P3D Launch Sequence Study (Part IV)

Started: July 3, 1997 -- Last Update: July 9, 1997

Viktor Kudielka (ÖVSV P3D Mission Analysis Project)

Introduction

This document is intended as a base for discussion of alternative launch sequences of P3D. This part IV considers alternative launch schedules, 15. October 1997, 15. November 1997, and 15. December 1997. Although currently the conflicting requirements for the start window are not yet resolved, a separation at 12:00 UTC is assumed.

The intention is, to present scenarios with a maximum bi-propellant deltaV of approx. 1100 m/s, allowing a start mass of up to about 620 kg. The second issue is, to prevent heights of perigee below 500 km. Additional arc-jet operations at apogee are necessary for this purpose.

Previous parts:
P3D Launch Sequence Study, Part I, Dec. 5, 1996,
P3D Launch Sequence Study, Part II, Feb. 12, 1997,
P3D Launch Sequence Study, Part III, July 1, 1997

Scenario 3A

Scenario 3A is similar to scenario T3 (see part III), but with additional arc-jet operations at apogee to maintain the height of perigee above 500 km. Since the height of perigee as well as the velocity at apogee is higher, the major inclination change is slightly more expensive.

day	orbit	RAaN	ArgP	sma	ecc	inc	HeightPer	HeightApo	VPer	VApo	deltaV	mass
#	#	deg	deg	km		deg	km	km	m/s	m/s	m/s	kg
000.5	001	018.40	178.00	24611	0.7175	07.76	0575	35890	09922	1632	000	600.0
062.7	130	358.10	218.78	27425	0.7445	07.90	0630	41464	09961	1459	084	588.4
088.9	180	350.66	233.91	27425	0.7435	07.93	0657	41436	09939	1462	000	588.4
088.9	180	350.66	233.91	45357	0.8449	07.93	0657	77300	10224	0860	285	535.1
170.1	253	342.48	252.04	45357	0.8473	08.01	0548	77410	10311	0852	000	535.1
183.5	265	341.24	255.01	45433	0.8454	08.03	0645	77456	10234	0857	009	534.0
288.1	349	338.77	269.81	51194	0.8616	08.10	0707	88925	10234	0761	048	528.0
289.4	350	252.64	350.97	51194	0.8614	63.72	0715	88917	10227	0761	801	404.3
386.2	434	247.19	351.45	42226	0.8366	63.85	0520	71175	10302	0916	081	396.7
403.2	451	246.09	351.56	42362	0.8317	63.89	0750	71219	10121	0930	017	395.2
523.9	599	236.39	352.18	32215	0.7825	63.32	0627	51046	10071	1229	147	381.9

Figures 3A.1A and 3A.1B show the whole period of powered flight. Figures 3A.2A and 3A.2B show the final drift phase.

Summary -- Scenario 3A

• Start date October 15, 1997
• GTO RAAN = 18.4°
• Increasing orbital period to 32 hours (arc-jet: deltaV = 132 m/s, bi-prop: deltaV = 285 m/s) and maintaining height of perigee above 500 km (arc-jet deltaV = 9 m/s)
• At ArgP = 270° rotation around major axis by 63.5° (bi-prop, deltaV = 801 m/s)
• Reducing orbital period to 16 hours (arc-jet, deltaV = 228 m/s) and increasing height of perigee above 600 km (arc-jet deltaV = 17 m/s) for final drift phase
• New orbit with ArgP = 352.2° and i = 63.3° after 524 days
• Total deltaV bi-prop = 1086 m/s
• Total deltaV arc-jet = 384 m/s
• Grand Total deltaV = 1470 m/s

Scenario 3B

Scenario 3B, due to the different ascending node, shows two effects. First, a nearly constant ArgP until about six years after the start (see figure 3B.2A). Second, a significant minimum in height of perigee around three years after start (see figure 3B.2B). More fine-tuning will be necessary to keep height of perigee also during the "final" drift phase above 500 km.

day	orbit	RAaN	ArgP	sma	ecc	inc	HeightPer	HeightApo	VPer	VApo	deltaV	mass
#	#	deg	deg	km		deg	km	km	m/s	m/s	m/s	kg
000.5	001	048.40	178.00	24611	0.7175	07.76	0575	35890	09922	1632	000	600.0
058.0	121	029.59	215.89	27206	0.7427	07.98	0622	41034	09961	1471	078	589.2
094.2	191	019.14	237.07	27206	0.7418	08.05	0648	41008	09941	1474	000	589.2
094.2	191	019.14	237.07	44768	0.8444	08.05	0648	76132	10226	0871	285	535.8
169.5	260	013.08	252.45	44768	0.8444	08.29	0586	76194	10275	0867	000	535.8
177.1	267	012.68	253.87	44812	0.8440	08.32	0611	76256	10255	0867	005	535.2
294.6	362	010.45	269.84	51266	0.8599	08.54	0802	88974	10162	0765	054	528.4
295.9	363	284.37	350.55	51266	0.8601	64.81	0794	88982	10168	0765	816	402.5
343.3	401	282.10	350.53	46799	0.8485	64.53	0710	80132	10196	0835	036	399.1
356.1	412	281.40	350.54	46897	0.8458	64.66	0855	80183	10086	0843	011	398.1
525.8	605	269.01	350.56	32202	0.7855	64.14	0529	51119	10151	1219	191	380.8

Figures 3B.1A and 3B.1B show the whole period of powered flight. Figures 3B.2A and 3B.2B show the final drift phase.

Summary -- Scenario 3B

• Start date November 15, 1997
• GTO RAAN = 48.4°
• Increasing orbital period to 32 hours (arc-jet: deltaV = 132 m/s, bi-prop: deltaV = 285 m/s) and maintaining height of perigee above 500 km (arc-jet deltaV = 5 m/s)
• At ArgP = 270° rotation around major axis by 64.5° (bi-prop, deltaV = 816 m/s)
• Reducing orbital period to 16 hours (arc-jet, deltaV = 227 m/s) and maintaining height of perigee above 500 km (arc-jet deltaV = 11 m/s)
• New orbit with ArgP = 350.6° and i = 64.1° after 526 days
• Total deltaV bi-prop = 1101 m/s
• Total deltaV arc-jet = 375 m/s
• Grand Total deltaV = 1476 m/s

Scenario 3C

Scenario 3C shows the two effects, which were already obvious in scenario 3B, even more pronounced. Corrective action is shown at the end of the powered phases, where the height of perigee is increased to 1000 km, in order to compensate for the later decrease.

day	orbit	RAaN	ArgP	sma	ecc	inc	HeightPer	HeightApo	VPer	VApo	deltaV	mass
#	#	deg	deg	km		deg	km	km	m/s	m/s	m/s	kg
000.5	001	078.40	178.00	24611	0.7175	07.76	0575	35890	09922	1632	000	600.0
055.5	116	060.28	214.41	27086	0.7416	08.00	0621	40794	09959	1478	074	589.6
091.4	186	049.64	235.75	27086	0.7402	08.07	0658	40756	09929	1482	000	589.6
091.4	186	049.64	235.75	44408	0.8416	08.07	0658	75402	10214	0879	285	536.2
165.8	255	043.65	251.06	44408	0.8423	08.38	0626	75435	10239	0877	000	536.2
173.3	262	043.19	252.46	44452	0.8414	08.41	0671	75477	10205	0879	005	535.6
280.1	350	038.50	269.83	51239	0.8595	08.68	0823	88899	10145	0767	058	528.4
281.5	351	312.30	350.48	51239	0.8596	65.80	0816	88906	10151	0766	829	400.8
496.4	580	298.15	349.48	32217	0.7850	64.85	0549	51129	10135	1221	226	380.1
523.2	620	295.61	349.26	32482	0.7716	64.91	1040	51167	09756	1258	041	376.5
526.6	625	295.31	349.26	32220	0.7701	64.95	1028	50655	09760	1268	005	376.1

Figures 3C.1A and 3C.1B show the whole period of powered flight. Figures 3C.2A and 3C.2B show the final drift phase.

Summary -- Scenario 3C

• Start date December 15, 1997
• GTO RAAN = 78.4°
• Increasing orbital period to 32 hours (arc-jet: deltaV = 132 m/s, bi-prop: deltaV = 285 m/s) and maintaining height of perigee above 500 km (arc-jet deltaV = 5 m/s)
• At ArgP = 270° rotation around major axis by 64.5° (bi-prop, deltaV = 829 m/s)
• Reducing orbital period to 16 hours (arc-jet, deltaV = 231 m/s) and increasing height of perigee above 1000 km (arc-jet deltaV = 41 m/s)
• New orbit with ArgP = 349.3° and i = 65.0° after 527 days
• Total deltaV bi-prop = 1114 m/s
• Total deltaV arc-jet = 409 m/s
• Grand Total deltaV = 1523 m/s

Scenario 3R

Scenario 3R is a modification of 3A, by increasing the major inclination change by just 2°, to the effect, that we can expect a reentry after 21.5 years.

day	orbit	RAaN	ArgP	sma	ecc	inc	HeightPer	HeightApo	VPer	VApo	deltaV	mass
#	#	deg	deg	km		deg	km	km	m/s	m/s	m/s	kg
000.5	001	018.40	178.00	24611	0.7175	07.76	0575	35890	09922	1632	000	600.0
062.7	130	358.10	218.78	27425	0.7445	07.90	0630	41464	09961	1459	084	588.4
099.3	200	347.66	239.96	27425	0.7434	07.94	0659	41434	09937	1463	000	588.4
099.3	200	347.66	239.96	45353	0.8448	07.94	0659	77290	10222	0860	285	535.1
172.8	266	340.23	256.34	45353	0.8473	07.98	0546	77404	10313	0852	000	535.1
188.4	280	338.76	259.82	45442	0.8454	07.99	0645	77482	10234	0857	010	533.8
255.8	336	336.90	270.00	50227	0.8607	08.02	0618	87080	10296	0771	041	528.8
257.1	337	250.58	351.20	50227	0.8609	65.78	0610	87088	10303	0770	834	400.5
293.8	367	248.91	351.15	46716	0.8513	64.99	0567	80109	10308	0828	029	397.8
318.3	388	247.68	351.10	46903	0.8445	64.85	0913	80137	10042	0846	020	395.9
488.8	582	235.89	350.54	32184	0.7813	64.94	0661	50950	10043	1233	193	378.4

Figures 3R.1A and 3R.1B show the whole period of powered flight. Figures 3R.2A and 3R.2B show the final drift phase.

Summary -- Scenario 3R

• Start date October 15, 1997
• GTO RAAN = 18.4°
• Increasing orbital period to near 32 hours (arc-jet: deltaV = 125 m/s, bi-prop: deltaV = 285 m/s) and maintaining height of perigee above 500 km (arc-jet deltaV = 10 m/s)
• At ArgP = 270° rotation around major axis by 65.5° (bi-prop, deltaV = 834 m/s)
• Reducing orbital period to 16 hours (arc-jet, deltaV = 222 m/s) and increasing height of perigee above 600 km (arc-jet deltaV = 20 m/s) for final drift phase
• New orbit with ArgP = 350.5° and i = 64.9° after 489 days
• Total deltaV bi-prop = 1119 m/s
• Total deltaV arc-jet = 376 m/s
• Grand Total deltaV = 1495 m/s

Summary Part IV

Maintaining the perigee height above 500 km has to be an integral part of the other operations, since a significant time span is required for the arc-jet operations - assuming one hour per orbit operations. On the other hand, the expense for the inclination changes increases with the height of perigee. A proper compromise has to be found.

With some more fine-tuning one can expect, that the bi-propellant deltaV requirement will be about 1100 m/s (without any contingencies). This would allow a start mass of slightly more than 600 kg. The elapsed time for the whole phase of orbital changes is in the order of 1.5 years. Three axis stabilized operation might be envisaged after the major inclination change, that is, 9 to 10 months after start. Since arc-jet operations are continuing, the power budget for transponder usage will be restricted.

The presented figures are still optimistic, since the lower efficiency of the arc-jet due to the geometry at perigee and apogee is not yet taken into account. A preliminary estimate for a one hour period at perigee of an 11 hour orbit (eccentricity = .8) yields an efficiency better than .9 . The situation at apogee is much better and we could probably plan for a two or three hour operation, when we are in three-axis stabilized mode with fully expanded panels. This will depend on the total power budget and the battery capacities.