL10B-2, with a world record specific impulse of over 462 seconds, is a new version of the venerable RL10 engine used in the Lockheed Martin Astronautics Centaur, the other US high energy upper stage. The liquid hydrogen tank for the Delta III second stage is build by Mitsubishi of Japan, which also builds the liquid hydrogen stage of the Japanese H-II rocket. The Delta III second stage is 4.0m in diameter, much larger than the Delta II stage which still uses tankage derived in part from the 1960-vintage Ablestar. However, the appearance of the new stage, with the narrower LOX tank held inside an interstage and the large nozzle assembly, is still reminiscent of the traditional Delta stage.

- The 4.0 meter fairing, much larger than the old 10-foot Delta II fairing. Boeing also builds the large Titan IV fairings, so has lots of experience in this field.

The launch profile involves igniting the RS-27A main engine and six of the GEM-46 solids at launch. At 80 seconds into flight the six solids separate and the remaining three GEM-46 solids ignite. At 40-50 seconds, however, an unexpected 4 Hz roll mode instability became significant and the solid motor TVC fuel ran out correcting the problem, causing the vehicle to go out of control.

The planned launch profile included a first burn of the second stage engine from T+4min to T+13 min, leaving Delta in a 157 x 1176 km parking orbit. After a 9 minute coase, the stage would burn again to enter a 185 x 35719 km x 27.5 deg geostationary transfer orbit, separating from the Galaxy 10 satellite payload.

Galaxy 10
Date	Time	Event	Orbit
1998 Aug 27	0117:00	Launch by Delta 3	CC LC17B
	0117:55	T+0:55 Guidance problem
	0118:12	T+1:12 Yaw 30 degrees, 18 km alt
	0118:15	T+1:15 auto destruct